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Sample records for active region formation

  1. Ab Initio Active Region Formation

    NASA Astrophysics Data System (ADS)

    Stein, Robert F.; Nordlund, A.

    2013-01-01

    The tachocline is not necessary to produce active regions with their global properties. Dynamo action within the convection zone can produce large scale reversing polarity magnetic fields as shown by ASH code and Charboneau et al simulations. Magneto-convection acting on this large scale field produces Omega-loops which emerge through the surface to produce active regions. The field first emerges as small bipoles with horizontal field over granules anchored in vertical fields in the intergranular lanes. The fields are quickly swept into the intergranular lanes and produce a mixed polarity "pepper and salt" pattern. The opposite polarities then migrate toward separate unipolar regions due to the underlying large scale loop structure. When sufficient flux concentrates, pores and sunspots form. We will show movies of magneto-convection simulations of the emerging flux, its migration, and concentration to form pores and spots, as well as the underlying magnetic field evolution. In addition, the same atmospheric data has been used as input to the LILIA Stokes Inversion code to calculate Stokes spectra for the Fe I 630 nm lines and then invert them to determine the magnetic field. Comparisons of the inverted field with the simulation field shows that small-scale, weak fields, less than 100 G, can not be accurately determined because of vertical gradients that are difficult to match in fitting the line profiles. Horizontal smoothing by telescope diffraction further degrades the inversion accuracy.

  2. ON THE FORMATION OF ACTIVE REGIONS

    SciTech Connect

    Stein, Robert F.; Nordlund, Ake E-mail: aake@nbi.dk

    2012-07-01

    Magnetoconvection can produce an active region without an initial coherent flux tube. A simulation was performed where a uniform, untwisted, horizontal magnetic field of 1 kG strength was advected into the bottom of a computational domain 48 Mm wide by 20 Mm deep. The up and down convective motions produce a hierarchy of magnetic loops with a wide range of scales, with smaller loops riding 'piggy-back' in a serpentine fashion on larger loops. When a large loop approaches the surface, it produces a small active region with a compact leading spot and more diffuse following spots.

  3. FORMATION OF CORONAL HOLES ON THE ASHES OF ACTIVE REGIONS

    SciTech Connect

    Karachik, Nina V.; Pevtsov, Alexei A.; Abramenko, Valentyna I. E-mail: apevtsov@nso.ed

    2010-05-10

    We investigate the formation of isolated non-polar coronal holes (CHs) on the remnants of decaying active regions (ARs) at the minimum/early ascending phase of sunspot activity. We follow the evolution of four bipolar ARs and measure several parameters of their magnetic fields including total flux, imbalance, and compactness. As regions decay, their leading and following polarities exhibit different dissipation rates: loose polarity tends to dissipate faster than compact polarity. As a consequence, we see a gradual increase in flux imbalance inside a dissipating bipolar region, and later a formation of a CH in place of more compact magnetic flux. Out of four cases studied in detail, two CHs had formed at the following polarity of the decaying bipolar AR, and two CHs had developed in place of the leading polarity field. All four CHs contain a significant fraction of magnetic field of their corresponding AR. Using potential field extrapolation, we show that the magnetic field lines of these CHs were closed on the polar CH at the North, which at the time of the events was in imbalance with the polar CH at the South. This topology suggests that the observed phenomenon may play an important role in transformation of toroidal magnetic field to poloidal field, which is a key step in transitioning from an old solar cycle to a new one. The timing of this observed transition may indicate the end of solar cycle 23 and the beginning of cycle 24.

  4. SIMULATION OF THE FORMATION OF A SOLAR ACTIVE REGION

    SciTech Connect

    Cheung, M. C. M.; Title, A. M.; Rempel, M.; Schuessler, M.

    2010-09-01

    We present a radiative magnetohydrodynamics simulation of the formation of an active region (AR) on the solar surface. The simulation models the rise of a buoyant magnetic flux bundle from a depth of 7.5 Mm in the convection zone up into the solar photosphere. The rise of the magnetic plasma in the convection zone is accompanied by predominantly horizontal expansion. Such an expansion leads to a scaling relation between the plasma density and the magnetic field strength such that B {proportional_to} rhov{sup 1/2}. The emergence of magnetic flux into the photosphere appears as a complex magnetic pattern, which results from the interaction of the rising magnetic field with the turbulent convective flows. Small-scale magnetic elements at the surface first appear, followed by their gradual coalescence into larger magnetic concentrations, which eventually results in the formation of a pair of opposite polarity spots. Although the mean flow pattern in the vicinity of the developing spots is directed radially outward, correlations between the magnetic field and velocity field fluctuations allow the spots to accumulate flux. Such correlations result from the Lorentz-force-driven, counterstreaming motion of opposite polarity fragments. The formation of the simulated AR is accompanied by transient light bridges between umbrae and umbral dots. Together with recent sunspot modeling, this work highlights the common magnetoconvective origin of umbral dots, light bridges, and penumbral filaments.

  5. Simulation of the Formation of a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Cheung, M. C. M.; Rempel, M.; Title, A. M.; Schüssler, M.

    2010-09-01

    We present a radiative magnetohydrodynamics simulation of the formation of an active region (AR) on the solar surface. The simulation models the rise of a buoyant magnetic flux bundle from a depth of 7.5 Mm in the convection zone up into the solar photosphere. The rise of the magnetic plasma in the convection zone is accompanied by predominantly horizontal expansion. Such an expansion leads to a scaling relation between the plasma density and the magnetic field strength such that B vprop rhov1/2. The emergence of magnetic flux into the photosphere appears as a complex magnetic pattern, which results from the interaction of the rising magnetic field with the turbulent convective flows. Small-scale magnetic elements at the surface first appear, followed by their gradual coalescence into larger magnetic concentrations, which eventually results in the formation of a pair of opposite polarity spots. Although the mean flow pattern in the vicinity of the developing spots is directed radially outward, correlations between the magnetic field and velocity field fluctuations allow the spots to accumulate flux. Such correlations result from the Lorentz-force-driven, counterstreaming motion of opposite polarity fragments. The formation of the simulated AR is accompanied by transient light bridges between umbrae and umbral dots. Together with recent sunspot modeling, this work highlights the common magnetoconvective origin of umbral dots, light bridges, and penumbral filaments.

  6. THE FORMATION AND MAGNETIC STRUCTURES OF ACTIVE-REGION FILAMENTS OBSERVED BY NVST, SDO, AND HINODE

    SciTech Connect

    Yan, X. L.; Xue, Z. K.; Wang, J. C.; Xiang, Y. Y.; Kong, D. F.; Yang, L. H.; Pan, G. M.

    2015-08-15

    To better understand the properties of solar active-region filaments, we present a detailed study on the formation and magnetic structures of two active-region filaments in active region NOAA 11884 during a period of four days. It is found that the shearing motion of the opposite magnetic polarities and the rotation of the small sunspots with negative polarity play an important role in the formation of two active-region filaments. During the formation of these two active-region filaments, one foot of the filaments was rooted in a small sunspot with negative polarity. The small sunspot rotated not only around another small sunspot with negative polarity, but also around the center of its umbra. By analyzing the nonlinear force-free field extrapolation using the vector magnetic fields in the photosphere, twisted structures were found in the two active-region filaments prior to their eruptions. These results imply that the magnetic fields were dragged by the shearing motion between opposite magnetic polarities and became more horizontal. The sunspot rotation twisted the horizontal magnetic fields and finally formed the twisted active-region filaments.

  7. Using Magnetic Helicity Diagnostics to Determine the Nature of Solar Active-Region Formation

    NASA Astrophysics Data System (ADS)

    Georgoulis, Manolis K.

    Employing a novel nonlinear force-free (NLFF) method that self-consistently infers instantaneous free magnetic-energy and relative magnetic-helicity budgets from single photospheric vector magnetograms, we recently constructed the magnetic energy-helicity (EH) diagram of solar active regions. The EH diagram implies dominant relative helicities of left-handed or right-handed chiralities for the great majority of active regions. The amplitude (budget) of these helicities scales monotonically with the free magnetic energy. This constructive, strongly preferential accumulation of a certain sense of magnetic helicity seems to disqualify recently proposed mechanisms relying on a largely random near-surface convection for the formation of the great majority of active regions. The existing qualitative formation mechanism for these regions remains the conventional Omega-loop emergence following a buoyant ascension from the bottom of the convection zone. However, exceptions to this rule include even eruptive active regions: NOAA AR 11283 is an obvious outlier to the EH diagram, involving significant free magnetic energy with a small relative magnetic helicity. Relying on a timeseries of vector magnetograms of this region, our methodology shows nearly canceling amounts of both senses of helicity and an overall course from a weakly left-handed to a weakly right-handed structure, in the course of which a major eruption occurs. For this and similarly behaving active regions the latest near-surface formation scenario might conceivably be employed successfully. Research partially supported by the EU Seventh Framework Programme under grant agreement No. PIRG07-GA-2010-268245 and by the European Union Social Fund (ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Thales. Investing in knowledge society through the European Social Fund.

  8. Mechanism of formation of a dipole magnetic field in the central regions of active galaxies

    NASA Astrophysics Data System (ADS)

    Andreasyan, R. R.

    1996-01-01

    A model of the formation of large-scale magnetic fields of dipole configuration in the central regions (r ≈ 100 pc) of active galaxies is studied. It is assumed that these regions contain a rapidly rotating, highly ionized gas (Ω ≈ 5·10-15 sec, Ne ≈ 103 cm-3). Ionized matter escapes from the center of the region with a velocity of several hundred km/sec and is entrained by the rotation of the surrounding medium. Biermann's "battery" effect [L. Biermann, Z. Naturforsch., 5a, 65 (1950)] operates under such conditions, and circular electric currents are formed in the medium, which amplify the dipole magnetic fields. During the active phase of a galaxy, about 108 years, the magnetic field strength at the boundary of this region may reach 10-4 10-3 G.

  9. ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

    SciTech Connect

    McIntosh, Scott W.; Leamon, Robert J.

    2014-11-20

    Recent work has revealed a phenomenological picture of the how the ∼11 yr sunspot cycle of the Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal magnetic flux systems that belong to the 22 yr magnetic activity cycle and are rooted deep in the Sun's convective interior. We present a conceptually simple extension of this work, presenting a hypothesis on how complex active regions can form as a direct consequence of the intra- and extra-hemispheric interaction taking place in the solar interior. Furthermore, during specific portions of the sunspot cycle, we anticipate that those complex active regions may be particularly susceptible to profoundly catastrophic breakdown, producing flares and coronal mass ejections of the most severe magnitude.

  10. Magnetically elevated accretion disks in active galactic nuclei: broad emission line regions and associated star formation

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Silk, Joseph

    2016-10-01

    We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal (φ -direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at R to large heights z ˜ 0.1 R and low densities, while leaving a thin dense layer containing most of the mass - but contributing very little accretion - around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: the formation of broad emission line regions and the suppression of fragmentation thought to inhibit accretion at the required rates. We show that the disk of stars that formed in the Galactic Center a few million years ago could have resulted from an episode of magnetically elevated accretion at ˜0.1 of the Eddington limit.

  11. On the formation of dipolar magnetic fields in the central regions of active galaxies

    NASA Astrophysics Data System (ADS)

    Andreasyan, R. R.

    A model of the formation of large-scale magnetic fields of dipolar configuration in the central regions of active galaxies is studied. It is assumed that these regions contain a rapidly rotating partly ionized gas. Ionized matter escapes with a high velocity from the center of this region and is entrained by the rotation of the surrounding medium. Biermann's "battery" effect (L.Biermann, Z. Naturforsch., 5a, 65, 1950) operates under such conditions, and circular electric curents are generated in the medium, which amplify the dipolar magnetic fields. Dipolar magnetic fields of opposite orientation with respect to the angular momentum of the central engine can be amplified where there is accretion of gaseous matter onto the rotating central part of a galaxy. The direction of the "Halo" magnetic field of our Galaxy is in accordance with the first model.

  12. A model for the formation of the active region corona driven by magnetic flux emergence

    NASA Astrophysics Data System (ADS)

    Chen, F.; Peter, H.; Bingert, S.; Cheung, M. C. M.

    2014-04-01

    Aims: We present the first model that couples the formation of the corona of a solar active region to a model of the emergence of a sunspot pair. This allows us to study when, where, and why active region loops form, and how they evolve. Methods: We use a 3D radiation magnetohydrodynamics (MHD) simulation of the emergence of an active region through the upper convection zone and the photosphere as a lower boundary for a 3D MHD coronal model. The coronal model accounts for the braiding of the magnetic fieldlines, which induces currents in the corona to heat up the plasma. We synthesize the coronal emission for a direct comparison to observations. Starting with a basically field-free atmosphere we follow the filling of the corona with magnetic field and plasma. Results: Numerous individually identifiable hot coronal loops form, and reach temperatures well above 1 MK with densities comparable to observations. The footpoints of these loops are found where small patches of magnetic flux concentrations move into the sunspots. The loop formation is triggered by an increase in upward-directed Poynting flux at their footpoints in the photosphere. In the synthesized extreme ultraviolet (EUV) emission these loops develop within a few minutes. The first EUV loop appears as a thin tube, then rises and expands significantly in the horizontal direction. Later, the spatially inhomogeneous heat input leads to a fragmented system of multiple loops or strands in a growing envelope. Animation associated with Fig. 2 is available in electronic form at http://www.aanda.org

  13. High Resolution Simulations of Tearing and Flux-Rope Formation in Active Region Jets

    NASA Astrophysics Data System (ADS)

    Wyper, P. F.; DeVore, C. R.; Karpen, J. T.

    2015-12-01

    Observations of coronal jets increasingly suggest that local fragmentation and the generation of small-scale structure plays an important role in the dynamics of these events. In the magnetically closed corona, jets most often occur near active regions and are associated with an embedded-bipole topology consisting of a 3D magnetic null point atop a domed fan separatrix surface at the base of a coronal loop. Impulsive reconnection in the vicinity of the null point between the magnetic fluxes inside and outside the dome launches the jet along the loop. Wyper & Pontin 2014 showed that the 3D current layers that facilitate such reconnection are explosively unstable to tearing, generating complex flux-rope structures. Utilizing the adaptive mesh capabilities of the Adaptively Refined Magnetohydrodynamics Solver, we investigate the generation of such fine-scale structure in high-resolution simulations of active-region jets. We observe the formation of multiple flux-rope structures forming across the fan separatrix surface and discuss the photospheric signatures of these flux ropes and the associated local topology change. We also introduce a new way of identifying such flux ropes in the magnetic field, based on structures observed in the magnetic squashing factor calculated on the photosphere. By tracking the position and number of new null points produced by the fragmentation, we also show that the formation of flux ropes can occur away from the main null region on the flanks of the separatrix dome and that the jet curtain has a highly complex magnetic structure. This work was funded through an appointment to the NASA Postdoctoral Program and by NASA's Living With a Star TR&T program.

  14. RADIO OBSERVATIONS OF THE STAR FORMATION ACTIVITIES IN THE NGC 2024 FIR 4 REGION

    SciTech Connect

    Choi, Minho; Kang, Miju; Lee, Jeong-Eun

    2015-07-15

    Star formation activities in the NGC 2024 FIR 4 region were studied by imaging centimeter continuum sources and water maser sources using several archival data sets from the Very Large Array. The continuum source VLA 9 is elongated in the northwest–southeast direction, consistent with the FIR 4 bipolar outflow axis, and has a flat spectrum in the 6.2–3.6 cm interval. The three water maser spots associated with FIR 4 are also distributed along the outflow axis. One of the spots is located close to VLA 9, and another one is close to an X-ray source. Examinations of the positions of compact objects in this region suggest that the FIR 4 cloud core contains a single low-mass protostar. VLA 9 is the best indicator of the protostellar position. VLA 9 may be a radio thermal jet driven by this protostar, and it is unlikely that FIR 4 contains a high-mass young stellar object (YSO). A methanol 6.7 GHz maser source is located close to VLA 9, at a distance of about 100 AU. The FIR 4 protostar must be responsible for the methanol maser action, which suggests that methanol class II masers are not necessarily excited by high-mass YSOs. Also discussed are properties of other centimeter continuum sources in the field of view and the water masers associated with FIR 6n. Some of the continuum sources are radio thermal jets, and some are magnetically active young stars.

  15. The Evolution of the Electric Current during the Formation and Eruption of Active-region Filaments

    NASA Astrophysics Data System (ADS)

    Wang, Jincheng; Yan, Xiaoli; Qu, Zhongquan; Xue, Zhike; Xiang, Yongyuan; Li, Hao

    2016-02-01

    We present a comprehensive study of the electric current related to the formation and eruption of active region filaments in NOAA AR 11884. The vertical current on the solar surface was investigated by using vector magnetograms (VMs) observed by HMI on board the Solar Dynamics Observatory. To obtain the electric current along the filament's axis, we reconstructed the magnetic fields above the photosphere by using nonlinear force-free field extrapolation based on photospheric VMs. Spatio-temporal evolutions of the vertical current on the photospheric surface and the horizontal current along the filament's axis were studied during the long-term evolution and eruption-related period, respectively. The results show that the vertical currents of the entire active region behaved with a decreasing trend and the magnetic fields also kept decreasing during the long-term evolution. For the eruption-related evolution, the mean transverse field strengths decreased before two eruptions and increased sharply after two eruptions in the vicinity of the polarity inversion lines underneath the filament. The related vertical current showed different behaviors in two of the eruptions. On the other hand, a very interesting feature was found: opposite horizontal currents with respect to the current of the filament's axis appeared and increased under the filament before the eruptions and disappeared after the eruptions. We suggest that these opposite currents were carried by the new flux emerging from the photosphere bottom and might be the trigger mechanism for these filament eruptions.

  16. δ-SUNSPOT FORMATION IN SIMULATION OF ACTIVE-REGION-SCALE FLUX EMERGENCE

    SciTech Connect

    Fang, Fang; Fan, Yuhong

    2015-06-10

    δ-sunspots, with highly complex magnetic structures, are very productive in energetic eruptive events, such as X-class flares and homologous eruptions. We here study the formation of such complex magnetic structures by numerical simulations of magnetic flux emergence from the convection zone into the corona in an active-region-scale domain. In our simulation, two pairs of bipolar sunspots form on the surface, originating from two buoyant segments of a single subsurface twisted flux rope, following the approach of Toriumi et al. Expansion and rotation of the emerging fields in the two bipoles drive the two opposite polarities into each other with apparent rotating motion, producing a compact δ-sunspot with a sharp polarity inversion line. The formation of the δ-sunspot in such a realistic-scale domain produces emerging patterns similar to those formed in observations, e.g., the inverted polarity against Hale's law, the curvilinear motion of the spot, and strong transverse field with highly sheared magnetic and velocity fields at the polarity inversion line (PIL). Strong current builds up at the PIL, giving rise to reconnection, which produces a complex coronal magnetic connectivity with non-potential fields in the δ-spot overlaid by more relaxed fields connecting the two polarities at the two ends.

  17. Formation of a Double-decker Magnetic Flux Rope in the Sigmoidal Solar Active Region 11520

    NASA Astrophysics Data System (ADS)

    Cheng, X.; Ding, M. D.; Zhang, J.; Sun, X. D.; Guo, Y.; Wang, Y. M.; Kliem, B.; Deng, Y. Y.

    2014-07-01

    In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s-1. The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.

  18. Formation of a double-decker magnetic flux rope in the sigmoidal solar active region 11520

    SciTech Connect

    Cheng, X.; Ding, M. D.; Zhang, J.; Guo, Y.; Sun, X. D.; Wang, Y. M.; Kliem, B.; Deng, Y. Y.

    2014-07-10

    In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s{sup –1}. The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.

  19. Numerical simulations of active region scale flux emergence: From spot formation to decay

    SciTech Connect

    Rempel, M.; Cheung, M. C. M.

    2014-04-20

    We present numerical simulations of active region scale flux emergence covering a time span of up to 6 days. Flux emergence is driven by a bottom boundary condition that advects a semi-torus of magnetic field with 1.7 × 10{sup 22} Mx flux into the computational domain. The simulations show that, even in the absence of twist, the magnetic flux is able the rise through the upper 15.5 Mm of the convection zone and emerge into the photosphere to form spots. We find that spot formation is sensitive to the persistence of upflows at the bottom boundary footpoints, i.e., a continuing upflow would prevent spot formation. In addition, the presence of a torus-aligned flow (such flow into the retrograde direction is expected from angular momentum conservation during the rise of flux ropes through the convection zone) leads to a significant asymmetry between the pair of spots, with the spot corresponding to the leading spot on the Sun being more axisymmetric and coherent, but also forming with a delay relative to the following spot. The spot formation phase transitions directly into a decay phase. Subsurface flows fragment the magnetic field and lead to intrusions of almost field free plasma underneath the photosphere. When such intrusions reach photospheric layers, the spot fragments. The timescale for spot decay is comparable to the longest convective timescales present in the simulation domain. We find that the dispersal of flux from a simulated spot in the first two days of the decay phase is consistent with self-similar decay by turbulent diffusion.

  20. Numerical Simulations of Active Region Scale Flux Emergence: From Spot Formation to Decay

    NASA Astrophysics Data System (ADS)

    Rempel, M.; Cheung, M. C. M.

    2014-04-01

    We present numerical simulations of active region scale flux emergence covering a time span of up to 6 days. Flux emergence is driven by a bottom boundary condition that advects a semi-torus of magnetic field with 1.7 × 1022 Mx flux into the computational domain. The simulations show that, even in the absence of twist, the magnetic flux is able the rise through the upper 15.5 Mm of the convection zone and emerge into the photosphere to form spots. We find that spot formation is sensitive to the persistence of upflows at the bottom boundary footpoints, i.e., a continuing upflow would prevent spot formation. In addition, the presence of a torus-aligned flow (such flow into the retrograde direction is expected from angular momentum conservation during the rise of flux ropes through the convection zone) leads to a significant asymmetry between the pair of spots, with the spot corresponding to the leading spot on the Sun being more axisymmetric and coherent, but also forming with a delay relative to the following spot. The spot formation phase transitions directly into a decay phase. Subsurface flows fragment the magnetic field and lead to intrusions of almost field free plasma underneath the photosphere. When such intrusions reach photospheric layers, the spot fragments. The timescale for spot decay is comparable to the longest convective timescales present in the simulation domain. We find that the dispersal of flux from a simulated spot in the first two days of the decay phase is consistent with self-similar decay by turbulent diffusion.

  1. Formation and Eruption of an Active Region Sigmoid: NLFFF Modeling and MHD Simulation

    NASA Astrophysics Data System (ADS)

    Jiang, C.; Wu, S.; Feng, X.; Hu, Q.

    2013-12-01

    We present a magnetic analysis of the formation and eruption of an active region sigmoid in AR 11283 from 2011 September 4 to 6, which is jointly based on observations, static nonlinear force-free field (NLFFF) extrapolation and dynamic MHD simulation. A time sequence of NLFFF model's outputs are used to reproduce the evolution of the magnetic field of the region over three days leading to a X-class flare near the end of 2011 September 6. In the first day, a new bipolar emerges into the negative polarity of a pre-existing mature bipolar, forming a magnetic topology with a coronal null on the magnetic separatrix surface between the two flux system, while the field is still near potential at the end of the day. After then photospheric shearing and twisting build up non-potentiality in the embedded core region, with a flux rope (FR) formed there above the polarity inversion line by tether-cutting reconnection between the strongly sheared field lines. Within this duration, the core field has gained a magnetic free energy of ˜ 1032 erg. In this core a sigmoid is observed distinctly at 22:00 UT on September 6, closely before its eruption at 22:12 UT. Comparison of the SDO/AIA observations with coronal magnetic field suggests that the sigmoid is formed by emission due to enhanced current sheet along the BPSS (bald-patch separatrix surface, in which the field lines graze the line-tied photosphere at the neutral line) that separates the FR from the ambient flux. Quantitative inspection of the pre-eruption field on 22:00 UT suggests a mechanism for the eruption: tether cutting at the null triggers a torus instability of the FR--overlying field system. This pre-eruption NLFFF is then input into a time-dependent MHD model to simulate the fast magnetic evolution during eruption, which successfully reproduces the observations. The highly asymmetric magnetic environment along with the lateral location of the null leads to a strongly inclined non-radial direction of the eruption

  2. Star Formation Activity in the Galactic H II Region Sh2-297

    NASA Astrophysics Data System (ADS)

    Mallick, K. K.; Ojha, D. K.; Samal, M. R.; Pandey, A. K.; Bhatt, B. C.; Ghosh, S. K.; Dewangan, L. K.; Tamura, M.

    2012-11-01

    We present a multiwavelength study of the Galactic H II region Sh2-297, located in the Canis Major OB1 complex. Optical spectroscopic observations are used to constrain the spectral type of ionizing star HD 53623 as B0V. The classical nature of this H II region is affirmed by the low values of electron density and emission measure, which are calculated to be 756 cm-3 and 9.15 × 105 cm-6 pc using the radio continuum observations at 610 and 1280 MHz, and Very Large Array archival data at 1420 MHz. To understand local star formation, we identified the young stellar object (YSO) candidates in a region of area ~7farcm5 × 7farcm5 centered on Sh2-297 using grism slitless spectroscopy (to identify the Hα emission line stars), and near infrared (NIR) observations. NIR YSO candidates are further classified into various evolutionary stages using color-color and color-magnitude (CM) diagrams, giving 50 red sources (H - K > 0.6) and 26 Class II-like sources. The mass and age range of the YSOs are estimated to be ~0.1-2 M ⊙ and 0.5-2 Myr using optical (V/V-I) and NIR (J/J-H) CM diagrams. The mean age of the YSOs is found to be ~1 Myr, which is of the order of dynamical age of 1.07 Myr of the H II region. Using the estimated range of visual extinction (1.1-25 mag) from literature and NIR data for the region, spectral energy distribution models have been implemented for selected YSOs which show masses and ages to be consistent with estimated values. The spatial distribution of YSOs shows an evolutionary sequence, suggesting triggered star formation in the region. The star formation seems to have propagated from the ionizing star toward the cold dark cloud LDN1657A located west of Sh2-297.

  3. EMERGENCE OF HELICAL FLUX AND THE FORMATION OF AN ACTIVE REGION FILAMENT CHANNEL

    SciTech Connect

    Lites, B. W.; Kubo, M.; Berger, T.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.; Okamoto, T. J.; Otsuji, K.

    2010-07-20

    We present comprehensive observations of the formation and evolution of a filament channel within NOAA Active Region (AR) 10978 from Hinode/Solar Optical Telescope and TRACE. We employ sequences of Hinode spectro-polarimeter maps of the AR, accompanying Hinode Narrowband Filter Instrument magnetograms in the Na I D1 line, Hinode Broadband Filter Instrument filtergrams in the Ca II H line and G-band, Hinode X-ray telescope X-ray images, and TRACE Fe IX 171 A image sequences. The development of the channel resembles qualitatively that presented by Okamoto et al. in that many indicators point to the emergence of a pre-existing sub-surface magnetic flux rope. The consolidation of the filament channel into a coherent structure takes place rapidly during the course of a few hours, and the filament form then gradually shrinks in width over the following two days. Particular to this filament channel is the observation of a segment along its length of horizontal, weak (500 G) flux that, unlike the rest of the filament channel, is not immediately flanked by strong vertical plage fields of opposite polarity on each side of the filament. Because this isolated horizontal field is observed in photospheric lines, we infer that it is unlikely that the channel formed as a result of reconnection in the corona, but the low values of inferred magnetic fill fraction along the entire length of the filament channel suggest that the bulk of the field resides somewhat above the low photosphere. Correlation tracking of granulation in the G band presents no evidence for either systematic flows toward the channel or systematic shear flows along it. The absence of these flows, along with other indications of these data from multiple sources, reinforces (but does not conclusively demonstrate) the picture of an emerging flux rope as the origin of this AR filament channel.

  4. Light Bridge in a Developing Active Region. II. Numerical Simulation of Flux Emergence and Light Bridge Formation

    NASA Astrophysics Data System (ADS)

    Toriumi, Shin; Cheung, Mark C. M.; Katsukawa, Yukio

    2015-10-01

    Light bridges, the bright structure dividing umbrae in sunspot regions, show various activity events. In Paper I, we reported on an analysis of multi-wavelength observations of a light bridge in a developing active region (AR) and concluded that the activity events are caused by magnetic reconnection driven by magnetconvective evolution. The aim of this second paper is to investigate the detailed magnetic and velocity structures and the formation mechanism of light bridges. For this purpose, we analyze numerical simulation data from a radiative magnetohydrodynamics model of an emerging AR. We find that a weakly magnetized plasma upflow in the near-surface layers of the convection zone is entrained between the emerging magnetic bundles that appear as pores at the solar surface. This convective upflow continuously transports horizontal fields to the surface layer and creates a light bridge structure. Due to the magnetic shear between the horizontal fields of the bridge and the vertical fields of the ambient pores, an elongated cusp-shaped current layer is formed above the bridge, which may be favorable for magnetic reconnection. The striking correspondence between the observational results of Paper I and the numerical results of this paper provides a consistent physical picture of light bridges. The dynamic activity phenomena occur as a natural result of the bridge formation and its convective nature, which has much in common with those of umbral dots and penumbral filaments.

  5. Formation and Eruption of an Active Region Sigmoid. I. A Study by Nonlinear Force-free Field Modeling

    NASA Astrophysics Data System (ADS)

    Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  6. Formation and eruption of an active region sigmoid. I. A study by nonlinear force-free field modeling

    SciTech Connect

    Jiang, Chaowei; Feng, Xueshang; Wu, S. T.; Hu, Qiang E-mail: fengx@spaceweather.ac.cn E-mail: qh0001@uah.edu

    2014-01-01

    We present a comprehensive study of the formation and eruption of an active region (AR) sigmoid in AR 11283. To follow the quasi-static evolution of the coronal magnetic field, we reconstruct a time sequence of static fields using a recently developed nonlinear force-free field model constrained by vector magnetograms. A detailed analysis of the fields compared with observations suggests the following scenario for the evolution of the region. Initially, a new bipole emerges into the negative polarity of a preexisting bipolar AR, forming a null-point topology between the two flux systems. A weakly twisted flux rope (FR) is then built up slowly in the embedded core region, largely through flux cancellation, forming a bald patch separatrix surface (BPSS). The FR grows gradually until its axis runs into a torus instability (TI) domain, and the BPSS also develops a full S-shape. The combined effects of the TI-driven expansion of the FR and the line tying at the BP tear the FR into two parts with the upper portion freely expelled and the lower portion remaining behind the postflare arcades. This process dynamically perturbs the BPSS and results in the enhanced heating of the sigmoid and the rope. The accelerated expansion of the upper-portion rope strongly pushes its envelope flux near the null point and triggers breakout reconnection at the null, which further drives the eruption. We discuss the important implications of these results for the formation and disruption of the sigmoid region with an FR.

  7. Formation of sunspots and active regions through the emergence of magnetic flux generated in a solar convective dynamo

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Rempel, Matthias D.; Fan, Yuhong

    2016-05-01

    We present a realistic numerical model of sunspot and active region formation through the emergence of flux tubes generated in a solar convective dynamo. The magnetic and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation are used as a time-dependent bottom boundary to drive the near surface layer radiation MHD simulations of magneto-convection and flux emergence with the MURaM code. The latter code simulates the emergence of the flux tubes through the upper most layer of the convection zone to the photosphere.The emerging flux tubes interact with the convection and break into small scale magnetic elements that further rise to the photosphere. At the photosphere, several bipolar pairs of sunspots are formed through the coalescence of the small scale magnetic elements. The sunspot pairs in the simulation successfully reproduce the fundamental observed properties of solar active regions, including the more coherent leading spots with a stronger field strength, and the correct tilts of the bipolar pairs. These asymmetries come most probably from the intrinsic asymmetries in the emerging fields imposed at the bottom boundary, where the horizontal fields are already tilted and the leading sides of the emerging flux tubes are usually up against the downdraft lanes of the giant cells. It is also found that penumbrae with numerous filamentary structures form in regions of strong horizontal magnetic fields that naturally comes from the ongoing flux emergence. In contrast to previous models, the penumbrae and umbrae are divided by very sharp boarders, which is highly consistent with observations.

  8. HISTORY AND MODES OF STAR FORMATION IN THE MOST ACTIVE REGION OF THE SMALL MAGELLANIC CLOUD, NGC 346

    SciTech Connect

    Cignoni, M.; Tosi, M.; Sabbi, E.; Nota, A.; Gallagher, J. S.

    2011-02-15

    We discuss the star formation history of the Small Magellanic Cloud (SMC) region NGC 346 based on Hubble Space Telescope images. The region contains both field stars and cluster members. Using a classical synthetic color-magnitude diagram (CMD) procedure applied to the field around NGC 346 we find that the star formation pace there has been rising, from a quite low rate 13 Gyr ago to {approx}1.4 x 10{sup -8} M{sub sun} yr{sup -1} pc{sup -2} in the last 100 Myr. This value is significantly higher than that in other star-forming regions of the SMC. For NGC 346 itself, we compare theoretical and observed CMDs of several stellar sub-clusters identified in the region, and we derive their basic evolution parameters. We find that NGC 346 experienced different star formation regimes, including a dominant and focused 'high-density mode', with the sub-clusters hosting both pre-main-sequence (PMS) and upper main-sequence (UMS) stars, and a diffuse 'low-density mode', as indicated by the presence of low-mass PMS sub-clusters. Quantitatively, the star formation in the oldest sub-clusters started about 6 Myr ago with remarkable synchronization, it continued at a high rate (up to 2 x 10{sup -5} M{sub sun} yr{sup -1} pc{sup -2}) for about 3 Myr and is now progressing at a lower rate. Interestingly, sub-clusters mainly composed of low-mass PMS stars now seem to experience the first episode of star formation, following multi-seeded spatial patterns, instead of resulting from a coherent trigger. Two speculative scenarios are put forth to explain the deficiency of UMS stars: the first invokes underthreshold conditions of the parent gas and the second speculates that the initial mass function is a function of time, with the youngest sub-clusters not having had sufficient time to form more massive stars.

  9. Star Formation Regions in LDN 1667

    NASA Astrophysics Data System (ADS)

    Gyulbudaghian, A. L.

    2015-09-01

    A group of three star formation regions in the dark cloud LDN 1667 is examined. All three of these regions contain Trapezium type systems. 12C(1-0) observations are made of the part of the molecular cloud LDN 1667 associated with one of the star formation regions. Three molecular clouds were detected, one of which (the main cloud) has a red and a blue outflow. Three stars from the star formation regions are found to have annular nebulae and one star has a conical nebula. The dark cloud LDN 1667 is associated with a radial system of dark globules which is formed by the star HD 57061.

  10. Active region seismology

    NASA Technical Reports Server (NTRS)

    Bogdan, Tom; Braun, D. C.

    1995-01-01

    Active region seismology is concerned with the determination and interpretation of the interaction of the solar acoustic oscillations with near-surface target structures, such as magnetic flux concentration, sunspots, and plage. Recent observations made with a high spatial resolution and a long temporal duration enabled measurements of the scattering matrix for sunspots and solar active regions to be carried out as a function of the mode properties. Based on this information, the amount of p-mode absorption, partial-wave phase shift, and mode mixing introduced by the sunspot, could be determined. In addition, the possibility of detecting the presence of completely submerged magnetic fields was raised, and new procedures for performing acoustic holography of the solar interior are being developed. The accumulating evidence points to the mode conversion of p-modes to various magneto-atmospheric waves within the magnetic flux concentration as being the unifying physical mechanism responsible for these diverse phenomena.

  11. OSL chronology of onshore cyclone deposits at Point Lefroy (Exmouth Gulf, Western Australia) - Implications for washover fan formation and regional cyclone activity

    NASA Astrophysics Data System (ADS)

    Brill, Dominik; May, Simon Matthias; Shah-Hosseini, Majid; Leopold, Matthias; Callow, Nik; Engel, Max; Scheffers, Anja; Brückner, Helmut

    2016-04-01

    Although frequently occurring, little is known about the geological imprint of (pre)historical tropical cyclones (TCs) in Northwestern Australia. Large washover fans at Point Lefroy (Exmouth Gulf) provide unambiguous morphological evidence of flooding by TCs capable to overtop and breach the local coastal barrier. Based on ground penetrating radar, unmanned aerial vehicle survey techniques, as well as geomorphological, sedimentological and chronological investigations, this research aims at reconstructing the formation of the washover fans, and understanding their significance for recording past TC activity. The stratigraphy of the washover fans is characterized by multiple depositional units, which are separated by palaeosurfaces with initial pedogenesis. Combining the chronostratigraphical record of the different washover fans at Point Lefroy is assumed to reflect the regional TC magnitude-frequency pattern, reaching far beyond historical records. While reworking of calcareous faunal remains biases the application of radiocarbon dating, we carried out optically stimulated luminescence (OSL) dating in order to establish a robust chronology of TC-induced washover deposition. OSL dating was challenged by spatially heterogeneous dose rates within the poorly sorted mixture of quartz and coral fragments, by incomplete signal resetting, and by sediment mixing during and, most likely, after transportation. However, by successfully constraining the contribution of each of these factors - using a combination of single-grain quartz dating, quasi-continuous luminescence profiling, spatially resolved dose rate determination, and dose rate modelling - the final chronology gives insight into the evolution of the geo-archive and, ultimately, into the local to regional TC history. Based on up to three sediment profiles from each fan structure, two different washover fans were OSL dated. While contemporaneous deposition at both landforms suggest that the two geomorphological

  12. EUV SPECTRAL LINE FORMATION AND THE TEMPERATURE STRUCTURE OF ACTIVE REGION FAN LOOPS: OBSERVATIONS WITH HINODE/EIS AND SDO/AIA

    SciTech Connect

    Brooks, David H.; Young, Peter R.; Warren, Harry P.

    2011-04-01

    With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines look very similar despite the fact that ionization equilibrium calculations suggest that they have significantly different formation temperatures: log(T{sub e} /K) = 5.6 and 5.8, respectively. It is important to resolve these issues because confidence has been undermined in their use for differential emission measure (DEM) analysis, and Fe VIII is the main contributor to the AIA 131 A channel at low temperatures. Furthermore, the strong Fe VIII 185.213 A and Si VII 275.368 A lines are the best EIS lines to use for velocity studies in the transition region, and for assigning the correct temperature to velocity measurements in the fans. We find that the Fe VIII 185.213 A line is particularly sensitive to the slope of the DEM, leading to disproportionate changes in its effective formation temperature. If the DEM has a steep gradient in the log(T{sub e} /K) = 5.6-5.8 temperature range, or is strongly peaked, Fe VIII 185.213 A and Si VII 275.368 A will be formed at the same temperature. We show that this effect explains the similarity of these images in the fans. Furthermore, we show that the most recent ionization balance compilations resolve the discrepancies in absolute intensities. With these difficulties overcome, we combine EIS and AIA data to determine the temperature structure of a number of fan loops and find that they have peak temperatures of 0.8-1.2 MK. The EIS data indicate that the temperature distribution has a finite (but narrow) width < log ({sigma}{sub Te}/K) = 5.5 which, in one detailed case, is found to broaden substantially toward the loop base. AIA and EIS yield similar results on the temperature, emission

  13. Solar active region display system

    NASA Astrophysics Data System (ADS)

    Golightly, M.; Raben, V.; Weyland, M.

    2003-04-01

    The Solar Active Region Display System (SARDS) is a client-server application that automatically collects a wide range of solar data and displays it in a format easy for users to assimilate and interpret. Users can rapidly identify active regions of interest or concern from color-coded indicators that visually summarize each region's size, magnetic configuration, recent growth history, and recent flare and CME production. The active region information can be overlaid onto solar maps, multiple solar images, and solar difference images in orthographic, Mercator or cylindrical equidistant projections. Near real-time graphs display the GOES soft and hard x-ray flux, flare events, and daily F10.7 value as a function of time; color-coded indicators show current trends in soft x-ray flux, flare temperature, daily F10.7 flux, and x-ray flare occurrence. Through a separate window up to 4 real-time or static graphs can simultaneously display values of KP, AP, daily F10.7 flux, GOES soft and hard x-ray flux, GOES >10 and >100 MeV proton flux, and Thule neutron monitor count rate. Climatologic displays use color-valued cells to show F10.7 and AP values as a function of Carrington/Bartel's rotation sequences - this format allows users to detect recurrent patterns in solar and geomagnetic activity as well as variations in activity levels over multiple solar cycles. Users can customize many of the display and graph features; all displays can be printed or copied to the system's clipboard for "pasting" into other applications. The system obtains and stores space weather data and images from sources such as the NOAA Space Environment Center, NOAA National Geophysical Data Center, the joint ESA/NASA SOHO spacecraft, and the Kitt Peak National Solar Observatory, and can be extended to include other data series and image sources. Data and images retrieved from the system's database are converted to XML and transported from a central server using HTTP and SOAP protocols, allowing

  14. Active region flows

    NASA Technical Reports Server (NTRS)

    Foukal, Peter

    1987-01-01

    A wide range of observations has shown that active region phenomena in the photospheric, chromospheric and coronal temperature regimes are dynamical in nature. At the photosphere, recent observations of full line profiles place an upper limit of about + or - 20/msec on any downflows at supergranule cell edges. Observations of the full Stokes 5 profiles in the network show no evidence for downflows in magnetic flux tubes. In the area of chromospheric dynamics, several models were put forward recently to reproduce the observed behavior of spicules. However, it is pointed out that these adiabatic models do not include the powerful radiative dissipation which tend to damp out the large amplitude disturbances that produce the spicular acceleration in the models. In the corona, loop flows along field lines clearly transport mass and energy at rates important for the dynamics of these structures. However, advances in understanding the heating and mass balance of the loop structures seem to require new kinds of observations. Some results are presented using a remote sensing diagnostic of the intensity and orientation of macroscopic plasma electric fields predicted by models of reconnective heating and also wave heating.

  15. Regional Activities Division. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures affecting…

  16. The Star-Formation Region SNO 87

    NASA Astrophysics Data System (ADS)

    Gyulbudaghian, A. L.

    2014-06-01

    The star-formation region SNO 87 is associated with the dark cloud LDN 212. 12CO(1-0) observations of a part of the molecular cloud associated with SNO 87 show that it lies somewhat to the north of the densest part of the molecular cloud. There is a bipolar molecular outflow from SNO 87, both branches of which are blue, i.e., the velocity is directed toward us with a velocity of ~3.5 km/s relative to the cloud. 12CO(1-0) observations of a part of the cloud lying to the E of SNO 87 show that this part of the cloud rotates with an angular velocity Ω = 2.44·10-14 s-1. SNO 87 contains several stars that are coupled with nebular filaments, bursts, and Herbig-Haro objects. It is also associated with the point source IRAS 18064-2413.

  17. The Hinge Region of Bovine Zona Pellucida Glycoprotein ZP3 Is Involved in the Formation of the Sperm-Binding Active ZP3/ZP4 Complex.

    PubMed

    Suzuki, Kaori; Tatebe, Nanami; Kojima, Sayuri; Hamano, Ayumi; Orita, Misaki; Yonezawa, Naoto

    2015-11-23

    The zona pellucida (ZP) surrounds the mammalian oocyte and mediates species-selective sperm-oocyte interactions. Bovine ZP consists of glycoproteins ZP2, ZP3, and ZP4. Neither ZP3 nor ZP4 alone shows inhibitory activity for the binding of sperm to the ZP; however, this activity is seen with the ZP3/ZP4 heterocomplex. Here, we constructed a series of bovine ZP3 mutants to identify the ZP4-binding site on ZP3. Each ZP3 mutant was co-expressed with ZP4 using a baculovirus-Sf9 cell expression system and examined for interaction with ZP4 as well as inhibitory activity for sperm-ZP binding. N-terminal fragment Arg-32 to Arg-160 of ZP3 interacted with ZP4 and inhibited sperm-ZP binding, whereas fragment Arg-32 to Thr-155 showed much weaker interaction with ZP4. Mutation of N-glycosylated Asn-146 to Asp in the N-terminal fragment Arg-32 to Glu-178 of ZP3 did not interrupt the interaction of this fragment with ZP4, but it did reduce the inhibitory activity of the complex for sperm-ZP binding. In contrast, mutation of N-glycosylated Asn-124 to Asp did not significantly reduce the activity. Taken together, these results suggest that one of the ZP4 binding sites exists in the flexible hinge region of ZP3 and that the N-glycosylation in this region is involved in the sperm binding.

  18. Star Formation in the Central Regions of Galaxies

    NASA Astrophysics Data System (ADS)

    Tsai, Mengchun

    2015-08-01

    The galactic central region connects the galactic nucleus to the host galaxy. If the central black hole co-evolved with the host galaxies, there should be some evidence left in the central region. We use the environmental properties in the central regions such as star-forming activity, stellar population and molecular abundance to figure out a possible scenario of the evolution of galaxies. In this thesis at first we investigated the properties of the central regions in the host galaxies of active and normal galaxies. We used radio emission around the nuclei of the host galaxies to represent activity of active galactic nuclei (AGNs), and used infrared ray (IR) emission to represent the star-forming activity and stellar population of the host galaxies. We determined that active galaxies have higher stellar masses (SMs) within the central kiloparsec radius than normal galaxies do independent of the Hubble types of the host galaxies; but both active and normal galaxies exhibit similar specific star formation rates (SSFRs). We also discovered that certain AGNs exhibit substantial inner stellar structures in the IR images; most of the AGNs with inner structures are Seyferts, whereas only a few LINERs exhibit inner structures. We note that the AGNs with inner structures show a positive correlation between the radio activity of the AGNs and the SFRs of the host galaxies, but the sources without inner structures show a negative correlation between the radio power and the SFRs. These results might be explained with a scenario of starburst-AGN evolution. In this scenario, AGN activities are triggered following a nuclear starburst; during the evolution, AGN activities are accompanied by SF activity in the inner regions of the host galaxies; at the final stage of the evolution, the AGNs might transform into LINERs, exhibiting weak SF activity in the central regions of the host galaxies. For further investigation about the inner structure, we choose the most nearby and luminous

  19. Active Region Release Two CMEs

    NASA Video Gallery

    Solar material can be seen blowing off the sun in this video captured by NASA’s Solar Dynamics Observatory (SDO) on the night of Feb. 5, 2013. This active region on the sun sent out two coronal ...

  20. Climatically controlled formation of river terraces in a tectonically active region along the southern piedmont of the Tian Shan, NW China

    NASA Astrophysics Data System (ADS)

    Huang, Wei-liang; Yang, Xiao-ping; Li, An; Thompson, Jessica A.; Zhang, Ling

    2014-09-01

    Combined tectonic uplift and Quaternary climate variability control the deposition and abandonment of terraces along the southern Tian Shan in northwest China. Several preserved terraces have been deformed by an actively growing anticline within the uplifted frontal thrust system of the southern Tian Shan. We combine geomorphic mapping, topographic surveys of the deformed terrace surfaces, 10Be terrestrial cosmogenic nuclide (TCN) depth profile dating, and optically stimulated luminescence (OSL) dating to develop a new chronology for the terraces along the Huangshui He since 550 ka. Our in situ 10Be dating of fluvial gravels capping strath terraces suggests a relationship between the formation and abandonment of the terraces and glacial climate cycles since the middle-late Pleistocene. These data indicate that the formation of the four terraces occurred at ~ 550, ~ 430, ~ 350, and ~ 60 ka. We suggest that episodes of aggradation were facilitated by high sediment supply during glacial periods, followed by subsequent incision that led to abandonment of these terraces during deglaciation. We also estimate that tectonically induced river incision may account for about 60-70% of the total incision. However, during the intervening time between 350 ka and present, only one terrace was formed and preserved. We suggest that this record might be caused by a gradually decreasing uplift rate of the anticline through time and thus has influenced the preservation of terraces. Therefore, our results demonstrate the utility of chronologic records from southern Tian Shan for deconvolving the effects of tectonics and climate on fluvial incision.

  1. M20: Star Formation in a Young HII Region

    NASA Astrophysics Data System (ADS)

    Rho, J.; Lefloch, B.; Reach, W. T.; Cernicharo, J.

    2008-12-01

    The Trifid Nebula (M20) has a remarkable optical appearance with a large, reddish nebula of gas ionized by an O7 star (HD 164492) and trisected by obscuring dust lanes, with a blue reflection nebula in the north. During the last two decades, M20 has generated considerable interest because of multi-wavelength identifications of sites of low- and high-mass star formation. M20 is a young HII region showing active, dynamic ``pre-Orion" star formation, containing massive, young stars undergoing collapse and violent mass ejection, as well as a dense population of protostars and more developed pre-main sequence stars. Different stages of star formation have been detected at various wavelengths, as well as optical jets, mid- and far-infrared protostars, near-infrared young stellar objects, Hα emission stars, X-ray sources, and OH masers. M20 is relatively close, at a distance of 1.67 kpc with a low line-of-sight extinction (A_v=1.3 mag), and it is compact, with a small diameter of only 3.5 pc. M20 is an isolated HII region with a single O star, which provides an ideal place to investigate the onset of star birth and triggered star formation. We review the highlights of studies of star forming activities in the Trifid Nebula.

  2. SDO Sees Active Region Outbursts

    NASA Video Gallery

    This close up video by NASA’s Solar Dynamics Observatory shows an active region near the right-hand edge of the sun’s disk, which erupted with at least a dozen minor events over a 30-hour period fr...

  3. Post-ischaemic mild hypothermia inhibits apoptosis in the penumbral region by reducing neuronal nitric oxide synthase activity and thereby preventing endothelin-1-induced hydroxyl radical formation.

    PubMed

    Van Hemelrijck, An; Hachimi-Idrissi, Said; Sarre, Sophie; Ebinger, Guy; Michotte, Yvette

    2005-09-01

    Previously, we showed that treatment with resuscitative, post-ischaemic mild hypothermia (34 degrees C for 2 h) reduced apoptosis in the penumbra (cortex), but not in the core (striatum) of an endothelin-1 (Et-1)-induced focal cerebral infarct in the anaesthetized rat. Therefore, the purpose of this study was to investigate by which pathways resuscitative mild hypothermia exerts its neuroprotective effect in this model. The amino acids glutamate, serine, glutamine, alanine, taurine, arginine and the NO-related compound citrulline were sampled from the striatum and cortex of the ischaemic hemisphere using in vivo microdialysis. The in vivo salicylate trapping method was applied for monitoring hydroxyl radical formation via 2,3 dihydroxybenzoic acid (2,3 DHBA) detection. Caspase-3, neuronal nitric oxide synthase (nNOS) immunoreactivity and the volume of ischaemic damage were determined 24 h after the insult. In both the striatum and the cortex, Et-1-induced increases in glutamate, taurine and alanine were refractory to mild hypothermia. However, mild hypothermia significantly attenuated the ischaemia-induced 2,3 DHBA levels and the nNOS immunoreactivity in the cortex, but not in the striatum. These observations were associated with a decreased caspase-3 immunoreactivity. These results suggest that mild hypothermia exerts its neuroprotective effect in the penumbra partially by reducing nNOS activity and thereby preventing oxidative stress. Furthermore, we confirm our previous findings that the neuroprotective effect of resuscitative hypothermia is not mediated by changes in ischaemia-induced amino acid release as they could not be associated with the ischaemia-induced damage in the Et-1 rat model.

  4. What makes active regions grow.

    NASA Technical Reports Server (NTRS)

    Weart, S.

    1972-01-01

    A study of magnetic flux growth or growth failure in over 100 active regions is shown to indicate that most growth is connected with the emergence of a large batch of flux in the shape of a new arch filament system (AFS). During the recent sunspot maximum, new AFSs appeared at a rate of nearly one per day over the entire sun. Evidence is presented for two proposed hypotheses, namely: (1) a twist in the flux tubes of new AFSs is a key factor in determining which new AFSs will grow; and (2) this twist is related to the well-known asymmetry of sunspot groups.

  5. Cometary nucleus and active regions

    NASA Technical Reports Server (NTRS)

    Whipple, F. L.

    1984-01-01

    On the basis of the icy conglomerate model of cometary nuclei, various observations demonstrate the spotted nature of many or most nuclei, i.e., regions of unusual activity, either high or low. Rotation periods, spin axes and even precession of the axes are determined. The observational evidence for variations in activity over the surfaces of cometary nuclei are listed and discussed. On June 11 the comet IRAS-ARAKI-ALCOCK approached the Earth to a distance of 0.031 AU, the nearest since C/Lexell, 1770 I, providing a unique opportunity for near-nucleus observations. Preliminary analysis of these images establishes the spin axis of the nucleus, with an oblioquity to the orbit plane of approximately 50 deg, and a lag angle of sublimation approximately 35 deg from the solar meridian on the nucleus. Asymmetries of the inner coma suggests a crazy-quilt distribution of ices with differing volatility over the surface of the nucleus. The observations of Comet P/Homes 1892 III, exhibiting two 8-10 magnitude bursts, are carefully analyzed. The grazing encounter produced, besides the first great burst, an active area on the nucleus, which was rotating retrograde with a period of 16.3hr and inclination nearly 180 deg. After the first burst the total magnitude fell less than two magnitudes from November 7 to November 30 (barely naked eye) while the nuclear region remained diffuse or complex, rarely if ever showing a stellar appearance. The fading was much more rapid after the second burst. The grazing encounter distributed a volume of large chunks in the neighborhood of the nucleus, maintaining activity for weeks.

  6. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Hasan, Hashima (Technical Monitor)

    2003-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our emphasis has been on star formation in external, bright IR galaxies, but other areas of research have included young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry, because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spectroscopic data sets. The program has the following goals: 1) Refine the data analysis of IS0 observations to obtain deeper and better SNR results on selected sources. The IS0 data itself underwent pipeline 10 reductions in early 2001, and the more 'hands-on data reduction packages' have been released. The IS0 Fabry-Perot database is particularly sensitive to noise and can have slight calibration errors, and improvements are anticipated. We plan to build on these deep analysis tools and contribute to their development. Model the atomic and molecular line shapes, in particular the OH lines, using revised montecarlo techniques developed by the Submillimeter Wave Astronomy Satellite (SWAS) team at the Center for Astrophysics. 2) 3) Use newly acquired space-based SIRTF or SOFIA spectroscopic data as they become available, and contribute to these observing programs as appropriate. 4) Attend scientific meetings and workshops. 5) E&PO activities, especially as related to infrared astrophysics and

  7. Star formation regions in galaxies: Star complexes and spiral arms

    NASA Astrophysics Data System (ADS)

    Efremov, Iurii N.

    This book describes observational data on star formation regions (from young star clusters to spiral arms) in the Milky Way and other galaxies. It is concluded that not only high-luminosity stars but also star clusters and associations are forming together in vast complexes. It is claimed that these complexes are the primary, fundamental entities of star formation.

  8. Evolution of active region outflows throughout an active region lifetime

    NASA Astrophysics Data System (ADS)

    Zangrilli, L.; Poletto, G.

    2016-10-01

    Context. We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind. Aims: Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, from the time the AR first forms until it dissolves, after several transits at the solar limb. Methods: Data acquired by SOHO/UVCS at the time of the AR limb transits, at medium latitudes and at altitudes ranging from 1.5 to 2.3 R⊙, were used to infer the physical properties of the outflows through the AR evolution. To this end, we applied the Doppler dimming technique to UVCS spectra. These spectra include the H i Lyα line and the O vi doublet lines at 1031.9 and 1037.6 Å. Results: Plasma speeds and electron densities of the outflows were inferred over several rotations of the Sun. AR outflows are present in the newly born AR and persist throughout the entire AR life. Moreover, we found two types of outflows at different latitudes, both possibly originating in the same negative polarity area of the AR. We also analyzed the behavior of the Si xii 520 Å line along the UVCS slit in an attempt to reveal changes in the Si abundance when different regions are traversed. Although we found some evidence for a Si enrichment in the AR outflows, alternative interpretations are also plausible. Conclusions: Our results demonstrate that outflows from ARs are detectable in the intermediate corona throughout the whole AR lifetime. This confirms that outflows contribute to the slow wind.

  9. The Object CLN 138 - a Double Star-Formation Region

    NASA Astrophysics Data System (ADS)

    Gyulbudaghian, A. L.

    2016-09-01

    A double star formation region associated with the biconical cometary nebula CLN 138 is studied. 12CO(1-0) observations of a molecular cloud associated with this object reveal the existence of several molecular clouds in this region, as well as the existence of red and blue molecular outflows. Several new Herbig-Haro objects are found, two of which have undergone a luminosity increase of at least 8m. The first star formation region is basically embedded in the molecular cloud; most of the stars in it are infrared stars and many have dust envelopes. The second star formation region has already left the molecular cloud; it has no IR stars and few of its stars have dust clouds.

  10. Axial Tilt Angles of Active Regions

    NASA Astrophysics Data System (ADS)

    Howard, Robert F.

    1996-12-01

    Separate Mount Wilson plage and sunspot group data sets are analyzed in this review to illustrate several interesting aspects of active region axial tilt angles. (1) The distribution of tilt angles differs between plages and sunspot groups in the sense that plages have slightly higher tilt angles, on average, than do spot groups. (2) The distributions of average plage total magnetic flux, or sunspot group area, with tilt angle show a consistent effect: those groups with tilt angles nearest the average values are larger (or have a greater total flux) on average than those farther from the average values. Moreover, the average tilt angles on which these size or flux distributions are centered differ for the two types of objects, and represent closely the actual different average tilt angles for these two features. (3) The polarity separation distances of plages and sunspot groups show a clear relationship to average tilt angles. In the case of each feature, smaller polarity separations are correlated with smaller tilt angles. (4) The dynamics of regions also show a clear relationship with region tilt angles. The spot groups with tilt angles nearest the average value (or perhaps 0-deg tilt angle) have on average a faster rotation rate than those groups with extreme tilt angles. All of these tilt-angle characteristics may be assumed to be related to the physical forces that affect the magnetic flux loop that forms the region. These aspects are discussed in this brief review within the context of our current view of the formation of active region magnetic flux at the solar surface.

  11. Emission measure distribution for diffuse regions in solar active regions

    SciTech Connect

    Subramanian, Srividya; Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2014-11-01

    Our knowledge of the diffuse emission that encompasses active regions is very limited. In this paper we investigate two off-limb active regions, namely, AR 10939 and AR 10961, to probe the underlying heating mechanisms. For this purpose, we have used spectral observations from Hinode/EIS and employed the emission measure (EM) technique to obtain the thermal structure of these diffuse regions. Our results show that the characteristic EM distributions of the diffuse emission regions peak at log T = 6.25 and the coolward slopes are in the range 1.4-3.3. This suggests that both low- as well as high-frequency nanoflare heating events are at work. Our results provide additional constraints on the properties of these diffuse emission regions and their contribution to the background/foreground when active region cores are observed on-disk.

  12. CME Productivity of Active Regions.

    NASA Astrophysics Data System (ADS)

    Liu, L.; Wang, Y.; Wang, J.; Shen, C.; Ye, P.; Zhang, Q.; Liu, R.; Wang, S.

    2015-12-01

    Solar active regions (ARs) are the major sources of two kinds of the most violent solar eruptions, namely flares and coronal mass ejections (CMEs). Although they are believed to be two phenomena in the same eruptive process, the productivity of them could be quiet different for various ARs. Why is an AR productive? And why is a flare-rich AR CME-poor? To answer these questions, we compared the recent super flare-rich but CME-poor AR 12192, with other four ARs; two were productive in both flares and CMEs and the other two were inert to produce any M-class or intenser flares or CMEs. By investigating the photospheric parameters based on the SDO/HMI vector magnetogram, we find the three productive ARs have larger magnetic flux, current and free magnetic energy than the inert ARs. Furthermore, the two ARs productive in both flares and CMEs contain higher current helicity, concentrating along both sides of the flaring neutral lines, indicating the presence of a seed magnetic structure( that is highly sheared or twisted) of a CME; they also have higher decay index in the low corona, showing weak constraint. The results suggest that productive ARs are always large and have strong current system and sufficient free energy to power flares, and more importantly whether or not a flare is accompanied by a CME is seemingly related to (1) if there is significant sheared or twisted core field serving as the seed of the CME and (2) if the constraint of the overlying arcades is weak enough. Moreover, some productive ARs may frequently produce more than one CME. How does this happen? We do a statistical investigation of waiting times of quasi-homologous CMEs ( CME ssuccessive originating from the same ARs within short intervals) from super ARs in solar cycle 23 to answer this question. The waiting times of quasi-homologous CMEs have a two-component distribution with a separation at about 18 hours, the first component peaks at 7 hours. The correlation analysis among CME waiting times

  13. Regional Book in Magazine Format: Project for Journalism Schools.

    ERIC Educational Resources Information Center

    Berthelot, Dolly

    "Pioneer Spirit 76," an original bicentennial anthology from the Smoky Mountains region, was begun to gain in-depth editing and publishing experience and to test the feasibility of having journalism students produce a publication for a market beyond campus. This report traces the development of this book in magazine format, offers a basic plan for…

  14. Activation of PAD4 in NET formation.

    PubMed

    Rohrbach, Amanda S; Slade, Daniel J; Thompson, Paul R; Mowen, Kerri A

    2012-01-01

    Peptidylarginine deiminases, or PADs, convert arginine residues to the non-ribosomally encoded amino acid citrulline in a variety of protein substrates. PAD4 is expressed in granulocytes and is essential for the formation of neutrophil extracellular traps (NETs) via PAD4-mediated histone citrullination. Citrullination of histones is thought to promote NET formation by inducing chromatin decondensation and facilitating the expulsion of chromosomal DNA that is coated with antimicrobial molecules. Numerous stimuli have been reported to lead to PAD4 activation and NET formation. However, how this signaling process proceeds and how PAD4 becomes activated in cells is largely unknown. Herein, we describe the various stimuli and signaling pathways that have been implicated in PAD4 activation and NET formation, including the role of reactive oxygen species generation. To provide a foundation for the above discussion, we first describe PAD4 structure and function, and how these studies led to the development of PAD-specific inhibitors. A comprehensive survey of the receptors and signaling pathways that regulate PAD4 activation will be important for our understanding of innate immunity, and the identification of signaling intermediates in PAD4 activation may also lead to the generation of pharmaceuticals to target NET-related pathogenesis. PMID:23264775

  15. Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies

    NASA Astrophysics Data System (ADS)

    Kong, X.; Lin, L.; Li, J. R.; Zhou, X.; Zou, H.; Li, H. Y.; Chen, F. Z.; Du, W.; Fan, Z.; Mao, Y. W.; Wang, J.; Zhu, Y. N.; Zhou, Z. M.

    2014-01-01

    During the late 1990s and the first decade of the 21st century, the 8˜10 m scale ground-based telescopes are helping astronomers learn much more about how galaxies develop. The existing 2˜4 m scale telescopes become less important for astrophysical researches. To use the existing 2˜4 m scale telescopes to address important issues in cosmology and extragalactic and galactic astronomy, we have to consider very carefully which kind of things we can do, and which we can not. For this reason, the Time Allocation Committee (TAC) of the National Astronomical Observatories of China (NAOC) 2.16 m telescope decides to support some key projects since 2013. Nearby galaxies supply us with the opportunity to study galaxy dynamics and star formation on large scales, yet are close enough to reveal the details. Star formation regions in nearby galaxies provide an excellent laboratory to study the star formation processes, the evolution of massive stars, and the properties of the surrounding interstellar medium. A wealth of information can be obtained from the spectral analysis of the bright emission lines and the stellar continuum. Considering these, we proposed a long-term project ``Spectroscopic Observations of the Star Formation Regions in Nearby Galaxies'', and it becomes the key project of the NAOC 2.16 m telescope since 2013, supported with 30 dark/grey nights per year. The primary goal of this project is to observe the spectroscopy of star formation regions in 20 nearby galaxies, with the NAOC 2.16 m telescope and the Hectospec/MMT (Multiple Mirror Telescope) multifiber spectrograph by Telescope Access Program (TAP). With the spectra of a large sample of star formation regions, combining multi-wavelength data from UV to IR, we can investigate, understand, and quantify the nature of the deviation from the starbursts' IRX-β (the IR/UV ratio ``IRX'' versus the UV color ``β'') correlation. It will be important for a better understanding of the interaction of dust and

  16. The Main Sequence of Explosive Solar Active Regions: Comparison of Emerging and Mature Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron

    2011-01-01

    For mature active regions, an active region s magnetic flux content determines the maximum free energy the active region can have. Most Large flares and CMEs occur in active regions that are near their free-energy limit. Active-region flare power radiated in the GOES 1-8 band increases steeply as the free-energy limit is approached. We infer that the free-energy limit is set by the rate of release of an active region s free magnetic energy by flares, CMEs and coronal heating balancing the maximum rate the Sun can put free energy into the active region s magnetic field. This balance of maximum power results in explosive active regions residing in a "mainsequence" in active-region (flux content, free energy content) phase space, which sequence is analogous to the main sequence of hydrogen-burning stars in (mass, luminosity) phase space.

  17. BOREAS Regional DEM in Raster Format and AEAC Projection

    NASA Technical Reports Server (NTRS)

    Knapp, David; Verdin, Kristine; Hall, Forrest G. (Editor)

    2000-01-01

    This data set is based on the GTOPO30 Digital Elevation Model (DEM) produced by the United States Geological Survey EROS Data Center (USGS EDC). The BOReal Ecosystem-Atmosphere Study (BOREAS) region (1,000 km x 1000 km) was extracted from the GTOPO30 data and reprojected by BOREAS staff into the Albers Equal-Area Conic (AEAC) projection. The pixel size of these data is 1 km. The data are stored in binary, image format files.

  18. A Case of Filament - Active Region Interaction

    NASA Astrophysics Data System (ADS)

    Dumitrache, C.; Dumitru, L.

    2010-09-01

    We analyze a huge filament observed between 5 and 19 September 2001. In its evolution it is linked to the active region 9612, observed between 7 and 16 September 2001. The filament has a strange morphology and dynamics: starting as two parallel components (A and B), it becomes a double sigmoid filament when a third component (C ) appears linking the other two. An unusual magnetic topology characterizes this evolution: the active region is located between the parallel components. When the third component becomes observable, it links these ones first below the active region. After a spectacular plasma movement registered in filament (A), this one becomes linked to (B) above the active region. In spite of these dramatically changes of the magnetic topology and filament -- active region switch, no CME is observed. Only a few flares occurring in AR9612 are registered and these ones can be seen in the dynamics of the filament as an expression of large scale magnetic reconnections.

  19. Star formation around active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Keel, William C.

    1987-01-01

    Active galactic nuclei (Seyfert nuclei and their relatives) and intense star formation can both deliver substantial amounts of energy to the vicinity of a galactic nucleus. Many luminous nuclei have energetics dominated by one of these mechanisms, but detailed observations show that some have a mixture. Seeing both phenomena at once raises several interesting questions: (1) Is this a general property of some kinds of nuclei? How many AGNs have surround starbursts, and vice versa? (2) As in 1, how many undiscovered AGNs or starbursts are hidden by a more luminous instance of the other? (3) Does one cause the other, and by what means, or do both reflect common influences such as potential well shape or level of gas flow? (4) Can surrounding star formation tell us anything about the central active nuclei, such as lifetimes, kinetic energy output, or mechanical disturbance of the ISM? These are important points in the understanding of activity and star formation in galactic nuclei. Unfortunately, the observational ways of addressing them are as yet not well formulated. Some preliminary studies are reported, aimed at clarifying the issues involved in study of the relationships between stellar and nonstellar excitement in galactic nuclei.

  20. Infrared Spectroscopy of Star Formation in Galactic and Extragalactic Regions

    NASA Technical Reports Server (NTRS)

    Frogel, Jay (Technical Monitor); Smith, Howard A.

    2004-01-01

    In this program we proposed to perform a series of spectroscopic studies, including data analysis and modeling, of star formation regions using an ensemble of archival space-based data from the Infrared Space Observatory's Long Wavelength Spectrometer and Short Wavelength Spectrometer, and to take advantage of other spectroscopic databases including the first results from SIRTF. Our empha- sis has been on star formation in external, bright IR galaxies, but other areas of research have in- cluded young, low or high mass pre-main sequence stars in star formation regions, and the galactic center. The OH lines in the far infrared were proposed as one key focus of this inquiry because the Principal Investigator (H. Smith) had a full set of OH IR lines from IS0 observations. It was planned that during the proposed 2-1/2 year timeframe of the proposal other data (including perhaps from SIRTF) would become available, and we intended to be responsive to these and other such spec- troscopic data sets. Three papers are included:The Infrared Lines of OH: Diagnostics of Molecular Cloud Conditions in Infrared Bright Galaxies; The Far-Infrared Spectrum of Arp 220; andThe Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068.

  1. Software Displays Data on Active Regions of the Sun

    NASA Technical Reports Server (NTRS)

    Golightly, Mike; Weyland, Mark; Raben, Vern

    2011-01-01

    The Solar Active Region Display System is a computer program that generates, in near real time, a graphical display of parameters indicative of the spatial and temporal variations of activity on the Sun. These parameters include histories and distributions of solar flares, active region growth, coronal mass ejections, size, and magnetic configuration. By presenting solar-activity data in graphical form, this program accelerates, facilitates, and partly automates what had previously been a time-consuming mental process of interpretation of solar-activity data presented in tabular and textual formats. Intended for original use in predicting space weather in order to minimize the exposure of astronauts to ionizing radiation, the program might also be useful on Earth for predicting solar-wind-induced ionospheric effects, electric currents, and potentials that could affect radio-communication systems, navigation systems, pipelines, and long electric-power lines. Raw data for the display are obtained automatically from the Space Environment Center (SEC) of the National Oceanic and Atmospheric Administration (NOAA). Other data must be obtained from the NOAA SEC by verbal communication and entered manually. The Solar Active Region Display System automatically accounts for the latitude dependence of the rate of rotation of the Sun, by use of a mathematical model that is corrected with NOAA SEC active-region position data once every 24 hours. The display includes the date, time, and an image of the Sun in H light overlaid with latitude and longitude coordinate lines, dots that mark locations of active regions identified by NOAA, identifying numbers assigned by NOAA to such regions, and solar-region visual summary (SRVS) indicators associated with some of the active regions. Each SRVS indicator is a small pie chart containing five equal sectors, each of which is color-coded to provide a semiquantitative indication of the degree of hazard posed by one aspect of the activity at

  2. CanSIS Regional Soils Data in Vector Format

    NASA Technical Reports Server (NTRS)

    Monette, Bryan; Knapp, David; Hall, Forrest G. (Editor)

    2000-01-01

    This data set is the original vector data set received from Canada Soil Information System (CanSIS). The data include the provinces of Saskatchewan and Manitoba. Attribute tables provide the various soil data for the polygons; there is one attribute table for Saskatchewan and one for Manitoba. The data are stored in ARC/INFO export format files. Based on agreements made with Agriculture Canada, these data are available only to individuals and groups that have an official relationship with the BOREAS project. These data are not included on the BOReal Ecosystem-Atmosphere Study (BOREAS) CD-ROM set. A raster version of this data set titled 'BOREAS Regional Soils Data in Raster Format and AEAC Projection' is publicly available and is included on the BOREAS CD-ROM set.

  3. Suppression of Active-Region CME Production by the Presence of Other Active Regions

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    From the SOHO mission s data base of MDI full-disk magnetograms spanning solar cycle 23, we have obtained a set of 40,000 magnetograms of 1,300 active regions, tracking each active region across the 30 degree central solar disk. Each active region magnetogram is cropped from the full-disk magnetogram by an automated code. The cadence is 96 minutes. From each active-region magnetogram, we have measured two whole-active-region magnetic quantities: (1) the magnetic size of the active region (the active region s total magnetic flux), and (2) a gauge of the active region s free magnetic energy (part of the free energy is released in the production of a flare and/or CME eruption). From NOAA Flare/CME catalogs, we have obtained the event (Flare/CME/SEP event) production history of each active region. Using all these data, we find that for each type of eruptive event, an active region s expected rate of event production increases as a power law of our gauge of active-region free magnetic energy. We have also found that, among active regions having nearly the same free energy, the rate of the CME production is less when there are many other active regions on the disk than when there are few or none, but there is no significant discernible suppression of the rate of flare production. This indicates that the presence of other active regions somehow tends to inhibit an active region s flare-producing magnetic explosions from becoming CMEs, contrary to the expectation from the breakout model for the production of CMEs.

  4. Pattern formation in Active Polar Fluids

    NASA Astrophysics Data System (ADS)

    Gopinath, Arvind; Hagan, Michael; Baskaran, Aparna

    2011-03-01

    Systems such as bacterial suspensions or cytoskeletal filaments and motility assays can be described within the paradigm of active polar fluids. These systems have been shown to exhibit pattern formation raging from asters and vortices to traveling stripes. A coarse-grained description of such a fluid is given by a scalar density field and a vector polarization field. We study such a macroscopic description of the system using weakly nonlinear analysis and numerical simulations to map out the emergent pattern formation as a function of the hydrodynamic parameters in the context of two specific microscopic models - a quasi-2D suspension of cytoskeletal filaments and motor proteins and a system of self propelled hard rods that interact through excluded volume interactions. The authors thank the Brandeis MRSEC center for financial support.

  5. Circular polarization in star- formation regions: implications for biomolecular homochirality

    PubMed

    Bailey; Chrysostomou; Hough; Gledhill; McCall; Clark; Menard; Tamura

    1998-07-31

    Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed. Circular polarization at shorter wavelengths might have been important in inducing chiral asymmetry in interstellar organic molecules that could be subsequently delivered to the early Earth by comets, interplanetary dust particles, or meteors. This could account for the excess of L-amino acids found in the Murchison meteorite and could explain the origin of the homochirality of biological molecules. PMID:9685254

  6. BOREAS Regional Soils Data in Raster Format and AEAC Projection

    NASA Technical Reports Server (NTRS)

    Monette, Bryan; Knapp, David; Hall, Forrest G. (Editor); Nickeson, Jaime (Editor)

    2000-01-01

    This data set was gridded by BOREAS Information System (BORIS) Staff from a vector data set received from the Canadian Soil Information System (CanSIS). The original data came in two parts that covered Saskatchewan and Manitoba. The data were gridded and merged into one data set of 84 files covering the BOREAS region. The data were gridded into the AEAC projection. Because the mapping of the two provinces was done separately in the original vector data, there may be discontinuities in some of the soil layers because of different interpretations of certain soil properties. The data are stored in binary, image format files.

  7. Active Region Emergence and Remote Flares

    NASA Astrophysics Data System (ADS)

    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.

  8. Hinode Captures Images of Solar Active Region

    NASA Video Gallery

    In these images, Hinode's Solar Optical Telescope (SOT) zoomed in on AR 11263 on August 4, 2011, five days before the active region produced the largest flare of this cycle, an X6.9. We show images...

  9. ISOCAM observations of the RCrA star formation region

    NASA Astrophysics Data System (ADS)

    Olofsson, G.; Huldtgren, M.; Kaas, A. A.; Bontemps, S.; Nordh, L.; Abergel, A.; André, P.; Boulanger, F.; Burgdorf, M.; Casali, M. M.; Cesarsky, C. J.; Davies, J.; Falgarone, E.; Montmerle, T.; Perault, M.; Persi, P.; Prusti, T.; Puget, J. L.; Sibille, F.

    1999-10-01

    The results of an ISOCAM survey of the RCrA star formation region are presented. The survey was carried out in two broad-band filters, LW2 (5-8.5 mu m) and LW3 (12-18 mu m). Although it was not possible to map the densest, central region due to saturation problems, 21 sources were identified which showed mid-IR excesses. Most of these sources have not previously been recognised as YSOs (Young Stellar Objects), mainly because they are relatively faint. We find evidence for a population of very low mass stars which are probably brown dwarfs in their early contraction phases. ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

  10. Differential regional expression of multiple ADAMs during feather bud formation.

    PubMed

    Lin, Juntang; Luo, Jiankai; Redies, Christoph

    2011-09-01

    The expression of seven members of the ADAM family was investigated by in situ hybridization in the developing feather buds of chicken. The expression profiles of the ADAMs in the cells and tissues of the feather buds differ from each other. ADAM9, ADAM10, and ADAM17 are expressed in the epidermis of the feather bud, whereas ADAM23 expression is restricted to the bud crest, with a distribution similar to that of sonic hedgehog. ADAM13 is not only expressed in the epidermis, but also in restricted regions of the dermis. Both ADAM12 and ADAM22 are expressed in the dermis of the feather bud, with an opposite mediolateral and anteroposterior polarity. Furthermore, the mRNAs of all investigated ADAMs show regional differences in their expression, for example, in the neck and in the roots of the leg and wing. These results suggest that ADAMs play a variety of roles during avian feather bud formation.

  11. H II REGIONS: WITNESSES TO MASSIVE STAR FORMATION

    SciTech Connect

    Peters, Thomas; Banerjee, Robi; Klessen, Ralf S.; Low, Mordecai-Mark Mac; Galvan-Madrid, Roberto; Keto, Eric R.

    2010-03-10

    We describe the first three-dimensional simulation of the gravitational collapse of a massive, rotating molecular cloud that includes heating by both non-ionizing and ionizing radiation. These models were performed with the FLASH code, incorporating a hybrid, long characteristic, ray-tracing technique. We find that as the first protostars gain sufficient mass to ionize the accretion flow, their H II regions are initially gravitationally trapped, but soon begin to rapidly fluctuate between trapped and extended states, in agreement with observations. Over time, the same ultracompact H II region can expand anisotropically, contract again, and take on any of the observed morphological classes. In their extended phases, expanding H II regions drive bipolar neutral outflows characteristic of high-mass star formation. The total lifetime of H II regions is given by the global accretion timescale, rather than their short internal sound-crossing time. This explains the observed number statistics. The pressure of the hot, ionized gas does not terminate accretion. Instead, the final stellar mass is set by fragmentation-induced starvation. Local gravitational instabilities in the accretion flow lead to the build-up of a small cluster of stars, all with relatively high masses due to heating from accretion radiation. These companions subsequently compete with the initial high-mass star for the same common gas reservoir and limit its mass growth. This is in contrast to the classical competitive accretion model, where the massive stars are never hindered in growth by the low-mass stars in the cluster. Our findings show that the most significant differences between the formation of low-mass and high-mass stars are all explained as the result of rapid accretion within a dense, gravitationally unstable, ionized flow.

  12. H II Regions: Witnesses to Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Peters, Thomas; Banerjee, Robi; Klessen, Ralf S.; Mac Low, Mordecai-Mark; Galván-Madrid, Roberto; Keto, Eric R.

    2010-03-01

    We describe the first three-dimensional simulation of the gravitational collapse of a massive, rotating molecular cloud that includes heating by both non-ionizing and ionizing radiation. These models were performed with the FLASH code, incorporating a hybrid, long characteristic, ray-tracing technique. We find that as the first protostars gain sufficient mass to ionize the accretion flow, their H II regions are initially gravitationally trapped, but soon begin to rapidly fluctuate between trapped and extended states, in agreement with observations. Over time, the same ultracompact H II region can expand anisotropically, contract again, and take on any of the observed morphological classes. In their extended phases, expanding H II regions drive bipolar neutral outflows characteristic of high-mass star formation. The total lifetime of H II regions is given by the global accretion timescale, rather than their short internal sound-crossing time. This explains the observed number statistics. The pressure of the hot, ionized gas does not terminate accretion. Instead, the final stellar mass is set by fragmentation-induced starvation. Local gravitational instabilities in the accretion flow lead to the build-up of a small cluster of stars, all with relatively high masses due to heating from accretion radiation. These companions subsequently compete with the initial high-mass star for the same common gas reservoir and limit its mass growth. This is in contrast to the classical competitive accretion model, where the massive stars are never hindered in growth by the low-mass stars in the cluster. Our findings show that the most significant differences between the formation of low-mass and high-mass stars are all explained as the result of rapid accretion within a dense, gravitationally unstable, ionized flow.

  13. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Török, T.; Titov, V. S.; Mikić, Z.; Leake, J. E.; Archontis, V.; Linton, M. G.; Dalmasse, K.; Aulanier, G.; Kliem, B.

    2014-02-10

    There has been a long-standing debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After the region has formed and flux emergence has ceased, the strong magnetic fields in the region's center are connected solely by direct currents, and the total direct current is several times larger than the total return current. These results suggest that active regions, the main sources of coronal mass ejections and flares, are born with substantial net currents, in agreement with recent observations. Furthermore, they support eruption models that employ pre-eruption magnetic fields containing such currents.

  14. Regional variations in formation water chemistry: Major and minor elements, Frio Formation fluids, Texas

    SciTech Connect

    Macpherson, G.L. )

    1992-05-01

    Spatial variation of major element content (Na, Ca, and Cl) in formation waters in the Oligocene Frio Formation, Texas, show that mixing occurs vertically and that the chemistry of Ca-rich fluids varies from northern coastal to southern Texas. Relative amounts of major and minor elements (Sr, Mg, and K) in Ca-rich fluids from south Texas differ from those in other areas of Texas and also are different from updip Mesozoic fluids. Such differences seem to preclude the known Mesozoic fluids as a source of Ca in the south Texas Frio Formation fluids, barring complicated, nonuniform water-rock alteration changing the Mesozoic-fluid composition. Approximately coast parallel (and strike parallel) cross sections show that Ca-rich fluids in the Frio are usually found at depth. Some anomalies occur where fluids are present near piercement structures and in a relatively large part of south Texas. In the latter region, Ca-rich fluids exist above the top of geopressure, suggesting that they may have been emplaced before geopressure became widespread (2-3 m.y. ago). Because there are no shallow Ca-rich fluids in the vicinity of major river systems in south Texas, meteoric fluids may have flushed Ca-rich fluids out of the areas near the rivers during past pluvial periods. This process does not preclude the dilution of formation water by clay dehydration reactions, another process that has been proposed to explain deep, dilute formation waters in Gulf basin reservoirs.

  15. Formation of the Bastille Day Merged Interaction Region

    NASA Astrophysics Data System (ADS)

    Whang, Y. C.; Burlaga, L. F.

    2001-12-01

    We present a simulation study for the radial evolution of the large solar wind stream associated with the flare of July 14, 2000 (Bastille day). An interaction region bounded between a forward-reverse shock pair first formed near 1 AU at the leading edge of the large stream; the interaction region continued to interact with the solar wind structures and other shocks identified at the leading edges of nearby streams to form a merged interaction region (MIR). The model treats shocks as surfaces of zero thickness, and the Rankine-Hugoniot relations are used to calculate the jump conditions at all shocks. The simulation shows how merging of shocks, collision of shocks, and formation of new shocks contributed to the evolution process. The solar wind was restructured from a series of large and small streams at 1 AU to a huge MIR outside 5 AU. The magnetic field structure outside 5 AU bore no resemblance to the parent structure at 1 AU; the magnetic field had relatively small variation throughout the interior of the MIR, and the field intensity was a few times stronger than that outside the MIR. This MIR can act as a barrier to the propagation of galactic cosmic rays. Possible Voyager 2 observation of this MIR at 63 AU in January 2001 has been reported by Burlaga et al. [2001] and by Wang et al. [2001].

  16. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-07-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We summarize the published evidence from observation and modeling of the influence of meridional flow variations and decaying active region flux's spatial distribution, such as the Joy's law tilt angle. Using NSO Kitt Peak synoptic magnetograms covering cycles 21-24, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed trailing-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with trailing-polarity flux located poleward of leading-polarity flux. The activity complexes of the cycle 21 and 22 maxima were larger and longer-lived than those of the cycle 23 and 24 maxima, and the poleward surges were stronger and more unipolar and the polar field changes larger and faster. The cycle 21 and 22 polar reversals were dominated by only a few long-lived complexes whereas the cycle 23 and 24 reversals were the cumulative effects of more numerous, shorter-lived regions. We conclude that sizes and lifetimes of activity complexes are key to

  17. An investigation of the role of the H II region environment on star formation

    NASA Astrophysics Data System (ADS)

    Healy, Kevin Robert

    Data from the Very Large Array, Hubble Space Telescope, and Two Micron All Sky Survey are used to investigate low-mass star formation in the vicinity of HII regions. The gas in H II regions is strongly affected by massive stars through their intense ultraviolet radiation and winds. The H II region environment is expected to affect the process of star formation, from triggering the collapse of cloud cores within the molecular cloud to truncating circumstellar disks in the interior of the H II region. Massive stars end their lives as supernovae, injecting freshly synthesized radionuclides and large amounts of radiant and kinetic energy into their surroundings. Most stars in the Galaxy form in such environments and recent measurements of meteorites demonstrate that the Solar System formed in this setting. The first part of this work describes a Very Large Array survey of water masers in portions of six H II regions. Previous observational studies demonstrate the link between star formation and water maser activity. This study uses high-resolution observations of water masers to pinpoint the sites of star formation in crowded or confused regions. The water maser survey identifies several sites of star formation that are very close to the ionization fronts being driven into the surrounding molecular cloud. The locations and numbers of these water masers indicate that the H II region environment may trigger the formation of protostars, but that the passage of the ionization front may play a role in prematurely terminating infall. Later evolutionary stages of star formation are characterized by infrared emission from circumstellar disks. Near-infrared photometry from the Two Micron All Sky Survey is used to show that stars with circumstellar disks in the star-forming region NGC 6357 cluster near ionization fronts, strongly suggesting exposure to the H II region environment rapidly (~10 4 years) evaporates circumstellar gas and dust. Hubble Space Telescope images in the

  18. The 17 GHz active region number

    SciTech Connect

    Selhorst, C. L.; Pacini, A. A.; Costa, J. E. R.; Giménez de Castro, C. G.; Valio, A.; Shibasaki, K.

    2014-08-01

    We report the statistics of the number of active regions (NAR) observed at 17 GHz with the Nobeyama Radioheliograph between 1992, near the maximum of cycle 22, and 2013, which also includes the maximum of cycle 24, and we compare with other activity indexes. We find that NAR minima are shorter than those of the sunspot number (SSN) and radio flux at 10.7 cm (F10.7). This shorter NAR minima could reflect the presence of active regions generated by faint magnetic fields or spotless regions, which were a considerable fraction of the counted active regions. The ratio between the solar radio indexes F10.7/NAR shows a similar reduction during the two minima analyzed, which contrasts with the increase of the ratio of both radio indexes in relation to the SSN during the minimum of cycle 23-24. These results indicate that the radio indexes are more sensitive to weaker magnetic fields than those necessary to form sunspots, of the order of 1500 G. The analysis of the monthly averages of the active region brightness temperatures shows that its long-term variation mimics the solar cycle; however, due to the gyro-resonance emission, a great number of intense spikes are observed in the maximum temperature study. The decrease in the number of these spikes is also evident during the current cycle 24, a consequence of the sunspot magnetic field weakening in the last few years.

  19. IS ACTIVE REGION CORE VARIABILITY AGE DEPENDENT?

    SciTech Connect

    Ugarte-Urra, Ignacio; Warren, Harry P.

    2012-12-10

    The presence of both steady and transient loops in active region cores has been reported from soft X-ray and extreme-ultraviolet observations of the solar corona. The relationship between the different loop populations, however, remains an open question. We present an investigation of the short-term variability of loops in the core of two active regions in the context of their long-term evolution. We take advantage of the nearly full Sun observations of STEREO and Solar Dynamics Observatory spacecraft to track these active regions as they rotate around the Sun multiple times. We then diagnose the variability of the active region cores at several instances of their lifetime using EIS/Hinode spectral capabilities. We inspect a broad range of temperatures, including for the first time spatially and temporally resolved images of Ca XIV and Ca XV lines. We find that the active region cores become fainter and steadier with time. The significant emission measure at high temperatures that is not correlated with a comparable increase at low temperatures suggests that high-frequency heating is viable. The presence, however, during the early stages, of an enhanced emission measure in the ''hot'' (3.0-4.5 MK) and ''cool'' (0.6-0.9 MK) components suggests that low-frequency heating also plays a significant role. Our results explain why there have been recent studies supporting both heating scenarios.

  20. Activation of immobilized plasminogen by tissue activator. Multimolecular complex formation

    SciTech Connect

    Silverstein, R.L.; Nachman, R.L.; Leung, L.L.; Harpel, P.C.

    1985-08-25

    Ternary complex formation of tissue plasminogen activator (TPA) and plasminogen (Plg) with thrombospondin (TSP) or histidine-rich glycoprotein (HRGP) has been demonstrated using an enzyme-linked immunosorbent assay, an affinity bead assay, and a rocket immunoelectrophoresis assay. The formation of these complexes was specific, concentration dependent, saturable, lysine binding site-dependent, and inhibitable by fluid phase plasminogen. Apparent Kd values were approximately 12-36 nM for the interaction of TPA with TSP-Plg complexes and 15-31 nM with HRGP-Plg complexes. At saturation the relative molar stoichiometry of Plg:TPA was 3:1 within the TSP-containing complexes and 1:1 within HRGP-containing complexes. The activation of Plg to plasmin by TPA on TSP- and HRGP-coated surfaces was studied using a synthetic fluorometric plasmin substrate (D-Val-Leu-Lys-7-amino-4-trifluoromethyl coumarin). Kinetic analysis demonstrated a marked increase in the affinity of TPA for plasminogen in the presence of surface-associated TSP or HRGP. Complex formation of locally released tissue plasminogen activator with Plg immobilized on TSP or HRGP surfaces may thus play an important role in effecting proteolytic events in nonfibrin-containing microenvironments.

  1. Organized Subsurface Flows near Active Regions

    NASA Astrophysics Data System (ADS)

    Haber, D. A.; Hindman, B. W.; Toomre, J.; Thompson, M. J.

    2004-04-01

    Local helioseismic techniques, such as ring analysis and time-distance helioseismology, have already shown that large-scale flows near the surface converge towards major active regions. Ring analysis has further demonstrated that at greater depths some active regions exhibit strong outflows. A critique leveled at the ring-analysis results is that the Regularized Least Squares (RLS) inversion kernels on which they are based have negative sidelobes near the surface. Such sidelobes could result in a surface inflow being misidentified as a diverging outflow at depth. In this paper we show that the Optimally Located Averages (OLA) inversion technique, which produces kernels without significant sidelobes, generates flows markedly similar to the RLS results. Active regions are universally zones of convergence near the surface, while large complexes evince strong outflows deeper down.

  2. The Magnetic Free Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

    2001-01-01

    The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

  3. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-04-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. Using NSO Kitt Peak synoptic magnetograms, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  4. Morphology, star formation, and nuclear activity in void galaxies

    NASA Astrophysics Data System (ADS)

    Wiedmann, Sophia; Miller, Brendan; Gallo, Elena; Pazar, Beni; Alfvin, Erik

    2015-01-01

    We report on new Chandra observations of six early-type galaxies located within cosmic voids, from a program examining the influence of Mpc-scale environment upon star formation and low-level supermassive black hole activity. Simple feedback prescriptions are predicted to operate independently of the surrounding density once outside the dark matter halo, and further link star formation quenching to black hole activity. Alternatively, mediation of the cold gas supply by the large-scale environment, for example through increased cold-stream accretion and reduced harassment or stripping within more isolated regions, could mutually enhance star formation and (perhaps indirectly) low-level supermassive black hole activity. The six targeted early-type galaxies have comparable stellar masses of 6-9e10 solar, chosen to be near the predicted "critical value" for efficient feedback, but span a wide range of star-formation rates. Specifically, they have SFRs of 6.5, 1.4, 0.45, 0.10, 0.04, and 0.03 solar masses per year. All galaxies are detected in the Chandra ACIS-S observations with 0.3-8 keV X-ray luminosities ranging from 2e39 to 1e41 erg/s. Specifically, they have log Lx values of 40.4, 41.1, 41.1, 39.3, 39.2, and 39.2, again ordered by decreasing SFR. The three galaxies with moderate-to-high star formation rates have nuclear X-ray luminosities that are significantly greater than those of the three galaxies with low star formation rates. This result is more consistent with a symbiotic relationship between current low-level star formation and supermassive black hole activity than with simple feedback quenching models. We additionally situate these galaxies in the context of void and cluster galaxies in the local universe, model their optical surface brightness profiles and color gradients, discuss caveats including the possibility of X-ray binary contamination, and consider other supermassive black hole activity indicators.

  5. Solar Eruptions Initiated in Sigmoidal Active Regions

    NASA Astrophysics Data System (ADS)

    Savcheva, Antonia

    2016-07-01

    active regions that have been shown to possess high probability for eruption. They present a direct evidence of the existence of flux ropes in the corona prior to the impulsive phase of eruptions. In order to gain insight into their eruptive behavior and how they get destabilized we need to know their 3D magnetic field structure. First, we review some recent observations and modeling of sigmoidal active regions as the primary hosts of solar eruptions, which can also be used as useful laboratories for studying these phenomena. Then, we concentrate on the analysis of observations and highly data-constrained non-linear force-free field (NLFFF) models over the lifetime of several sigmoidal active regions, where we have captured their magnetic field structure around the times of major flares. We present the topology analysis of a couple of sigmoidal regions pointing us to the probable sites of reconnection. A scenario for eruption is put forward by this analysis. We demonstrate the use of this topology analysis to reconcile the observed eruption features with the standard flare model. Finally, we show a glimpse of how such a NLFFF model of an erupting region can be used to initiate a CME in a global MHD code in an unprecedented realistic manner. Such simulations can show the effects of solar transients on the near-Earth environment and solar system space weather.

  6. Asia Section. Regional Activities Division. Paper.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Two papers on library and information activities in developing nations, particularly in India and other Asian countries, were presented at the 1983 International Federation of Library Associations (IFLA) conference. In "IFLA in Asia: A Review of the Work of the Regional Section for Asia," Edward Lim Huck Tee (Malaysia) describes the low level of…

  7. Pneumolysin activates neutrophil extracellular trap formation.

    PubMed

    G Nel, J; Theron, A J; Durandt, C; Tintinger, G R; Pool, R; Mitchell, T J; Feldman, C; Anderson, R

    2016-06-01

    The primary objective of the current study was to investigate the potential of the pneumococcal toxin, pneumolysin (Ply), to activate neutrophil extracellular trap (NET) formation in vitro. Isolated human blood neutrophils were exposed to recombinant Ply (5-20 ng ml(-1) ) for 30-90 min at 37°C and NET formation measured using the following procedures to detect extracellular DNA: (i) flow cytometry using Vybrant® DyeCycle™ Ruby; (ii) spectrofluorimetry using the fluorophore, Sytox(®) Orange (5 μM); and (iii) NanoDrop(®) technology. These procedures were complemented by fluorescence microscopy using 4', 6-diamino-2-phenylindole (DAPI) (nuclear stain) in combination with anti-citrullinated histone monoclonal antibodies to visualize nets. Exposure of neutrophils to Ply resulted in relatively rapid (detected within 30-60 min), statistically significant (P < 0·05) dose- and time-related increases in the release of cellular DNA impregnated with both citrullinated histone and myeloperoxidase. Microscopy revealed that NETosis appeared to be restricted to a subpopulation of neutrophils, the numbers of NET-forming cells in the control and Ply-treated systems (10 and 20 ng ml(-1) ) were 4·3 (4·2), 14.3 (9·9) and 16·5 (7·5), respectively (n = 4, P < 0·0001 for comparison of the control with both Ply-treated systems). Ply-induced NETosis occurred in the setting of retention of cell viability, and apparent lack of involvement of reactive oxygen species and Toll-like receptor 4. In conclusion, Ply induces vital NETosis in human neutrophils, a process which may either contribute to host defence or worsen disease severity, depending on the intensity of the inflammatory response during pneumococcal infection. PMID:26749379

  8. Triggered star formation on the borders of the Galactic Hii region RCW 82

    NASA Astrophysics Data System (ADS)

    Pomarès, M.; Zavagno, A.; Deharveng, L.; Cunningham, M.; Jones, P.; Kurtz, S.; Russeil, D.; Caplan, J.; Comerón, F.

    2009-02-01

    Context: We are engaged in a multi-wavelength study of several Galactic H ii regions that exhibit signposts of triggered star formation on their borders, where the collect and collapse process could be at work. Aims: When addressing the question of triggered star formation, it is critical to ensure the real association between the ionized gas and the neutral material observed nearby. In this paper we stress this point and present CO observations of the RCW 82 star forming region. Methods: The velocity distribution of the molecular gas is combined with the study of young stellar objects (YSOs) detected in the direction of RCW 82. We discuss the YSO's evolutionary status using near- and mid-IR data. The spatial and velocity distributions of the molecular gas are used to discuss the possible scenarios for the star formation around RCW 82. Results: Several massive molecular condensations, together with star formation sites, are observed on the borders of RCW 82. The shapes of the three brightest condensations suggest that they were pre-existent, i.e. not formed through the collect and collapse process. A thin layer of molecular material is observed surrounding the ionized gas, adjacent to the ionization front. This results from the sweeping up of neutral material around the expanding region. Several Class I YSOs are detected in the direction of this layer. Conclusions: The numerous YSOs observed towards the bright molecular condensations bordering (and velocity-associated with) the ionized gas reveal the intense star formation activity in RCW 82. But this region is probably too young to have triggered star formation via the collect and collapse process.

  9. TRACE Observations of Active Region Births

    NASA Astrophysics Data System (ADS)

    Wolfson, C. J.; Shine, R. A.

    2000-05-01

    TRACE has recorded the births of a few bona-fide active regions, as well as many ephemeral regions and so-called X-ray bright points. The observations have usually been made serendipitously while studying a nearby, well formed active region. However, a couple of events have been recorded when deliberately looking for emerging flux in quiet portions of an active region belt. This poster will discuss some of the best observations to date, where the quality ranking of the observation is closely coupled to the observing mode TRACE was in and the availability of high resolution (temporal and/or spatial) MDI magnetograms. Included will be the birth of NOAA AR#8699 on 11 September 1999 at about 14 UT (N22E34), AR#8637 on 17 July 1999 at about 4 UT (N11W1), and AR#8885 on 21 February 2000 at about 6 UT (N11W7); these specifics being provided to encourage coordination with other observations. The temporal relationships between the first appearances of magnetic bipoles, EUV loops, chromospheric plage, pores, and sunspots will be discussed as will the growth rate and spatial relationships of these different features and any associated photospheric flows.

  10. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1998-06-02

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  11. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1996-01-30

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  12. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1998-06-02

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  13. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1996-01-01

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  14. Magnetic helicity in emerging solar active regions

    SciTech Connect

    Liu, Y.; Hoeksema, J. T.; Bobra, M.; Hayashi, K.; Sun, X.; Schuck, P. W.

    2014-04-10

    Using vector magnetic field data from the Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory, we study magnetic helicity injection into the corona in emerging active regions (ARs) and examine the hemispheric helicity rule. In every region studied, photospheric shearing motion contributes most of the helicity accumulated in the corona. In a sample of 28 emerging ARs, 17 follow the hemisphere rule (61% ± 18% at a 95% confidence interval). Magnetic helicity and twist in 25 ARs (89% ± 11%) have the same sign. The maximum magnetic twist, which depends on the size of an AR, is inferred in a sample of 23 emerging ARs with a bipolar magnetic field configuration.

  15. A multiwavelength investigation of the H II region S311: young stellar population and star formation

    NASA Astrophysics Data System (ADS)

    Yadav, Ram Kesh; Pandey, A. K.; Sharma, Saurabh; Ojha, D. K.; Samal, M. R.; Mallick, K. K.; Jose, J.; Ogura, K.; Richichi, Andrea; Irawati, Puji; Kobayashi, N.; Eswaraiah, C.

    2016-09-01

    We present a multiwavelength investigation of the young stellar population and star formation activities around the H II region Sharpless 311. Using our deep near-infrared observations and archival Spitzer-IRAC observations, we have detected a total of 125 young stellar objects (YSOs) in an area of ˜86 arcmin2. The YSO sample includes eight Class I and 117 Class II candidate YSOs. The mass completeness of the identified YSO sample is estimated to be 1.0 M⊙. The ages and masses of the majority of the candidate YSOs are estimated to be in the range ˜0.1-5 Myr and ˜0.3-6 M⊙, respectively. The 8-μm image of S311 displays an approximately spherical cavity around the ionizing source, which was possibly created by the expansion of the H II region. The spatial distribution of the candidate YSOs reveals that a significant number of them are distributed systematically along the 8-μm emission with a majority clustered around the eastern border of the H II region. Four clumps/compact H II regions are detected in the radio continuum observations at 1280 MHz, which may have been formed during the expansion of the H II region. The estimated dynamical age of the region, main-sequence lifetime of the ionizing source, the spatial distribution and ages of the candidate YSOs indicate triggered star formation in the complex.

  16. Supergranule Diffusion and Active Region Decay

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2004-01-01

    Models of the Sun's magnetic dynamo include turbulent diffusion to parameterize the effects of convective motions on the evolution of the Sun's magnetic field. Supergranules are known to dominate the evolution of the surface magnetic field structure as evidenced by the structure of both the active and quiet magnetic network. However, estimates for the dif hivity attributed to su perymules differ by an order of magnitude from about 100 km sup2/s to more than 1000 km sup2/s. We examine this question of the e i v i t y using three merent approaches. 1) We study the decay of more than 30,000 active regions by determining the rate of change in the sunspot area of each active region from day-to-day. 2) We study the decay of a single isolated active region near the time of solar minimum by examining the magnetic field evolution over five solar rotations fiom SOHOMDI magnetograms obtained at 96-minute intervals. 3) We study the characteristics of supergranules that influence the estimates of their diffusive properties - flow speeds and lifetimes as functions of size - fiom SOHO/MDI Dopplergrams.

  17. Active region evolution in the chromosphere and transtition region

    NASA Technical Reports Server (NTRS)

    Shine, R. A.; Schrijver, C. J.

    1988-01-01

    Images in the C IV 1548 A and the Si II 1526 S lines taken with the ultraviolet spectrometer polarimeter (UVSP) instrument on board the Solar Maximum Mission (SMM) satellite were combined into movies showing the evolution of active regions and the neighboring supergranulation over several days. The data sets generally consist of 240 by 240 arc second rasters with 3 arc second pixels taken one per orbit (about every 90 minutes). The images are projected on a latitude/longitude grid to remove the forshortening as the region rotates across the solar disk and further processed to remove jitter and gain variations. Movies were made with and without differential rotation. Although there are occasional missing orbits, these series do not suffer from the long nighttime gaps that occur in observations taken at a single groundbased observatory and are excellent for studying changes on time scales of several hours. The longest sequence processed to date runs from 20 Oct. 1980 to 25 Oct. 1980. This was taken during an SMM flare buildup study on AR 2744. Several shorter sequences taken in 1980 and 1984 will also be shown. The results will be presented on a video disk which can be interactively controlled to view the movies.

  18. Solar luminosity fluctuations and active region photometry

    SciTech Connect

    Chapman, G.A.; Herzog, A.D.; Lawrence, J.K.; Shelton, J.C.

    1984-07-15

    We present monochromatic observations, obtained with a 512 element diode array, of the irradiance fluctuations of the sunspots and faculae of an active region during its disk transit in 1982 August. Bolometric and stray light corrections are approximately equal in magnitude but opposite in sign, so they have not been applied. The maximum sunspot fluctuation, as a fraction of the quiet-Sun irradiance, is -800 parts per million (ppm). Faculae have a maximum irradiance fluctuation of about +200 ppm near the limbs. We find that the facular energy excess is more than 50% of the sunspot energy deficit, which is -5.8 x 10/sup 35/ ergs. These observations show that faculae are an important element in active region energy balance.

  19. The Intermediate-line Region in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Adhikari, T. P.; Różańska, A.; Czerny, B.; Hryniewicz, K.; Ferland, G. J.

    2016-11-01

    We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate-line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate-velocity FWHM ∼ 700–1200 km s‑1. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As was previously proved, the apparent gap is assumed to be caused by the presence of dust beyond the sublimation radius. Our computations with the use of the cloudy photoionization code show that the differences in the shape of the spectral energy distribution from the central region of AGNs do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission versus radius exists for all lines at the dust sublimation radius. However, increasing the gas density to ∼{10}11.5 cm‑3 at the sublimation radius provides the continuous line emission versus radius and fully explains the recently observed lack of apparent gap in some AGNs. We show that such a high density is consistent with the density of upper layers of an accretion disk atmosphere. Therefore, the upper layers of the disk atmosphere can give rise to the formation of observed emission-line clouds.

  20. VLBA Reveals Formation Region of Giant Cosmic Jet

    NASA Astrophysics Data System (ADS)

    1999-10-01

    Astronomers have gained their first glimpse of the mysterious region near a black hole at the heart of a distant galaxy, where a powerful stream of subatomic particles spewing outward at nearly the speed of light is formed into a beam, or jet, that then goes nearly straight for thousands of light-years. The astronomers used radio telescopes in Europe and the U.S., including the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) to make the most detailed images ever of the center of the galaxy M87, some 50 million light-years away. "This is the first time anyone has seen the region in which a cosmic jet is formed into a narrow beam," said Bill Junor of the University of New Mexico, in Albuquerque. "We had always speculated that the jet had to be made by some mechanism relatively near the black hole, but as we looked closer and closer to the center, we kept seeing an already-formed beam. That was becoming embarrassing, because we were running out of places to put the formation mechanism that we knew had to be there." Junor, along with John Biretta and Mario Livio of the Space Telescope Science Institute, in Baltimore, MD, now have shown that M87's jet is formed within a few tenths of a light-year of the galaxy's core, presumed to be a black hole three billion times more massive than the sun. In the formation region, the jet is seen opening widely, at an angle of about 60 degrees, nearest the black hole, but is squeezed down to only 6 degrees a few light-years away. "The 60-degree angle of the inner part of M87's jet is the widest such angle yet seen in any jet in the universe," said Junor. "We found this by being able to see the jet to within a few hundredths of a light-year of the galaxy's core -- an unprecedented level of detail." The scientists reported their findings in the October 28 issue of the journal Nature. At the center of M87, material being drawn inward by the strong gravitation of the black hole is formed into a rapidly-spinning flat

  1. Wintertime Air Quality Impacts from Oil and Natural Gas Drilling Operations in the Bakken Formation Region

    NASA Astrophysics Data System (ADS)

    Evanoski-Cole, Ashley; Sive, Barkley; Zhou, Yong; Prenni, Anthony; Schurman, Misha; Day, Derek; Sullivan, Amy; Li, Yi; Hand, Jenny; Gebhart, Kristi; Schichtel, Bret; Collett, Jeffrey

    2016-04-01

    Oil and natural gas extraction has dramatically increased in the last decade in the United States due to the increased use of unconventional drilling techniques which include horizontal drilling and hydraulic fracturing. The impact of these drilling activities on local and regional air quality in oil and gas basins across the country are still relatively unknown, especially in recently developed basins such as the Bakken shale formation. This study is the first to conduct a comprehensive characterization of the regional air quality in the Bakken region. The Bakken shale formation, part of the Williston basin, is located in North Dakota and Montana in the United States and Saskatchewan and Manitoba in Canada. Oil and gas drilling operations can impact air quality in a variety of ways, including the generation of atmospheric particulate matter (PM), hazardous air pollutants, ozone, and greenhouse gas emissions. During the winter especially, PM formation can be enhanced and meteorological conditions can favor increased concentrations of PM and other pollutants. In this study, ground-based measurements throughout the Bakken region in North Dakota and Montana were collected over two consecutive winters to gain regional trends of air quality impacts from the oil and gas drilling activities. Additionally, one field site had a comprehensive suite of instrumentation operating at high time resolution to gain detailed characterization of the atmospheric composition. Measurements included organic carbon and black carbon concentrations in PM, the characterization of inorganic PM, inorganic gases, volatile organic compounds (VOCs), precipitation and meteorology. These elevated PM episodes were further investigated using the local meteorological conditions and regional transport patterns. Episodes of elevated concentrations of nitrogen oxides and sulfur dioxide were also detected. The VOC concentrations were analyzed and specific VOCs that are known oil and gas tracers were used

  2. Photogeneration of active formate decomposition catalysts to produce hydrogen from formate and water

    DOEpatents

    King, Jr., Allen D.; King, Robert B.; Sailers, III, Earl L.

    1983-02-08

    A process for producing hydrogen from formate and water by photogenerating an active formate decomposition catalyst from transition metal carbonyl precursor catalysts at relatively low temperatures and otherwise mild conditions is disclosed. Additionally, this process may be expanded to include the generation of formate from carbon monoxide and hydroxide such that the result is the water gas shift reaction.

  3. Solar irradiance variations due to active regions

    SciTech Connect

    Oster, L.; Schatten, K.H.; Sofia, S.

    1982-05-15

    We have been able to reproduce the variations of the solar irradiance observed by ACRIM to an accuracy of better than +- 0.4 W m/sup -2/, assuming that during the 6 month observation period in 1980 the solar luminosity was constant. The improvement over previous attempts is primarily due to the inclusion of faculae. The reproduction scheme uses simple geometrical data on spot and facula areas, and conventional parameters for the respective fluxes and angular dependencies. The quality of reproduction is not very sensitive to most of the details of these parameters; nevertheless, there conventional parameters cannot be very different from their actual values in the solar atmosphere. It is interesting that the time average of the integrated excess emission (over directions) of the faculae cancels out the integrated deficit produced by the spots, within an accuracy of about 10%. If this behavior were maintained over longer periods of time, say, on the order of an activity cycle, active regions could be viewed as a kind of lighthouse where the energy deficit near the normal direction, associated with the spots, is primarily reemitted close to the tangential directions by the faculae. The currently available data suggest that energy ''storage'' associated with the redirection of flux near active regions on the Sun is comparable to the lifetime of the faculae.

  4. Helioseismology of pre-emerging active regions. III. Statistical analysis

    SciTech Connect

    Barnes, G.; Leka, K. D.; Braun, D. C.; Birch, A. C.

    2014-05-01

    The subsurface properties of active regions (ARs) prior to their appearance at the solar surface may shed light on the process of AR formation. Helioseismic holography has been applied to samples taken from two populations of regions on the Sun (pre-emergence and without emergence), each sample having over 100 members, that were selected to minimize systematic bias, as described in Paper I. Paper II showed that there are statistically significant signatures in the average helioseismic properties that precede the formation of an AR. This paper describes a more detailed analysis of the samples of pre-emergence regions and regions without emergence based on discriminant analysis. The property that is best able to distinguish the populations is found to be the surface magnetic field, even a day before the emergence time. However, after accounting for the correlations between the surface field and the quantities derived from helioseismology, there is still evidence of a helioseismic precursor to AR emergence that is present for at least a day prior to emergence, although the analysis presented cannot definitively determine the subsurface properties prior to emergence due to the small sample sizes.

  5. Observations of an active region filament

    NASA Astrophysics Data System (ADS)

    Zong, W. G.; Tang, Y. H.; Fang, C.; Xu, A. A.

    An active region filament was well observed on September 4, 2002 with THEMIS at the Teide observatory and SOHO/MDI. The full Stokes parameters of the filament were obtained in Hα and FeI 6302 Å lines. Using the data, we have studied the fine structure of the filament and obtained the parameters at the barb endpoints, including intensity, velocity and longitudinal magnetic field. Our results indicate: (a) the Doppler velocities are quiet different at barb endpoints; (b) the longitudinal magnetic fields at the barb endpoints are very weak; (c) there is a strong magnetic field structure under the filament spine.

  6. Hinode Observations of an Eruption from a Sigmoidal Active Region

    NASA Astrophysics Data System (ADS)

    Green, L. M.; Wallace, A. J.; Kliem, B.

    2012-08-01

    We analyse the evolution of a bipolar active region which produces an eruption during its decay phase. The soft X-ray arcade develops high shear over a time span of two days and transitions to sigmoidal shortly before the eruption. We propose that the continuous sigmoidal soft X-ray threads indicate that a flux rope has formed which is lying low in the solar atmosphere with a bald patch separatrix surface topology. The formation of the flux rope is driven by the photospheric evolution which is dominated by fragmentation of the main polarities, motion due to supergranular flows and cancellation at the polarity inversion line.

  7. Triassic alluvial braidplain and braided river deposits of the La Ternera Formation, Atacama region, northern Chile

    NASA Astrophysics Data System (ADS)

    Bell, C. M.; Suárez, M.

    1995-01-01

    The La Ternera Formation is a thick (>2,100 m) succession of terrigenous clastic sediments, with andesitic and basaltic intercalations, exposed in the Quebrada de Paipote area of the Atacama Region, northern Chile. The strata were deposited in an active rift basin during Late Triassic to (?) Early Jurassic times. The lower 1,000 m of the studied elastic succession comprises pebbly granule paraconglomerates, unconformably overlying Upper Paleozoic sedimentary successions, volcanics, and granitoids. These sediments were derived from the east and are interpreted as braid-plain deposits. The upper 800 m of the succession comprises interbedded orthoconglomerates, sandstones and mudstones. Abundant plant fossils include trees in growth position and carbonaceous horizons. Small scale depositional cycles were the product of migrating braided-river channel systems. Larger scale successions resulted from tectonic uplift. The sediments of the La Ternera Formation were derived predominantly from a tectonically uplifted area of Upper Paleozoic acidic volcanic and plutonic rocks (Pantanoso Formation, Choiyoi Group). Active uplift on the eastern margin of the sedimentary basin probably occurred along north-south trending faults. Continued subsidence of the basin resulted in a Sinemurian to Bajocian marine transgression. Occurrences of Triassic andesitic and basaltic volcanic rocks both to the west and the east of the La Ternera formation suggest deposition in an intea-volcanic graben or half-graben.

  8. Pederson Current Dissipation In Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Leake, James E.; Linton, M. G.

    2011-05-01

    Pederson current dissipation in emerging active regions. Certain regions of the solar atmosphere, such as the photosphere and chromosphere, as well as prominences, contain a significant amount of neutral atoms, and a complete description of the plasma requires including the effects of partial ionization. In the chromosphere the dissipation of Pederson currents is important for the evolution of emerging magnetic fields. Due to the relatively high number density in the chromosphere, the ion-neutral collision time-scale is much smaller than timescales associated with flux emergence. Hence we use a single-fluid approach to model the partially ionized plasma. Looking at both the emergence of large-scale sub-surface structures, and the emergence and reconnection of undulatory fields, we investigate the effect of Pederson current dissipation on the state of the emerging field, on magnetic reconnection and on dissipative heating of the atmosphere. Specifically we examine the effect of motions across fieldlines in the partially ionized regions, and how this can increase the free energy supplied to the corona by flux emergence. We also look at reconnection associated with flux emergence in the partially ionized atmosphere, and how this can account for observed small-scale brightenings (Ellerman Bombs).

  9. HEROES Observations of a Quiescent Active Region

    NASA Astrophysics Data System (ADS)

    Shih, A. Y.; Christe, S.; Gaskin, J.; Wilson-Hodge, C.

    2014-12-01

    Hard X-ray (HXR) observations of solar flares reveal the signatures of energetic electrons, and HXR images with high dynamic range and high sensitivity can distinguish between where electrons are accelerated and where they stop. Even in the non-flaring corona, high-sensitivity HXR measurements may be able to detect the presence of electron acceleration. The High Energy Replicated Optics to Explore the Sun (HEROES) balloon mission added the capability of solar observations to an existing astrophysics balloon payload, HERO, which used grazing-incidence optics for direct HXR imaging. HEROES measures HXR emission from ~20 to ~75 keV with an angular resolution of 33" HPD. HEROES launched on 2013 September 21 from Fort Sumner, New Mexico, and had a successful one-day flight. We present the detailed analysis of the 7-hour observation of AR 11850, which sets new upper limits on the HXR emission from a quiescent active region, with corresponding constraints on the numbers of tens of keV energetic electrons present. Using the imaging capability of HEROES, HXR upper limits are also obtained for the quiet Sun surrounding the active region. We also discuss what can be achieved with new and improved HXR instrumentation on balloons.

  10. Formation of Inner Structure of a Reconnection Separatrix Region

    SciTech Connect

    Khotyaintsev, Yu. V.; Vaivads, A.; Retino, A.; Andre, M.; Owen, C. J.; Nilsson, H.

    2006-11-17

    We present multipoint spacecraft observations at the dayside magnetopause of a magnetic reconnection separatrix region. This region separates two plasmas with significantly different temperatures and densities, at a large distance from the X line. We identify which terms in the generalized Ohm's law balance the observed electric field throughout the separatrix region. The electric field inside a thin {approx}c/{omega}{sub pi} Hall layer is balanced by the jxB/ne term while other terms dominate elsewhere. On the low density side of the region we observe a density cavity which forms due to the escape of magnetospheric electrons along the newly opened field lines. The perpendicular electric field inside the cavity constitutes a potential jump of several kV. The observed potential jump and field aligned currents can be responsible for strong aurora.

  11. FIP bias in a sigmoidal active region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

    2014-01-01

    We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

  12. Three dimensional structures of solar active regions

    NASA Technical Reports Server (NTRS)

    Kundu, M. R.

    1986-01-01

    Three dimensional structure of an active region is determined from observations with the Very Large Array (VLA) at 2, 6, and 20 cm. This region exhibits a single magnetic loop of length approx. 10 to the 10th power cm. The 2 cm radiation is mostly thermal bremsstrahlung and originates from the footpoints of the loop. The 6 and 20 cm radiation is dominated by the low harmonic gyroresonance radiation and originates from the upper portion of the legs or the top of the loop. The loop broadens toward the apex. The top of the loop is not found to be the hottest point, but two temperature maxima on either side of the loop apex are observed, which is consistent with the model proposed for long loops. From 2 and 6 cm observations it can be concluded that the electron density and temperature cannot be uniform in a plane perpendicular to the axis of the loop; the density should decrease away from the axis of the loop.

  13. Multiple Wavelength Observations of Flaring Active Regions

    NASA Astrophysics Data System (ADS)

    Lang, Kenneth R.

    The radio emission of quiescent active regions at 6 cm wavelength marks the legs of magnetic dipoles, and the emission at 20 cm wavelength delineates the radio wavelength counterpart of the coronal loops previously detected at X-ray wavelengths. At both wavelengths the temperatures have coronal values of a few million degrees. The polarization of the radio emission specifies the structure and strength of the coronal magnetic field (H ≈ 600 Gauss at heights h ≈ 4 x 109 cm above sunspot umbrae). At 6 cm and 20 cm wavelength the solar bursts have angular sizes between 5" and 30", brightness temperatures between 2 x 107 K and 2 x 108 K, and degrees of circular polarization between 10% and 90%. The location of the burst energy release is specified with second-of-arc accuracy. At radio wavelengths the bursts occur within the central regions of magnetic loops, while the flaring Ha kernels are located at the loop footpoints. Coronal loops exhibit enhanced radio emission (preburst heating) a few minutes before the release of burst energy. The radio polarization data indicate magnetic changes before and during solar bursts.

  14. Regional effects on chimera formation in 454 pyrosequenced amplicons from a mock community.

    PubMed

    Shin, Sunguk; Lee, Tae Kwon; Han, Jung Min; Park, Joonhong

    2014-07-01

    Chimeras are a frequent artifact in polymerase chain reaction and could be the underlying causes of erroneous taxonomic identifications, overestimated microbial diversity, and spurious sequences. However, little is known about the regional effects on chimera formation. Therefore, we investigated the chimera formation rates in different regions of phylogenetically important biomarker genes to test the regional effects on chimera formation. An empirical study of chimera formation rates was performed using the Roche GSFLX™ system with sequences of the V1/V2/V3 and V4/V5 regions of the 16S rRNA gene and sequences of the nifH gene from a mock microbial community. The chimera formation rates for the 16S V1/V2/V3 region, V4/V5 region, and nifH gene were 22.1-38.5%, 3.68-3.88%, and 0.31-0.98%, respectively. Some amplicons from the V1/V2/V3 regions were shorter than the typical length (∼7-31%), reflecting incomplete extension. In the V1/V2/V3 and V4/V5 regions, conserved and hypervariable regions were identified. Chimeric hot spots were located in parts of conserved regions near the ends of the amplicons. The 16S V1/V2/V3 region had the highest chimera formation rate, likely because of long template lengths and incomplete extension. The amplicons of the nifH gene had the lowest frequency of chimera formation most likely because of variations in their wobble positions in triplet codons. Our results suggest that the main reasons for chimera formation are sequence similarity and premature termination of DNA extension near primer regions. Other housekeeping genes can be a good substitute for 16S rRNA genes in molecular microbial studies to reduce the effects of chimera formation.

  15. Regional effects on chimera formation in 454 pyrosequenced amplicons from a mock community.

    PubMed

    Shin, Sunguk; Lee, Tae Kwon; Han, Jung Min; Park, Joonhong

    2014-07-01

    Chimeras are a frequent artifact in polymerase chain reaction and could be the underlying causes of erroneous taxonomic identifications, overestimated microbial diversity, and spurious sequences. However, little is known about the regional effects on chimera formation. Therefore, we investigated the chimera formation rates in different regions of phylogenetically important biomarker genes to test the regional effects on chimera formation. An empirical study of chimera formation rates was performed using the Roche GSFLX™ system with sequences of the V1/V2/V3 and V4/V5 regions of the 16S rRNA gene and sequences of the nifH gene from a mock microbial community. The chimera formation rates for the 16S V1/V2/V3 region, V4/V5 region, and nifH gene were 22.1-38.5%, 3.68-3.88%, and 0.31-0.98%, respectively. Some amplicons from the V1/V2/V3 regions were shorter than the typical length (∼7-31%), reflecting incomplete extension. In the V1/V2/V3 and V4/V5 regions, conserved and hypervariable regions were identified. Chimeric hot spots were located in parts of conserved regions near the ends of the amplicons. The 16S V1/V2/V3 region had the highest chimera formation rate, likely because of long template lengths and incomplete extension. The amplicons of the nifH gene had the lowest frequency of chimera formation most likely because of variations in their wobble positions in triplet codons. Our results suggest that the main reasons for chimera formation are sequence similarity and premature termination of DNA extension near primer regions. Other housekeeping genes can be a good substitute for 16S rRNA genes in molecular microbial studies to reduce the effects of chimera formation. PMID:24879347

  16. Active region upflows. I. Multi-instrument observations

    NASA Astrophysics Data System (ADS)

    Vanninathan, K.; Madjarska, M. S.; Galsgaard, K.; Huang, Z.; Doyle, J. G.

    2015-12-01

    responsible for the formation of the upflow region. High cadence Hα observations are used to study the chromosphere at the footpoints of the upflow region. We find no significant jet-like (spicule/rapid blue excursion) activity to account for several hours/days of plasma upflow. The jet-like activity in this region is not continuous and blueward asymmetries are a bare minimum. Using an image enhancement technique for imaging and spectral data, we show that the coronal structures seen in the AIA 193 Å channel are comparable to the EIS Fe xii images, while images in the AIA 171 Å channel reveal additional loops that are a result of contribution from cooler emission to this channel. Conclusions: Our results suggest that at chromospheric heights there are no signatures that support the possible contribution of spicules to active region upflows. We suggest that magnetic flux diffusion is responsible for the formation of the coronal upflows. The existence of two velocity components possibly indicates the presence of two different flows, which are produced by two different physical mechanisms, e.g. magnetic reconnection and pressure-driven jets. Movies associated to Figs. A.1-A.3 are available in electronic form at http://www.aanda.org

  17. The Spectrum of Methyl Formate in the Thz Region

    NASA Astrophysics Data System (ADS)

    Tudorie, M.; Huet, T. R.; Margules, L.; Goubet, M.; Pirali, O.; Roy, P.; Ilyushin, V. V.; Kleiner, I.

    2009-06-01

    The THz spectrum of methyl formate-HCOOCH_3 is currently investigated. At first a multi-pass cell having an optical path of 150 m coupled to an internal source of the Fourier Transform spectrometer of the AILES beamline, synchrotron SOLEIL (France), was used to obtain the methyl formate THz spectrum. Preliminary assignments of the pure rotation spectrum up to 80 cm^{-1}, and of the very weak torsion band v_t = 1-0 around 130 cm^{-1} are carried out. The assignments are based on the rotation-torsion energy levels calculated using the RAM approach. The particular interest in Δ v_t = 1 torsion-rotation band lies in the direct experimental determination of the barrier height V_3, which up to now was determined from pure rotational transitions only, and consequently in the contribution to the improvement of the global study of the rotational levels in the lowest torsional states of methyl formate. Secondly further measurements using the synchrotron radiation are planned. The latest results will be presented. [2] Ilyushin, Kryvda, Alekseev, J. Mol. Spectrosc. (2009), doi: 10.1016/j.jms.2009.01.016

  18. Star Formation Activity in a z>4 Protocluster

    NASA Astrophysics Data System (ADS)

    Menéndez-Delmestre, Karín; Capak, Peter; Sheth, Kartik

    2015-08-01

    Local studies show that galaxy properties are linked to the galaxy number density within their local environment. Galaxy clusters represent the most extreme density environments and are ideal laboratories to investigate the interplay between galaxy evolution and the environment. However, to understand the origin of the galaxy-environment relation, one needs to look back at the epoch of galaxy formation (z > 1), where the local high-density environments of well-established, virialized clusters give way to looser large-scale structures (LSS) extending over regions of several megaparsecs in size (protoclusters). Clustering analysis indicate that at z~2 submm-selected galaxies (SMGs) reside in very massive halos, suggesting that these may trace high-density environments that likely evolve into rich clusters of galaxies. Conversely, recent work has suggests that SMGs are tracers of a broader range of environments, including structures with more modest masses caught in highly active periods. This suggests that since galaxies in these structures are likely caught during episodes of peak starbursts, SMGs may be tracers of a wider range of environments beyond the progenitors of today’s very rich clusters, opening a window for a more complete exploration of the details underpinning the process of galaxy evolution in concert with the assembly of LSS. We undertook a large observing program comprising deep narrow-band Ly-alpha imaging and multi-object spectroscopy using the IMACS camera on Magellan (Las Campanas) to probe for the presence of a galaxy overdensity in the vicinity of a 4-member group of SMGs at z>4. With ~100 spectroscopically-confirmed Ly-alpha emitters, we are in a position to gauge the level of galaxy overdensity in this region. Furthermore, we have initiated a detailed follow-up study of these Ly-alpha emitters to obtain star-formation rates based on the IRAC and MIPS Spitzer archives, in an effort to probe for trends in the intra-LSS distribution.

  19. The distribution and nature of star formation regions in NGC 1792

    NASA Technical Reports Server (NTRS)

    Dahlem, Michael; Bomans, Dominik J.; Will, Jean-Marie

    1994-01-01

    A strong asymmetry with respect to the major axis has been found in the spatial distribution of H II regions in NGC 1792 detected on our H(alpha) image. In the radio continuum, this asymmetry is even stronger than in H(alpha), indicating that supernova activity set in earlier in the northeastern half of the disk than southwest of the nucleus. This suggests that we are viewing spatially propagating star formation (SF) in the disk, which set in about 10(exp 7) yr ago. The most luminous H II regions are distinctly different from the rest of the star-forming regions in NGC 1792, showing up as a peak in the H(alpha) luminosity near L(H(alpha)) approximately equals 3 x 10(exp 39) ergs/s. Around these giant H II regions large amounts of diffuse ionized gas are found, suggesting that this gas is heated by UV radiation escaping these regions. Attributing the radiation coming from the luminous H II regions to a temporarily increased level of SF activity, we estimate that on the order of 1200 OB stars were formed in each of them, with integrated Lyman-continuum luminosites in the range of 6 x 10(exp 51)/s. Although increased significantly near the galactic turnover of rotation, the global SF rate in NGC 1792 is only marginally affected (approximately 20%) by this phenomenon. The most plausible explanation of these results and those obtained for NGC 1808, the interaction partner of NGC 1792, is that the currently on-going SF was triggered by an interaction some 10(exp 8) yr ago.

  20. Hairpin formation within the enhancer region of the human enkephalin gene

    SciTech Connect

    McMurray, C.T.; Douglass, J.O. ); Wilson, W.D. )

    1991-01-15

    The 3{prime},5{prime}-cyclic adenosine monophosphate (cAMP)-inducible enhancer of the human enkephaline gene is located within an imperfect palindrom of 23 base pairs. The authors have found that a 23-base-pair oligonucleotide duplex containing the enhancer undergoes a reversible conformational transition from the duplex to two individual hairpin structures each formed from one strand of the duplex. Each individual hairpin forms with mismatched base pairs, one containing two GT pairs and the other containing two AC pairs. The conformational transition is stabilized by proton transfer to the hairpin containing AC mismatched pairs. The unique physical and thermodynamic properties of the enkephalin enhancer DNA suggest a model in which DNA secondary structure within the enhancer region plays and active role incAMP-inducible activation of the human enkephalin gene via formation of cruciform structures.

  1. Formation of the nucleobases around the star forming region

    NASA Astrophysics Data System (ADS)

    Saha, Rajdeep; Majumdar, Liton; Das, Ankan; Chakrabarti, Sandip K.; Chakrabarti, Sonali

    2013-06-01

    Chemistry of the dense and cold interstellar clouds are mainly dominated by the ion-molecular and radical-radical interactions though some neutral-neutral reactions are also barrierless and feasible at this condition. The base pairs of RNA are guanine (G) & uracil (U) (G-U pair) and adenine (A) & cytosine (C) (A-C pair). We perform quantum chemical calculations to predict the energetically most economical as well as favorable root for the formation of major bases of the nucleic acids. The outcome of this quantum chemical calculations could be used into our hydro-chemical model to obtain the abundances of some of the important bases of RNA during the formation of a proto star. It is well known that the thymine (T) and uracil (U) are the two nucleobases which are not common in DNA and RNA. Our quantum chemical calculation suggests that uracil could be produced prior to thymine in our chemical network. These findings could be used to support the RNA world hypothesis.

  2. The Life Cycle of Active Region Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Cheung, M. C. M.; van Driel-Gesztelyi, L.; Martínez Pillet, V.; Thompson, M. J.

    2016-08-01

    We present a contemporary view of how solar active region magnetic fields are understood to be generated, transported and dispersed. Empirical trends of active region properties that guide model development are discussed. Physical principles considered important for active region evolution are introduced and advances in modeling are reviewed.

  3. The stellar content and formation history of the Giant HII region W51 using IRMOS

    NASA Astrophysics Data System (ADS)

    Davies, Ben; MacKenty, John; Clark, Simon; Figer, Don

    2007-08-01

    The W51 Giant Molecular Cloud is amongst the most massive within the Galaxy, and harbours widespread and significant massive star formation (SF). However this activity appears qualitatively different from the spatially segregated, sequentially triggered SF occuring in e.g. the G305 and the 30 Dor star forming regions, apparently being quasi- simultaneous and multi-seeded. We propose to obtain near-IR spectroscopy of selected regions within W51 to complement planned deep imaging observations, in order to (i) determine if SF at these sites is proceeding independently or instead is triggered by older, adjacent activity and (ii) to investigate the claims of Okumura et al. (2000) for a top heavy IMF and hence to investigate if the IMF shows an environmental dependence. Finally, a measurement of the total stellar mass in W51 will enable the SF efficiency to be determined and compared to other star forming regions, to investigate potential dependencies on environment or the mode of SF, e.g triggered or multi-seeded.

  4. MAGNETIC ENERGY SPECTRA IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Abramenko, Valentyna; Yurchyshyn, Vasyl

    2010-09-01

    Line-of-sight magnetograms for 217 active regions (ARs) with different flare rates observed at the solar disk center from 1997 January until 2006 December are utilized to study the turbulence regime and its relationship to flare productivity. Data from the SOHO/MDI instrument recorded in the high-resolution mode and data from the BBSO magnetograph were used. The turbulence regime was probed via magnetic energy spectra and magnetic dissipation spectra. We found steeper energy spectra for ARs with higher flare productivity. We also report that both the power index, {alpha}, of the energy spectrum, E(k) {approx} k{sup -}{alpha}, and the total spectral energy, W = {integral}E(k)dk, are comparably correlated with the flare index, A, of an AR. The correlations are found to be stronger than those found between the flare index and the total unsigned flux. The flare index for an AR can be estimated based on measurements of {alpha} and W as A = 10{sup b}({alpha}W){sup c}, with b = -7.92 {+-} 0.58 and c = 1.85 {+-} 0.13. We found that the regime of the fully developed turbulence occurs in decaying ARs and in emerging ARs (at the very early stage of emergence). Well-developed ARs display underdeveloped turbulence with strong magnetic dissipation at all scales.

  5. Formation of secondary organic aerosol in the Paris pollution plume and its impact on surrounding regions

    NASA Astrophysics Data System (ADS)

    Zhang, Q. J.; Beekmann, M.; Freney, E.; Sellegri, K.; Pichon, J. M.; Schwarzenboeck, A.; Colomb, A.; Bourrianne, T.; Michoud, V.; Borbon, A.

    2015-03-01

    Secondary pollutants such as ozone, secondary inorganic aerosol, and secondary organic aerosol formed in the plume of megacities can affect regional air quality. In the framework of the FP7/EU MEGAPOLI project, an intensive campaign was launched in the Greater Paris Region in July 2009. The major objective was to quantify different sources of organic aerosol (OA) within a megacity and in its plume. In this study, we use airborne measurements aboard the French ATR-42 aircraft to evaluate the regional chemistry-transport model CHIMERE within and downwind the Paris region. Slopes of the plume OA levels vs. Ox (= O3 + NO2) show secondary OA (SOA) formation normalized with respect to photochemical activity and are used for specific evaluation of the OA scheme in the model. Simulated and observed slopes are in good agreement, when the most realistic "high-NOx" yields are used in the Volatility-Basis-Set scheme implemented into the model. In addition, these slopes are relatively stable from one day to another, which suggest that they are characteristic for the given megacity plume environment. Since OA within the plume is mainly formed from anthropogenic precursors (VOC and primary OA, POA), this work allows a specific evaluation of anthropogenic SOA and SOA formed from primary semi-volatile and intermediate volatile VOCs (SI-SOA) formation scheme in a model. For specific plumes, this anthropogenic OA build-up can reach about 10 μg m-3. For the average of the month of July 2009, maximum increases occur close to the agglomeration for primary OA are noticed at several tens (for POA) to hundred (for SI-SOA) kilometers of distance from the Paris agglomeration.

  6. GUM 48d: AN EVOLVED H II REGION WITH ONGOING STAR FORMATION

    SciTech Connect

    Karr, J. L.; Ohashi, N.; Manoj, P.

    2009-05-20

    High-mass star formation and the evolution of H II regions have a substantial impact on the morphology and star formation history of molecular clouds. The H II region Gum 48d, located in the Centaurus Arm at a distance of 3.5 kpc, is an old, well evolved H II region whose ionizing stars have moved off the main sequence. As such, it represents a phase in the evolution of H II regions that is less well studied than the earlier, more energetic, main-sequence phase. In this paper, we use multiwavelength archive data from a variety of sources to perform a detailed study of this interesting region. Morphologically, Gum 48d displays a ring-like faint H II region associated with diffuse emission from the associated photodissociation region, and is formed from part of a large, massive molecular cloud complex. There is extensive ongoing star formation in the region, at scales ranging from low to high mass, which is consistent with triggered star formation scenarios. We investigate the dynamical history and evolution of this region, and conclude that the original H II region was once larger and more energetic than the faint region currently seen. The proposed history of this molecular cloud complex is one of multiple, linked generations of star formation, over a period of 10 Myr. Gum 48d differs significantly in morphology and star formation from the other H II regions in the molecular cloud; these differences are likely the result of the advanced age of the region, and its different evolutionary status.

  7. NEW ACTIVE MEDIA AND ELEMENTS OF LASER SYSTEMS: Dynamic profiling of an electric field in the case of formation of a volume self-sustained discharge under conditions of strong ionization of the electrode regions

    NASA Astrophysics Data System (ADS)

    Apollonov, V. V.; Baĭtsur, G. G.; Prokhorov, A. M.; Semenov, S. K.; Firsov, K. N.

    1987-11-01

    It was found that a volume self-sustained discharge could be ignited in a system of two electrodes with sharp edges under conditions of strong ionization of the electrode regions. The conditions for such ignition were determined. A discharge of this kind could be used in compact CO2 lasers with apertures up to 30 cm and specific output energies up to 48 J/liter when preionization was provided by radiation from commercial flashlamps with quartz bulbs.

  8. Low-land Gully Formation in the Amhara Region, Ethiopia

    NASA Astrophysics Data System (ADS)

    Rijkee, Pim; Keesstra, Saskia; Mekonnen Gethahun, Mulatie

    2015-04-01

    Land degradation and related processes such as gullying, flooding and sedimentation, are global phenomena. Their economic consequences however are more severe in developing countries, which lack resources for prevention and mitigation. In Ethiopia, therefore, gully erosion as a form of land degradation is a prime issue. Over the past decade, gullies have formed in the foothills of the Minizr sub-catchment in the highlands of North-Western Ethiopia. Local extension workers have reported increased gully growth rates in the past five years in the downslope foothill areas. This study answers the following questions: has the gully growth rate indeed increased over the past five years compared to historical rates? What is the mechanism behind gully formation in the study area? In addition, this study looked at three possible root causes for increased erosion rates: changing land use, an increase in the ground water level, and the implementation of soil and water conservation measures in the watershed of the study area. The merit of this study is twofold. First, it shows the applicability of a fast, accessible and accurate way to digitally represent gullies through the use of video footage and photogrammetry. Secondly, it shows the dominant processes in gully formation in the area, allowing for a justified selection of measures to halt further gully growth and rehabilitate existing gullies. Two medium and one large gully were selected for detailed analysis. All gullies were located in gently-sloped areas (0-5%), with Vertisol-dominated soils. Gully shape and volume were derived using terrestrial photogrammetry in AgiSoft PhotoScan Professional. Still frames exported from video footage served as input. Approximately 30 points per gully were sampled weekly for soil moisture content over the course of September, November, and December 2014. In addition, the sites were checked for signs of subsurface flow at the end of the rainy season and again 3 months into the dry season

  9. The Limit of Free Magnetic Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2012-01-01

    By measuring from active-region magnetograms a proxy of the free energy in the active region fs magnetic field, it has been found previously that (1) there is an abrupt upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) the free energy is usually near its limit when the field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy ]limit line in (flux content, free-energy proxy) phase space. Here, from measurement of Marshall Space Flight Center vector magnetograms, we find the magnetic condition that underlies the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free ]energy proxy measured from vector magnetograms of 44 active regions, we find that (1) in active regions at and near their free ]energy limit, the ratio of magnetic-shear free energy to the non ]free magnetic energy the potential field would have is approximately 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. This shows that most active regions in which this core-field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1 or greater, most active regions are compelled to explode. From these results we surmise the magnetic condition that determines the free ]energy limit is the ratio of the free magnetic energy to the non-free energy the active region fs field would have were it completely relaxed to its potential ]field configuration, and that this ratio is approximately 1 at the free-energy limit and in the main sequence of explosive active regions.

  10. Chromospheric magnetic fields of an active region filament

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Solanki, S.; Lagg, A.

    2012-06-01

    Vector magnetic fields of an active region filament are co-spatially and co-temporally mapped in photosphere and upper chromosphere, by using spectro-polarimetric observations made by Tenerife Infrared Polarimeter (TIP II) at the German Vacuum Tower Telescope (VTT). A Zeeman-based ME inversion is performed on the full Stokes vectors of both the photospheric Si I 1082.7 nm and the chromospheric He I 1083.0 nm lines. We found that the strong magnetic fields, with the field strength of 600 - 800 G in the He I line formation height, are not uncommon among AR filaments. But such strong magnetic field is not always found in AR filaments.

  11. Data-driven Simulations of Evolving Active Regions

    NASA Astrophysics Data System (ADS)

    Cheung, M.; DeRosa, M. L.

    2011-12-01

    We present results from numerical simulations of coronal field evolution in response to photospheric driving. In the simulations, the coronal field evolves according to magnetofriction, which ensures that the model field evolves toward a non-linear force-free state. Unlike static field extrapolation methods, this approach takes into account the history of the photospheric field evolution. This allows for the formation of flux ropes as well as current sheets between magnetic domains of connectivity. Using time sequences of HMI magnetograms as the bottom boundary condition, we apply this method to model the emergence and evolution of various active regions. Comparisons of the models with AIA observations and with HMI vector magnetogram inversions will be discussed.

  12. LOW-LATITUDE CORONAL HOLES, DECAYING ACTIVE REGIONS, AND GLOBAL CORONAL MAGNETIC STRUCTURE

    SciTech Connect

    Petrie, G. J. D.; Haislmaier, K. J.

    2013-10-01

    We study the relationship between decaying active-region magnetic fields, coronal holes, and the global coronal magnetic structure using Global Oscillations Network Group synoptic magnetograms, Solar TErrestrial RElations Observatory extreme-ultraviolet synoptic maps, and coronal potential-field source-surface models. We analyze 14 decaying regions and associated coronal holes occurring between early 2007 and late 2010, 4 from cycle 23 and 10 from cycle 24. We investigate the relationship between asymmetries in active regions' positive and negative magnetic intensities, asymmetric magnetic decay rates, flux imbalances, global field structure, and coronal hole formation. Whereas new emerging active regions caused changes in the large-scale coronal field, the coronal fields of the 14 decaying active regions only opened under the condition that the global coronal structure remained almost unchanged. This was because the dominant slowly varying, low-order multipoles prevented opposing-polarity fields from opening and the remnant active-region flux preserved the regions' low-order multipole moments long after the regions had decayed. Thus, the polarity of each coronal hole necessarily matched the polar field on the side of the streamer belt where the corresponding active region decayed. For magnetically isolated active regions initially located within the streamer belt, the more intense polarity generally survived to form the hole. For non-isolated regions, flux imbalance and topological asymmetry prompted the opposite to occur in some cases.

  13. Star Formation in the DR21 Region (B)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Annotated mosaic

    Hidden behind a shroud of dust in the constellation Cygnus is an exceptionally bright source of radio emission called DR21. Visible light images reveal no trace of what is happening in this region because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion).

    New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud.

    The upper image is a large-scale mosaic assembled from individual photographs obtained with the InfraRed Array Camera (IRAC) aboard Spitzer. The image covers an area about two times that of a full moon. The mosaic is a composite of images obtained at mid-infrared wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red). The brightest infrared cloud near the top center corresponds to DR21, which presumably contains a cluster of newly forming stars at a distance of 10,000 light-years.

    Protruding out from DR21 toward the bottom left of the image is a gaseous outflow (green), containing both carbon monoxide and molecular hydrogen. Data from the Spitzer spectrograph, which breaks light into its constituent individual wavelengths, indicate the presence of hot steam formed as the outflow heats the surrounding molecular gas. Outflows are physical signatures of processes that create supersonic beams, or jets, of gas. They are usually accompanied by discs of material around the new star, which likely contain the materials from which future planetary systems are formed. Additional newborn stars

  14. X-ray sources in regions of star formation. I - The naked T Tauri stars

    NASA Technical Reports Server (NTRS)

    Walter, F. M.

    1986-01-01

    Einstein X-ray observations of regions of active star formation in Taurus, Ophiuchus, and Corona Australis show a greatly enhanced surface density of stellar X-ray sources over that seen in other parts of the sky. Many of the X-ray sources are identified with low-mass, pre-main-sequence stars which are not classical T Tauri stars. The X-ray, photometric, and spectroscopic data for these stars are discussed. Seven early K stars in Oph and CrA are likely to be 1-solar-mass post-T Tauri stars with ages of 10-million yr. The late K stars in Taurus are not post-T Tauri, but 'naked' T Tauri stars, which are coeval with the T Tauri stars, differing mainly in the lack of a circumstellar envelope.

  15. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  16. Bullous pemphigoid autoantibodies directly induce blister formation without complement activation.

    PubMed

    Ujiie, Hideyuki; Sasaoka, Tetsumasa; Izumi, Kentaro; Nishie, Wataru; Shinkuma, Satoru; Natsuga, Ken; Nakamura, Hideki; Shibaki, Akihiko; Shimizu, Hiroshi

    2014-11-01

    Complement activation and subsequent recruitment of inflammatory cells at the dermal/epidermal junction are thought to be essential for blister formation in bullous pemphigoid (BP), an autoimmune blistering disease induced by autoantibodies against type XVII collagen (COL17); however, this theory does not fully explain the pathological features of BP. Recently, the involvement of complement-independent pathways has been proposed. To directly address the question of the necessity of the complement activation in blister formation, we generated C3-deficient COL17-humanized mice. First, we show that passive transfer of autoantibodies from BP patients induced blister formation in neonatal C3-deficient COL17-humanized mice without complement activation. By using newly generated human and murine mAbs against the pathogenic noncollagenous 16A domain of COL17 with high (human IgG1, murine IgG2), low (murine IgG1), or no (human IgG4) complement activation abilities, we demonstrate that the deposition of Abs, and not complements, is relevant to the induction of blister formation in neonatal and adult mice. Notably, passive transfer of BP autoantibodies reduced the amount of COL17 in lesional mice skin, as observed in cultured normal human keratinocytes treated with the same Abs. Moreover, the COL17 depletion was associated with a ubiquitin/proteasome pathway. In conclusion, the COL17 depletion induced by BP autoantibodies, and not complement activation, is essential for the blister formation under our experimental system.

  17. Star Formation in the DR21 Region (A)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Annotated mosaic

    Hidden behind a shroud of dust in the constellation Cygnus is a stellar nursery called DR21, which is giving birth to some of the most massive stars in our galaxy. Visible light images reveal no trace of this interstellar cauldron because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion).

    New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud.

    The colorful image (top panel) is a large-scale composite mosaic assembled from data collected at a variety of different wavelengths. Views at visible wavelengths appear blue, near-infrared light is depicted as green, and mid-infrared data from the InfraRed Array Camera (IRAC) aboard NASA's Spitzer Space Telescope is portrayed as red. The result is a contrast between structures seen in visible light (blue) and those observed in the infrared (yellow and red). A quick glance shows that most of the action in this image is revealed to the unique eyes of Spitzer. The image covers an area about two times that of a full moon.

    Each of the constituent images is shown below the large mosaic. The Digital Sky Survey (DSS) image (lower left) provides a familiar view of deep space, with stars scattered around a dark field. The reddish hue is from gas heated by foreground stars in this region. This fluorescence fades away in the near-infrared Two-Micron All-Sky Survey (2MASS) image (lower center), but other features start to appear through the obscuring clouds of dust, now increasingly transparent. Many more

  18. Characterization of Most Promising Sequestration Formations in the Rocky Mountain Region (RMCCS)

    SciTech Connect

    McPherson, Brian; Matthews, Vince

    2013-09-30

    The primary objective of the “Characterization of Most Promising Carbon Capture and Sequestration Formations in the Central Rocky Mountain Region” project, or RMCCS project, is to characterize the storage potential of the most promising geologic sequestration formations within the southwestern U.S. and the Central Rocky Mountain region in particular. The approach included an analysis of geologic sequestration formations under the Craig Power Station in northwestern Colorado, and application or extrapolation of those local-scale results to the broader region. A ten-step protocol for geologic carbon storage site characterization was a primary outcome of this project.

  19. The structure of star formation regions. III - Individual regions - Spatial extent, mass, and age of SFR Sagittarius I

    NASA Astrophysics Data System (ADS)

    Stalbovsky, O. I.; Shevchenko, V. S.

    1981-02-01

    Photoelectric UBV photometry was used to study selected stars in the clusters NGC 6530, 6531, 6611, 6613 and near the nebulae M17 and M20. These clusters as well as Bo 14, NGC 6544, 6546, 6595, 6604, Cr 367 and Cr 469, along with field stars in the region and the molecular cloud common to all the objects, make up the unified star formation region Sgr I. Distended along the galactic plane, this region measures 900 x 140 pc. Its stars have a combined mass of about 100,000 solar masses; the mass of the molecular cloud is 10 million to 40 million solar masses. Thirteen Cepheids occur in the region; CR Ser and X Sct are about 50 million years old. The age of the oldest clusters in the region is 20 million to 30 million years old; Sgr I itself is more than 100 million years old.

  20. Embedded star formation in the extended narrow line region of Centaurus A: Extreme mixing observed by MUSE

    NASA Astrophysics Data System (ADS)

    Santoro, F.; Oonk, J. B. R.; Morganti, R.; Oosterloo, T. A.; Tadhunter, C.

    2016-05-01

    We present a detailed study of the complex ionization structure in a small (~250 pc) extended narrow line region (ENLR) cloud near Centaurus A using the Multi Unit Spectroscopic Explorer. This cloud is located in the so-called outer filament of ionized gas (about 15 kpc from the nucleus) where jet-induced star formation has been suggested to occur by different studies. We find that, despite the small size, a mixture of ionization mechanisms is operating, resulting in considerable complexity in the spatial ionization structure. The area includes two H ii regions where star formation is occurring and another location where star formation must have ceased very recently. Interestingly, the extreme Balmer decrement of one of the star forming regions (Hα/Hβobs ~ 6) indicates that it is still heavily embedded in its natal cocoon of gas and dust. At all three locations a continuum counterpart is found with spectra matching those of O/B stars local to Centaurus A. The H ii regions are embedded in a larger gas complex which is photoionized by the radiation of the central active galactic nucleus (AGN), but the O/B stars affect the spatial ionization pattern in the ENLR cloud very locally. In particular, in the surroundings of the youngest star forming region, we can isolate a tight mixing sequence in the diagnostic diagram going from gas with ionization due to a pure stellar continuum to gas only photoionized by the AGN. These results emphasize the complexity and the mixture of processes occurring in star forming regions under the influence of an AGN radiation. This is relevant for our understanding of AGN-induced star formation suggested to occur in a number of objects, including this region of Centaurus A. They also illustrate that these young stars influence the gas over only a limited region.

  1. Narrow-band Imaging of Massive Star-Forming Regions: Tracing Outflows and the Rate of Star-Formation

    NASA Astrophysics Data System (ADS)

    Hall, Kendall; Willis, Sarah; Hora, Joseph L.

    2016-01-01

    Narrowband images targeting ionized hydrogen (Brackett gamma, 2.17 microns) and molecular hydrogen (2.12 microns) were obtained for six massive star-forming regions within the Milky Way, NGC 6334, G305, G3333, G3264, G3266, and G351. These regions are within 1-4 kpc from our solar system. The narrowband flux in Brackett gamma was used as a star-formation tracer to calculate a star-formation rate for each region. This is compared with other star-formation rates found using other methods such as the count of young stars and YSOs, and rates calculated from using other tracers (e.g. 70 micron monochromatic luminosity). The molecular hydrogen narrowband images were manually searched to locate outflows from young stars. Once these outflows are identified, it may help to get a better survey of the young stellar population. A better understanding of the stellar population distribution can lead to more accurate star-formation rates to compare to those calculated from star-formation tracers. We found the regions NGC 6334 and G3266 to have the highest levels of ongoing star formation activity as indicated by the number of molecular hydrogen objects (MHOs) detected. There are a total of 279 cataloged MHOs in 181 categorized systems for the six regions. There are a total of 150 identified potential driving sources.This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  2. Formation of secondary organic aerosol in the Paris pollution plume and its impact on surrounding regions

    NASA Astrophysics Data System (ADS)

    Zhang, Q. J.; Beekmann, M.; Freney, E.; Sellegri, K.; Pichon, J. M.; Schwarzenboeck, A.; Colomb, A.; Bourrianne, T.; Michoud, V.; Borbon, A.

    2015-12-01

    Secondary pollutants such as ozone, secondary inorganic aerosol, and secondary organic aerosol formed in the plumes of megacities can affect regional air quality. In the framework of the FP7/EU MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation) project, an intensive campaign was launched in the greater Paris region in July 2009. The major objective was to quantify different sources of organic aerosol (OA) within a megacity and in its plume. In this study, we use airborne measurements aboard the French ATR-42 aircraft to evaluate the regional chemistry-transport model CHIMERE within and downwind of the Paris region. Two mechanisms of secondary OA (SOA) formation are used, both including SOA formation from oxidation and chemical aging of primary semivolatile and intermediate volatility organic compounds (SI-SOA) in the volatility basis set (VBS) framework. As for SOA formed from traditional VOC (volatile organic compound) precursors (traditional SOA), one applies chemical aging in the VBS framework adopting different SOA yields for high- and low-NOx environments, while another applies a single-step oxidation scheme without chemical aging. Two emission inventories are used for discussion of emission uncertainties. The slopes of the airborne OA levels versus Ox (i.e., O3 + NO2) show SOA formation normalized with respect to photochemical activity and are used for specific evaluation of the OA scheme in the model. The simulated slopes were overestimated slightly by factors of 1.1, 1.7 and 1.3 with respect to those observed for the three airborne measurements, when the most realistic "high-NOx" yields for traditional SOA formation in the VBS scheme are used in the model. In addition, these slopes are relatively stable from one day to another, which suggests that they are characteristic for the given megacity plume environment. The configuration with increased primary

  3. Mineral-organic formations in Berezitovy deposit (the Amur region, Russia)

    NASA Astrophysics Data System (ADS)

    Vakh, E. A.; Vakh, A. S.; Petukhov, V. I.; Nikulina, T. V.; Tarasenko, I. A.

    2016-03-01

    The article examines the structure and composition of mineral-organic formations within the hypergenesis zone of Berezitovy deposit (the Amur region). The detailed study has shown that these recent formations are represented by algae identified as Trentepohlia jolithus (Linnaeus) Wallroth. The process of macro and micro element accumulation in these formations is likely to have a complex sediment-chemogenic-organogenic nature and results from the flow of the suspended and dissolved substances formed within the hypergenesis zone of sulphide ores. It is also assumed that some elements accumulated in the formations were previously absorbed by algae from the mineralized water environment.

  4. Structural Basis for Glycyl Radical Formation By Pyruvate Formate-Lyase Activating Enzyme

    SciTech Connect

    Vey, J.L.; Yang, J.; Li, M.; Broderick, W.E.; Broderick, J.B.; Drennan, C.L.

    2009-05-26

    Pyruvate formate-lyase activating enzyme generates a stable and catalytically essential glycyl radical on G{sup 734} of pyruvate formate-lyase via the direct, stereospecific abstraction of a hydrogen atom from pyruvate formate-lyase. The activase performs this remarkable feat by using an iron-sulfur cluster and S-adenosylmethionine (AdoMet), thus placing it among the AdoMet radical superfamily of enzymes. We report here structures of the substrate-free and substrate-bound forms of pyruvate formate-lyase-activating enzyme, the first structures of an AdoMet radical activase. To obtain the substrate-bound structure, we have used a peptide substrate, the 7-mer RVSGYAV, which contains the sequence surrounding G{sup 734}. Our structures provide fundamental insights into the interactions between the activase and the G{sup 734} loop of pyruvate formate-lyase and provide a structural basis for direct and stereospecific H atom abstraction from the buried G{sup 734}4 of pyruvate formate-lyase.

  5. Unmaking old age: political and cognitive formats of active ageing.

    PubMed

    Lassen, Aske Juul; Moreira, Tiago

    2014-08-01

    Active ageing is a policy tool that dominates the way the ageing society has been constituted during the last decades. The authors argue that active ageing is an attempt at unmaking the concept of old age, by engaging in the plasticity of ageing in various ways. Through a document study of the different epistemes, models and forms used in the constitution of active ageing policies, the authors show how active ageing is not one coordinated set of policy instruments, but comes in different formats. In the WHO, active ageing configures individual lifestyle in order to expand the plasticity of ageing, based on epidemiological and public health conventions. In the EU, active ageing reforms the retirement behaviour of populations in order to integrate the plasticity of ageing into the institutions, based on social gerontological and demographic conventions. These conventional arrangements are cognitive and political in the way they aim at unmaking both the structures and the expectations that has made old age and format a new ideal of the 'good late life'. The paper examines the role of knowledge in policy and questions whether the formats of active ageing should be made to co-exist, or whether the diversity and comprehensiveness enable a local adaptation and translation of active ageing policies.

  6. Different regions of line formation in the envelope of the early emission line star HD 190073

    NASA Technical Reports Server (NTRS)

    Ringuelet, A. E.; Rovira, M.; Cidale, L.; Sahade, J.

    1987-01-01

    A description is presented of the spectral features that characterize the spectrum of HD 190073 both in the photographic region (360-660 nm), and in the IUE UV (115-320 nm). A number of different types of profiles can be distinguished, and this seems to imply that many different 'broad' regions of line formation coexist in the extended envelope of the star, including regions with densities differing in several orders of magnitude.

  7. Effects of regional differences in waste composition on the thermal formation of polychlorinated aromatics during incineration.

    PubMed

    Phan, Duong Ngoc Chau; Jansson, Stina; Marklund, Stellan

    2013-11-01

    Two artificial wastes (A and B) whose contents reflect regional differences in municipal solid waste composition, were used to investigate the thermal formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs) during incineration. Flue gas samples were simultaneously collected at three ports in the post-combustion zone corresponding to flue gas temperatures of 400, 300, and 200 °C. The combustion of Waste B, which had a higher chlorine and metal content than Waste A, produced greater levels of highly-chlorinated homologues, as demonstrated by a higher degree of chlorination. The total concentrations of PCDDs, PCDFs, PCBs, and PCNs formed in the combustion of both wastes increased as temperature decreased along the convector. There were no significant differences in total concentrations between Waste A and Waste B combustion at specific temperatures, with exception of PCDFs at 400 °C. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) modeling, used to evaluate the data for all compound groups, suggest that during flue gas quenching at temperatures of 400 °C low-chlorinated homologues are preferentially formed in the presence of copper, which is known to be a very active catalyst for this process. At 300 and 200 °C, the formation of highly-chlorinated homologues is favored.

  8. Effects of regional differences in waste composition on the thermal formation of polychlorinated aromatics during incineration.

    PubMed

    Phan, Duong Ngoc Chau; Jansson, Stina; Marklund, Stellan

    2013-11-01

    Two artificial wastes (A and B) whose contents reflect regional differences in municipal solid waste composition, were used to investigate the thermal formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs) during incineration. Flue gas samples were simultaneously collected at three ports in the post-combustion zone corresponding to flue gas temperatures of 400, 300, and 200 °C. The combustion of Waste B, which had a higher chlorine and metal content than Waste A, produced greater levels of highly-chlorinated homologues, as demonstrated by a higher degree of chlorination. The total concentrations of PCDDs, PCDFs, PCBs, and PCNs formed in the combustion of both wastes increased as temperature decreased along the convector. There were no significant differences in total concentrations between Waste A and Waste B combustion at specific temperatures, with exception of PCDFs at 400 °C. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) modeling, used to evaluate the data for all compound groups, suggest that during flue gas quenching at temperatures of 400 °C low-chlorinated homologues are preferentially formed in the presence of copper, which is known to be a very active catalyst for this process. At 300 and 200 °C, the formation of highly-chlorinated homologues is favored. PMID:24007615

  9. Vanadium promotes hydroxyl radical formation by activated human neutrophils.

    PubMed

    Fickl, Heidi; Theron, Annette J; Grimmer, Heidi; Oommen, Joyce; Ramafi, Grace J; Steel, Helen C; Visser, Susanna S; Anderson, Ronald

    2006-01-01

    This study was undertaken to investigate the effects of vanadium in the +2, +3, +4, and +5 valence states on superoxide generation, myeloperoxidase (MPO) activity, and hydroxyl radical formation by activated human neutrophils in vitro, using lucigenin-enhanced chemiluminescence (LECL), autoiodination, and electron spin resonance with 5,5-dimethyl-l-pyrroline N-oxide as the spin trap, respectively. At concentrations of up to 25 microM, vanadium, in the four different valence states used, did not affect the LECL responses of neutrophils activated with either the chemoattractant, N-formyl-l-methionyl-l-leucyl-l-phenylalanine (1 microM), or the phorbol ester, phorbol 12-myristate 12-acetate (25 ng/ml). However, exposure to vanadium in the +2, +3, and +4, but not the +5, valence states was accompanied by significant augmentation of hydroxyl radical formation by activated neutrophils and attenuation of MPO-mediated iodination. With respect to hydroxyl radical formation, similar effects were observed using cell-free systems containing either hydrogen peroxide (100 microM) or xanthine/xanthine oxidase together with vanadium (+2, +3, +4), while the activity of purified MPO was inhibited by the metal in these valence states. These results demonstrate that vanadium in the +2, +3, and +4 valence states interacts prooxidatively with human neutrophils, competing effectively with MPO for hydrogen peroxide to promote formation of the highly toxic hydroxyl radical.

  10. Tracked Active Region Patches for MDI and HMI

    NASA Astrophysics Data System (ADS)

    Turmon, Michael; Hoeksema, J. Todd; Bobra, Monica

    2014-06-01

    We describe tracked active-region patch data products that have been developed for HMI (HMI Active Region Patches, or HARPs) and for MDI (MDI Tracked Active Region Patches, or MDI TARPs). Both data products consist of tracked magnetic features on the scale of solar active regions. The now-released HARP data product covers 2010-present (>2000 regions to date). Like the HARPs, the MDI TARP data set is a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. The TARPs contain 6170 regions spanning 72000 images taken over 1996-2010, and will be availablein the MDI resident archive (RA).MDI TARPs are computed based on the 96-minute synoptic magnetograms and intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that they are in. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Also, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a cross-calibration between the HMI and MDI magnetograms (Liu et al. 2012), it is straightforward to use the same classification and tracking rules for the HMI HARPs and the MDI TARPs. We show results demonstrating region correspondence, region boundary agreement, and agreement of flux metadata using the approximately 140 regions in the May 2010-October 2010 time period. We envision several uses for these data

  11. DOME-SHAPED EUV WAVES FROM ROTATING ACTIVE REGIONS

    SciTech Connect

    Selwa, M.; Poedts, S.; DeVore, C. R. E-mail: stefaan.poedts@wis.kuleuven.be

    2012-03-10

    Recent STEREO observations enabled the study of the properties of EUV waves in more detail. They were found to have a three-dimensional (3D) dome-shaped structure. We investigate, by means of 3D MHD simulations, the formation of EUV waves as the result of the interaction of twisted coronal magnetic loops. The numerical simulation is initialized with an idealized dipolar active region and is performed under coronal (low {beta}) conditions. A sheared rotational motion is applied to the central parts of both the positive and negative flux regions at the photosphere so that the flux tubes in between them become twisted. We find that the twisting motion results in a dome-shaped structure followed in space by a dimming and in time by an energy release (flare). The rotation of the sunspots is the trigger of the wave which initially consists of two fronts that later merge together. The resulting EUV wave propagates nearly isotropically on the disk and {approx}2 times faster in the upward direction. The initial stage of the evolution is determined by the driver, while later the wave propagates freely with a nearly Alfvenic speed.

  12. GLOBAL DYNAMICS OF SUBSURFACE SOLAR ACTIVE REGIONS

    SciTech Connect

    Jouve, L.; Brun, A. S.

    2013-01-01

    We present three-dimensional numerical simulations of a magnetic loop evolving in either a convectively stable or unstable rotating shell. The magnetic loop is introduced into the shell in such a way that it is buoyant only in a certain portion in longitude, thus creating an {Omega}-loop. Due to the action of magnetic buoyancy, the loop rises and develops asymmetries between its leading and following legs, creating emerging bipolar regions whose characteristics are similar to those of observed spots at the solar surface. In particular, we self-consistently reproduce the creation of tongues around the spot polarities, which can be strongly affected by convection. We further emphasize the presence of ring-shaped magnetic structures around our simulated emerging regions, which we call 'magnetic necklace' and which were seen in a number of observations without being reported as of today. We show that those necklaces are markers of vorticity generation at the periphery and below the rising magnetic loop. We also find that the asymmetry between the two legs of the loop is crucially dependent on the initial magnetic field strength. The tilt angle of the emerging regions is also studied in the stable and unstable cases and seems to be affected both by the convective motions and the presence of a differential rotation in the convective cases.

  13. OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

    SciTech Connect

    Testa, Paola; DeLuca, Ed; Golub, Leon; Korreck, Kelly; Weber, Mark; De Pontieu, Bart; Martinez-Sykora, Juan; Title, Alan; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy; Kobayashi, Ken; Kuzin, Sergey; Walsh, Robert; DeForest, Craig

    2013-06-10

    The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial ({approx}0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to {approx}15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 A channel, and by the Hinode/X-Ray Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 10{sup 23} erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s).

  14. Subsurface helicity of active regions 12192 and 10486

    NASA Astrophysics Data System (ADS)

    Komm, Rudolf; Tripathy, Sushant; Howe, Rachel; Hill, Frank

    2015-04-01

    The active region 10486 that produced the Halloween flares in 2003 initiated our interest in the kinetic helicity of subsurface flows associated with active regions. This lead to the realization that the helicity of subsurface flows is related to the flare activity of active regions. Eleven years later, a similarly enormous active region (12192) appeared on the solar surface. We plan to study the kinetic helicity of the subsurface flows associated with region 12192 and compare it to that of region 10486. For 10486, we have analyzed Dopplergrams obtained with the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO) and the Global Oscillation Network Group (GONG) with a dense-pack ring-diagram analysis. For 12192, we have analyzed Dopplergrams from GONG and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). We will present the latest results.

  15. A Fractal Dimension Survey of Active Region Complexity

    NASA Technical Reports Server (NTRS)

    McAteer, R. T. James; Gallagher, Peter; Ireland, Jack

    2005-01-01

    A new approach to quantifying the magnetic complexity of active regions using a fractal dimension measure is presented. This fully-automated approach uses full disc MDI magnetograms of active regions from a large data set (2742 days of the SoHO mission; 9342 active regions) to compare the calculated fractal dimension to both Mount Wilson classification and flare rate. The main Mount Wilson classes exhibit no distinct fractal dimension distribution, suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimensions. Specifically a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares respectively .

  16. Exploring Formative Assessment Using Cultural Historical Activity Theory

    ERIC Educational Resources Information Center

    Asghar, Mandy

    2013-01-01

    Formative assessment is a pedagogic practice that has been the subject of much research and debate, as to how it can be used most effectively to deliver enhanced student learning in the higher education setting. Often described as a complex concept it embraces activities that range from facilitating students understanding of assessment standards,…

  17. The birth and evolution of solar active regions

    NASA Astrophysics Data System (ADS)

    Gaizauskas, V.

    1993-09-01

    The growth of solar active regions is a well-observed surface phenomenon with its origins concealed in the solar interior. We review the salient facts about the emergence of active regions and the consequences of their growth on the solar atmosphere. The most powerful flares, the ones which display a range of phenomena that still pose serious challenges for high-energy astrophysics, are associated with regions of high magnetic complexity. How does that degree of complexity arise when the vast majority of active regions are simple bipolar entities? In order to gain some insight into that problem, we compare the emergence of magnetic flux in ordinary regions with an instance when magnetic complexity is apparent from the very first appearance of a new region - clearly a subsurface prefabrication of complexity - and with others wherein a new region interacts with a pre-existing one to create the complexity in plain view.

  18. On the temperature and gas composition in the region of comet formation

    NASA Astrophysics Data System (ADS)

    Bar-Nun, A.; Kleinfeld, I.

    1989-08-01

    The gas composition and temperature in the region of Comet Halley's formation are estimated on the basis of Giotto and Vega spacecraft results, in conjunction with an experimental study of gas-mixture trapping in amorphous water ice. A CO/CH4 ratio of the order of 100, and temperature about 48 K, are inferred for the case of Halley formation in the solar nebula through water vapor condensation in the presence of gas. This formation temperature, which implies that the ice was in amorphous form, is noted to be close to the temperatures observed in circumstellar dust shells by IRAS; it also lends support to the suggestion that short-period comets were formed outside the planet-formation region.

  19. In situ conversion process systems utilizing wellbores in at least two regions of a formation

    SciTech Connect

    Vinegar, Harold J.; Hsu, Chia-Fu

    2011-09-27

    A system for heating a subsurface formation is described. The system includes a plurality of elongated heaters located in a plurality of openings in the formation. At least two of the heaters are substantially parallel to each other for at least a portion of the lengths of the heaters. At least two of the heaters have first end portions in a first region of the formation and second end portions in a second region of the formation. A source of time-varying current is configured to apply time-varying current to at least two of the heaters. The first end portions of at least two heaters are configured to have substantially the same voltage applied to them. The second portions of at least two heaters are configured to have substantially the same voltage applied to them.

  20. On the temperature and gas composition in the region of comet formation

    NASA Technical Reports Server (NTRS)

    Bar-Nun, Akiva; Kleinfeld, Idit

    1989-01-01

    The gas composition and temperature in the region of Comet Halley's formation are estimated on the basis of Giotto and Vega spacecraft results, in conjunction with an experimental study of gas-mixture trapping in amorphous water ice. A CO/CH4 ratio of the order of 100, and temperature about 48 K, are inferred for the case of Halley formation in the solar nebula through water vapor condensation in the presence of gas. This formation temperature, which implies that the ice was in amorphous form, is noted to be close to the temperatures observed in circumstellar dust shells by IRAS; it also lends support to the suggestion that short-period comets were formed outside the planet-formation region.

  1. IFLA General Conference, 1985. Division on Regional Activities. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on regional library activities which were presented at the 1985 International Federation of Library Associations (IFLA) conference include: (1) "Importance of Information Resources in National Development with Particular Reference to the Asian Scene" (Yogendra P. Dubey, India); (2) "Report of the Activities of the Regional Section for Asia…

  2. The Importance of Ammonia for Winter Haze Formation in Two Oil and Gas Production Regions

    NASA Astrophysics Data System (ADS)

    Collett, J. L., Jr.; Li, Y.; Evanoski-Cole, A. R.; Sullivan, A.; Day, D.; Archuleta, C.; Tigges, M.; Sewell, H. J.; Prenni, A. J.; Schichtel, B. A.

    2014-12-01

    Fine particle ammonium nitrate formation results from the atmospheric reaction of gaseous ammonia and nitric acid. This reaction is most important in winter when low temperatures thermodynamically enhance particle formation. Nitrogen oxides emissions from oil and gas operations partially react in the atmosphere to form nitric acid. The availability of atmospheric ammonia plays an important role in determining whether the nitric acid formed results in wintertime ammonium nitrate formation. Here we contrast situations in two important U.S. oil and gas production regions. Measurements of ammonia, nitric acid, ammonium nitrate and other species were made from 2007 to present near Boulder, Wyoming and in winters 2013 and 2014 in western North Dakota. The Boulder, Wyoming site is close to the large Jonah and Pinedale Anticline gas fields. Field sites at the north unit of Theodore Roosevelt National Park and Fort Union are situated in the large Bakken Formation oil and gas production region. Wintertime formation of nitric acid and ammonium nitrate, together comprising nitrogen in the +5 oxidation state (N(V)), was observed in both locations. Concentrations of N(V), however, are generally much lower at Boulder, WY than in the Bakken. An even bigger difference is seen in fine particle ammonium nitrate concentrations; limited regional ammonia is available in western Wyoming to react with nitric acid, leaving a portion of the nitric acid trapped in the gas phase. Higher concentrations of ammonia are observed in the Bakken where they support formation of much higher concentrations of ammonium nitrate. Comparison of these two regions clearly indicates the importance of understanding both local NOx emissions and regional concentrations of ammonia in predicting source impacts on formation of fine particles and haze.

  3. A WIDE-FIELD NARROWBAND OPTICAL SURVEY OF THE BRAID NEBULA STAR FORMATION REGION IN CYGNUS OB7

    SciTech Connect

    Magakian, Tigran Yu.; Nikogossian, Elena H.; Movsessian, Tigran; Aspin, Colin; Pyo, Tae-Soo; Khanzadyan, Tigran; Smith, Michael D.; Mitchison, Sharon; Davis, Chris J.; Beck, Tracy L.; Moriarty-Schieven, Gerald H. E-mail: elena@bao.sci.am E-mail: pyo@subaru.naoj.org E-mail: smm23@kent.ac.uk E-mail: c.davis@jach.hawaii.edu E-mail: gerald.schieven@nrc-cnrc.gc.ca

    2010-03-15

    We study the population of Herbig-Haro (HH) flows and jets in an area of Cygnus OB7 designated the Braid Nebula star formation region. This complex forms part of the L 1003 dark cloud, and hosts two FU Orionis (FUor)-like objects as well as several other active young stars. To trace outflow activity and to relate both known and newly discovered flows to young star hosts we intercompare new, deep, narrowband H{alpha} and [S II] optical images taken on the Subaru 8 m Telescope on Mauna Kea, Hawaii. Our images show that there is considerable outflow and jet activity in this region suggesting the presence of an extensive young star population. We confirm that both of the FUor-like objects drive extensive HH flows and document further members of the flows in both objects. The L 1003 star formation complex is a highly kinematically active region with young stars in several different stages of evolution. We trace collimated outflows from numerous young stars although the origin of some HH objects remains elusive.

  4. Turing pattern formation in fractional activator-inhibitor systems

    NASA Astrophysics Data System (ADS)

    Henry, B. I.; Langlands, T. A. M.; Wearne, S. L.

    2005-08-01

    Activator-inhibitor systems of reaction-diffusion equations have been used to describe pattern formation in numerous applications in biology, chemistry, and physics. The rate of diffusion in these applications is manifest in the single parameter of the diffusion constant, and stationary Turing patterns occur above a critical value of d representing the ratio of the diffusion constants of the inhibitor to the activator. Here we consider activator-inhibitor systems in which the diffusion is anomalous subdiffusion; the diffusion rates are manifest in both a diffusion constant and a diffusion exponent. A consideration of this problem in terms of continuous-time random walks with sources and sinks leads to a reaction-diffusion system with fractional order temporal derivatives operating on the spatial Laplacian. We have carried out an algebraic stability analysis of the homogeneous steady-state solution in fractional activator-inhibitor systems, with Gierer-Meinhardt reaction kinetics and with Brusselator reaction kinetics. For each class of reaction kinetics we identify a Turing instability bifurcation curve in the two-dimensional diffusion parameter space. The critical value of d , for Turing instabilities, decreases monotonically with the anomalous diffusion exponent between unity (standard diffusion) and zero (extreme subdiffusion). We have also carried out numerical simulations of the governing fractional activator-inhibitor equations and we show that the Turing instability precipitates the formation of complex spatiotemporal patterns. If the diffusion of the activator and inhibitor have the same anomalous scaling properties, then the surface profiles of these patterns for values of d slightly above the critical value varies from smooth stationary patterns to increasingly rough and nonstationary patterns as the anomalous diffusion exponent varies from unity towards zero. If the diffusion of the activator is anomalous subdiffusion but the diffusion of the inhibitor

  5. Turing pattern formation in fractional activator-inhibitor systems.

    PubMed

    Henry, B I; Langlands, T A M; Wearne, S L

    2005-08-01

    Activator-inhibitor systems of reaction-diffusion equations have been used to describe pattern formation in numerous applications in biology, chemistry, and physics. The rate of diffusion in these applications is manifest in the single parameter of the diffusion constant, and stationary Turing patterns occur above a critical value of d representing the ratio of the diffusion constants of the inhibitor to the activator. Here we consider activator-inhibitor systems in which the diffusion is anomalous subdiffusion; the diffusion rates are manifest in both a diffusion constant and a diffusion exponent. A consideration of this problem in terms of continuous-time random walks with sources and sinks leads to a reaction-diffusion system with fractional order temporal derivatives operating on the spatial Laplacian. We have carried out an algebraic stability analysis of the homogeneous steady-state solution in fractional activator-inhibitor systems, with Gierer-Meinhardt reaction kinetics and with Brusselator reaction kinetics. For each class of reaction kinetics we identify a Turing instability bifurcation curve in the two-dimensional diffusion parameter space. The critical value of d , for Turing instabilities, decreases monotonically with the anomalous diffusion exponent between unity (standard diffusion) and zero (extreme subdiffusion). We have also carried out numerical simulations of the governing fractional activator-inhibitor equations and we show that the Turing instability precipitates the formation of complex spatiotemporal patterns. If the diffusion of the activator and inhibitor have the same anomalous scaling properties, then the surface profiles of these patterns for values of d slightly above the critical value varies from smooth stationary patterns to increasingly rough and nonstationary patterns as the anomalous diffusion exponent varies from unity towards zero. If the diffusion of the activator is anomalous subdiffusion but the diffusion of the inhibitor

  6. 3D MHD Models of Active Region Loops

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2004-01-01

    Present imaging and spectroscopic observations of active region loops allow to determine many physical parameters of the coronal loops, such as the density, temperature, velocity of flows in loops, and the magnetic field. However, due to projection effects many of these parameters remain ambiguous. Three dimensional imaging in EUV by the STEREO spacecraft will help to resolve the projection ambiguities, and the observations could be used to setup 3D MHD models of active region loops to study the dynamics and stability of active regions. Here the results of 3D MHD models of active region loops are presented, and the progress towards more realistic 3D MHD models of active regions. In particular the effects of impulsive events on the excitation of active region loop oscillations, and the generation, propagations and reflection of EIT waves are shown. It is shown how 3D MHD models together with 3D EUV observations can be used as a diagnostic tool for active region loop physical parameters, and to advance the science of the sources of solar coronal activity.

  7. MAGNETIC FIELD TOPOLOGY AND THE THERMAL STRUCTURE OF THE CORONA OVER SOLAR ACTIVE REGIONS

    SciTech Connect

    Schrijver, Carolus J.; DeRosa, Marc L.; Title, Alan M.

    2010-08-20

    Solar extreme ultraviolet (EUV) images of quiescent active-region coronae are characterized by ensembles of bright 1-2 MK loops that fan out from select locations. We investigate the conditions associated with the formation of these persistent, relatively cool, loop fans within and surrounding the otherwise 3-5 MK coronal environment by combining EUV observations of active regions made with TRACE with global source-surface potential-field models based on the full-sphere photospheric field from the assimilation of magnetograms that are obtained by the Michelson Doppler Imager (MDI) on SOHO. We find that in the selected active regions with largely potential-field configurations these fans are associated with (quasi-)separatrix layers (QSLs) within the strong-field regions of magnetic plage. Based on the empirical evidence, we argue that persistent active-region cool-loop fans are primarily related to the pronounced change in connectivity across a QSL to widely separated clusters of magnetic flux, and confirm earlier work that suggested that neither a change in loop length nor in base field strengths across such topological features are of prime importance to the formation of the cool-loop fans. We discuss the hypothesis that a change in the distribution of coronal heating with height may be involved in the phenomenon of relatively cool coronal loop fans in quiescent active regions.

  8. The relation between star formation and active nuclei

    NASA Technical Reports Server (NTRS)

    Rieke, G. H.

    1987-01-01

    Three questions relevant to the relation between an active nucleus and surrounding star formation are discussed. The infrared stellar CO absorption bands can be used to identify galaxies with large populations of young, massive stars and thus can identify strong starburst unambiguously, such as in NGC 6240, and can help identify composite active/starburst systems such as Arp 220. An active nucleus is probably not required for LINER spectral characteristics; dusty starburst galaxies, particularly if they are nearly edge-on, can produce LINER spectra through the shock heating of their interstellar media by supernovae combined with the obscuration of their nuclei in the optical. The Galactic Center would be an ideal laboratory for studying the interaction of starbursts and active nuclei, if both could be demonstrated to occur there. Failure to detect a cusp in the stellar distribution raises questions about the presence of an active nucleus, which should be answered by additional observations in the near future.

  9. Bacterial Cyclic AMP-Phosphodiesterase Activity Coordinates Biofilm Formation

    PubMed Central

    Kalivoda, Eric J.; Brothers, Kimberly M.; Stella, Nicholas A.; Schmitt, Matthew J.; Shanks, Robert M. Q.

    2013-01-01

    Biofilm-related infections are a major contributor to human disease, and the capacity for surface attachment and biofilm formation are key attributes for the pathogenesis of microbes. Serratia marcescens type I fimbriae-dependent biofilms are coordinated by the adenylate cyclase, CyaA, and the cyclic 3′,5′-adenosine monophosphate (cAMP)-cAMP receptor protein (CRP) complex. This study uses S. marcescens as a model system to test the role of cAMP-phosphodiesterase activity in controlling biofilm formation. Herein we describe the characterization of a putative S. marcescens cAMP-phosphodiesterase gene (SMA3506), designated as cpdS, and demonstrated to be a functional cAMP-phosphodiesterase both in vitro and in vivo. Deletion of cpdS resulted in defective biofilm formation and reduced type I fimbriae production, whereas multicopy expression of cpdS conferred a type I fimbriae-dependent hyper-biofilm. Together, these results support a model in which bacterial cAMP-phosphodiesterase activity modulates biofilm formation. PMID:23923059

  10. STELLAR POPULATIONS AND THE STAR FORMATION HISTORIES OF LOW SURFACE BRIGHTNESS GALAXIES. II. H II REGIONS

    SciTech Connect

    Schombert, James; McGaugh, Stacy; Maciel, Tamela E-mail: stacy.mcgaugh@case.edu

    2013-08-01

    The luminosities, colors, and H{alpha} emission for 429 H II regions in 54 low surface brightness (LSB) galaxies are presented. While the number of H II regions per galaxy is lower in LSB galaxies compared to star-forming irregulars and spirals, there is no indication that the size or luminosity function of H II regions differs from other galaxy types. The lower number of H II regions per galaxy is consistent with their lower total star formation rates. The fraction of the total L{sub H{alpha}} contributed by H II regions varies from 10% to 90% in LSB galaxies (the rest of the H{alpha} emission being associated with a diffuse component) with no correlation with galaxy stellar or gas mass. Bright H II regions have bluer colors, similar to the trend in spirals; their number and luminosities are consistent with the hypothesis that they are produced by the same H II luminosity function as spirals. Comparison with stellar population models indicates that the brightest H II regions in LSB galaxies range in cluster mass from a few 10{sup 3} M{sub Sun} (e.g., {rho} Oph) to globular-cluster-sized systems (e.g., 30 Dor) and that their ages are consistent with clusters from 2 to 15 Myr old. The faintest H II regions are comparable to those in the LMC powered by a single O or B star. Thus, star formation in LSB galaxies covers the full range of stellar cluster mass.

  11. Pattern formation in chemically interacting active rotors with self-propulsion.

    PubMed

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

    2016-09-21

    We demonstrate that active rotations in chemically signalling particles, such as autochemotactic E. coli close to walls, create a route for pattern formation based on a nonlinear yet deterministic instability mechanism. For slow rotations, we find a transient persistence of the uniform state, followed by a sudden formation of clusters contingent on locking of the average propulsion direction by chemotaxis. These clusters coarsen, which results in phase separation into a dense and a dilute region. Faster rotations arrest phase separation leading to a global travelling wave of rotors with synchronized roto-translational motion. Our results elucidate the physics resulting from the competition of two generic paradigms in active matter, chemotaxis and active rotations, and show that the latter provides a tool to design programmable self-assembly of active matter, for example to control coarsening.

  12. Pattern formation in chemically interacting active rotors with self-propulsion.

    PubMed

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

    2016-09-21

    We demonstrate that active rotations in chemically signalling particles, such as autochemotactic E. coli close to walls, create a route for pattern formation based on a nonlinear yet deterministic instability mechanism. For slow rotations, we find a transient persistence of the uniform state, followed by a sudden formation of clusters contingent on locking of the average propulsion direction by chemotaxis. These clusters coarsen, which results in phase separation into a dense and a dilute region. Faster rotations arrest phase separation leading to a global travelling wave of rotors with synchronized roto-translational motion. Our results elucidate the physics resulting from the competition of two generic paradigms in active matter, chemotaxis and active rotations, and show that the latter provides a tool to design programmable self-assembly of active matter, for example to control coarsening. PMID:27526180

  13. Coagulation activity and white thrombus formation in the microminipig.

    PubMed

    Miura, Naoki; Kawaguchi, Hiroaki; Nagasato, Tomoka; Yamada, Tomonobu; Ito, Takashi; Izumi, Hiroyuki; Shameshima, Hisayo; Miyoshi, Noriaki; Tanimoto, Akihide; Maruyama, Ikuro

    2013-01-01

    Swine are becoming increasingly attractive as animal models for clinical research and the recently developed Microminipig (MMPig) has emerged as a possible experimental animal model. In this study, we demonstrated age-dependent changes in hematological parameters and coagulation activity in healthy MMPigs (58 male and 67 females, aged 0-34 months), and investigated white thrombus formation (WTF) using an in vitro microchip flow-chamber system (four males and four females, aged 22-23 months). There was no clear sex or age-dependent differences in any hematological parameters. While activated partial thromboplastin time (APTT) was shorter than prothrombin time (PT), with APTT:PT of 0.88:1, microchip flow-chamber system analysis showed that WTF time was shorter than that in humans, suggesting a possible thrombotic tendency in the MMPig. These results could be useful to life science researchers in the use of the MMPig as an experimental model animal for thrombus formation. PMID:23606691

  14. Star formation in quasar and active galaxy environments

    NASA Astrophysics Data System (ADS)

    Coldwell, Georgina V.; Lambas, Diego G.

    2003-09-01

    We use the 2dF public 100 K data release of galaxies and samples of quasars and active galaxies taken from the Véron-Cetty and Véron catalogue to study the nature of galaxies in the surroundings of active objects with redshifts in the range 0.1 < z < 0.2. We explore the distribution of neighbour 2dF galaxy spectral types, η, at different projected distances from the quasars and active galaxies with radial velocity difference ΔV= 500 km s-1. For comparison, we perform a similar analysis on the environment of typical galaxies in the 2dF catalogue, a sample of bright early-type galaxies, i.e. η < -1.4 and MbJ < -21, and also on a sample of 2dF galaxy groups. We find a higher relative fraction of emission-line galaxies, i.e. with 2dF spectral type indices η >3.5, in the vicinity of quasars and active galaxies compared to that in the neighbourhood of typical galaxies, bright early types and groups. This effect extends up to projected distance rp~ 1 h-1 Mpc for active galaxies and rp~ 3 h-1 Mpc for quasars. We also find a tendency for companion galaxies of quasars to be brighter than the neighbours of active galaxies within rp~ 3 h-1 Mpc. We estimate average star-formation rates for objects at different distances from quasars, active galaxies, galaxies and groups. We find a significantly higher star-formation activity within ~2.0 h-1 Mpc from quasars with respect to typical galaxies, which reinforces the idea that star formation is enhanced in the neighbourhood of quasars. Our tests with the group environment provide evidence against quasars being associated with groups. Also, our analysis of the neighbours of bright early types shows that although these galaxies are typical hosts of quasars, their companion galaxies are significantly different in terms of the star-formation activity.

  15. Observations of the Growth of an Active Region Filament

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong

    2016-10-01

    We present observations of the growth of an active region filament caused by magnetic interactions among the filament and its adjacent superpenumbral filament (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the filament is the first step reconnection, which resulted in the filament bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to the disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the filament and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed filament threads, appeared. H α observations show that this twisted structure is a longer sinistral filament. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the filament consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among filaments and their adjacent SFs and T could lead to the growth of the filaments, and the filament is probably supported in a flux rope.

  16. Regional Observation of Seismic Activity in Baekdu Mountain

    NASA Astrophysics Data System (ADS)

    Kim, Geunyoung; Che, Il-Young; Shin, Jin-Soo; Chi, Heon-Cheol

    2015-04-01

    Seismic unrest in Baekdu Mountain area between North Korea and Northeast China region has called attention to geological research community in Northeast Asia due to her historical and cultural importance. Seismic bulletin shows level of seismic activity in the area is higher than that of Jilin Province of Northeast China. Local volcanic observation shows a symptom of magmatic unrest in period between 2002 and 2006. Regional seismic data have been used to analyze seismic activity of the area. The seismic activity could be differentiated from other seismic phenomena in the region by the analysis.

  17. Active-region designs in quantum cascade lasers

    SciTech Connect

    Zasavitskii, I I

    2012-10-31

    This paper analyses the development of active-region designs in quantum cascade lasers. Active-region designs have been demonstrated to date that employ various radiative transitions (vertical, diagonal, interminiband and interband). The lower laser level is depopulated through nonradiative transitions, such as one- or two-phonon (and even three-phonon) relaxation or bound state {yields} continuum transitions. Advances in active-region designs and energy diagram optimisation in the past few years have led to significant improvements in important characteristics of quantum cascade lasers, such as their output power, emission bandwidth, characteristic temperature and efficiency. (invited paper)

  18. Windblown soil crust formation under light rainfall in a semiarid region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many soils in arid and semi-arid regions of the world are affected by crusting, the process of forming a compact layer or thin mantle of consolidated material at the soil surface. Our objective was to evaluate the effect of rainfall quantity on crust formation of five soil types prominent in the Col...

  19. Professional Motivation Formation of Future Specialists under the Conditions of Regional Educational Complex

    ERIC Educational Resources Information Center

    Kargina, Elena Mikhaylovna

    2015-01-01

    Motivation plays the leading role in the organization of the personality structure. It is a driving force of the activity. Motivation accounts for the behavior and activity and has a great impact on professional self-determination and person's satisfaction with the work. The problem of professional motivation formation of a future specialist is…

  20. Neotectonic stage in the formation of the Khokhlovskoe uranium deposit, eastern Transural region: Structural, hydrochemical, mineralogical, and geochemical formation conditions

    NASA Astrophysics Data System (ADS)

    Vinokurov, S. F.; Prokof'ev, V. Yu.; Malkovsky, V. I.; Dymkov, Yu. M.; Chugaev, A. V.; Nesterova, M. V.

    2013-11-01

    The structural, hydrochemical, mineralogical, and geochemical features of the Khokhlovskoe uranium deposit related to neotectonic processes are considered. The structural feature is expressed in neotectonic dislocations in the form of overall intense fragmentation of host rocks and widespread low-amplitude strike-slip faulting. The hydrochemical specificity is determined by the appearance of thermal carbonated formation water in ore-bearing aquifers. This water is similar in chemical and gas composition to hydrothermal solutions in fluid inclusions and mineral waters abundant in this district. The mineralogical and geochemical features comprise the occurrence of newly formed ferroan carbonates and late iron hydroxides in altered (bleached) pelitic rocks; the formation of silicic opal segregations in ore-bearing sand and sandstone; late sulfides, arsenides, and selenides of iron and other metals; and multiphase gel-pitchblende enriched in Zr especially typical of high-grade uranium ore. The age of high-grade ore determined by a precision uranium-ionium method coincides with the time when thermal carbonated water appeared in the host rocks. This time was estimated from a mathematical model of heat transfer and regional dynamics of underground water. This coincidence clearly indicates that the aforementioned processes are related to the late Quaternary neotectonic reactivation of the eastern Transural region.

  1. Molecular hydrogen emission from the Cepheus A star-formation region

    SciTech Connect

    Doyon, R.; Nadeau, D.

    1988-11-01

    Fabry-Perot spectrometry of H2 emission lines in the Cepheus A star-formation region is presented. It is found that the H2 emission in Cep A(E) is associated with dense condensations of NH3 and CS, while the emission in Cep A(W) is associated with Herbig-Haro objects and reflection nebulae. The data support the hypothesis that the two lobes of emission are produced by a single outflow originating from the region of maser and compact H II regions at the western edge of Cep A(E). 49 references.

  2. The temperature of C II emission-line formation regions in cool stars

    NASA Technical Reports Server (NTRS)

    Brown, A.; Carpenter, K. G.

    1984-01-01

    An investigation has been conducted of the temperature of C II emission-line formation regions in the outer atmospheres of late-type giant and supergiant stars. A distinct dichotomy is seen in the C II lambda 2325/lambda 1335 ratio between coronal and noncoronal stars. It is found that C II emission from noncoronal giant and supergiant stars comes from regions with temperatures of 7000-9000 K, with the mean temperature being approximately 8500 K, whereas the C II emission from coronal stars likely comes from hotter regions. The C II ratio provides a powerful empirical tool for estimating the chromospheric temperatures of cool giants and supergiants.

  3. Formation and decomposition of chemically activated and stabilized hydrazine.

    PubMed

    Asatryan, Rubik; Bozzelli, Joseph W; da Silva, Gabriel; Swinnen, Saartje; Nguyen, Minh Tho

    2010-06-01

    Recombination of two amidogen radicals, NH(2) (X(2)B1), is relevant to hydrazine formation, ammonia oxidation and pyrolysis, nitrogen reduction (fixation), and a variety of other N/H/X combustion, environmental, and interstellar processes. We have performed a comprehensive analysis of the N(2)H(4) potential energy surface, using a variety of theoretical methods, with thermochemical kinetic analysis and master equation simulations used to treat branching to different product sets in the chemically activated NH(2) + NH(2) process. For the first time, iminoammonium ylide (NH(3)NH), the less stable isomer of hydrazine, is involved in the kinetic modeling of N(2)H(4). A new, low-energy pathway is identified for the formation of NH(3) plus triplet NH, via initial production of NH(3)NH followed by singlet-triplet intersystem crossing. This new reaction channel results in the formation of dissociated products at a relatively rapid rate at even moderate temperatures and above. A further novel pathway is described for the decomposition of activated N(2)H(4), which eventually leads to the formation of the simple products N(2) + 2H(2), via H(2) elimination to cis-N(2)H(2). This process, termed as "dihydrogen catalysis", may have significant implications in the formation and decomposition chemistry of hydrazine and ammonia in diverse environments. In this mechanism, stereoselective attack of cis-N(2)H(2) by molecular hydrogen results in decomposition to N(2) with a fairly low barrier. The reverse termolecular reaction leading to the gas-phase formation of cis-N(2)H(2) + H(2) achieves non-heterogeneous catalytic nitrogen fixation with a relatively low activation barrier (77 kcal mol(-1)), much lower than the 125 kcal mol(-1) barrier recently reported for bimolecular addition of H(2) to N(2). This termolecular reaction is an entropically disfavored path, but it does describe a new means of activating the notoriously unreactive N(2). We design heterogeneous analogues of this

  4. Braided rivers, lakes and sabkhas of the upper Triassic Cifuncho formation, Atacama region, Chile

    NASA Astrophysics Data System (ADS)

    Suárez, M.; Bell, C. M.

    1994-01-01

    A 1,000-m-thickness of Upper Triassic (to possibly Hettangian) sediments of the Cifuncho Formation are exposed in the coastal Cordillera of the Atacama Region, Chile. These coarse-grained clastic terrigenous strata are interpreted as the deposits of braided rivers, ephemeral lakes, sabkhas and volcaniclastic alluvial fans. They include conglomerates, pebbly sandstones, fine to medium-grained sandstones and thin, finely-laminated limestones. Halite hopper-casts are abundant in sandstones near the top of the section. Approximately 90% of the clastic detritus was derived from an upper Paleozoic metasedimentary accretionary complex located to the west. Andesitic debris flow and pyroclastic flow deposits occur near the base of the sequence. Isolated tuff intercalations and an ignimbritic lava flow occur higher in the section. The great thickness of coarse-grained and ill-sorted clastic sediments suggests deposition in an actively subsiding basin, probably a graben, adjacent to rising highlands. Overlying Hettangian-Sinemurian marine sediments were deposited by a transgression which occurred during a world-wide lowstand. This suggests that thermal subsidence followed the Triassic rifting.

  5. Europe in world regional perspective: formations of modernity and major historical transformations.

    PubMed

    Delanty, Gerard

    2015-09-01

    The paper seeks to present a world regional approach to the analysis of modernity and in doing so it also aims to make a contribution to comparative sociology and social theory. It is argued that world regions are the most suitable entry-point for comparing different socio-political constellations of our time, preferable to continents, civilizations and nation-states. However, a world regional foundation on its own is insufficient, due to the internal plurality and historically changing forms of world regions, and therefore needs to be accompanied by a concept that provides some degree of coherence within world regions and a tool for comparison with other world regions. The notion of modernity offers this level of generality while at the same time allowing for variety in its historical forms. Six main formations of modernity are identified, of which the European model was the first one and often a cultural reference for many other parts of the world. The thesis is that in the present day the most important developments are in the Asian and Latin American varieties, which unlike Europe are witnessing major historical transformation. Decisive in all of this is the question of democratization in the shaping of social imaginaries. Beginning with the problem of how to define the specificity of Europe, the paper provides an exploratory analysis of some of the salient considerations around a number of world regions, their formations of modernity, and the extent of major historical transformations in their present constitution.

  6. MOLECULAR GAS AND STAR-FORMATION PROPERTIES IN THE CENTRAL AND BAR REGIONS OF NGC 6946

    SciTech Connect

    Pan, Hsi-An; Sorai, Kazuo; Kuno, Nario; Koda, Jin; Hirota, Akihiko; Kaneko, Hiroyuki

    2015-12-10

    In this work, we investigate the molecular gas and star-formation properties in the barred spiral galaxy NGC 6946 using multiple molecular lines and star-formation tracers. A high-resolution image (100 pc) of {sup 13}CO (1–0) is created for the inner 2 kpc disk by the single-dish Nobeyama Radio Observatory 45 m telescope and interferometer Combined Array for Research in Millimeter-wave Astronomy, including the central region (nuclear ring and bar) and the offset ridges of the primary bar. Single-dish HCN (1–0) observations were also made to constrain the amount of dense gas. The physical properties of molecular gas are inferred from (1) the large velocity gradient calculations using our observations and archival {sup 12}CO (1–0), {sup 12}CO(2–1) data, (2) the dense gas fraction suggested by the luminosity ratio of HCN to {sup 12}CO (1–0), and (3) the infrared color. The results show that the molecular gas in the central region is warmer and denser than that of the offset ridges. The dense gas fraction of the central region is similar to that of luminous infrared galaxies/ultraluminous infrared galaxies, whereas the offset ridges are close to the global average of normal galaxies. The coolest and least-dense region is found in a spiral-like structure, which was misunderstood to be part of the southern primary bar in previous low-resolution observations. The star-formation efficiency (SFE) changes by about five times in the inner disk. The variation of SFE agrees with the prediction in terms of star formation regulated by the galactic bar. We find a consistency between the star-forming region and the temperature inferred by the infrared color, suggesting that the distribution of subkiloparsec-scale temperature is driven by star formation.

  7. Molecular Gas and Star-formation Properties in the Central and Bar Regions of NGC 6946

    NASA Astrophysics Data System (ADS)

    Pan, Hsi-An; Kuno, Nario; Koda, Jin; Hirota, Akihiko; Sorai, Kazuo; Kaneko, Hiroyuki

    2015-12-01

    In this work, we investigate the molecular gas and star-formation properties in the barred spiral galaxy NGC 6946 using multiple molecular lines and star-formation tracers. A high-resolution image (100 pc) of 13CO (1-0) is created for the inner 2 kpc disk by the single-dish Nobeyama Radio Observatory 45 m telescope and interferometer Combined Array for Research in Millimeter-wave Astronomy, including the central region (nuclear ring and bar) and the offset ridges of the primary bar. Single-dish HCN (1-0) observations were also made to constrain the amount of dense gas. The physical properties of molecular gas are inferred from (1) the large velocity gradient calculations using our observations and archival 12CO (1-0), 12CO(2-1) data, (2) the dense gas fraction suggested by the luminosity ratio of HCN to 12CO (1-0), and (3) the infrared color. The results show that the molecular gas in the central region is warmer and denser than that of the offset ridges. The dense gas fraction of the central region is similar to that of luminous infrared galaxies/ultraluminous infrared galaxies, whereas the offset ridges are close to the global average of normal galaxies. The coolest and least-dense region is found in a spiral-like structure, which was misunderstood to be part of the southern primary bar in previous low-resolution observations. The star-formation efficiency (SFE) changes by about five times in the inner disk. The variation of SFE agrees with the prediction in terms of star formation regulated by the galactic bar. We find a consistency between the star-forming region and the temperature inferred by the infrared color, suggesting that the distribution of subkiloparsec-scale temperature is driven by star formation.

  8. Formation of structures around HII regions: ionization feedback from massive stars

    NASA Astrophysics Data System (ADS)

    Tremblin, P.; Audit, E.; Minier, V.; Schmidt, W.; Schneider, N.

    2015-03-01

    We present a new model for the formation of dense clumps and pillars around HII regions based on shocks curvature at the interface between a HII region and a molecular cloud. UV radiation leads to the formation of an ionization front and of a shock ahead. The gas is compressed between them forming a dense shell at the interface. This shell may be curved due to initial interface or density modulation caused by the turbulence of the molecular cloud. Low curvature leads to instabilities in the shell that form dense clumps while sufficiently curved shells collapse on itself to form pillars. When turbulence is high compared to the ionized-gas pressure, bubbles of cold gas have sufficient kinetic energy to penetrate into the HII region and detach themselves from the parent cloud, forming cometary globules. Using computational simulations, we show that these new models are extremely efficient to form dense clumps and stable and growing elongated structures, pillars, in which star formation might occur (see Tremblin et al. 2012a). The inclusion of turbulence in the model shows its importance in the formation of cometary globules (see Tremblin et al. 2012b). Globally, the density enhancement in the simulations is of one or two orders of magnitude higher than the density enhancement of the classical ``collect and collapse`` scenario. The code used for the simulation is the HERACLES code, that comprises hydrodynamics with various equation of state, radiative transfer, gravity, cooling and heating. Our recent observations with Herschel (see Schneider et al. 2012a) and SOFIA (see Schneider et al. 2012b) and additional Spitzer data archives revealed many more of these structures in regions where OB stars have already formed such as the Rosette Nebula, Cygnus X, M16 and Vela, suggesting that the UV radiation from massive stars plays an important role in their formation. We present a first comparison between the simulations described above and recent observations of these regions.

  9. Communication: Activation energy of tension-induced pore formation in lipid membranes.

    PubMed

    Karal, Mohammad Abu Sayem; Yamazaki, Masahito

    2015-08-28

    Tension plays a vital role in pore formation in biomembranes, but the mechanism of pore formation remains unclear. We investigated the temperature dependence of the rate constant of constant tension (σ)-induced pore formation in giant unilamellar vesicles of lipid membranes using an experimental method we developed. By analyzing this result, we determined the activation energy (Ua) of tension-induced pore formation as a function of tension. A constant (U0) that does not depend on tension was found to contribute significantly to Ua. Analysis of the activation energy clearly indicated that the dependence of Ua on σ in the classical theory is correct, but that the classical theory of pore formation is not entirely correct due to the presence of U0. We can reasonably consider that U0 is a nucleation free energy to form a hydrophilic pre-pore from a hydrophobic pre-pore or a region with lower lateral lipid density. After obtaining U0, the evolution of a pre-pore follows a classical theory. Our data provide valuable information that help explain the mechanism of tension-induced pore formation in biomembranes and lipid membranes.

  10. BRIGHT ULTRAVIOLET REGIONS AND STAR FORMATION CHARACTERISTICS IN NEARBY DWARF GALAXIES

    SciTech Connect

    Melena, Nicholas W.; Hunter, Deidre A.; Zernow, Lea; Elmegreen, Bruce G. E-mail: dah@lowell.edu E-mail: bge@us.ibm.com

    2009-11-15

    We compare star formation in the inner and outer disks of 11 dwarf irregular galaxies (dIm) within 3.6 Mpc. The regions are identified on Galaxy Evolution Explorer near-UV images, and modeled with UV, optical, and near-IR colors to determine masses and ages. A few galaxies have made 10{sup 5}-10{sup 6} M {sub sun} complexes in a starburst phase, while others have not formed clusters in the last 50 Myr. The maximum region mass correlates with the number of regions as expected from the size-of-sample effect. We find no radial gradients in region masses and ages, even beyond the realm of H{alpha} emission, although there is an exponential decrease in the luminosity density and number density of the regions with radius. H{alpha} is apparently lacking in the outer parts only because nebular emission around massive stars is too faint to see. The outermost regions for the five galaxies with H I data formed at average gas surface densities of 1.9-5.9 M {sub sun} pc{sup -2}. These densities are at the low end of commonly considered thresholds for star formation and imply either that local gas densities are higher before star formation begins or subthreshold star formation is possible. The first case could be explained by supernovae triggering and other local processes, while the second case could be explained by gravitational instabilities with angular momentum loss in growing condensations. The distribution of regions on a log(mass) - log(age) plot is examined. The distribution is usually uniform along log(age) for equal intervals of log(mass) and this implies a region count that varies as 1/age. This variation results from either an individual region mass that varies as 1/age or a region disruption probability that varies as 1/age. A correlation between fading-corrected surface brightness and age suggests the former. The implied loss of mass is from fading of region envelopes below the surface brightness limit.

  11. STAR FORMATION ACTIVITY IN CLASH BRIGHTEST CLUSTER GALAXIES

    SciTech Connect

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

    2015-11-10

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

  12. Endocannabinoids Control Platelet Activation and Limit Aggregate Formation under Flow

    PubMed Central

    De Angelis, Valentina; Koekman, Arnold C.; Weeterings, Cees; Roest, Mark; de Groot, Philip G.; Herczenik, Eszter; Maas, Coen

    2014-01-01

    Background The endocannabinoid system has previously been implicated in the regulation of neurons and inflammatory cells. Additionally, it has been reported that endocannabinoid receptors are present on circulating platelets, but there has been conflicting evidence on their contribution to platelet function. Objectives Our aim was to examine the role of endocannabinoids in platelet function in vitro and in vivo. Methods and Results We studied the effects of the well-characterized endogenous endocannabinoid anandamide on platelet aggregation in suspension, α-granule release, calcium mobilization, Syk phosphorylation, as well as platelet spreading and aggregate formation under flow. Anandamide inhibits platelet aggregation and α-granule release by collagen, collagen-derived peptide CRP-XL, ADP, arachidonic acid and thromboxane A2 analogue U46619. However, activation via thrombin receptor PAR-1 stays largely unaffected. Calcium mobilization is significantly impaired when platelets are stimulated with collagen or CRP-XL, but remains normal in the presence of the other agonists. In line with this finding, we found that anandamide prevents collagen-induced Syk phosphorylation. Furthermore, anandamide-treated platelets exhibit reduced spreading on immobilized fibrinogen, have a decreased capacity for binding fibrinogen in solution and show perturbed platelet aggregate formation under flow over collagen. Finally, we investigated the influence of Cannabis sativa consumption by human volunteers on platelet activation. Similar to our in vitro findings with anandamide, ex vivo collagen-induced platelet aggregation and aggregate formation on immobilized collagen under flow were impaired in whole blood of donors that had consumed Cannabis sativa. Conclusions Endocannabinoid receptor agonists reduce platelet activation and aggregate formation both in vitro and ex vivo after Cannabis sativa consumption. Further elucidation of this novel regulatory mechanism for platelet function

  13. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  14. The suppression of star formation by powerful active galactic nuclei.

    PubMed

    Page, M J; Symeonidis, M; Vieira, J D; Altieri, B; Amblard, A; Arumugam, V; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Castro-Rodríguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dubois, E N; Dunlop, J S; Dwek, E; Dye, S; Eales, S; Elbaz, D; Farrah, D; Fox, M; Franceschini, A; Gear, W; Glenn, J; Griffin, M; Halpern, M; Hatziminaoglou, E; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Marchetti, L; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Panuzzo, P; Papageorgiou, A; Pearson, C P; Pérez-Fournon, I; Pohlen, M; Rawlings, J I; Rigopoulou, D; Riguccini, L; Rizzo, D; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Sánchez Portal, M; Schulz, B; Scott, D; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Trichas, M; Tugwell, K E; Vaccari, M; Valtchanov, I; Viero, M; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

    2012-05-09

    The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight correlation between the mass of the black hole and the mass of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming galaxies are usually dust-obscured and are brightest at infrared and submillimetre wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expelling the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.

  15. The Suppression of Star Formation by Powerful Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    2012-01-01

    The old, red stars that constitute the bulges of galaxies, and the massive black holes at their centres, are the relics of a period in cosmic history when galaxies formed stars at remarkable rates and active galactic nuclei (AGN) shone brightly as a result of accretion onto black holes. It is widely suspected, but unproved, that the tight corre1ation between the mass of the black hole and the mas. of the stellar bulge results from the AGN quenching the surrounding star formation as it approaches its peak luminosity. X-rays trace emission from AGN unambiguously, whereas powerful star-forming ga1axies are usually dust-obscured and are brightest at infrared and submillimeter wavelengths. Here we report submillimetre and X-ray observations that show that rapid star formation was common in the host galaxies of AGN when the Universe was 2-6 billion years old, but that the most vigorous star formation is not observed around black holes above an X-ray luminosity of 10(exp 44) ergs per second. This suppression of star formation in the host galaxy of a powerful AGN is a key prediction of models in which the AGN drives an outflow, expe11ing the interstellar medium of its host and transforming the galaxy's properties in a brief period of cosmic time.

  16. Active Ageing Level of Older Persons: Regional Comparison in Thailand.

    PubMed

    Haque, Md Nuruzzaman

    2016-01-01

    Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South) of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1) has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p < 0.001)). Mean AAI in Central region is lower than North, Northeast, and South regions but there is no significant difference in the latter three regions of Thailand. Special emphasis should be given to Central region and policy should be undertaken for increasing active ageing level. Implementation of an Integrated Active Ageing Package (IAAP), containing policies for older persons to improve their health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons' active ageing level in Thailand. PMID:27375903

  17. Active Ageing Level of Older Persons: Regional Comparison in Thailand.

    PubMed

    Haque, Md Nuruzzaman

    2016-01-01

    Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South) of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1) has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p < 0.001)). Mean AAI in Central region is lower than North, Northeast, and South regions but there is no significant difference in the latter three regions of Thailand. Special emphasis should be given to Central region and policy should be undertaken for increasing active ageing level. Implementation of an Integrated Active Ageing Package (IAAP), containing policies for older persons to improve their health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons' active ageing level in Thailand.

  18. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (Editor); Chapman, G. A. (Editor); Hudson, H. S. (Editor); Willson, R. C. (Editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

  19. Photospheric Magnetic Diffusion by Measuring Moments of Active Regions

    NASA Astrophysics Data System (ADS)

    Engell, Alexander; Longcope, D.

    2013-07-01

    Photospheric magnetic surface diffusion is an important constraint for the solar dynamo. The HMI Active Region Patches (HARPs) program automatically identify all magnetic regions above a certain flux. In our study we measure the moments of ARs that are no longer actively emerging and can thereby give us good statistical constraints on photospheric diffusion. We also present the diffusion properties as a function of latitude, flux density, and single polarity (leading or following) within each HARP.

  20. Radio Coronal Magnetography of a Large Active Region

    NASA Astrophysics Data System (ADS)

    Bastian, Timothy S.; Gary, Dale E.; White, Stephen; Fleishman, Gregory; Chen, Bin

    2015-04-01

    Quantitative knowledge of coronal magnetic fields is fundamental to understanding energetic phenomena such as solar flares. Flares occur in solar active regions where strong, non-potential magnetic fields provide free energy. While constraints on the coronal magnetic field topology are readily available through high resolution SXR and EUV imaging of solar active regions, useful quantitative measurements of coronal magnetic fields have thus far been elusive. Recent progress has been made at infrared (IR) wavelengths in exploiting both the Zeeman and Hanle effects to infer the line-of-sight magnetic field strength or the orientation of the magnetic field vector in the plane of the sky above the solar limb. However, no measurements of coronal magnetic fields against the solar disk are possible using IR observations. Radio observations of gyroresonance emission from active regions offer the means of measuring coronal magnetic fields above the limb and on the solar disk. In particular, for plasma plasma conditions in the solar corona, active regions typically become optically thick to emission over a range of radio frequencies through gyroresonance absorption at a low harmonic of the electron gyrofrequency. The specific range of resonant frequencies depends on the range of coronal magnetic field strengths present in the active region.The Karl G. Jansky Very Large Array was used in November 2014 to image NOAA/USAF active region AR12209 over a continuous frequency range of 1-8 GHz, corresponding to a wavelength range of 3.75-30 cm. This frequency range is sensitive to coronal magnetic field strengths ranging from ~120-1400G. The active region was observed on four different dates - November 18, 20, 22, and 24 - during which the active region longitude ranged from -15 to +70 degrees, providing a wide range of aspect angles. In this paper we provide a preliminary description of the coronal magnetic field measurements derived from the radio observations.

  1. Odours stimulate neuronal activity in the dorsolateral area of the hippocampal formation during path integration.

    PubMed

    Jorge, P E; Phillips, J B; Gonçalves, A; Marques, P A M; Nĕmec, P

    2014-05-22

    The dorsolateral area of the hippocampal formation of birds is commonly assumed to play a central role in processing information needed for geographical positioning and homing. Previous work has interpreted odour-induced activity in this region as evidence for an 'olfactory map'. Here, we show, using c-Fos expression as a marker, that neuronal activation in the dorsolateral area of the hippocampal formation of pigeons is primarily a response to odour novelty, not to the spatial distribution of odour sources that would be necessary for an olfactory map. Pigeons exposed to odours had significantly more neurons activated in this area of the brain than pigeons exposed to filtered air with odours removed. This increased activity was observed only in response to unfamiliar odours. No change in activity was observed when pigeons were exposed to home odours. These findings are consistent with non-home odours activating non-olfactory components of the pigeon's navigation system. The pattern of neuronal activation in the triangular and dorsomedial areas of the hippocampal formation was, by contrast, consistent with the possibility that odours play a role in providing spatial information. PMID:24671977

  2. Odours stimulate neuronal activity in the dorsolateral area of the hippocampal formation during path integration

    PubMed Central

    Jorge, P. E.; Phillips, J. B.; Gonçalves, A.; Marques, P. A. M.; Nĕmec, P.

    2014-01-01

    The dorsolateral area of the hippocampal formation of birds is commonly assumed to play a central role in processing information needed for geographical positioning and homing. Previous work has interpreted odour-induced activity in this region as evidence for an ‘olfactory map’. Here, we show, using c-Fos expression as a marker, that neuronal activation in the dorsolateral area of the hippocampal formation of pigeons is primarily a response to odour novelty, not to the spatial distribution of odour sources that would be necessary for an olfactory map. Pigeons exposed to odours had significantly more neurons activated in this area of the brain than pigeons exposed to filtered air with odours removed. This increased activity was observed only in response to unfamiliar odours. No change in activity was observed when pigeons were exposed to home odours. These findings are consistent with non-home odours activating non-olfactory components of the pigeon's navigation system. The pattern of neuronal activation in the triangular and dorsomedial areas of the hippocampal formation was, by contrast, consistent with the possibility that odours play a role in providing spatial information. PMID:24671977

  3. Active Transport Can Greatly Enhance Cdc20:Mad2 Formation

    PubMed Central

    Ibrahim, Bashar; Henze, Richard

    2014-01-01

    To guarantee genomic integrity and viability, the cell must ensure proper distribution of the replicated chromosomes among the two daughter cells in mitosis. The mitotic spindle assembly checkpoint (SAC) is a central regulatory mechanism to achieve this goal. A dysfunction of this checkpoint may lead to aneuploidy and likely contributes to the development of cancer. Kinetochores of unattached or misaligned chromosomes are thought to generate a diffusible “wait-anaphase” signal, which is the basis for downstream events to inhibit the anaphase promoting complex/cyclosome (APC/C). The rate of Cdc20:C-Mad2 complex formation at the kinetochore is a key regulatory factor in the context of APC/C inhibition. Computer simulations of a quantitative SAC model show that the formation of Cdc20:C-Mad2 is too slow for checkpoint maintenance when cytosolic O-Mad2 has to encounter kinetochores by diffusion alone. Here, we show that an active transport of O-Mad2 towards the spindle mid-zone increases the efficiency of Mad2-activation. Our in-silico data indicate that this mechanism can greatly enhance the formation of Cdc20:Mad2 and furthermore gives an explanation on how the “wait-anaphase” signal can dissolve abruptly within a short time. Our results help to understand parts of the SAC mechanism that remain unclear. PMID:25338047

  4. Active transport can greatly enhance Cdc20:Mad2 formation.

    PubMed

    Ibrahim, Bashar; Henze, Richard

    2014-01-01

    To guarantee genomic integrity and viability, the cell must ensure proper distribution of the replicated chromosomes among the two daughter cells in mitosis.The mitotic spindle assembly checkpoint (SAC) is a central regulatory mechanism to achieve this goal. A dysfunction of this checkpoint may lead to aneuploidy and likely contributes to the development of cancer. Kinetochores of unattached or misaligned chromosomes are thought to generate a diffusible ''wait-anaphase'' signal, which is the basis for downstream events to inhibit the anaphase promoting complex/cyclosome (APC/C). The rate of Cdc20:C-Mad2 complex formation at the kinetochore is a key regulatory factor in the context of APC/C inhibition. Computer simulations of a quantitative SAC model show that the formation of Cdc20:C-Mad2 is too slow for checkpoint maintenance when cytosolic O-Mad2 has to encounter kinetochores by diffusion alone. Here, we show that an active transport of O-Mad2 towards the spindle mid-zone increases the efficiency of Mad2-activation. Our data indicate that this mechanism can greatly enhance the formation of Cdc20:Mad2 and furthermore gives an explanation on how the ''wait-anaphase'' signal can dissolve abruptly within a short time. Our results help to understand parts of the SAC mechanism that remain unclear.

  5. Radio Emission Toward Regions of Massive Star Formation in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Johanson, Adam K.

    2015-01-01

    Four regions of massive star formation in the Large Magellanic Cloud (LMC) were observed for water and methanol maser emission and radio continuum emission. A total of 42 radio detections were made including 27 new radio sources, four water masers, and eight compact H II regions. The lobes of a radio galaxy were resolved for the first time, and the host galaxy identified. Seven sources were associated with known massive young stellar objects (YSOs). A multi-wavelength analysis using both the infrared and radio spectrum was used to characterize the sources. Mid-infrared color-magnitude selection criteria for ultracompact H II (UCHII) regions in the LMC are presented, yielding 136 UCHII region candidates throughout that galaxy. New maser detections identified two previously unknown massive YSOs. No methanol masers were detected, consistent with previous studies and supporting the hypothesis that the LMC may be deficient in these molecules. These discoveries contribute to the history of star formation in the LMC, which will lead to a better understanding of star formation in the Milky Way and throughout the universe.

  6. FOXO1 mediates RANKL-induced osteoclast formation and activity.

    PubMed

    Wang, Yu; Dong, Guangyu; Jeon, Hyeran Helen; Elazizi, Mohamad; La, Lan B; Hameedaldeen, Alhassan; Xiao, E; Tian, Chen; Alsadun, Sarah; Choi, Yongwon; Graves, Dana T

    2015-03-15

    We have previously shown that the transcription factor FOXO1 is elevated in conditions with high levels of bone resorption. To investigate the role of FOXO1 in the formation of osteoclasts, we examined mice with lineage-specific deletion of FOXO1 in osteoclast precursors and by knockdown of FOXO1 with small interfering RNA. The receptor activator for NF-κB ligand (RANKL), a principal bone-resorbing factor, induced FOXO1 expression and nuclear localization 2 d after stimulation in bone marrow macrophages and RAW264.7 osteoclast precursors. RANKL-induced osteoclast formation and osteoclast activity was reduced in half in vivo and in vitro with lineage-specific FOXO1 deletion (LyzM.Cre(+)FOXO1(L/L)) compared with matched controls (LyzM.Cre(-)FOXO1(L/L)). Similar results were obtained by knockdown of FOXO1 in RAW264.7 cells. Moreover, FOXO1-mediated osteoclast formation was linked to regulation of NFATc1 nuclear localization and expression as well as a number of downstream factors, including dendritic cell-specific transmembrane protein, ATP6vod2, cathepsin K, and integrin αv. Lastly, FOXO1 deletion reduced M-CSF-induced RANK expression and migration of osteoclast precursors. In the present study, we provide evidence that FOXO1 plays a direct role in osteoclast formation by mediating the effect of RANKL on NFATc1 and several downstream effectors. This is likely to be significant because FOXO1 and RANKL are elevated in osteolytic conditions.

  7. Earth resources-regional transfer activity contracts review

    NASA Technical Reports Server (NTRS)

    Bensko, J., Jr.; Daniels, J. L.; Downs, S. W., Jr.; Jones, N. L.; Morton, R. R.; Paludan, C. T.

    1977-01-01

    A regional transfer activity contracts review held by the Earth Resources Office was summarized. Contracts in the earth resources field primarily directed toward applications of satellite data and technology in solution of state and regional problems were reviewed. A summary of the progress of each contract was given in order to share experiences of researchers across a seven state region. The region included Missouri, Kentucky, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. Research in several earth science disciplines included forestry, limnology, water resources, land use, geology, and mathematical modeling. The use of computers for establishment of information retrieval systems was also emphasized.

  8. A SPITZER CENSUS OF STAR FORMATION ACTIVITY IN THE PIPE NEBULA

    SciTech Connect

    Forbrich, Jan; Lada, Charles J.; Muench, August A.; Alves, Joao

    2009-10-10

    The Pipe Nebula, a large nearby molecular cloud, lacks obvious signposts of star formation in all but one of more than 130 dust extinction cores that have been identified within it. In order to quantitatively determine the current level of star formation activity in the Pipe Nebula, we analyzed 13 deg{sup 2} of sensitive mid-infrared maps of the entire cloud, obtained with the Multiband Imaging Photometer for Spitzer at wavelengths of 24 mum and 70 mum, to search for candidate young stellar objects (YSOs) in the high-extinction regions. We argue that our search is complete for class I and typical class II YSOs with luminosities of L {sub bol} approx 0.2 L {sub sun} and greater. We find only 18 candidate YSOs in the high-extinction regions of the entire Pipe cloud. Twelve of these sources are previously known members of a small cluster associated with Barnard 59, the largest and most massive dense core in the cloud. With only six candidate class I and class II YSOs detected toward extinction cores outside of this cluster, our findings emphatically confirm the notion of an extremely low level of star formation activity in the Pipe Nebula. The resulting star formation efficiency for the entire cloud mass is only approx0.06%.

  9. Spitzer Follow-up of HST Observations of Star Formation in H II Regions

    NASA Astrophysics Data System (ADS)

    Hester, Jeff; Bally, John; Desch, Steve; Healy, Kevin; Snider, Keely

    2005-06-01

    Images of regions of star formation taken with HST have given us an extraordinary view of young stellar objects and their natal environments. These views differ tremendously between low-mass YSOs seen in regions of isolated low-mass star formation such as Taurus-Auriga, and the proplyds, EGGs, and other structures seen in regions of massive star formation. While YSOs in Taurus spend their adolescence buried in the dark interiors of molecular clouds, YSOs near massive stars quickly find themselves overrun by ionization fronts and exposed to the intense UV radiation from nearby massive stars. This difference in environment has a profound effect on the way in which the protoplanetary disk around a star evolves -- a fact that is of great importance to us, given the strength of the evidence suggesting that the Sun formed near a massive star. But HST while HST can inform us about the evolution of YSOs in HII region environments once they are overrun by ionization fronts, it cannot show us the birth of the stars themselves. These remain hidden in the dense molecular material beyond the ionized volumes of these regions. Only Spitzer can show us the properties of the YSOs that lie hidden in the dark shadows of HST images of HII regions, and only Spitzer can provide us with information about PDRs, warm dust, and other tracers of the interaction of massive stars with their surroundings. The combination of HST and Spitzer observations of star forming regions is far greater than the sum of its parts. If we are to build a complete picture of low-mass star formation and the evolution of disks near massive stars, we need to combine HST and Spitzer observations of the same regions. In this proposal we request time to obtain both IRAC and MIPS 24 micron images of each HII region that has been observed by HST, but has yet to be observed with Spitzer. Together with previous images obtained from the archives, this will comprise an indispensible data set for testing hypotheses about

  10. Tracking Active Region NOAA 12192 in Multiple Carrington Rotations

    NASA Astrophysics Data System (ADS)

    Jain, Kiran; Tripathy, Sushant C.; Hill, Frank

    2015-04-01

    Active region NOAA 12192 appeared on the visible solar disk on October 18, 2014 and grew rapidly into the largest such region since 1990. During its entire transit across the Earth facing side of the Sun, it produced a significant number of X- and M-class flares. The combination of front-side and helioseismic far-side images clearly indicated that it lived through several Carrington rotations. In this paper, using Dopplergrams from GONG and HMI, we present a study on mode parameters, viz. oscillation frequencies, amplitude, and sub-surface flows and investigate how these vary with the evolution of active region in multiple rotations. We also present a detailed comparison between NOAA 10486 (the biggest active region in cycle 23) and NOAA 12192, and discuss the similarities/differences between them.

  11. A connection between star formation activity and cosmic rays in the starburst galaxy M82.

    PubMed

    2009-12-10

    Although Galactic cosmic rays (protons and nuclei) are widely believed to be mainly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size-more than 50 times the diameter of similar Galactic regions-uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density. The cosmic rays produced in the formation, life and death of massive stars in these regions are expected to produce diffuse gamma-ray emission through interactions with interstellar gas and radiation. M82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in terms of gamma-ray emission. Here we report the detection of >700-GeV gamma-rays from M82. From these data we determine a cosmic-ray density of 250 eV cm(-3) in the starburst core, which is about 500 times the average Galactic density. This links cosmic-ray acceleration to star formation activity, and suggests that supernovae and massive-star winds are the dominant accelerators.

  12. A connection between star formation activity and cosmic rays in the starburst galaxy M82

    NASA Astrophysics Data System (ADS)

    VERITAS Collaboration; Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M.; Benbow, W.; Boltuch, D.; Bradbury, S. M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cannon, A.; Celik, O.; Cesarini, A.; Chow, Y. C.; Ciupik, L.; Cogan, P.; Colin, P.; Cui, W.; Dickherber, R.; Duke, C.; Fegan, S. J.; Finley, J. P.; Finnegan, G.; Fortin, P.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gibbs, K.; Gillanders, G. H.; Godambe, S.; Grube, J.; Guenette, R.; Gyuk, G.; Hanna, D.; Holder, J.; Horan, D.; Hui, C. M.; Humensky, T. B.; Imran, A.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Kildea, J.; Konopelko, A.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Lebohec, S.; Maier, G.; McArthur, S.; McCann, A.; McCutcheon, M.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nagai, T.; Ong, R. A.; Otte, A. N.; Pandel, D.; Perkins, J. S.; Pizlo, F.; Pohl, M.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Roache, E.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Smith, A. W.; Steele, D.; Swordy, S. P.; Theiling, M.; Thibadeau, S.; Varlotta, A.; Vassiliev, V. V.; Vincent, S.; Wagner, R. G.; Wakely, S. P.; Ward, J. E.; Weekes, T. C.; Weinstein, A.; Weisgarber, T.; Williams, D. A.; Wissel, S.; Wood, M.; Zitzer, B.

    2009-12-01

    Although Galactic cosmic rays (protons and nuclei) are widely believed to be mainly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size-more than 50 times the diameter of similar Galactic regions-uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density. The cosmic rays produced in the formation, life and death of massive stars in these regions are expected to produce diffuse γ-ray emission through interactions with interstellar gas and radiation. M82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in terms of γ-ray emission. Here we report the detection of >700-GeV γ-rays from M82. From these data we determine a cosmic-ray density of 250eVcm-3 in the starburst core, which is about 500 times the average Galactic density. This links cosmic-ray acceleration to star formation activity, and suggests that supernovae and massive-star winds are the dominant accelerators.

  13. Active Tectonics And Modern Geodynamics Of Sub-Yerevan Region

    NASA Astrophysics Data System (ADS)

    Avanesyan, M.

    2004-05-01

    The given work is dedicated to active tectonics and modern geodynamics of Sub-Yerevan region. This region is interesting as a one of regions with maximal seismic activity in Armenia. The high level of seismic risk of this region is conditioned by high level of seismic hazard, high density of the population, as well as presence of objects of special importance and industrial capacities. The modern structure of Sub-Yerevan region and the adjacent area, as well as the Caucasus entirely, has mosaic-block appearance, typical for collision zone of Arabian and Eurasian plates. Distinctively oriented active faults of various ranges and morphological types are distinguished. These faults, in their turn, form various-scale active blocks of the Earth's crust and their movement defines seismic activity of the region. The researches show, that all strong earthquakes in the region were caused by movements by newest and activated ancient faults. In order to reveal the character of Earth's crust active blocks movement, separation of high gradients of horizontal and vertical movements and definition of stress fields highest concentration regions by GPS observations, high-accuracy leveling and study of earthquake focal mechanisms a new seismotectonic model is developed, which represents a combination of tectonic structure, seismic data, newest and modern movements. On the basis of comparison and analysis of these data zones with potential maximal seismic hazard are separated. The zone of joint of Azat-Sevan active and Yerevan abysmal faults is the most active on the territory of Sub-Yerevan region. The directions relatively the Earth's crust movement in the zones of horizontal and vertical movement gradients lead to conclusion, that Aragats-Tsakhkunian and Gegam active blocks undergo clockwise rotation. This means, that additional concentration of stress must be observed in block corners, that is confirmed by location of strong earthquakes sources. Thus, on the North 1988 Spitak (M

  14. Aircraft Spacings that Produce a Vortex-Free Region Below Flight Formation

    NASA Technical Reports Server (NTRS)

    Rossow, Vernon J.

    2000-01-01

    Theoretical estimates are presented for the motion of vortex wakes shed by multiple aircraft flying in close formation. The purpose of the theoretical study was to determine whether the spacings between adjacent aircraft in close formations could be designed so that the lift-generated vortices being trailed would move upward rather than downward. In this way, a region below the formation is produced that is free of vortices. It was found that aircraft can be arranged in formations so that the inboard wake vortices all move upward rather than downward. The two outboard vortices travel downward at a greatly reduced velocity that depends on the number of aircraft in the formation. If the desired motions are to be produced, the lateral spacings between adjacent aircraft centerlines must be between 1.1 and 1.5 wingspans, and the vertical spacings between -0.025 and -0.15 wingspans. Since the range of acceptable spacings is small, it is recommended that the position accuracy between aircraft in the formation be kept within about + or - 0.01 wingspan of the center of acceptable spacings so that aircraft meandering do not cause unwanted vortex excursions. It was also found that, if the in-trail spacings between adjacent aircraft are more than 4 wingspans, the foregoing vertical spacings must be adjusted to allow for the additional downward travel of the vortices shed by leading aircraft.

  15. Universities and Economic Development Activities: A UK Regional Comparison

    ERIC Educational Resources Information Center

    Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

    2011-01-01

    A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

  16. Integrin activation and focal complex formation in cardiac hypertrophy

    NASA Technical Reports Server (NTRS)

    Laser, M.; Willey, C. D.; Jiang, W.; Cooper, G. 4th; Menick, D. R.; Zile, M. R.; Kuppuswamy, D.

    2000-01-01

    Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

  17. Contrail formation in the tropopause region caused by emissions from an Ariane 5 rocket

    NASA Astrophysics Data System (ADS)

    Voigt, Ch.; Schumann, U.; Graf, K.

    2016-07-01

    Rockets directly inject water vapor and aerosol into the atmosphere, which promotes the formation of ice clouds in ice supersaturated layers of the atmosphere. Enhanced mesospheric cloud occurrence has frequently been detected near 80-kilometer altitude a few days after rocket launches. Here, unique evidence for cirrus formation in the tropopause region caused by ice nucleation in the exhaust plume from an Ariane 5-ECA rocket is presented. Meteorological reanalysis data from the European Centre for Medium-Range Weather Forecasts show significant ice supersaturation at the 100-hectopascal level in the American tropical tropopause region on November 26, 2011. Near 17-kilometer altitudes, the temperatures are below the Schmidt-Appleman threshold temperature for rocket condensation trail formation on that day. Immediately after the launch from the Ariane 5-ECA at 18:39 UT (universal time) from Kourou, French Guiana, the formation of a rocket contrail is detected in the high resolution visible channel from the SEVIRI (Spinning Enhanced Visible and InfraRed Imager) on the METEOSAT9 satellite. The rocket contrail is transported to the south and its dispersion is followed in SEVIRI data for almost 2 h. The ice crystals predominantly nucleated on aluminum oxide particles emitted by the Ariane 5-ECA solid booster and further grow by uptake of water vapor emitted from the cryogenic main stage and entrained from the ice supersaturated ambient atmosphere. After rocket launches, the formation of rocket contrails can be a frequent phenomenon under ice supersaturated conditions. However, at present launch rates, the global climate impact from rocket contrail cirrus in the tropopause region is small.

  18. Circular polarization in star-formation regions: implications for biomolecular homochirality.

    PubMed

    Bailey, J; Chrysostomou, A; Hough, J H; Gledhill, T M; McCall, A; Clark, S; Ménard, F; Tamura, M

    1998-07-31

    Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed. Circular polarization at shorter wavelengths might have been important in inducing chiral asymmetry in interstellar organic molecules that could be subsequently delivered to the early Earth by comets, interplanetary dust particles, or meteors. This could account for the excess of L-amino acids found in the Murchison meteorite and could explain the origin of the homochirality of biological molecules.

  19. Eruptions that Drive Coronal Jets in a Solar Active Region

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-01-01

    Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

  20. Star Formation Activity in CLASH Brightest Cluster Galaxies

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  1. SNAP-25 in hippocampal CA3 region is required for long-term memory formation

    SciTech Connect

    Hou Qiuling; Gao Xiang; Lu Qi; Zhang Xuehan; Tu Yanyang; Jin Meilei; Zhao Guoping; Yu Lei; Jing Naihe; Li Baoming . E-mail: bmli@fudan.edu.cn

    2006-09-08

    SNAP-25 is a synaptosomal protein of 25 kDa, a key component of synaptic vesicle-docking/fusion machinery, and plays a critical role in exocytosis and neurotransmitter release. We previously reported that SNAP-25 in the hippocampal CA1 region is involved in consolidation of contextual fear memory and water-maze spatial memory (Hou et al. European J Neuroscience, 20: 1593-1603, 2004). SNAP-25 is expressed not only in the CA1 region, but also in the CA3 region, and the SNAP-25 mRNA level in the CA3 region is higher than in the CA1 region. Here, we provide evidence that SNAP-25 in the CA3 region is also involved in learning/memory. Intra-CA3 infusion of SNAP-25 antisense oligonucleotide impaired both long-term contextual fear memory and water-maze spatial memory, with short-term memory intact. Furthermore, the SNAP-25 antisense oligonucleotide suppressed the long-term potentiation (LTP) of field excitatory post-synaptic potential (fEPSP) in the mossy-fiber pathway (DG-CA3 pathway), with no effect on paired-pulse facilitation of the fEPSP. These results are consistent with the notion that SNAP-25 in the hippocampal CA3 region is required for long-term memory formation.

  2. TARPs: Tracked Active Region Patches from SoHO/MDI

    NASA Astrophysics Data System (ADS)

    Turmon, M.; Hoeksema, J. T.; Bobra, M.

    2013-12-01

    We describe progress toward creating a retrospective MDI data product consisting of tracked magnetic features on the scale of solar active regions, abbreviated TARPs (Tracked Active Region Patches). The TARPs are being developed as a backward-looking extension (covering approximately 3500 regions spanning 1996-2010) to the HARP (HMI Active Region Patch) data product that has already been released for HMI (2010-present). Like the HARPs, the MDI TARP data set is designed to be a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. TARPs from MDI are computed based on the 96-minute synoptic magnetograms and pseudo-continuum intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that the faculae/sunspots are part of. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. The final data product is indexed by a nominal AR number and time. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Additionaly, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a calibration between the HMI and MDI magnetograms (Liu, Hoeksema et al. 2012), it is straightforward to use the same classification and tracking rules for the HARPs (from HMI) and the MDI TARPs. We anticipate that this will allow a consistent catalog spanning both instruments. We envision several uses for the TARP data product, which will be

  3. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    NASA Astrophysics Data System (ADS)

    Shan, Tzu-Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-01

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed by coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. The formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.

  4. Extended asymmetric hot region formation due to shockwave interactions following void collapse in shocked high explosive

    DOE PAGES

    Shan, Tzu -Ray; Wixom, Ryan R.; Thompson, Aidan P.

    2016-08-11

    In both continuum hydrodynamics simulations and also multimillion atom reactive molecular dynamics simulations of shockwave propagation in single crystal pentaerythritol tetranitrate (PETN) containing a cylindrical void, we observed the formation of an initial radially symmetric hot spot. By extending the simulation time to the nanosecond scale, however, we observed the transformation of the small symmetric hot spot into a longitudinally asymmetric hot region extending over a much larger volume. Performing reactive molecular dynamics shock simulations using the reactive force field (ReaxFF) as implemented in the LAMMPS molecular dynamics package, we showed that the longitudinally asymmetric hot region was formed bymore » coalescence of the primary radially symmetric hot spot with a secondary triangular hot zone. We showed that the triangular hot zone coincided with a double-shocked region where the primary planar shockwave was overtaken by a secondary cylindrical shockwave. The secondary cylindrical shockwave originated in void collapse after the primary planar shockwave had passed over the void. A similar phenomenon was observed in continuum hydrodynamics shock simulations using the CTH hydrodynamics package. Furthermore, the formation and growth of extended asymmetric hot regions on nanosecond timescales has important implications for shock initiation thresholds in energetic materials.« less

  5. Footpoint Separation and Evershed Flow of Active Regions

    NASA Astrophysics Data System (ADS)

    Norton, Aimee Ann; Jones, E. H.

    2012-05-01

    The bipolar nature of active regions and sunspot groups within the Sun’s photosphere is generally attributed to the emergence of magnetic flux tubes that originate from shear and turbulent pumping at the base of the Sun’s convection zone. There is debate, however, as to exactly how well-connected active regions are to solar interior. A connection to the solar interior during the ascent of a flux tube through the convection zone is a requirement within numerical models designed to describe the observed characteristics of active regions, e.g. Joy’s law tilt and latitude emergence, however, these models also predict post-emergence behavior of sunspots that is not supported observationally (Schussler and Rempel, 1995; Fan, 2009; Toth and Gerlei, 2003). It has been suggested (Rubio et al., 2008; Schussler and Rempel, 1995) that a bipolar magnetic region might lose its connection quickly upon emergence. Using data from SDO/HMI, we examine the footpoint separation and the Evershed flow of a number of active regions over time to detect the disconnection process of a sunspot from its magnetic roots.

  6. Characterization of the upstream region of the formate dehydrogenase operon of Methanobacterium formicicum.

    PubMed Central

    Patel, P S; Ferry, J G

    1988-01-01

    The fdhA and fdhB genes of Methanobacterium formicicum, which code for the alpha and beta subunits of formate dehydrogenase, were cotranscribed as part of a large transcript. By using Northern (RNA) gel blot analysis, the transcription start site was located within a 1.6-kilobase BglII-NcoI fragment 4.3 kilobases upstream from the fdhA gene. The precise transcription start site within the fragment was determined with the aid of primer extension analysis and S1 nuclease protection studies. A putative promoter sequence for structural genes of methanogenic archaebacteria is proposed based on a comparison of DNA sequences of the upstream region of methanogen operons for which transcription initiation sites are known. Comparison of the DNA sequence of the upstream region of the fdh operon of M. formicicum with the sequence upstream of the fdhF gene of Escherichia coli revealed regions of considerable identity. Images PMID:2457012

  7. Formation of Tankyrase Inhibitor-Induced Degradasomes Requires Proteasome Activity

    PubMed Central

    Pedersen, Nina Marie; Thorvaldsen, Tor Espen; Schultz, Sebastian Wolfgang; Wenzel, Eva Maria; Stenmark, Harald

    2016-01-01

    In canonical Wnt signaling, the protein levels of the key signaling mediator β-catenin are under tight regulation by the multimeric destruction complex that mediates proteasomal degradation of β-catenin. In colorectal cancer, destruction complex activity is often compromised due to mutations in the multifunctional scaffolding protein Adenomatous Polyposis Coli (APC), leading to a stabilization of β-catenin. Recently, tankyrase inhibitors (TNKSi), a novel class of small molecule inhibitors, were shown to re-establish a functional destruction complex in APC-mutant cancer cell lines by stabilizing AXIN1/2, whose protein levels are usually kept low via poly(ADP-ribosyl)ation by the tankyrase enzymes (TNKS1/2). Surprisingly, we found that for the formation of the morphological correlates of destruction complexes, called degradasomes, functional proteasomes are required. In addition we found that AXIN2 is strongly upregulated after 6 h of TNKS inhibition. The proteasome inhibitor MG132 counteracted TNKSi-induced degradasome formation and AXIN2 stabilization, and this was accompanied by reduced transcription of AXIN2. Mechanistically we could implicate the transcription factor FoxM1 in this process, which was recently shown to be a transcriptional activator of AXIN2. We observed a substantial reduction in TNKSi-induced stabilization of AXIN2 after siRNA-mediated depletion of FoxM1 and found that proteasome inhibition reduced the active (phosphorylated) fraction of FoxM1. This can explain the decreased protein levels of AXIN2 after MG132 treatment. Our findings have implications for the design of in vitro studies on the destruction complex and for clinical applications of TNKSi. PMID:27482906

  8. Blockade of mast cell activation reduces cutaneous scar formation.

    PubMed

    Chen, Lin; Schrementi, Megan E; Ranzer, Matthew J; Wilgus, Traci A; DiPietro, Luisa A

    2014-01-01

    Damage to the skin initiates a cascade of well-orchestrated events that ultimately leads to repair of the wound. The inflammatory response is key to wound healing both through preventing infection and stimulating proliferation and remodeling of the skin. Mast cells within the tissue are one of the first immune cells to respond to trauma, and upon activation they release pro-inflammatory molecules to initiate recruitment of leukocytes and promote a vascular response in the tissue. Additionally, mast cells stimulate collagen synthesis by dermal fibroblasts, suggesting they may also influence scar formation. To examine the contribution of mast cells in tissue repair, we determined the effects the mast cell inhibitor, disodium cromoglycate (DSCG), on several parameters of dermal repair including, inflammation, re-epithelialization, collagen fiber organization, collagen ultrastructure, scar width and wound breaking strength. Mice treated with DSCG had significantly reduced levels of the inflammatory cytokines IL-1α, IL-1β, and CXCL1. Although DSCG treatment reduced the production of inflammatory mediators, the rate of re-epithelialization was not affected. Compared to control, inhibition of mast cell activity caused a significant decrease in scar width along with accelerated collagen re-organization. Despite the reduced scar width, DSCG treatment did not affect the breaking strength of the healed tissue. Tryptase β1 exclusively produced by mast cells was found to increase significantly in the course of wound healing. However, DSCG treatment did not change its level in the wounds. These results indicate that blockade of mast cell activation reduces scar formation and inflammation without further weakening the healed wound.

  9. THz quantum cascade lasers with wafer bonded active regions.

    PubMed

    Brandstetter, M; Deutsch, C; Benz, A; Cole, G D; Detz, H; Andrews, A M; Schrenk, W; Strasser, G; Unterrainer, K

    2012-10-01

    We demonstrate terahertz quantum-cascade lasers with a 30 μm thick double-metal waveguide, which are fabricated by stacking two 15 μm thick active regions using a wafer bonding process. By increasing the active region thickness more optical power is generated inside the cavity, the waveguide losses are decreased and the far-field is improved due to a larger facet aperture. In this way the output power is increased by significantly more than a factor of 2 without reducing the maximum operating temperature and without increasing the threshold current.

  10. Kink Waves in an Active Region Dynamic Fibril

    NASA Astrophysics Data System (ADS)

    Pietarila, A.; Aznar Cuadrado, R.; Hirzberger, J.; Solanki, S. K.

    2011-10-01

    We present high spatial and temporal resolution Ca II 8542 Å observations of a kink wave in an on-disk chromospheric active region fibril. The properties of the wave are similar to those observed in off-limb spicules. From the observed phase and period of the wave we determine a lower limit for the field strength in the chromospheric active region fibril located at the edge of a sunspot to be a few hundred gauss. We find indications that the event was triggered by a small-scale reconnection event higher up in the atmosphere.

  11. Head formation: OTX2 regulates Dkk1 and Lhx1 activity in the anterior mesendoderm.

    PubMed

    Ip, Chi Kin; Fossat, Nicolas; Jones, Vanessa; Lamonerie, Thomas; Tam, Patrick P L

    2014-10-01

    The Otx2 gene encodes a paired-type homeobox transcription factor that is essential for the induction and the patterning of the anterior structures in the mouse embryo. Otx2 knockout embryos fail to form a head. Whereas previous studies have shown that Otx2 is required in the anterior visceral endoderm and the anterior neuroectoderm for head formation, its role in the anterior mesendoderm (AME) has not been assessed specifically. Here, we show that tissue-specific ablation of Otx2 in the AME phenocopies the truncation of the embryonic head of the Otx2 null mutant. Expression of Dkk1 and Lhx1, two genes that are also essential for head formation, is disrupted in the AME of the conditional Otx2-deficient embryos. Consistent with the fact that Dkk1 is a direct target of OTX2, we showed that OTX2 can interact with the H1 regulatory region of Dkk1 to activate its expression. Cross-species comparative analysis, RT-qPCR, ChIP-qPCR and luciferase assays have revealed two conserved regions in the Lhx1 locus to which OTX2 can bind to activate Lhx1 expression. Abnormal development of the embryonic head in Otx2;Lhx1 and Otx2;Dkk1 compound mutant embryos highlights the functional intersection of Otx2, Dkk1 and Lhx1 in the AME for head formation.

  12. Pattern Formation on Networks: from Localised Activity to Turing Patterns

    PubMed Central

    McCullen, Nick; Wagenknecht, Thomas

    2016-01-01

    Networks of interactions between competing species are used to model many complex systems, such as in genetics, evolutionary biology or sociology and knowledge of the patterns of activity they can exhibit is important for understanding their behaviour. The emergence of patterns on complex networks with reaction-diffusion dynamics is studied here, where node dynamics interact via diffusion via the network edges. Through the application of a generalisation of dynamical systems analysis this work reveals a fundamental connection between small-scale modes of activity on networks and localised pattern formation seen throughout science, such as solitons, breathers and localised buckling. The connection between solutions with a single and small numbers of activated nodes and the fully developed system-scale patterns are investigated computationally using numerical continuation methods. These techniques are also used to help reveal a much larger portion of of the full number of solutions that exist in the system at different parameter values. The importance of network structure is also highlighted, with a key role being played by nodes with a certain so-called optimal degree, on which the interaction between the reaction kinetics and the network structure organise the behaviour of the system. PMID:27273339

  13. Pattern Formation on Networks: from Localised Activity to Turing Patterns

    NASA Astrophysics Data System (ADS)

    McCullen, Nick; Wagenknecht, Thomas

    2016-06-01

    Networks of interactions between competing species are used to model many complex systems, such as in genetics, evolutionary biology or sociology and knowledge of the patterns of activity they can exhibit is important for understanding their behaviour. The emergence of patterns on complex networks with reaction-diffusion dynamics is studied here, where node dynamics interact via diffusion via the network edges. Through the application of a generalisation of dynamical systems analysis this work reveals a fundamental connection between small-scale modes of activity on networks and localised pattern formation seen throughout science, such as solitons, breathers and localised buckling. The connection between solutions with a single and small numbers of activated nodes and the fully developed system-scale patterns are investigated computationally using numerical continuation methods. These techniques are also used to help reveal a much larger portion of of the full number of solutions that exist in the system at different parameter values. The importance of network structure is also highlighted, with a key role being played by nodes with a certain so-called optimal degree, on which the interaction between the reaction kinetics and the network structure organise the behaviour of the system.

  14. Pattern Formation on Networks: from Localised Activity to Turing Patterns.

    PubMed

    McCullen, Nick; Wagenknecht, Thomas

    2016-01-01

    Networks of interactions between competing species are used to model many complex systems, such as in genetics, evolutionary biology or sociology and knowledge of the patterns of activity they can exhibit is important for understanding their behaviour. The emergence of patterns on complex networks with reaction-diffusion dynamics is studied here, where node dynamics interact via diffusion via the network edges. Through the application of a generalisation of dynamical systems analysis this work reveals a fundamental connection between small-scale modes of activity on networks and localised pattern formation seen throughout science, such as solitons, breathers and localised buckling. The connection between solutions with a single and small numbers of activated nodes and the fully developed system-scale patterns are investigated computationally using numerical continuation methods. These techniques are also used to help reveal a much larger portion of of the full number of solutions that exist in the system at different parameter values. The importance of network structure is also highlighted, with a key role being played by nodes with a certain so-called optimal degree, on which the interaction between the reaction kinetics and the network structure organise the behaviour of the system. PMID:27273339

  15. Chlorogenic Acid Inhibits Human Platelet Activation and Thrombus Formation

    PubMed Central

    Fuentes, Eduardo; Caballero, Julio; Alarcón, Marcelo; Rojas, Armando; Palomo, Iván

    2014-01-01

    Background Chlorogenic acid is a potent phenolic antioxidant. However, its effect on platelet aggregation, a critical factor in arterial thrombosis, remains unclear. Consequently, chlorogenic acid-action mechanisms in preventing platelet activation and thrombus formation were examined. Methods and Results Chlorogenic acid in a dose-dependent manner (0.1 to 1 mmol/L) inhibited platelet secretion and aggregation induced by ADP, collagen, arachidonic acid and TRAP-6, and diminished platelet firm adhesion/aggregation and platelet-leukocyte interactions under flow conditions. At these concentrations chlorogenic acid significantly decreased platelet inflammatory mediators (sP-selectin, sCD40L, CCL5 and IL-1β) and increased intraplatelet cAMP levels/PKA activation. Interestingly, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent A2A receptor antagonist) attenuated the antiplatelet effect of chlorogenic acid. Chlorogenic acid is compatible to the active site of the adenosine A2A receptor as revealed through molecular modeling. In addition, chlorogenic acid had a significantly lower effect on mouse bleeding time when compared to the same dose of aspirin. Conclusions Antiplatelet and antithrombotic effects of chlorogenic acid are associated with the A2A receptor/adenylate cyclase/cAMP/PKA signaling pathway. PMID:24598787

  16. Evolution of magmatic and hydrothermal activity in the western Arctic and North Atlantic regions

    NASA Astrophysics Data System (ADS)

    Sorokhtin, N. O.; Lobkovsky, L. I.; Novikov, G. V.; Kozlov, E. E.; Bogdanova, O. Yu.; Nikiforov, S. L.

    2016-07-01

    This paper discusses the geodynamic evolution of the lithosphere in the Arctic region during the Phaneorozic and its polyphase lithotectonic reorganization. Spatiotemporal patterns of the mosaic junction of lithospheric plates of different age are presented for the Caledonian-Hercynian stage and for the Cenozoic evolution of the North Atlantic and Arctic oceanic basins. Special attention is given to the intersections of fault systems with different kinematics, which control the manifestation of peculiar magmatism and the formation of numerous mineral deposits. It is shown that the hydrothermal activity of the region is related to the ocean opening in the Eocene and is confined to the mid-ocean ridge.

  17. 77 FR 75198 - Standard Format and Content for Post-Shutdown Decommissioning Activities Report

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-19

    ... COMMISSION Standard Format and Content for Post-Shutdown Decommissioning Activities Report AGENCY: Nuclear... Format and Content for Post-shutdown Decommissioning Activities Report.'' This guide describes a method...) 1.185, ``Standard Format and Content for Post-shutdown Decommissioning Activities Report,''...

  18. Socioeconomic and regional differences in active transportation in Brazil

    PubMed Central

    de Sá, Thiago Hérick; Pereira, Rafael Henrique Moraes; Duran, Ana Clara; Monteiro, Carlos Augusto

    2016-01-01

    ABSTRACT OBJECTIVE To present national estimates regarding walking or cycling for commuting in Brazil and in 10 metropolitan regions. METHODS By using data from the Health section of 2008’s Pesquisa Nacional por Amostra de Domicílio (Brazil’s National Household Sample Survey), we estimated how often employed people walk or cycle to work, disaggregating our results by sex, age range, education level, household monthly income per capita, urban or rural address, metropolitan regions, and macro-regions in Brazil. Furthermore, we estimated the distribution of this same frequency according to quintiles of household monthly income per capita in each metropolitan region of the country. RESULTS A third of the employed men and women walk or cycle from home to work in Brazil. For both sexes, this share decreases as income and education levels rise, and it is higher among younger individuals, especially among those living in rural areas and in the Northeast region of the country. Depending on the metropolitan region, the practice of active transportation is two to five times more frequent among low-income individuals than among high-income individuals. CONCLUSIONS Walking or cycling to work in Brazil is most frequent among low-income individuals and the ones living in less economically developed areas. Active transportation evaluation in Brazil provides important information for public health and urban mobility policy-making PMID:27355465

  19. THE STAR-FORMATION RELATION FOR REGIONS IN THE GALACTIC PLANE: THE EFFECT OF SPATIAL RESOLUTION

    SciTech Connect

    Vutisalchavakul, Nalin; Evans II, Neal J.; Battersby, Cara

    2014-12-20

    We examined the relations between molecular gas surface density and star-formation rate surface density in an 11 deg{sup 2} region of the Galactic plane. Dust continua at 1.1 mm from the Bolocam Galactic Plane Survey and 22 μm emission from the Wide-field Infrared Survey Explorer (WISE) all-sky survey were used as tracers of molecular gas and the star-formation rate, respectively, across the Galactic longitude of 31.5 ≥ l ≥ 20.5 and Galactic latitude of 0.5 ≥ b ≥ –0.5. The relation was studied over a range of resolutions from 33'' to 20' by convolving images to larger scales. The pixel-by-pixel correlation between 1.1 mm and 22 μm increases rapidly at small scales and levels off at the scale of 5'-8'. We studied the star-formation relation based on a pixel-by-pixel analysis and on an analysis of the 1.1 mm and 22 μm peaks. The star-formation relation was found to be nearly linear with no significant changes in the form of the relation across all spatial scales, and it lies above the extragalactic relation from Kennicutt. The average gas-depletion time is ≈200 Myr and does not change significantly at different scales, but the scatter in the depletion time decreases as the scale increases.

  20. Intense star formation within resolved compact regions in a galaxy at z = 2.3.

    PubMed

    Swinbank, A M; Smail, I; Longmore, S; Harris, A I; Baker, A J; De Breuck, C; Richard, J; Edge, A C; Ivison, R J; Blundell, R; Coppin, K E K; Cox, P; Gurwell, M; Hainline, L J; Krips, M; Lundgren, A; Neri, R; Siana, B; Siringo, G; Stark, D P; Wilner, D; Younger, J D

    2010-04-01

    Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimetre wavelengths and which may be forming stars at a rate of 1,000 solar masses (M(middle dot in circle)) per year. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies. Probing the properties of individual star-forming regions within these galaxies, however, is beyond the spatial resolution and sensitivity of even the largest telescopes at present. Here we report observations of the sub-millimetre galaxy SMMJ2135-0102 at redshift z = 2.3259, which has been gravitationally magnified by a factor of 32 by a massive foreground galaxy cluster lens. This magnification, when combined with high-resolution sub-millimetre imaging, resolves the star-forming regions at a linear scale of only 100 parsecs. We find that the luminosity densities of these star-forming regions are comparable to the dense cores of giant molecular clouds in the local Universe, but they are about a hundred times larger and 10(7) times more luminous. Although vigorously star-forming, the underlying physics of the star-formation processes at z approximately 2 appears to be similar to that seen in local galaxies, although the energetics are unlike anything found in the present-day Universe.

  1. IFLA General Conference, 1989. Division of Regional Activities. Section on Regional Activities--Africa; Section on Regional Activities--Asia and Oceania; Section on Regional Activities--Latin America and the Caribbean. Booklet 80.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    There are five papers in this collection from the Division of Regional Activities: (1) "Communication and Information in Contemporary African Society" (Bimpe Aboyade), which discusses how libraries can make themselves relevant to other institutions concerned with information transfer; (2) "Libraries and Rural Development: Village Reading Rooms in…

  2. Inferred flows of electric currents in solar active regions

    NASA Technical Reports Server (NTRS)

    Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.

    1985-01-01

    Techniques to identify sources of major current systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the current systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and currents are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral filaments were the source of vertical currents at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong current system flowed; (3) The inferred current systems produced a neutral sheet and oppositely-flowing currents in the area of the magnetic delta configuration that was the site of flaring.

  3. IFLA General Conference, 1987. Division of Regional Activities. Papers.

    ERIC Educational Resources Information Center

    International Federation of Library Associations, The Hague (Netherlands).

    Six of the seven papers in this collection focus on regional library activities in Africa, Asia and Oceania, and Latin America and the Caribbean: (1) "Libraries and Information Services in a Changing World: The Challenges African Information Services Face at the End of the 1980s" (Dejen Abate, Ethiopia); (2) "The Computer and Knowledge Information…

  4. Urban, Rural, and Regional Variations in Physical Activity

    ERIC Educational Resources Information Center

    Martin, Sarah Levin; Kirkner, Gregory J.; Mayo, Kelly; Matthews, Charles E.; Durstine, J. Larry; Hebert, James R.

    2005-01-01

    Purpose: There is some speculation about geographic differences in physical activity (PA) levels. We examined the prevalence of physical inactivity (PIA) and whether US citizens met the recommended levels of PA across the United States. In addition, the association between PIA/PA and degree of urbanization in the 4 main US regions (Northeast,…

  5. Early life stress affects limited regional brain activity in depression.

    PubMed

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-05-03

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients.

  6. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  7. Unwinding motion of a twisted active region filament

    SciTech Connect

    Yan, X. L.; Xue, Z. K.; Kong, D. F.; Liu, J. H.; Xu, C. L.

    2014-12-10

    To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

  8. Early life stress affects limited regional brain activity in depression

    PubMed Central

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-01-01

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients. PMID:27138376

  9. Common regulatory control of CTP synthase enzyme activity and filament formation

    PubMed Central

    Noree, Chalongrat; Monfort, Elena; Shiau, Andrew K.; Wilhelm, James E.

    2014-01-01

    The ability of enzymes to assemble into visible supramolecular complexes is a widespread phenomenon. Such complexes have been hypothesized to play a number of roles; however, little is known about how the regulation of enzyme activity is coupled to the assembly/disassembly of these cellular structures. CTP synthase is an ideal model system for addressing this question because its activity is regulated via multiple mechanisms and its filament-forming ability is evolutionarily conserved. Our structure–function studies of CTP synthase in Saccharomyces cerevisiae reveal that destabilization of the active tetrameric form of the enzyme increases filament formation, suggesting that the filaments comprise inactive CTP synthase dimers. Furthermore, the sites responsible for feedback inhibition and allosteric activation control filament length, implying that multiple regions of the enzyme can influence filament structure. In contrast, blocking catalysis without disrupting the regulatory sites of the enzyme does not affect filament formation or length. Together our results argue that the regulatory sites that control CTP synthase function, but not enzymatic activity per se, are critical for controlling filament assembly. We predict that the ability of enzymes to form supramolecular structures in general is closely coupled to the mechanisms that regulate their activity. PMID:24920825

  10. Quaternary North Atlantic Surface Paleoceanography in Regions of Potential Deep-water Formation

    NASA Technical Reports Server (NTRS)

    Ruddiman, W. F.

    1984-01-01

    At the time scale of the Quaternary climate cycles, the sites of formation of North Atlantic Deep Water are not known. The interglacial extreme is presumably exemplified by the modern regions; the Norwegian, Greenland and Labrador Seas. During the major glacial-age coolings in the North Atlantic, the sites may have shifted well to the south, perhaps as far as the limit of the polar front at 40 to 50 N. Still other sites may have been important during intermediate climatic conditions. Because of the close coupling of high-latitude surface waters to North Atlantic Deep Water in the modern ocean, the history of sea-surface temperature (SST) oscillations across the high-latitude North Atlantic is relevant to an understanding of deep-water formation on the longer time scales.

  11. Evolution of two Flaring Active Regions With CME Association

    NASA Astrophysics Data System (ADS)

    Thalmann, J. K.; Wiegelmann, T.

    2008-12-01

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

  12. A conserved motif mediates both multimer formation and allosteric activation of phosphoglycerate mutase 5.

    PubMed

    Wilkins, Jordan M; McConnell, Cyrus; Tipton, Peter A; Hannink, Mark

    2014-09-01

    Phosphoglycerate mutase 5 (PGAM5) is an atypical mitochondrial Ser/Thr phosphatase that modulates mitochondrial dynamics and participates in both apoptotic and necrotic cell death. The mechanisms that regulate the phosphatase activity of PGAM5 are poorly understood. The C-terminal phosphoglycerate mutase domain of PGAM5 shares homology with the catalytic domains found in other members of the phosphoglycerate mutase family, including a conserved histidine that is absolutely required for catalytic activity. However, this conserved domain is not sufficient for maximal phosphatase activity. We have identified a highly conserved amino acid motif, WDXNWD, located within the unique N-terminal region, which is required for assembly of PGAM5 into large multimeric complexes. Alanine substitutions within the WDXNWD motif abolish the formation of multimeric complexes and markedly reduce phosphatase activity of PGAM5. A peptide containing the WDXNWD motif dissociates the multimeric complex and reduces but does not fully abolish phosphatase activity. Addition of the WDXNWD-containing peptide in trans to a mutant PGAM5 protein lacking the WDXNWD motif markedly increases phosphatase activity of the mutant protein. Our results are consistent with an intermolecular allosteric regulation mechanism for the phosphatase activity of PGAM5, in which the assembly of PGAM5 into multimeric complexes, mediated by the WDXNWD motif, results in maximal activation of phosphatase activity. Our results suggest the possibility of identifying small molecules that function as allosteric regulators of the phosphatase activity of PGAM5. PMID:25012655

  13. The Impact of Oil and Natural Gas Activity on Ozone Formation in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hornbrook, R. S.; Apel, E. C.; Hills, A. J.; Blake, D. R.; Blake, N. J.; Schroeder, J.; Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Mauldin, L.; Cantrell, C. A.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Montzka, D.; Orlando, J. J.; Tyndall, G. S.; Campos, T. L.; Stell, M. H.; Heikes, B.; Treadaway, V.; O'Sullivan, D. W.; Huey, L. G.; Tanner, D.; Cohen, R. C.; Flocke, F. M.; Pfister, G.; Knote, C. J.; Emmons, L. K.

    2014-12-01

    The 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPE) was a ground-based and airborne field study designed to characterize and understand air quality in the Colorado Front Range, where National Ambient Air Quality Standards (NAAQS) ozone levels are frequently exceeded during summertime. A primary goal of the study was to determine the factors controlling surface ozone in the Front Range. As part of the project, measurements of many trace gases were observed on board the NSF/NCAR C-130 by a suite of instrumentation, including the NCAR Trace Organic Gas Analyzer (TOGA), which made measurements of a set of volatile organic compounds (VOCs). VOCs are crucial for characterizing emissions and photochemical processing in the Front Range, as well as the air transported into the region. During recent years, oil and natural gas (O&NG) activity in the Front Range has been growing rapidly. Ratios of observed aromatic hydrocarbons, butanes and pentanes demonstrate distinct fingerprinting that can be used to distinguish both between different types of O&NG activities and between O&NG extraction regions in the FRAPPE study region and beyond. Using the observed hydrocarbon data along with other trace gas observations, we will compare contributions of O&NG emissions to OH reactivities in different regions in the Front Range, and present box model results demonstrating the impact of O&NG activities on ozone formation.

  14. The Impact of Oil and Natural Gas Activity on Ozone Formation in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hornbrook, R. S.; Apel, E. C.; Hills, A. J.; Blake, D. R.; Blake, N. J.; Schroeder, J.; Fried, A.; Weibring, P.; Richter, D.; Walega, J.; Mauldin, L.; Cantrell, C. A.; Hall, S. R.; Ullmann, K.; Weinheimer, A. J.; Montzka, D.; Orlando, J. J.; Tyndall, G. S.; Campos, T. L.; Stell, M. H.; Heikes, B.; Treadaway, V.; O'Sullivan, D. W.; Huey, L. G.; Tanner, D.; Cohen, R. C.; Flocke, F. M.; Pfister, G.; Knote, C. J.; Emmons, L. K.

    2015-12-01

    The 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPE) was a ground-based and airborne field study designed to characterize and understand air quality in the Colorado Front Range, where National Ambient Air Quality Standards (NAAQS) ozone levels are frequently exceeded during summertime. A primary goal of the study was to determine the factors controlling surface ozone in the Front Range. As part of the project, measurements of many trace gases were observed on board the NSF/NCAR C-130 by a suite of instrumentation, including the NCAR Trace Organic Gas Analyzer (TOGA), which made measurements of a set of volatile organic compounds (VOCs). VOCs are crucial for characterizing emissions and photochemical processing in the Front Range, as well as the air transported into the region. During recent years, oil and natural gas (O&NG) activity in the Front Range has been growing rapidly. Ratios of observed aromatic hydrocarbons, butanes and pentanes demonstrate distinct fingerprinting that can be used to distinguish both between different types of O&NG activities and between O&NG extraction regions in the FRAPPE study region and beyond. Using the observed hydrocarbon data along with other trace gas observations, we will compare contributions of O&NG emissions to OH reactivities in different regions in the Front Range, and present box model results demonstrating the impact of O&NG activities on ozone formation.

  15. Depositional facies of the Cambrian Araba Formation in the Taba region, east Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    El-Araby, A.; Abdel-Motelib, A.

    1999-10-01

    A thick succession of Cambrian sediments is exposed in the Taba region, east Sinai, and subdivided into the Araba Formation and the overlying Naqus Formation. The vertical and lateral distribution of the Araba Formation in the Taba region provides an outstanding example of an overall retrograding sequence. Three distinctive units (I, II and III) are distinguished within this succession on the basis of depositional geometries, stratified patterns, sedimentary features and petrographic examinations. They record different depositional environments and each unit is distinguished by a particular facies association, which records processes characteristic of these environments. The lower unit (I) is dominated by five depositional facies (la-le) which belong to low sinuosity braided channels associated with floodplain fines and alluvial fans. Channel deposits are represented by tabular cross-bedded and horizontally stratified pebbly coarse-grained sandstones. The middle unit (II) reveals a relative sea level rise and is composed of fine- to coarse-grained sandstone, shale and mudstone with carbonate intercalcations. From four depositional facies (Ila-Ild), recognised facies (Ila, Ilc and Ild) are comparable to upper-lower shoreface and tidal channel environments. The fourth facies (Ilb) is carbonate-dominated with trilobite tracks, and reflects deposition in the upper-middle intertidal flat. The latter facies (llb) is subjected to intea-Cambrian karstification, which is deduced from the presence of macro- and microscopic fresh water calcite fillings, botryoidal Fe and Mn oxides and terra rossa. The uppermost unit (III) is shale-dominated from the inner shelf and is represented by two facies (Illa and Illb). Despite the general rise in sea-level in the Araba Formation, the uppermost facies (Illb) points to a progradational-upward tendency in unit (III), and this is coeval with an increase in the percentage of interbedded fine-grained sandstones.

  16. Regional differences in rat conjunctival ion transport activities

    PubMed Central

    Yu, Dongfang; Thelin, William R.; Rogers, Troy D.; Stutts, M. Jackson; Randell, Scott H.; Grubb, Barbara R.

    2012-01-01

    Active ion transport and coupled osmotic water flow are essential to maintain ocular surface health. We investigated regional differences in the ion transport activities of the rat conjunctivas and compared these activities with those of cornea and lacrimal gland. The epithelial sodium channel (ENaC), sodium/glucose cotransporter 1 (Slc5a1), transmembrane protein 16 (Tmem16a, b, f, and g), cystic fibrosis transmembrane conductance regulator (Cftr), and mucin (Muc4, 5ac, and 5b) mRNA expression was characterized by RT-PCR. ENaC proteins were measured by Western blot. Prespecified regions (palpebral, fornical, and bulbar) of freshly isolated conjunctival tissues and cell cultures were studied electrophysiologically with Ussing chambers. The transepithelial electrical potential difference (PD) of the ocular surface was also measured in vivo. The effect of amiloride and UTP on the tear volume was evaluated in lacrimal gland excised rats. All selected genes were detected but with different expression patterns. We detected αENaC protein in all tissues, βENaC in palpebral and fornical conjunctiva, and γENaC in all tissues except lacrimal glands. Electrophysiological studies of conjunctival tissues and cell cultures identified functional ENaC, SLC5A1, CFTR, and TMEM16. Fornical conjunctiva exhibited the most active ion transport under basal conditions amongst conjunctival regions. PD measurements confirmed functional ENaC-mediated Na+ transport on the ocular surface. Amiloride and UTP increased tear volume in lacrimal gland excised rats. This study demonstrated that the different regions of the conjunctiva exhibited a spectrum of ion transport activities. Understanding the specific functions of distinct regions of the conjunctiva may foster a better understanding of the physiology maintaining hydration of the ocular surface. PMID:22814399

  17. Formation of proteasome-PA700 complexes directly correlates with activation of peptidase activity.

    PubMed

    Adams, G M; Crotchett, B; Slaughter, C A; DeMartino, G N; Gogol, E P

    1998-09-15

    The proteolytic activity of the eukaryotic 20S proteasome is stimulated by a multisubunit activator, PA700, which forms both 1:1 and 2:1 complexes with the proteasome. Formation of the complexes is enhanced by an additional protein assembly called modulator, which also stimulates the enzymatic activity of the proteasome only in the presence of PA700. Here we show that the binding of PA700 to the proteasome is cooperative, as is the activation of the proteasome's intrinsic peptidase activity. Modulator increases the extent of complex formation and peptidase activation, while preserving the cooperative kinetics. Furthermore, the increase in activity is not linear with the number of PA700 assemblies bound to the proteasome, but rather with the number of proteasome-PA700 complexes, regardless of the PA700:proteasome stoichiometry. Hence the stimulation of peptidase activity is fully (or almost fully) effected by the binding of a single PA700 to the 20S proteasome. The stimulation of peptidase by modulator is explained entirely by the increased number of proteasome-PA700 complexes formed in its presence, rather than by any substantial direct stimulation of catalysis. These observations are consistent with a model in which PA700, either alone or assisted by modulator, promotes conformational changes in the proteasome that activate the catalytic sites and/or facilitate access of peptide substrates to these sites. PMID:9737872

  18. Active sonar, beaked whales and European regional policy.

    PubMed

    Dolman, Sarah J; Evans, Peter G H; Notarbartolo-di-Sciara, Giuseppe; Frisch, Heidrun

    2011-01-01

    Various reviews, resolutions and guidance from international and regional fora have been produced in recent years that acknowledge the significance of marine noise and its potential impacts on cetaceans. Within Europe, ACCOBAMS and ASCOBANS have shown increasing attention to the issue. The literature highlights concerns surrounding the negative impacts of active sonar on beaked whales in particular, where concerns primarily relate to the use of mid-frequency active sonar (1-10kHz), as used particularly in military exercises. The authors review the efforts that European regional policies have undertaken to acknowledge and manage possible negative impacts of active sonar and how these might assist the transition from scientific research to policy implementation, including effective management and mitigation measures at a national level.

  19. Circular polarization in star-formation regions: implications for biomolecular homochirality.

    PubMed

    Bailey, J; Chrysostomou, A; Hough, J H; Gledhill, T M; McCall, A; Clark, S; Ménard, F; Tamura, M

    1998-07-31

    Strong infrared circular polarization resulting from dust scattering in reflection nebulae in the Orion OMC-1 star-formation region has been observed. Circular polarization at shorter wavelengths might have been important in inducing chiral asymmetry in interstellar organic molecules that could be subsequently delivered to the early Earth by comets, interplanetary dust particles, or meteors. This could account for the excess of L-amino acids found in the Murchison meteorite and could explain the origin of the homochirality of biological molecules. PMID:9714676

  20. UV circular polarisation in star formation regions: the origin of homochirality?

    PubMed

    Lucas, P W; Hough, J H; Bailey, Jeremy; Chrysostomou, Antonio; Gledhill, T M; McCall, Alan

    2005-02-01

    Ultraviolet circularly polarised light has been suggested as the initial cause of the homochirality of organic molecules in terrestrial organisms, via enantiomeric selection of prebiotic molecules by asymmetric photolysis. We present a theoretical investigation of mechanisms by which ultraviolet circular polarisation may be produced in star formation regions. In the scenarios considered here, light scattering produces only a small percentage of net circular polarisation at any point in space, due to the forward throwing nature of the phase function in the ultraviolet. By contrast, dichroic extinction can produce a fairly high percentage of net circular polarisation ( approximately 10%) and may therefore play a key role in producing an enantiomeric excess.

  1. Patterns of Activity Revealed by a Time Lag Analysis of a Model Active Region

    NASA Astrophysics Data System (ADS)

    Bradshaw, Stephen; Viall, Nicholeen

    2016-05-01

    We investigate the global activity patterns predicted from a model active region heated by distributions of nanoflares that have a range of average frequencies. The activity patterns are manifested in time lag maps of narrow-band instrument channel pairs. We combine an extrapolated magnetic skeleton with hydrodynamic and forward modeling codes to create a model active region, and apply the time lag method to synthetic observations. Our aim is to recover some typical properties and patterns of activity observed in active regions. Our key findings are: 1. Cooling dominates the time lag signature and the time lags between the channel pairs are generally consistent with observed values. 2. Shorter coronal loops in the core cool more quickly than longer loops at the periphery. 3. All channel pairs show zero time lag when the line-of-sight passes through coronal loop foot-points. 4. There is strong evidence that plasma must be re-energized on a time scale comparable to the cooling timescale to reproduce the observed coronal activity, but it is likely that a relatively broad spectrum of heating frequencies operates across active regions. 5. Due to their highly dynamic nature, we find nanoflare trains produce zero time lags along entire flux tubes in our model active region that are seen between the same channel pairs in observed active regions.

  2. Formation of Golgi-derived active zone precursor vesicles.

    PubMed

    Maas, Christoph; Torres, Viviana I; Altrock, Wilko D; Leal-Ortiz, Sergio; Wagh, Dhananjay; Terry-Lorenzo, Ryan T; Fejtova, Anna; Gundelfinger, Eckart D; Ziv, Noam E; Garner, Craig C

    2012-08-01

    Vesicular trafficking of presynaptic and postsynaptic components is emerging as a general cellular mechanism for the delivery of scaffold proteins, ion channels, and receptors to nascent and mature synapses. However, the molecular mechanisms leading to the selection of cargos and their differential transport to subneuronal compartments are not well understood, in part because of the mixing of cargos at the plasma membrane and/or within endosomal compartments. In the present study, we have explored the cellular mechanisms of active zone precursor vesicle assembly at the Golgi in dissociated hippocampal neurons of Rattus norvegicus. Our studies show that Piccolo, Bassoon, and ELKS2/CAST exit the trans-Golgi network on a common vesicle that requires Piccolo and Bassoon for its proper assembly. In contrast, Munc13 and synaptic vesicle proteins use distinct sets of Golgi-derived transport vesicles, while RIM1α associates with vesicular membranes in a post-Golgi compartment. Furthermore, Piccolo and Bassoon are necessary for ELKS2/CAST to leave the Golgi in association with vesicles, and a core domain of Bassoon is sufficient to facilitate formation of these vesicles. While these findings support emerging principles regarding active zone differentiation, the cellular and molecular analyses reported here also indicate that the Piccolo-Bassoon transport vesicles leaving the Golgi may undergo further changes in protein composition before arriving at synaptic sites.

  3. Hot flow anomaly formation by magnetic deflection. [regions of hot plasma in earth magnetosphere

    NASA Technical Reports Server (NTRS)

    Onsager, T. G.; Thomsen, M. F.; Winske, D.

    1990-01-01

    Hot flow anomalies (HFAs) are localized plasma structures observed in the solar wind and magnetosheath near the earth's quasi-parallel bow shock. This paper presents one-dimensional hybrid computer simulations illustrating a formation mechanism for HFAs in which the single hot ion population results from a spatial separation of two counterstreaming ion beams. The higher-density cooler regions are dominated by the background (solar wind) ions, and the lower-density hotter internal regions are dominated by the beam ions. The spatial separation of the beam and background is caused by the deflection of the ions in large-amplitude magnetic fields which are generated by ion/ion streaming instabilities.

  4. Risk Assessment of Geologic Formation Sequestration in The Rocky Mountain Region, USA

    SciTech Connect

    Lee, Si-Yong; McPherson, Brian

    2013-08-01

    The purpose of this report is to describe the outcome of a targeted risk assessment of a candidate geologic sequestration site in the Rocky Mountain region of the USA. Specifically, a major goal of the probabilistic risk assessment was to quantify the possible spatiotemporal responses for Area of Review (AoR) and injection-induced pressure buildup associated with carbon dioxide (CO₂) injection into the subsurface. Because of the computational expense of a conventional Monte Carlo approach, especially given the likely uncertainties in model parameters, we applied a response surface method for probabilistic risk assessment of geologic CO₂ storage in the Permo-Penn Weber formation at a potential CCS site in Craig, Colorado. A site-specific aquifer model was built for the numerical simulation based on a regional geologic model.

  5. On the formation and destruction of chlorine negative ions in the D region

    NASA Technical Reports Server (NTRS)

    Turco, R. P.

    1977-01-01

    We have investigated the possible reactions of chlorine atoms, chlorine monoxide, and hydrogen chloride with D region negative ions. The mesospheric concentrations of the neutral chlorine gases have been predicted with a diurnally varying one-dimensional model of the upper atmosphere. Despite the low abundances of chlorine compounds in air their high reactivity leads to the formation of substantial quantities of clorine negative ions at high altitudes. The concentration of chlorine ions is limited in daylight by rapid reactions with oxygen and hydrogen atoms and at night by the competitive production of other stable ions. The presence of chlorine negative ions in the upper atmosphere is consistent with in situ mass spectrometer observations of charged species. The abundance of chlorinated ions in the D region may be correlated with mesospheric nitric oxide and water vapor concentrations.

  6. DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

    SciTech Connect

    Jain, Kiran; Tripathy, S. C.; Hill, F. E-mail: stripathy@nso.edu

    2015-07-20

    We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

  7. THE EVOLUTION OF DARK CANOPIES AROUND ACTIVE REGIONS

    SciTech Connect

    Wang, Y.-M.; Robbrecht, E.; Muglach, K. E-mail: eva.robbrecht@oma.be

    2011-05-20

    As observed in spectral lines originating from the chromosphere, transition region, and low corona, active regions are surrounded by an extensive 'circumfacular' area which is darker than the quiet Sun. We examine the properties of these dark moat- or canopy-like areas using Fe IX 17.1 nm images and line-of-sight magnetograms from the Solar Dynamics Observatory. The 17.1 nm canopies consist of fibrils (horizontal fields containing extreme-ultraviolet-absorbing chromospheric material) clumped into featherlike structures. The dark fibrils initially form a quasiradial or vortical pattern as the low-lying field lines fanning out from the emerging active region connect to surrounding network and intranetwork elements of opposite polarity. The area occupied by the 17.1 nm fibrils expands as supergranular convection causes the active-region flux to spread into the background medium; the outer boundary of the dark canopy stabilizes where the diffusing flux encounters a unipolar region of opposite sign. The dark fibrils tend to accumulate in regions of weak longitudinal field and to become rooted in mixed-polarity flux. To explain the latter observation, we note that the low-lying fibrils are more likely to interact with small loops associated with weak, opposite-polarity flux elements in close proximity, than with high loops anchored inside strong unipolar network flux. As a result, the 17.1 nm fibrils gradually become concentrated around the large-scale polarity inversion lines (PILs), where most of the mixed-polarity flux is located. Systematic flux cancellation, assisted by rotational shearing, removes the field component transverse to the PIL and causes the fibrils to coalesce into long PIL-aligned filaments.

  8. Carma Large Area Star Formation Survey: Dense Gas in the Young L1451 Region of Perseus

    NASA Astrophysics Data System (ADS)

    Storm, Shaye; Mundy, Lee G.; Lee, Katherine I.; Fernández-López, Manuel; Looney, Leslie W.; Teuben, Peter; Arce, Héctor G.; Rosolowsky, Erik W.; Meisner, Aaron M.; Isella, Andrea; Kauffmann, Jens; Shirley, Yancy L.; Kwon, Woojin; Plunkett, Adele L.; Pound, Marc W.; Segura-Cox, Dominique M.; Tassis, Konstantinos; Tobin, John J.; Volgenau, Nikolaus H.; Crutcher, Richard M.; Testi, Leonardo

    2016-10-01

    We present a 3 mm spectral line and continuum survey of L1451 in the Perseus Molecular Cloud. These observations are from the CARMA Large Area Star Formation Survey (CLASSy), which also imaged Barnard 1, NGC 1333, Serpens Main, and Serpens South. L1451 is the survey region with the lowest level of star formation activity—it contains no confirmed protostars. HCO+, HCN, and N2H+ (J=1\\to 0) are all detected throughout the region, with HCO+ being the most spatially widespread, and molecular emission seen toward 90% of the area above N(H2) column densities of 1.9 × 1021 cm‑2. HCO+ has the broadest velocity dispersion, near 0.3 km s‑1 on average, compared with ∼0.15 km s‑1 for the other molecules, thus representing a range of subsonic to supersonic gas motions. Our non-binary dendrogram analysis reveals that the dense gas traced by each molecule has a similar hierarchical structure, and that gas surrounding the candidate first hydrostatic core (FHSC), L1451-mm, and other previously detected single-dish continuum clumps has similar hierarchical structure; this suggests that different subregions of L1451 are fragmenting on the pathway to forming young stars. We determined that the three-dimensional morphology of the largest detectable dense-gas structures was relatively ellipsoidal compared with other CLASSy regions, which appeared more flattened at the largest scales. A virial analysis shows that the most centrally condensed dust structures are likely unstable against collapse. Additionally, we identify a new spherical, centrally condensed N2H+ feature that could be a new FHSC candidate. The overall results suggest that L1451 is a young region starting to form its generation of stars within turbulent, hierarchical structures.

  9. Formation of double sheaths and the J-V characteristics of the obstructed region

    SciTech Connect

    Wang, C.C.

    1980-06-01

    The arc drop of the vapor thermionic converter is determined by the difference of sheath heights and the potential difference across the plasma. The J-V characteristics of cesium vapor diodes operating in the ignited mode show a knee corresponding to near optimum power. When the diode is operating in the region above the knee, the dominant contributor to the arc drop is the difference of the sheath heights (i.e., the potential difference across the plasma produces either a very small loss or may, in fact, reverse sign and reduce the arc drop). In this region the power decreases because the increase in output current is usually not able to compensate for the loss of output voltage. When the diode is operating in the region below the knee, the potential difference in the plasma becomes the dominant contributor to the arc drop. For these reasons, the shape of the J-V characteristics below the knee is different from that above the knee. The location of the knee is a good indicator of the maximum power and the maximum efficiency points. Under the fully optimized conditions, the knee also indicates the barrier index of the diode. Therefore, how and where the knee will appear is of great theoretical and practical interest. Some workers in the thermionic field have speculated that the appearance of the knee is due to the formation of the double sheath. However, this study indicates that the formation of the double sheath takes place significantly below the knee. In addition, this study evaluates J-V characteristics in the obstructed region.

  10. Fine thermal structure of a coronal active region.

    PubMed

    Reale, Fabio; Parenti, Susanna; Reeves, Kathy K; Weber, Mark; Bobra, Monica G; Barbera, Marco; Kano, Ryouhei; Narukage, Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon

    2007-12-01

    The determination of the fine thermal structure of the solar corona is fundamental to constraining the coronal heating mechanisms. The Hinode X-ray Telescope collected images of the solar corona in different passbands, thus providing temperature diagnostics through energy ratios. By combining different filters to optimize the signal-to-noise ratio, we observed a coronal active region in five filters, revealing a highly thermally structured corona: very fine structures in the core of the region and on a larger scale further away. We observed continuous thermal distribution along the coronal loops, as well as entangled structures, and variations of thermal structuring along the line of sight.

  11. Armenia as a Regional Centre for Astronomy for Development activities

    NASA Astrophysics Data System (ADS)

    Mickaelian, A.

    2015-03-01

    The Byurakan Astrophysical Observatory (BAO, Armenia, http://www.bao.am) are among the candidate IAU Regional Nodes for Astronomy for Development activities. It is one of the main astronomical centers of the former Soviet Union and the Middle East region. At present there are 48 qualified researchers at BAO, including six Doctors of Science and 30 PhDs. Five important observational instruments are installed at BAO, the larger ones being 2.6m Cassegrain (ZTA-2.6) and 1m Schmidt (the one that provided the famous Markarian survey). BAO is regarded as a national scientific-educational center, where a number of activities are being organized, such as: international conferences (4 IAU symposia and 1 IAU colloquium, JENAM-2007, etc.), small workshops and discussions, international summer schools (1987, 2006, 2008 and 2010), and Olympiads. BAO collaborates with scientists from many countries. The Armenian Astronomical Society (ArAS, http://www.aras.am/) is an NGO founded in 2001; it has 93 members and it is rather active in the organization of educational, amateur, popular, promotional and other matters. The Armenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) is one of the 17 national VO projects forming the International Virtual Observatories Alliance (IVOA) and is the only VO project in the region serving also for educational purposes. A number of activities are planned, such as management, coordination and evaluation of the IAU programs in the area of development and education, establishment of the new IAU endowed lectureship program and organization of seminars and public lectures, coordination and initiation of fundraising activities for astronomy development, organization of regional scientific symposia, conferences and workshops, support to Galileo Teacher Training Program (GTTP), production/publication of educational and promotional materials, etc.

  12. Src kinase activity is required for avoidance memory formation and recall.

    PubMed

    Bevilaqua, L R M; Rossato, J I; Medina, J H; Izquierdo, I; Cammarota, M

    2003-12-01

    Using 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-D]pyrimidine (PP2), a specific inhibitor of the Src family of tyrosine kinases, here we show a direct involvement of these enzymes in memory formation and recall. When infused into the CA1 region of the dorsal hippocampus, immediately or 30 min after training rats in a one-trial inhibitory avoidance task, PP2 but not its inactive analog 4-amino-7-phenylpyrazol[3,4-D]pyrimidine (PP3), blocked short- (STM) and long-term memory (LTM) formation, as tested 2 or 24 h post-training, respectively. PP2 had no effect on STM when given at 60 min post-training or on LTM when administered at 60, 120 or 180 min after the training session, but blocked memory recall when infused into CA1 15 min before a LTM expression test. Hence, activity of the Src family of tyrosine kinases is required in the CA1 region of the rat dorsal hippocampus for the normal formation and retrieval of one-trial inhibitory avoidance memory.

  13. Structure and polarization of active region microwave emission

    NASA Technical Reports Server (NTRS)

    Kundu, M. R.; Alissandrakis, C. E.

    1984-01-01

    Active region radio emission observations made at 6.16 cm wavelength during May 20-27, 1980, are the bases of maps of total intensity and circular polarization presented for the three regions whose Hale numbers are 16850, 16863, and 16864. A detailed comparison is made between these maps and on- and off-band H-alpha pictures and magnetograms. The neutral lines with which the strongest sources were associated have their two opposite polarities close to each other, implying a high magnetic field gradient, and are also associated with arch filament systems. A detailed analysis is undertaken of observations of the circular polarization sense inversion in region 16863. The large scale structure of the magnetic field can be approximated by a dipole with its axis inclined by 11 deg with respect to the photosphere, and with a dipole moment of about 2 x 10 to the 31 power cgs units.

  14. IPS observations of heliospheric density structures associated with active regions

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.; Altrock, R.; Woan, G.; Slater, G.

    1996-01-01

    Interplanetary scintillation (IPS) measurements of the 'disturbance factor' g, obtained with the Cambridge (UK) array can be used to explore the heliospheric density structure. We have used these data to construct synoptic (Carrington) maps, representing the large-scale enhancements of the g-factor in the inner heliosphere. These maps emphasize the stable corotating, rather than the transient heliospheric density enhancements. We have compared these maps with Carrington maps of Fe XIV observations National Solar Observatory ((NSO), Sacramento Peak) and maps based on Yohkoh Soft X-Ray Telescope (SXT) X-ray observations. Our results indicate that the regions of enhanced g tend to map to active regions rather than the current sheet. The implication is that act ve regions are the dominant source of the small-scale (approximately equal 200 km) density variations present in the quiet solar wind.

  15. Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

    NASA Astrophysics Data System (ADS)

    Timms, W. A.; Crane, R.; Anderson, D. J.; Bouzalakos, S.; Whelan, M.; McGeeney, D.; Rahman, P. F.; Guinea, A.; Acworth, R. I.

    2015-03-01

    Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, the extraction of fuels from strata such as coal beds, and the confinement of waste within the earth. The current work demonstrates that relatively rapid and reliable hydraulic conductivity (K) measurement of aquitard cores using accelerated gravity can inform and constrain larger scale assessments of hydraulic connectivity. Steady state fluid velocity through a low K porous sample is linearly related to accelerated gravity (g-level) in a centrifuge permeameter (CP) unless consolidation or geochemical reactions occur. The CP module was custom designed to fit a standard 2 m diameter geotechnical centrifuge (550 g maximum) with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length, and a maximum total stress of ~2 MPa at the base of the core. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the permeability. Vertical hydraulic conductivity (Kv) results from CP testing of cores from three sites within the same regional clayey silt formation varied (10-7 to 10-9 m s-1, n = 14). Results at one of these sites (1.1 × 10-10 to 3.5 × 10-9 m s-1, n = 5) that were obtained in < 24 h were similar to in situ Kv values (3 × 10-9 m s-1) from pore pressure responses over several weeks within a 30 m clayey sequence. Core scale and in situ Kv results were compared with vertical connectivity within a regional flow model, and considered in the context of heterogeneity and preferential flow paths at site and formation scale. More reliable assessments of leakage and solute transport though aquitards over multi-decadal timescales can be achieved by accelerated core testing together with advanced geostatistical and numerical methods.

  16. Modeled aerosol nitrate formation pathways during wintertime in the Great Lakes region of North America

    NASA Astrophysics Data System (ADS)

    Kim, Yoo Jung; Spak, Scott N.; Carmichael, Gregory R.; Riemer, Nicole; Stanier, Charles O.

    2014-11-01

    Episodic wintertime particle pollution by ammonium nitrate is an important air quality concern across the Midwest U.S. Understanding and accurately forecasting PM2.5 episodes are complicated by multiple pathways for aerosol nitrate formation, each with uncertain rate parameters. Here, the Community Multiscale Air Quality model (CMAQ) simulated regional atmospheric nitrate budgets during the 2009 LADCO Winter Nitrate Study, using integrated process rate (IPR) and integrated reaction rate (IRR) tools to quantify relevant processes. Total nitrate production contributing to PM2.5 episodes is a regional phenomenon, with peak production over the Ohio River Valley and southern Great Lakes. Total nitrate production in the lower troposphere is attributed to three pathways, with 57% from heterogeneous conversion of N2O5, 28% from the reaction of OH and NO2, and 15% from homogeneous conversion of N2O5. TNO3 formation rates varied day-to-day and on synoptic timescales. Rate-limited production does not follow urban-rural gradients and NOx emissions due, to counterbalancing of urban enhancement in daytime HNO3 production with nocturnal reductions. Concentrations of HNO3 and N2O5 and nighttime TNO3 formation rates have maxima aloft (100-500 m), leading to net total nitrate vertical flux during episodes, with substantial vertical gradients in nitrate partitioning. Uncertainties in all three pathways are relevant to wintertime aerosol modeling and highlight the importance of interacting transport and chemistry processes during ammonium nitrate episodes, as well as the need for additional constraint on the system through field and laboratory experiments.

  17. Ordovician carbonate formation waters in the Illinois Basin: Chemical and isotopic evolution beneath a regional aquitard

    SciTech Connect

    Stueber, A.M. ); Walter, L.M. . Dept. of Geological Sciences)

    1992-01-01

    Formation waters from carbonate reservoirs in the upper Ordovician Galena Group of the Illinois Basin have been analyzed geochemically to study origin of salinity, chemical and isotopic evolution, and relation to paleohydrologic flow systems. These carbonate reservoirs underlie the Maquoketa Shale Group of Cincinnatian age, which forms a regional aquitard. Cl-Br relations and Na/Br-Cl/Br systematics indicate that initial brine salinity resulted from subaerial evaporation of seawater to a point not significantly beyond halite saturation. Subsequent dilution in the subsurface by meteoric waters is supported by delta D-delta O-18 covariance. Systematic relations between Sr-87/Sr-86 and 1/Sr suggest two distinct mixing events: introduction of a Sr-87 enriched fluid from a siliciclastic source, and a later event which only affected reservoir waters from the western shelf of the basin. The second mixing event is supported by covariance between Sr-87/Sr-86 and concentrations of cations and anions; covariance between Sr and O-D isotopes suggests that the event is related to meteoric water influx. Systematic geochemical relations in ordovician Galena Group formation waters have been preserved by the overlying Maquoketa shale aquitard. Comparison with results from previous studies indicates that waters from Silurian-Devonian carbonate strata evolved in a manner similar to yet distinct from that of the Ordovician carbonate waters, whereas waters from Mississippian-Pennsylvanian strata that overlie the New Albany Shale Group regional aquitard are marked by fundamentally different Cl-Br-Na and Sr isotope systematics. Evolution of these geochemical formation-water regimes apparently has been influenced significantly by paleohydrologic flow systems.

  18. Diagnostics of Coronal Heating in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Fludra, Andrzej; Hornsey, Christopher; Nakariakov, Valery

    2015-04-01

    We aim to develop a diagnostic method for the coronal heating mechanism in active region loops. Observational constraints on coronal heating models have been sought using measurements in the X-ray and EUV wavelengths. Statistical analysis, using EUV emission from many active regions, was done by Fludra and Ireland (2008) who studied power-law relationships between active region integrated magnetic flux and emission line intensities. A subsequent study by Fludra and Warren (2010) for the first time compared fully resolved images in an EUV spectral line of OV 63.0 nm with the photospheric magnetic field, leading to the identification of a dominant, ubiquitous variable component of the transition region EUV emission and a discovery of a steady basal heating, and deriving the dependence of the basal heating rate on the photospheric magnetic flux density. In this study, we compare models of single coronal loops with EUV observations. We assess to what degree observations of individual coronal loops made in the EUV range are capable of providing constraints on the heating mechanism. We model the coronal magnetic field in an active region using an NLFF extrapolation code applied to a photospheric vector magnetogram from SDO/HMI and select several loops that match an SDO/AIA 171 image of the same active region. We then model the plasma in these loops using a 1D hydrostatic code capable of applying an arbitrary heating rate as a function of magnetic field strength along the loop. From the plasma parameters derived from this model, we calculate the EUV emission along the loop in AIA 171 and 335 bands, and in pure spectral lines of Fe IX 17.1 nm and Fe XVI 33.5 nm. We use different spatial distributions of the heating function: concentrated near the loop top, uniform and concentrated near the footpoints, and investigate their effect on the modelled EUV intensities. We find a diagnostics based on the dependence of the total loop intensity on the shape of the heating function

  19. Electron acceleration and radiation in evolving complex active regions

    NASA Astrophysics Data System (ADS)

    Anastasiadis, A.; Gontikakis, C.; Vilmer, N.; Vlahos, L.

    2004-07-01

    We present a model for the acceleration and radiation of solar energetic particles (electrons) in evolving complex active regions. The spatio - temporal evolution of active regions is calculated using a cellular automaton model, based on self-organized criticality. The acceleration of electrons is due to the presence of randomly placed, localized electric fields produced by the energy release process, simulated by the cellular automaton model. We calculate the resulting kinetic energy distributions of the particles and their emitted X-ray radiation spectra using the thick target approximation, and we perform a parametric study with respect to number of electric fields present and thermal temperature of the injected distribution. Finally, comparing our results with the existing observations, we find that they are in a good agreement with the observed X-ray spectra in the energy range 100-1000 keV.

  20. Evidence of active region imprints on the solar wind structure

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.

    1995-01-01

    A common descriptive framework for discussing the solar wind structure in the inner heliosphere uses the global magnetic field as a reference: low density, high velocity solar wind emanates from open magnetic fields, with high density, low speed solar wind flowing outward near the current sheet. In this picture, active regions, underlying closed magnetic field structures in the streamer belt, leave little or no imprint on the solar wind. We present evidence from interplanetary scintillation measurements of the 'disturbance factor' g that active regions play a role in modulating the solar wind and possibly contribute to the solar wind mass output. Hence we find that the traditional view of the solar wind, though useful in understanding many features of solar wind structure, is oversimplified and possibly neglects important aspects of solar wind dynamics

  1. Electric currents and coronal heating in NOAA active region 6952

    NASA Technical Reports Server (NTRS)

    Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey, D. L.; Wulser, J. -P.; Martens, P. C. H.; Tsuneta, S.

    1994-01-01

    We examine the spatial and temporal relationship between coronal structures observed with the soft X-ray telescope (SXT) on board the Yohkoh spacecraft and the vertical electric current density derived from photospheric vector magnetograms obtained using the Stokes Polarimeter at the Mees Solar Observatory. We focus on a single active region: AR 6952 which we observed on 7 days during 1991 December. For 11 independent maps of the vertical electric current density co-aligned with non-flaring X-ray images, we search for a morphological relationship between sites of high vertical current density in the photosphere and enhanced X-ray emission in the overlying corona. We find no compelling spatial or temporal correlation between the sites of vertical current and the bright X-ray structures in this active region.

  2. Formation of low-dimensional crystalline nucleus region during insulin amyloidogenesis process

    SciTech Connect

    Amdursky, Nadav; Gazit, Ehud; Rosenman, Gil

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer We observe lag-phase crystallization process in insulin. Black-Right-Pointing-Pointer The crystallization is a result of the formation of higher order oligomers. Black-Right-Pointing-Pointer The crystallization also changes the secondary structure of the protein. Black-Right-Pointing-Pointer The spectroscopic signature can be used for amyloid inhibitors assay. -- Abstract: Insulin, as other amyloid proteins, can form amyloid fibrils at certain conditions. The self-assembled aggregation process of insulin can result in a variety of conformations, starting from small oligomers, going through various types of protofibrils, and finishing with bundles of fibrils. One of the most common consensuses among the various self-assembly processes that are suggested in the literature is the formation of an early stage nucleus conformation. Here we present an additional insight for the self-assembly process of insulin. We show that at the early lag phase of the process (prior to fibril formation) the insulin monomers self-assemble into ordered nanostructures. The most notable feature of this early self-assembly process is the formation of nanocrystalline nucleus regions with a strongly bound electron-hole confinement, which also change the secondary structure of the protein. Each step in the self-assembly process is characterized by an optical spectroscopic signature, and possesses a narrow size distribution. By following the spectroscopic signature we can measure the potency of amyloid fibrils inhibitors already at the lag phase. We further demonstrate it by the use of epigallocatechin gallate, a known inhibitor for insulin fibrils. The findings can result in a spectroscopic-based application for the analysis of amyloid fibrils inhibitors.

  3. The star formation rates of active galactic nuclei host galaxies

    NASA Astrophysics Data System (ADS)

    Ellison, Sara L.; Teimoorinia, Hossen; Rosario, David J.; Mendel, J. Trevor

    2016-05-01

    Using artificial neural network predictions of total infrared luminosities (LIR), we compare the host galaxy star formation rates (SFRs) of ˜21 000 optically selected active galactic nuclei (AGN), 466 low-excitation radio galaxies (LERGs) and 721 mid-IR-selected AGN. SFR offsets (ΔSFR) relative to a sample of star-forming `main-sequence' galaxies (matched in M⋆, z and local environment) are computed for the AGN hosts. Optically selected AGN exhibit a wide range of ΔSFR, with a distribution skewed to low SFRs and a median ΔSFR = -0.06 dex. The LERGs have SFRs that are shifted to even lower values with a median ΔSFR = -0.5 dex. In contrast, mid-IR-selected AGN have, on average, SFRs enhanced by a factor of ˜1.5. We interpret the different distributions of ΔSFR amongst the different AGN classes in the context of the relative contribution of triggering by galaxy mergers. Whereas the LERGs are predominantly fuelled through low accretion rate secular processes which are not accompanied by enhancements in SFR, mergers, which can simultaneously boost SFRs, most frequently lead to powerful, obscured AGN.

  4. Traction force dynamics predict gap formation in activated endothelium.

    PubMed

    Valent, Erik T; van Nieuw Amerongen, Geerten P; van Hinsbergh, Victor W M; Hordijk, Peter L

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. PMID:27498166

  5. Airborne Measurements of Secondary Organic Aerosol Formation in the Oil Sands Region of Alberta

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Hayden, K.; Liu, P.; Leithead, A.; Moussa, S. G.; Staebler, R. M.; Gordon, M.; O'brien, J.; Li, S. M.

    2014-12-01

    The Alberta oil sands (OS) region represents a strategic natural resource and is a key driver of economic development. Its rapid expansion has led to a need for a more comprehensive understanding of the associated potential cumulative environmental impacts. In summer 2013, airborne measurements of various gaseous and particulate substances were made in the Athabasca oil sands region between August 13 and Sept 7, 2013. In particular, organic aerosol mass and composition measurements were performed with a High Resolution Time of flight Aerosol Mass Spectrometer (HR-ToF-AMS) supported by gaseous measurements of organic aerosol precursors with Proton Transfer Reaction (PTR) and Chemical Ionization (CI) mass spectrometers. These measurement data on selected flights were used to estimate the potential for local anthropogenic OS emissions to form secondary organic aerosol (SOA) downwind of precursor sources, and to investigate the importance of the surrounding biogenic emissions to the overall SOA burden in the region. The results of several flights conducted to investigate these transformations demonstrate that multiple distinct plumes were present downwind of OS industrial sources, each with differing abilities to form SOA depending upon factors such as NOx level, precursor VOC composition, and oxidant concentration. The results indicate that approximately 100 km downwind of an OS industrial source most of the measured organic aerosol (OA) was secondary in nature, forming at rates of ~6.4 to 13.6 μgm-3hr-1. Positive matrix factor (PMF) analysis of the HR-ToF-AMS data suggests that the SOA was highly oxidized (O/C~0.6) resulting in a measured ΔOA (difference above regional background OA) of approximately 2.5 - 3 despite being 100 km away from sources. The relative contribution of biogenic SOA to the total SOA and the factors affecting SOA formation during a number of flights in the OS region will be described.

  6. Simulation of Active-Region-Scale Flux Emergence

    NASA Astrophysics Data System (ADS)

    Manchester, W.; van der Holst, B.

    2015-12-01

    Shear flows long observed in solar active regions are now understood to be a consequence of the Lorentz force that develops from a complex interaction between magnetic fields and the thermal pressure of the Sun's gravitationally stratified atmosphere. The shearing motions transport magnetic flux and energy from the submerged portion of the field to the corona providing the necessary energy for flares, filament eruptions and CMEs. To further examine this shearing process, we simulate flux emergence on the scale of active regions with a large-scale model of the near surface convection zone constructed on an adaptive spherical grid. This model is designed to simulate flux emerging on the scale of active regions from a depth of 30 Mm. Here, we show results of a twisted flux rope emerging through the hierarchy of granular convection, and examine the flow patterns that arise as the flux approaches the photosphere. We show how these organized flows driven by the Lorentz force cause the coronal field evolve to a highly non-potential configuration capable of driving solar eruptions such as CMEs and flares.

  7. Evidence for coronal turbulence in a quiescent active region

    NASA Technical Reports Server (NTRS)

    Saba, Julia L. R.; Strong, Keith T.

    1986-01-01

    The first evidence for nonthermal broadening of X-ray lines in a quiescent active region was based on a single observation of a limb active region by the Flat Crystal Spectrometer (FCS) on the SMM satellite, reported by Acton et al. (1981). With the renewal of SMM operations, the FCS has been used to further investigate this phenomenon. On April 28, 1984 a map of Mg XI resonance line profiles was made for a bright area in NOAA Active Region 4474 during a nonflaring period. The narrowest line profiles are consistent with the nominal instrumental width plus a thermal width equivalent to about 3 million K, the temperature derived from line ratios of O VIII, Ne IX, and Mg XI. The broadest line profiles are consistent with the instrumental width plus a thermal width equivalent to about 7 million K, but a substantial amount of plasma at this temperature would result in much greater flux in the FCS higher-temperature channels than was seen. If the excess width is attributed solely to plasma turbulence, the corresponding velocity would be about 40 + or - 10 km/s.

  8. A theoretical approach to spot active regions in antimicrobial proteins

    PubMed Central

    2009-01-01

    Background Much effort goes into identifying new antimicrobial compounds able to evade the increasing resistance of microorganisms to antibiotics. One strategy relies on antimicrobial peptides, either derived from fragments released by proteolytic cleavage of proteins or designed from known antimicrobial protein regions. Results To identify these antimicrobial determinants, we developed a theoretical approach that predicts antimicrobial proteins from their amino acid sequence in addition to determining their antimicrobial regions. A bactericidal propensity index has been calculated for each amino acid, using the experimental data reported from a high-throughput screening assay as reference. Scanning profiles were performed for protein sequences and potentially active stretches were identified by the best selected threshold parameters. The method was corroborated against positive and negative datasets. This successful approach means that we can spot active sequences previously reported in the literature from experimental data for most of the antimicrobial proteins examined. Conclusion The method presented can correctly identify antimicrobial proteins with an accuracy of 85% and a sensitivity of 90%. The method can also predict their key active regions, making this a tool for the design of new antimicrobial drugs. PMID:19906288

  9. YB-1 regulates stress granule formation and tumor progression by translationally activating G3BP1

    PubMed Central

    Somasekharan, Syam Prakash; El-Naggar, Amal; Leprivier, Gabriel; Cheng, Hongwei; Hajee, Shamil; Grunewald, Thomas G.P.; Zhang, Fan; Ng, Tony; Delattre, Olivier; Evdokimova, Valentina; Wang, Yuzhuo; Gleave, Martin

    2015-01-01

    Under cell stress, global protein synthesis is inhibited to preserve energy. One mechanism is to sequester and silence mRNAs in ribonucleoprotein complexes known as stress granules (SGs), which contain translationally silent mRNAs, preinitiation factors, and RNA-binding proteins. Y-box binding protein 1 (YB-1) localizes to SGs, but its role in SG biology is unknown. We now report that YB-1 directly binds to and translationally activates the 5′ untranslated region (UTR) of G3BP1 mRNAs, thereby controlling the availability of the G3BP1 SG nucleator for SG assembly. YB-1 inactivation in human sarcoma cells dramatically reduces G3BP1 and SG formation in vitro. YB-1 and G3BP1 expression are highly correlated in human sarcomas, and elevated G3BP1 expression correlates with poor survival. Finally, G3BP1 down-regulation in sarcoma xenografts prevents in vivo SG formation and tumor invasion, and completely blocks lung metastasis in mouse models. Together, these findings demonstrate a critical role for YB-1 in SG formation through translational activation of G3BP1, and highlight novel functions for SGs in tumor progression. PMID:25800057

  10. Seasonal distribution of microbial activity in bioaerosols in the outdoor environment of the Qingdao coastal region

    NASA Astrophysics Data System (ADS)

    Zhong, Xi; Qi, Jianhua; Li, Hongtao; Dong, Lijie; Gao, Dongmei

    2016-09-01

    Microbial activities in the atmosphere can indicate the physiological processes of microorganisms and can indirectly affect cloud formation and environmental health. In this study, the microbial activity in bioaerosols collected in the Qingdao coastal region was investigated using the fluorescein diacetate (FDA) hydrolysis method to detect the enzyme activity of microorganisms. The results showed that the microbial activity ranged from 5.49 to 102 ng/m3 sodium fluorescein from March 2013 to February 2014; the average value was 34.4 ng/m3. Microbial activity has no statistical correlation with total microbial quantity. Multiple linear regression analysis showed that meteorological factors such as atmospheric temperature, relative humidity and wind speed accounted for approximately 35.7% of the variation of the microbial activity, although their individual impacts on microbial activity varied. According to the correlation analysis, atmospheric temperature and wind speed had a significant positive and negative influence on microbial activity, respectively, whereas relative humidity and wind direction had no significant influence. The seasonal distribution of microbial activity in bioaerosols was in the order of summer > autumn > winter > spring, with high fluctuations in the summer and autumn. Microbial activity in bioaerosols differed in different weather conditions such as the sunny, foggy, and hazy days of different seasons. Further in situ observations in different weather conditions at different times and places are needed to understand the seasonal distribution characteristics of microbial activity in bioaerosols and the influence factors of microbial activity.

  11. Periplasmic nitrate reductase and formate dehydrogenase: similar molecular architectures with very different enzymatic activities.

    PubMed

    Cerqueira, Nuno M F S A; Gonzalez, Pablo J; Fernandes, Pedro A; Moura, José J G; Ramos, Maria João

    2015-11-17

    It is remarkable how nature has been able to construct enzymes that, despite sharing many similarities, have simple but key differences that tune them for completely different functions in living cells. Periplasmic nitrate reductase (Nap) and formate dehydrogenase (Fdh) from the DMSOr family are representative examples of this. Both enzymes share almost identical three-dimensional protein foldings and active sites, in terms of coordination number, geometry and nature of the ligands. The substrates of both enzymes (nitrate and formate) are polyatomic anions that also share similar charge and stereochemistry. In terms of the catalytic mechanism, both enzymes have a common activation mechanism (the sulfur-shift mechanism) that ensures a constant coordination number around the metal ion during the catalytic cycle. In spite of these similarities, they catalyze very different reactions: Nap abstracts an oxygen atom from nitrate releasing nitrite, whereas FdH catalyzes a hydrogen atom transfer from formate and releases carbon dioxide. In this Account, a critical analysis of structure, function, and catalytic mechanism of the molybdenum enzymes periplasmic nitrate reductase (Nap) and formate dehydrogenase (Fdh) is presented. We conclude that the main structural driving force that dictates the type of reaction, catalyzed by each enzyme, is a key difference on one active site residue that is located in the top region of the active sites of both enzymes. In both enzymes, the active site is centered on the metal ion of the cofactor (Mo in Nap and Mo or W in Fdh) that is coordinated by four sulfur atoms from two pyranopterin guanosine dinucleotide (PGD) molecules and by a sulfido. However, while in Nap there is a Cys directly coordinated to the Mo ion, in FdH there is a SeCys instead. In Fdh there is also an important His that interacts very closely with the SeCys, whereas in Nap the same position is occupied by a Met. The role of Cys in Nap and SeCys in FdH is similar in both

  12. Regional differences in muscle activation during hamstrings exercise.

    PubMed

    Schoenfeld, Brad J; Contreras, Bret; Tiryaki-Sonmez, Gul; Wilson, Jacob M; Kolber, Morey J; Peterson, Mark D

    2015-01-01

    It is believed that regional activation within a muscle may lead to greater site-specific muscular adaptations in the activated portion of the muscle. Because the hamstrings are a biarticular muscle, it can be theorized that single-joint exercises where movement originates at the hip vs. the knee will result in differential activation of the muscle complex. The purpose of the present study was to assess electromyographic activity in the proximal and distal aspects of the medial and lateral hamstrings during performance of the stiff-legged deadlift (SLDL), a hip-dominant exercise, and the lying leg curl (LLC), a knee-dominant exercise. Ten young, resistance-trained men were recruited from a university population to participate in the study. Employing a within-subject design, participants performed the SLDL and LLC to muscular failure using a load equating to their 8 repetition maximum for each exercise. The order of performance of exercises was counterbalanced between participants so that approximately half of the subjects performed SLDL first and the other half performed LLC first. Surface electromyography was used to record mean normalized muscle activity of the upper lateral hamstrings, lower lateral hamstrings, upper medial hamstrings, and lower medial hamstrings. Results showed that the LLC elicited significantly greater normalized mean activation of the lower lateral and lower medial hamstrings compared with the SLDL (p ≤ 0.05). These findings support the notion that the hamstrings can be regionally targeted through exercise selection. Further investigations are required to determine whether differences in activation lead to greater muscular adaptations in the muscle complex. PMID:24978835

  13. Hubble Tarantula Treasury Project. II. The Star-formation History of the Starburst Region NGC 2070 in 30 Doradus

    NASA Astrophysics Data System (ADS)

    Cignoni, M.; Sabbi, E.; van der Marel, R. P.; Tosi, M.; Zaritsky, D.; Anderson, J.; Lennon, D. J.; Aloisi, A.; de Marchi, G.; Gouliermis, D. A.; Grebel, E. K.; Smith, L. J.; Zeidler, P.

    2015-10-01

    We present a study of the recent star formation (SF) of 30 Doradus in the Large Magellanic Cloud (LMC) using the panchromatic imaging survey Hubble Tarantula Treasury Project. In this paper we focus on the stars within 20 pc of the center of 30 Doradus, the starburst region NGC 2070. We recovered the SF history by comparing deep optical and near-infrared color-magnitude diagrams (CMDs) with state-of-the-art synthetic CMDs generated with the latest PAdova and TRieste Stellar Evolution Code (PARSEC) models, which include all stellar phases from pre-main-sequence to post-main-sequence. For the first time in this region we are able to measure the SF using intermediate- and low-mass stars simultaneously. Our results suggest that NGC 2070 experienced prolonged activity. In particular, we find that the SF in the region (1) exceeded the average LMC rate ≈ 20 Myr ago, (2) accelerated dramatically ≈ 7 Myr ago, and (3) reached a peak value 1-3 Myr ago. We did not find significant deviations from a Kroupa initial mass function down to 0.5 {M}⊙ . The average internal reddening E(B-V) is found to be between 0.3 and 0.4 mag. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA Inc., under NASA contract NAS 5-26555.

  14. Active region upflows. II. Data driven magnetohydrodynamic modelling

    NASA Astrophysics Data System (ADS)

    Galsgaard, K.; Madjarska, M. S.; Vanninathan, K.; Huang, Z.; Presmann, M.

    2015-12-01

    Context. Observations of many active regions show a slow systematic outflow/upflow from their edges lasting from hours to days. At present no physical explanation has been proven, while several suggestions have been put forward. Aims: This paper investigates one possible method for maintaining these upflows assuming, that convective motions drive the magnetic field to initiate them through magnetic reconnection. Methods: We use Helioseismic and Magnetic Imager (HMI) data to provide an initial potential 3D magnetic field of the active region NOAA 11123 on 2010 November 13 where the characteristic upflow velocities are observed. A simple 1D hydrostatic atmospheric model covering the region from the photosphere to the corona is derived. Local correlation tracking of the magnetic features in the HMI data is used to derive a proxy for the time dependent velocity field. The time dependent evolution of the system is solved using a resistive 3D magnetohydrodynamic code. Results: The magnetic field contains several null points located well above the photosphere, with their fan planes dividing the magnetic field into independent open and closed flux domains. The stressing of the interfaces between the different flux domains is expected to provide locations where magnetic reconnection can take place and drive systematic flows. In this case, the region between the closed and open flux is identified as the region where observations find the systematic upflows. Conclusions: In the present experiment, the driving only initiates magneto-acoustic waves without driving any systematic upflows at any of the flux interfaces. Movie is available in electronic form at http://www.aanda.org

  15. Coordinated activation of the secretory pathway during notochord formation in the Xenopus embryo

    PubMed Central

    Tanegashima, Kosuke; Zhao, Hui; Rebbert, Martha L.; Dawid, Igor B.

    2009-01-01

    Summary We compared the transcriptome in the developing notochord of Xenopus laevis embryos with that of other embryonic regions. A coordinated and intense activation of a large set of secretory pathway genes was observed in the notochord, but not in notochord precursors in the axial mesoderm at early gastrula stage. The genes encoding Xbp1 and Creb3l2 were also activated in the notochord. These two transcription factors are implicated in the activation of secretory pathway genes during the unfolded protein response, where cells react to the stress of a build-up of unfolded proteins in their endoplasmic reticulum. Xbp1 and Creb3l2 are differentially expressed but not differentially activated in the notochord. Reduction of expression of Xbp1 or Creb3l2 by injection of antisense morpholinos led to strong deficits in notochord but not somitic muscle development. In addition, the expression of some, but not all, genes encoding secretory proteins was inhibited by injection of xbp1 morpholinos. Furthermore, expression of activated forms of Xbp1 or Creb3l2 in animal explants could activate a similar subset of secretory pathway genes. We conclude that coordinated activation of a battery of secretory pathway genes mediated by Xbp1 and Creb/ATF factors is a characteristic and necessary feature of notochord formation. PMID:19793890

  16. On the Periodicity of Energy Release in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Goldvarg, T. B.; Nagovitsyn, Yu. A.; Solov'Ev, A. A.

    2005-06-01

    We investigate the periodic regimes of energy release on the Sun, namely, the recurrence of solar flares in active regions using the Solar Geophysical Data Journal on Hα flares from 1979 until 1981, which corresponds to the maximum of solar cycle 21. We obtained the following series of periods in the manifestation of flare activity bymeans of a correlation periodogram analysis, a self-similarity function, and a wavelet analysis: ˜1, 2, 3 h as well as ˜0.4, 1, 2, 5 days. We suggest a diffusive model for the quasi-periodic transfer of toroidal magnetic fields from under the photosphere to interpret the retrieved sequence of periods in the enhancement of flare activity. We estimated the typical spatial scales of the magnetic field variations in the solar convection zone: ˜17 000 km.

  17. Investigation of secondary formation of formic acid: urban environment vs. oil and gas producing region

    NASA Astrophysics Data System (ADS)

    Yuan, B.; Veres, P. R.; Warneke, C.; Roberts, J. M.; Gilman, J. B.; Koss, A.; Edwards, P. M.; Graus, M.; Kuster, W. C.; Li, S.-M.; Wild, R. J.; Brown, S. S.; Dubé, W. P.; Lerner, B. M.; Williams, E. J.; Johnson, J. E.; Quinn, P. K.; Bates, T. S.; Lefer, B.; Hayes, P. L.; Jimenez, J. L.; Weber, R. J.; Zamora, R.; Ervens, B.; Millet, D. B.; Rappenglück, B.; de Gouw, J. A.

    2015-02-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere. However, current photochemical models cannot fully explain observed concentrations and in particular secondary formation of formic acid across various environments. In this work, formic acid measurements made at an urban receptor site (Pasadena) in June-July 2010 during CalNex (California Research at the Nexus of Air Quality and Climate Change) and a site in an oil and gas producing region (Uintah Basin) in January-February 2013 during UBWOS 2013 (Uintah Basin Winter Ozone Studies) will be discussed. Although the VOC (volatile organic compounds) compositions differed dramatically at the two sites, measured formic acid concentrations were comparable: 2.3 ± 1.3 in UBWOS 2013 and 2.0 ± 1.0 ppb in CalNex. We determine that concentrations of formic acid at both sites were dominated by secondary formation (> 99%). A constrained box model using the Master Chemical Mechanism (MCM v3.2) underestimates the measured formic acid concentrations drastically at both sites (by a factor of > 10). Compared to the original MCM model that includes only ozonolysis of unsaturated organic compounds and OH oxidation of acetylene, when we updated yields of ozonolysis of alkenes and included OH oxidation of isoprene, vinyl alcohol chemistry, reaction of formaldehyde with HO2, oxidation of aromatics, and reaction of CH3O2 with OH, the model predictions for formic acid were improved by a factor of 6.4 in UBWOS 2013 and 4.5 in CalNex, respectively. A comparison of measured and modeled HCOOH/acetone ratios is used to evaluate the model performance for formic acid. We conclude that the modified chemical mechanism can explain 19 and 45% of secondary formation of formic acid in UBWOS 2013 and CalNex, respectively. The contributions from aqueous reactions in aerosol and heterogeneous reactions on aerosol surface to formic acid are estimated to be 0-6 and 0-5% in UBWOS 2013 and CalNex, respectively. We observe that

  18. Monitoring rice farming activities in the Mekong Delta region

    NASA Astrophysics Data System (ADS)

    Nguyen, S. T.; Chen, C. F.; Chen, C. R.; Chiang, S. H.; Chang, L. Y.; Khin, L. V.

    2015-12-01

    Half of the world's population depends on rice for survival. Rice agriculture thus plays an important role in the developing world's economy. Vietnam is one of the largest rice producers and suppliers on earth and more than 80% of the exported rice was produced from the Mekong Delta region, which is situated in the southwestern Vietnam and encompasses approximately 40,000 km2. Changes in climate conditions could likely trigger the increase of insect populations and rice diseases, causing the potential loss of rice yields. Monitoring rice-farming activities through crop phenology detection can provide policymakers with timely strategies to mitigate possible impacts on the potential yield as well as rice grain exports to ensure food security for the region. The main objective of this study is to develop a logistic-based algorithm to investigate rice sowing and harvesting activities from the multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS)-Landsat fusion data. We processed the data for two main cropping seasons (i.e., winter-spring and summer-autumn seasons) through a three-step procedure: (1) MODIS-Landsat data fusion, (2) construction of the time-series enhanced vegetation index 2 (EVI2) data, (3) rice crop phenology detection. The EVI2 data derived from the fusion results between MODIS and Landsat data were compared with that of Landsat data indicated close correlation between the two datasets (R2 = 0.93). The time-series EVI2 data were processed using the double logistic method to detect the progress of sowing and harvesting activities in the region. The comparisons between the estimated sowing and harvesting dates and the field survey data revealed the root mean squared error (RMSE) values of 8.4 and 5.5 days for the winter-spring crop and 9.4 and 12.8 days for the summer-autumn crop, respectively. This study demonstrates the effectiveness of the double logistic-based algorithm for rice crop monitoring from temporal MODIS-Landsat fusion data

  19. An Analysis of Water Line Profiles in Star Formation Regions Observed by SWAS

    NASA Technical Reports Server (NTRS)

    Ashby, Matthew L. N.; Bergin, Edwin A.; Plume, Rene; Carpenter, John M.; Neufeld, David A.; Chin, Gordon; Erickson, Neal R.; Goldsmith, Paul F.; Harwit, Martin; Howe, J. E.

    2000-01-01

    We present spectral line profiles for the 557 GHz 1(sub 1,0) yields 1(sub 0,1) ground-state rotational transition of ortho-H2(16)O for 18 galactic star formation regions observed by SWAS. 2 Water is unambiguously detected in every source. The line profiles exhibit a wide variety of shapes, including single-peaked spectra and self-reversed profiles. We interpret these profiles using a Monte Carlo code to model the radiative transport. The observed variations in the line profiles can be explained by variations in the relative strengths of the bulk flow and small-scale turbulent motions within the clouds. Bulk flow (infall, outflow) must be present in some cloud cores, and in certain cases this bulk flow dominates the turbulent motions.

  20. A genomic region involved in the formation of adhesin fibers in Bacillus cereus biofilms

    PubMed Central

    Caro-Astorga, Joaquín; Pérez-García, Alejandro; de Vicente, Antonio; Romero, Diego

    2015-01-01

    Bacillus cereus is a bacterial pathogen that is responsible for many recurrent disease outbreaks due to food contamination. Spores and biofilms are considered the most important reservoirs of B. cereus in contaminated fresh vegetables and fruits. Biofilms are bacterial communities that are difficult to eradicate from biotic and abiotic surfaces because of their stable and extremely strong extracellular matrix. These extracellular matrixes contain exopolysaccharides, proteins, extracellular DNA, and other minor components. Although B. cereus can form biofilms, the bacterial features governing assembly of the protective extracellular matrix are not known. Using the well-studied bacterium B. subtilis as a model, we identified two genomic loci in B. cereus, which encodes two orthologs of the amyloid-like protein TasA of B. subtilis and a SipW signal peptidase. Deletion of this genomic region in B. cereus inhibited biofilm assembly; notably, mutation of the putative signal peptidase SipW caused the same phenotype. However, mutations in tasA or calY did not completely prevent biofilm formation; strains that were mutated for either of these genes formed phenotypically different surface attached biofilms. Electron microscopy studies revealed that TasA polymerizes to form long and abundant fibers on cell surfaces, whereas CalY does not aggregate similarly. Heterologous expression of this amyloid-like cassette in a B. subtilis strain lacking the factors required for the assembly of TasA amyloid-like fibers revealed (i) the involvement of this B. cereus genomic region in formation of the air-liquid interphase pellicles and (ii) the intrinsic ability of TasA to form fibers similar to the amyloid-like fibers produced by its B. subtilis ortholog. PMID:25628606

  1. Regional-scale flow of formation waters in the Williston basin

    SciTech Connect

    Bachu, S.; Hitchon, B.

    1996-02-01

    The Williston basin is a structurally simple intracratonic sedimentary basin that straddles the United States-Canada border east of the Rocky Mountains and that contains an almost continuous stratigraphic record since the Middle Cambrian. Based on the wealth of data generated by the oil industry, the regional-scale characteristics of the flow of formation waters were analyzed for the Canadian side of the basin, and integrated with previous studies performed on the American side. Several aquifers and aquifer systems identified in the basin were separated by intervening aquitards and aquicludes. The Basal, Devonian, and Mannville (Dakota) aquifers are open systems, being exposed at the land surface in both recharge and discharge areas. Recharge takes place in the west-southwest at relatively high altitude in the Bighorn and Big Snowy mountains and at the Black Hills and Central Montana uplifts, whereas discharge takes place in the east and northeast at outcrop along the Canadian Precambrian shield in Manitoba and the Dakotas. The Mississippian and Pennsylvanian aquifer systems are semi-open, cropping out only in the west-southwest where they recharge, but discharging in the northeast into adjacent aquifers through confining aquitards. On regional and geological scales, the entire system seems to be at steady-state, although locally transient flow is present in places due to water use and hydrocarbon exploitation, and to some erosional rebound in the uppermost confining shales. On the western flank of the basin, the interplay between the northeastward structural downdip direction and the northeastward flow of formation waters creates conditions favorable for hydrodynamic oil entrapment.

  2. Auroral ionospheric F region density cavity formation and evolution: MICA campaign results

    NASA Astrophysics Data System (ADS)

    Zettergren, M.; Lynch, K.; Hampton, D.; Nicolls, M.; Wright, B.; Conde, M.; Moen, J.; Lessard, M.; Miceli, R.; Powell, S.

    2014-04-01

    Auroral ionospheric F region density depletions observed by PFISR (Poker Flat Incoherent Scatter Radar) during the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) sounding rocket campaign are critically examined alongside complementary numerical simulations. Particular processes of interest include cavity formation due to intense frictional heating and Pedersen drifts, evolution in the presence of structured precipitation, and refilling due to impact ionization and downflows. Our analysis uses an ionospheric fluid model which solves conservation of mass, momentum, and energy equations for all major ionospheric species. These fluid equations are coupled to an electrostatic current continuity equation to self-consistently describe auroral electric fields. Energetic electron precipitation inputs for the model are specified by inverting optical data, and electric field boundary conditions are obtained from direct PFISR measurements. Thus, the model is driven in as realistic a manner as possible. Both incoherent scatter radar (ISR) data and simulations indicate that the conversion of the F region plasma to molecular ions and subsequent recombination is the dominant process contributing to the formation of the observed cavities, all of which occur in conjunction with electric fields exceeding ˜90 mV/m. Furthermore, the cavities often persist several minutes past the point when the frictional heating stops. Impact ionization and field-aligned plasma flows modulate the cavity depth in a significant way but are of secondary importance to the molecular generation process. Informal comparisons of the ISR density and temperature fits to the model verify that the simulations reproduce most of the observed cavity features to a reasonable level of detail.

  3. Magnetic field configuration in a flaring active region

    NASA Astrophysics Data System (ADS)

    Palacios, J.; Balmaceda, L. A.; Vieira, L. E.

    2015-10-01

    The Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) provides continuous monitoring of the Sun's vector magnetic field through full-disk photospheric data with both high cadence and high spatial resolution. Here we investigate the evolution of AR 11249 from March 6 to March 7, 2012. We make use of HMI Stokes imaging, SDO/SHARPs, the HMI magnetic field line-of-sight (LOS) maps and the transverse components of the magnetic field as well as LOS velocity maps in order to detect regions with significant flux emergence and/or cancellation. In addition, we apply the Local Correlation Tracking (LCT) technique to the total and signed magnetic flux data and derive maps of horizontal velocity. From this analysis, we were able to pinpoint localized shear regions (and a shear channel) where penumbrae and pore formation areas, with strong linear polarization signals, are stretched and squeezed, showing also important downflows and upflows. We have also utilized Hinode/SP data and compared them to the HMI-SHARPs and the HMI-Stokes spectrograms. The aforementioned shear channel seems to correspond well with the X-class flare main channel of March 7 2012, as observed in AIA/SDO 171, 304 and 1600 Å.

  4. Nucleoporin translocated promoter region (Tpr) associates with dynein complex, preventing chromosome lagging formation during mitosis.

    PubMed

    Nakano, Hiroshi; Funasaka, Tatsuyoshi; Hashizume, Chieko; Wong, Richard W

    2010-04-01

    Gain or loss of whole chromosomes is often observed in cancer cells and is thought to be due to aberrant chromosome segregation during mitosis. Proper chromosome segregation depends on a faithful interaction between spindle microtubules and kinetochores. Several components of the nuclear pore complex/nucleoporins play critical roles in orchestrating the rapid remodeling events that occur during mitosis. Our recent studies revealed that the nucleoporin, Rae1, plays critical roles in maintaining spindle bipolarity. Here, we show association of another nucleoporin, termed Tpr (translocated promoter region), with the molecular motors dynein and dynactin, which both orchestrate with the spindle checkpoints Mad1 and Mad2 during cell division. Overexpression of Tpr enhanced multinucleated cell formation. RNA interference-mediated knockdown of Tpr caused a severe lagging chromosome phenotype and disrupted spindle checkpoint proteins expression and localization. Next, we performed a series of rescue and dominant negative experiments to confirm that Tpr orchestrates proper chromosome segregation through interaction with dynein light chain. Our data indicate that Tpr functions as a spatial and temporal regulator of spindle checkpoints, ensuring the efficient recruitment of checkpoint proteins to the molecular motor dynein to promote proper anaphase formation.

  5. Research on Magnetic Evolution in Solar Active Regions and Related Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Yan, X. L.

    2014-07-01

    Research on sunspot activity and solar eruptions is one of the key and difficult issues in solar physics. The relationship between sunspot formation and its magnetic field evolution, and solar eruptions is not well understood. Magnetic emergence, magnetic cancellation, and sunspot motion can greatly affect the upper solar atmosphere, and even produce flares, coronal mass ejections (CMEs), filament eruptions, surges, and so on. Especially, large solar eruptions toward the earth can exert a huge influence on the Sun-Earth space weather. The observations of the Sun have been developed from those at a single wavelength based on the ground station to those at multi-wavelengths based on both the ground and space stations. In particular, from the launch of rockets in 1940s---1950s to the launch of the current spacecraft, the great achievements have been made based on the multi-wavelength and high resolution observations. This thesis is dedicated to the study of the evolution of active regions and related solar eruptions, especially the exploration on the origin of solar activities by using a great many data obtained by space and ground-based telescopes. Chapter 1 introduces the basic knowledge of sunspots (formation, fine-structure, magnetic field, material flow, and periodicity), filaments (formation, theoretical models, and triggering mechanisms), flares (classification, and theoretical models), and CMEs (structures, and physical models). In chapter 2, we investigate the relationship between magnetic emergence, magnetic cancellation, flares, CMEs, and filament eruptions in active regions by using ground and space observational data. Half of filament eruptions in active regions in our examples are accompanied by CMEs. The occurrence and speed of CMEs have a close relationship with the associated flares accompanied by filament eruptions. The halo CMEs are associated with large flares (≥ M-class flares). Magnetic emergence and cancellation often appear in the active

  6. Active tectonics and earthquake potential of the Myanmar region

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Sieh, Kerry; Tun, Soe Thura; Lai, Kuang-Yin; Myint, Than

    2014-04-01

    This paper describes geomorphologic evidence for the principal neotectonic features of Myanmar and its immediate surroundings. We combine this evidence with published structural, geodetic, and seismic data to present an overview of the active tectonic architecture of the region and its seismic potential. Three tectonic systems accommodate oblique collision of the Indian plate with Southeast Asia and extrusion of Asian territory around the eastern syntaxis of the Himalayan mountain range. Subduction and collision associated with the Sunda megathrust beneath and within the Indoburman range and Naga Hills accommodate most of the shortening across the transpressional plate boundary. The Sagaing fault system is the predominant locus of dextral motion associated with the northward translation of India. Left-lateral faults of the northern Shan Plateau, northern Laos, Thailand, and southern China facilitate extrusion of rocks around the eastern syntaxis of the Himalaya. All of these systems have produced major earthquakes within recorded history and continue to present major seismic hazards in the region.

  7. Time Dependence of Joy's Law for Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Chintzoglou, Georgios; Zhang, J.; Liu, Y.

    2013-07-01

    Joy's law governs the tilt of Active Regions (ARs) with respect to their absolute heliographic latitude. Together with Hale's law of hemispheric polarity, it is essential in constraining solar dynamo models. However, previous studies on Joy's law show only a weak positive trend between AR tilt angles and latitudes. In this study, we are focusing on the time dependence of Joy's law, for the cases of emerging ARs of Solar Cycle 24. We selected 40 ARs that emerge on the East hemisphere, effectively maximizing the observing time for each AR. Then, by converting the helioprojective maps into heliographic, we determine the geometrical as well as the magnetic-flux-weighted centroids for each emergence case. That way we are able to track the temporal evolution of their physical properties, including locations, fluxes of positive and negative polarities, as well as the tilt angles of these regions in a continuous manner until emergence stops and the ARs assume their final state.

  8. Multi-wavelength Observations of Solar Active Region NOAA 7154

    NASA Technical Reports Server (NTRS)

    Bruner, M. E.; Nitta, N. V.; Frank. Z. A.; Dame, L.; Suematsu, Y.

    2000-01-01

    We report on observations of a solar active region in May 1992 by the Solar Plasma Diagnostic Experiment (SPDE) in coordination with the Yohkoh satellite (producing soft X-ray images) and ground-based observatories (producing photospheric magnetograms and various filtergrams including those at the CN 3883 A line). The main focus is a study of the physical conditions of hot (T is approximately greater than 3 MK) coronal loops at their foot-points. The coronal part of the loops is fuzzy but what appear to be their footpoints in the transition region down to the photosphere are compact. Despite the morphological similarities, the footpoint emission at 10(exp 5) K is not quantitatively correlated with that at approximately 300 km above the tau (sub 5000) = 1 level, suggesting that the heat transport and therefore magnetic field topology in the intermediate layer is complicated. High resolution imaging observations with continuous temperature coverage are crucially needed.

  9. Geography of follicle formation in the embryonic mouse ovary impacts activation pattern during the first wave of folliculogenesis.

    PubMed

    Cordeiro, Marília H; Kim, So-Youn; Ebbert, Katherine; Duncan, Francesca E; Ramalho-Santos, João; Woodruff, Teresa K

    2015-10-01

    During embryonic development, mouse female germ cells enter meiosis in an anterior-to-posterior wave believed to be driven by retinoic acid. It has been proposed that ovarian follicle formation and activation follow the same general wave of meiotic progression; however, the precise anatomic specification of these processes has not been delineated. Here, we created a mouse line using Mvh, Gdf9, and Zp3 promoters to drive distinct temporal expression of three fluorescent proteins in the oocytes and to identify where the first follicle cohort develops. The fluorescent profile revealed that the first growing follicles consistently appeared in a specific region of the ovary, the anterior-dorsal region, which led us to analyze if meiotic onset occurred earlier in the dorsal ovarian region. Surprisingly, in addition to the anterior-to-posterior wave, we observed an early meiotic entry in the ventral region of the ovary. This additional anatomic stratification of meiosis contrasts with the localization of the initial follicle formation and activation in the dorsal region of the ovary. Therefore, our study suggests that the specification of cortical and medullar areas in the ventral and dorsal regions on the ovary, rather than the onset of meiosis, impacts where the first follicle activation event occurs. PMID:26246221

  10. TESTING 24 {mu}m AND INFRARED LUMINOSITY AS STAR FORMATION TRACERS FOR GALACTIC STAR-FORMING REGIONS

    SciTech Connect

    Vutisalchavakul, Nalin; Evans, Neal J. II

    2013-03-10

    We have tested some relations for star formation rates used in extragalactic studies for regions within the Galaxy. In nearby molecular clouds, where the initial mass function is not fully sampled, the dust emission at 24 {mu}m greatly underestimates star formation rates (by a factor of 100 on average) when compared to star formation rates determined from counting young stellar objects. The total infrared emission does no better. In contrast, the total far-infrared method agrees within a factor of two on average with star formation rates based on radio continuum emission for massive, dense clumps that are forming enough massive stars to have L{sub TIR} exceed 10{sup 4.5} L{sub Sun }. The total infrared and 24 {mu}m also agree well with each other for both nearby, low-mass star-forming regions and the massive, dense clump regions.

  11. Influence of the Cardiac Myosin Hinge Region on Contractile Activity

    NASA Astrophysics Data System (ADS)

    Margossian, Sarkis S.; Krueger, John W.; Sellers, James R.; Cuda, Giovanni; Caulfield, James B.; Norton, Paul; Slayter, Henry S.

    1991-06-01

    The participation of cardiac myosin hinge in contractility was investigated by in vitro motility and ATPase assays and by measurements of sarcomere shortening. The effect on contractile activity was analyzed using an antibody directed against a 20-amino acid peptide within the hinge region of myosin. This antibody bound specifically at the hinge at a distance of 55 nm from the S1/S2 junction, was specific to human, dog, and rat cardiac myosins, did not crossreact with gizzard or skeletal myosin, and had no effect on ATPase activity of purified S1 and myofibrils. However, it completely suppressed the movement of actin filaments in in vitro motility assays and reduced active shortening of sarcomeres of skinned cardiac myocytes by half. Suppression of motion by the antihinge antibody may reflect a mechanical constraint imposed by the antibody upon the mobility of the S2 region of myosin. The results suggest that the steps in the mechanochemical energy transduction can be separately influenced through S2.

  12. Influence of the cardiac myosin hinge region on contractile activity.

    PubMed

    Margossian, S S; Krueger, J W; Sellers, J R; Cuda, G; Caulfield, J B; Norton, P; Slayter, H S

    1991-06-01

    The participation of cardiac myosin hinge in contractility was investigated by in vitro motility and ATPase assays and by measurements of sarcomere shortening. The effect on contractile activity was analyzed using an antibody directed against a 20-amino acid peptide within the hinge region of myosin. This antibody bound specifically at the hinge at a distance of 55 nm from the S1/S2 junction, was specific to human, dog, and rat cardiac myosins, did not crossreact with gizzard or skeletal myosin, and had no effect on ATPase activity of purified S1 and myofibrils. However, it completely suppressed the movement of actin filaments in in vitro motility assays and reduced active shortening of sarcomeres of skinned cardiac myocytes by half. Suppression of motion by the anti-hinge antibody may reflect a mechanical constraint imposed by the antibody upon the mobility of the S2 region of myosin. The results suggest that the steps in the mechanochemical energy transduction can be separately influenced through S2.

  13. High Spatial Resolution Fe XII Observations of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Testa, Paola; De Pontieu, Bart; Hansteen, Viggo

    2016-08-01

    We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (˜0.33″). We find that by using appropriate observational strategies (i.e., long exposures, lossless compression), Fe xii emission can be studied with IRIS at high spatial and spectral resolution, at least for high-density plasma (e.g., post-flare loops and active region moss). We find that upper transition region (TR; moss) Fe xii emission shows very small average Doppler redshifts ({v}{{D}} ˜ 3 km s‑1) as well as modest non-thermal velocities (with an average of ˜24 km s‑1 and the peak of the distribution at ˜15 km s‑1). The observed distribution of Doppler shifts appears to be compatible with advanced three-dimensional radiative MHD simulations in which impulsive heating is concentrated at the TR footpoints of a hot corona. While the non-thermal broadening of Fe xii 1349.4 Å peaks at similar values as lower resolution simultaneous Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) measurements of Fe xii 195 Å, IRIS observations show a previously undetected tail of increased non-thermal broadening that might be suggestive of the presence of subarcsecond heating events. We find that IRIS and EIS non-thermal line broadening measurements are affected by instrumental effects that can only be removed through careful analysis. Our results also reveal an unexplained discrepancy between observed 195.1/1349.4 Å Fe xii intensity ratios and those predicted by the CHIANTI atomic database.

  14. Ancient Tectonic and Volcanic Activity in the Tharsis Region

    NASA Astrophysics Data System (ADS)

    Werner, S. C.; Kronberg, P.; Hauber, E.; Grott, M.; Steinberger, B.; Torsvik, T. H.; Neukum, G.

    The two topographically dominating volcanic provinces on Mars are the Tharsis and the Elysium regions, situated close to the equator on the dichotomy boundary between the heavily cratered (older) highlands and the northern lowlands (about 100 degrees apart). The regions are characterized by volcanoes whose morphologies are analogous to volcanic landforms on Earth, and the huge volcanoes in the Tharsis region (Olympus Mons and Tharsis Montes) are prime examples resembling many characteristics of Hawaiian shield volcanoes. The main difference between the Martian and terrestrial volcanoes are their size and the length of the flows, possibly due to higher eruption rates, the "stationary" character of the source (no plate tectonics) and the lower gravity. The Tharsis plateau is the topographically most prominent region on Mars, and associated with an areoid high. On Earth, large geoid highs are related to longlived heterogeneities near the core-mantle boundary that are sources for large igneous provinces. The Tharsis' volcanic vent structures were active at least episodically over the past 4 billion years (based on crater count statistics), which indicates long-lived volcanic and magmatic activity. Two major groups of tectonic features are related to the Tharsis bulge: a concentric set of wrinkle ridges indicating compression radial to Tharsis,and several sets of extensional structures that radiate outward from different centers within Tharsis, indicating tension circumferential to Tharsis. No landforms imply ancient plate tectonics. Here, we present surface ages associated with volcanic and tectonic landforms with a special focus on the ancient magma-tectonic environment (see Grott et al. 2006, this volume). We will examine the long-lived volcanism and tectonic surface expressions and discuss whether Mars volcanism could represent deep mantle plumes.

  15. High Spatial Resolution Fe XII Observations of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Testa, Paola; De Pontieu, Bart; Hansteen, Viggo

    2016-08-01

    We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (˜0.33″). We find that by using appropriate observational strategies (i.e., long exposures, lossless compression), Fe xii emission can be studied with IRIS at high spatial and spectral resolution, at least for high-density plasma (e.g., post-flare loops and active region moss). We find that upper transition region (TR; moss) Fe xii emission shows very small average Doppler redshifts ({v}{{D}} ˜ 3 km s-1) as well as modest non-thermal velocities (with an average of ˜24 km s-1 and the peak of the distribution at ˜15 km s-1). The observed distribution of Doppler shifts appears to be compatible with advanced three-dimensional radiative MHD simulations in which impulsive heating is concentrated at the TR footpoints of a hot corona. While the non-thermal broadening of Fe xii 1349.4 Å peaks at similar values as lower resolution simultaneous Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) measurements of Fe xii 195 Å, IRIS observations show a previously undetected tail of increased non-thermal broadening that might be suggestive of the presence of subarcsecond heating events. We find that IRIS and EIS non-thermal line broadening measurements are affected by instrumental effects that can only be removed through careful analysis. Our results also reveal an unexplained discrepancy between observed 195.1/1349.4 Å Fe xii intensity ratios and those predicted by the CHIANTI atomic database.

  16. From snakes to region-based active contours defined by region-dependent parameters.

    PubMed

    Jehan-Besson, Stéphanie; Gastaud, Muriel; Precioso, Frédéric; Barlaud, Michel; Aubert, Gilles; Debreuve, Eric

    2004-01-10

    Image and sequence segmentation of a the segmentation task are discussed from the point of view of optimizing the segmentation criterion. Such a segmentation criterion involves so-called (boundary and region) descriptors, which, in general, may depend on their respective boundaries or regions. This dependency must be taken into account when one is computing the criterion derivative with respect to the unknown object domain (defined by its boundary). If this dependency not considered, some correctional terms may be omitted. Computing the derivative of the segmentation criterion with a dynamic scheme is described. The scheme is general enough to provide a framework for a wide variety of applications in segmentation. It also provides a theoretical meaning to the philosophy of active contours.

  17. The coronal and transition region temperature structure of a solar active region

    NASA Technical Reports Server (NTRS)

    Levine, R. H.; Pye, J. P.

    1980-01-01

    Using measurements of EUV and X-ray spectral lines, the differential emission measure vs electron temperature from the transition region to the corona of an active region (electron temperature between 100,000 and 5,000,000 K) is derived. The total emission measure and radiative losses are of the order 3 x 10 to the 48th/cu cm and 4 x 10 to the 26th ergs/sec, respectively. The emission measure at electron temperatures greater than approximately 1,000,000 K (i.e. that mainly responsible for the X-ray emission) is about 75% of the total. The use of the Mg x line at 625 A as an indicator of coronal electron density is also examined. A set of theoretical energy balance models of coronal loops in which the loop divergence is a variable parameter is presented and compared with the observations.

  18. Free Magnetic Energy and Helicity in Active and Quiet Solar Regions and their role in Solar

    NASA Astrophysics Data System (ADS)

    Tziotziou, K.; Georgoulis, M. K.; Tsiropoula, G.; Moraitis, K.; Kontogiannis, I.

    2013-09-01

    We present a novel nonlinear force-free method designed to calculate the instantaneous free magnetic energy and relative magnetic helicity budgets of a solar region from a single photospheric/chromospheric vector magnetogram of the region. Our objective is to study the role of these quantities in solar eruptions and quiet-Sun dynamics. We apply the method to (1) derive the energy/helicity diagram of solar active regions from a sample of 162 vector magnetograms corresponding to 42 different active regions (ARs), suggesting that there exist 4 1031 erg and 2 1042 Mx2 thresholds in free energy and relative helicity, respectively, for ARs to enter eruptive territory, (2) study the dynamics of eruptive NOAA AR 11158 using a high-cadence 5-day time series of vector magnetograms, suggesting the formation of increasingly helical pre-eruption structures and a causal relation between flares and Coronal Mass Ejections (CMEs) and, (3) derive helicity and energy budgets in quiet Sun regions and construct the respective energy/helicity diagram. Our results highlight the importance of these two parameters in AR evolution and quiet-Sun dynamics and instigate further research including detailed analysis with synthetic, magnetohydrodynamical models. This work is supported by EU's Seventh Framework Programme via a Marie Curie Fellowship and by the Hellenic National Space Weather Research Network (HNSWRN) via the THALIS Programme.

  19. Implications of Special Regions to Conducting Human Activities on Mars

    NASA Astrophysics Data System (ADS)

    Rummel, J. D.; Barlow, N. G.; Beaty, D. W.; Jones, M. A.; Hipkin, V.

    2014-12-01

    A MEPAG Science Analysis Group (SAG) has undertaken an analysis of Special Regions (SR) on Mars—regions where indigenous martian life could exist or where Earth microbes, if introduced, could survive and reproduce. The SR-SAG has considered the impact of SR on future human activities on the martian surface. Human exploration requires access to in-situ resources, some of which may be found in SR. Water and oxygen for ISRU are found in the atmosphere, surface/near-surface ice, hydrated minerals, and perchlorates. Water ice is most abundant at latitudes poleward of ~60 degrees, but polar darkness, cold temperatures, and CO2 degassing present hazards to human operations in these regions. Accessible water is more limited toward the equator, though temperature and solar energy conditions become more favorable. The possible presence of liquid water in Recurring Slope Lineae and active gullies leads to their treatment as SR. Fuel for surface operations and propellants for crew ascent could be manufactured from the martian atmosphere and surface materials, but dust in the atmosphere may clog ISRU equipment and perchlorate is toxic to humans. Power may be produced from solar or nuclear energy. Reliance on solar energy limits operations to the equatorial zone where easily accessible ice resources are limited. Nuclear power allows surface operations at a range of latitudes, but waste heat could convert some non-SR into SR. Radiation shielding is necessary for long-term human operations on Mars and could be obtained by deposition of regolith or by water storage in tanks or as ice around habitats, or the use of underground habitats. SR-SAG recognizes that it will be impossible for all human-associated processes and operations to be conducted within entirely closed systems. Protocols need to be established so (1) human missions to Mars will not contaminate SR nor be contaminated by materials from them, and (2) human activities on Mars will avoid converting areas into SR.

  20. Temporal evolution of continental lithospheric strength in actively deforming regions

    USGS Publications Warehouse

    Thatcher, W.; Pollitz, F.F.

    2008-01-01

    It has been agreed for nearly a century that a strong, load-bearing outer layer of earth is required to support mountain ranges, transmit stresses to deform active regions and store elastic strain to generate earthquakes. However the dept and extent of this strong layer remain controversial. Here we use a variety of observations to infer the distribution of lithospheric strength in the active western United States from seismic to steady-state time scales. We use evidence from post-seismic transient and earthquake cycle deformation reservoir loading glacio-isostatic adjustment, and lithosphere isostatic adjustment to large surface and subsurface loads. The nearly perfectly elastic behavior of Earth's crust and mantle at the time scale of seismic wave propagation evolves to that of a strong, elastic crust and weak, ductile upper mantle lithosphere at both earthquake cycle (EC, ???10?? to 103 yr) and glacio-isostatic adjustment (GIA, ???103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ???106-107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subtrate. These comparisons suggest that the upper mantle lithosphere is weaker than the crust at all time scales longer than seismic. In contrast, the lower crust has a chameleon-like behavior, strong at EC and GIA time scales and weak for LIA and steady-state deformation processes. The lower crust might even take on a third identity in regions of rapid crustal extension or continental collision, where anomalously high temperatures may lead to large-scale ductile flow in a lower crustal layer that is locally weaker than the upper mantle. Modeling of lithospheric processes in active regions thus cannot use a one-size-fits-all prescription of rheological layering (relation between applied stress and deformation as a function of depth) but must be tailored to the time scale and tectonic

  1. THE EXPANSION OF ACTIVE REGIONS INTO THE EXTENDED SOLAR CORONA

    SciTech Connect

    Morgan, Huw; Jeska, Lauren; Leonard, Drew

    2013-06-01

    Advanced image processing of Large Angle and Spectrometric Coronagraph Experiment (LASCO) C2 observations reveals the expansion of the active region closed field into the extended corona. The nested closed-loop systems are large, with an apparent latitudinal extent of 50 Degree-Sign , and expanding to heights of at least 12 R{sub Sun }. The expansion speeds are {approx}10 km s{sup -1} in the AIA/SDO field of view, below {approx}20 km s{sup -1} at 2.3 R{sub Sun }, and accelerate linearly to {approx}60 km s{sup -1} at 5 R{sub Sun }. They appear with a frequency of one every {approx}3 hr over a time period of around three days. They are not coronal mass ejections (CMEs) since their gradual expansion is continuous and steady. They are also faint, with an upper limit of 3% of the brightness of background streamers. Extreme ultraviolet images reveal continuous birth and expansion of hot, bright loops from a new active region at the base of the system. The LASCO images show that the loops span a radial fan-like system of streamers, suggesting that they are not propagating within the main coronal streamer structure. The expanding loops brighten at low heights a few hours prior to a CME eruption, and the expansion process is temporarily halted as the closed field system is swept away. Closed magnetic structures from some active regions are not isolated from the extended corona and solar wind, but can expand to large heights in the form of quiescent expanding loops.

  2. The formation of active protoclusters in the Aquila rift: a millimeter continuum view

    NASA Astrophysics Data System (ADS)

    Maury, A. J.; André, P.; Men'shchikov, A.; Könyves, V.; Bontemps, S.

    2011-11-01

    While most stars are believed to form in stellar clusters, the formation and early evolution of young stellar clusters is still largely unknown. Improving our knowledge of the earliest phases of clustered star formation is crucial for understanding the origin of the stellar initial mass function and the efficiency of the star formation process, which both play a key role in the evolution of galaxies. Here, we present an analysis of the Aquila rift complex which addresses the questions of the star formation rate (SFR), star formation efficiency (SFE) and typical lifetime of the Class 0 protostellar phase in two nearby cluster-forming clumps: the Serpens South and W40 protoclusters. We carried out a 1.2 mm dust continuum mapping of the Aquila rift complex with the MAMBO bolometer array on the IRAM 30 m telescope. Using a multi-scale source extraction method, we perform a systematic source extraction in our millimeter continuum map. Based on complementary data from the Herschel Gould Belt survey and Spitzer maps, we characterize the spectral energy distributions (SEDs) of the 77 mm continuum sources detected with MAMBO and estimate their evolutionary stages. Taking advantage of the comprehensive dataset available for the Serpens South region, spanning wavelengths from 2 μm to 1.2 mm, we estimate the numbers of young stellar objects (YSOs) at different evolutionary stages and find a ratio of Class 0 to Class I protostars N(0)/N(I) = 0.19-0.27. This low ratio supports a scenario of relatively fast accretion at the beginning of the protostellar phase, and leads to a Class 0 lifetime of ~4-9 × 104 yr. We also show that both the Serpens South and W40 protoclusters are characterized by large fractions of protostars and high SFRs ~ 20-50M⊙ Myr-1 pc-2, in agreement with the idea that these two nearby clumps are active sites of clustered star formation currently undergoing bursts of star formation, and have the potential ability to form bound star clusters. While the

  3. Storm activity in North Atlantic and precipitation anomalies in European region during winter seasons

    NASA Astrophysics Data System (ADS)

    Vyazilova, N. A.; Vyazilova, A. E.

    2009-09-01

    The purpose of this paper is to show the storm activity influence on the formation of wet and dry zone in North Atlantic and European region during winter seasons 1994/95, 2006/07 and 2007/08 years with positive mode of NAO, 1995/96, 2000/01 and 2005/06 years with negative mode of NAO. The study of storm activity includes the analyses of cyclonic intensity and cyclone track number. Analyses of cyclonic intensity based on calculation cyclone centers number (CCN) and sum of cyclone centers MSLP anomalies (CCMA). This analyses based on automated cyclone tracking algorithm and the 6-hourly MSLP from the NCEP/NCAR reanalyses 2 from 1979 to 2009. Precipitation anomalies were calculated from CMAP archive. Analyses had included the calculation of cyclone track number in all region [30°N-80°N, 50°W-70°E]and selected latitude zone for long cyclones (with lifetime more 2 day) and short cyclones (with lifetime less 2 day). The study had shown the special features of CCN and CCMA patterns in region for long and short cyclones. The study shows, that every winter season short cyclone track number twice as much long cyclone track number. However, the contribution of long cyclones in main determines the CCMA in region. Study had shown that winter seasons with positive NAO mode Nord Europe were outstanding by strong positive precipitation anomalies and strong cyclonic intensity, and during winter seasons with negative NAO mode in this region were observed negative precipitation anomalies and weak cyclonic activity. Standartizide anomalies of integral CCMA for selected latitude zone [55°N-80°N, 50°W-70°E] had shown the intensification of cyclonic activity over North Atlantic and North European region in last years.

  4. Chromospheric Evolution and the Flare Activity of Super-Active Region NOAA 6555

    NASA Technical Reports Server (NTRS)

    PrasadC, Debi; Ambastha, Ashok; Srivastava, Nandita; Tripathy, Sushanta C.; Hagyard, Mona J.

    1997-01-01

    Super-active region NOAA 6555 was highly flare productive during the period March 21st - 27th, 1991 of its disk passage. We have studied its chromospheric activity using high spatial resolution H alpha filtergrams taken at Udaipur along with MSFC vector magnetograms. A possible relationship of flare productivity and the variation in shear has been explored. Flares were generally seen in those subareas of the active region which possessed closed magnetic field configuration, whereas only minor flares and/or surges occurred in subareas showing open magnetic field configuration. Physical mechanisms responsible for the observed surges are also discussed.

  5. SOI/MDI studies of active region seismology and evolution

    NASA Technical Reports Server (NTRS)

    Tarbell, Ted D.; Title, Alan; Hoeksema, J. Todd; Scherrer, Phil; Zweibel, Ellen

    1995-01-01

    The solar oscillations investigation (SOI) will study solar active regions using both helioseismic and conventional observation techniques. The Michelson Doppler imager (MDI) can perform Doppler continuum and line depth imagery and can produce longitudinal magnetograms, showing either the full disk or a high resolution field of view. A dynamics program of continuous full disk Doppler observations for two months per year, campaign programs of eight hours of continuous observation per day, and a synoptic magnetic program of about 15 full disk magnetograms per day, are planned. The scientific plans, measurements and observation programs, are described.

  6. The distribution of maximum temperatures of coronal active region loops

    NASA Technical Reports Server (NTRS)

    Teske, R. G.; Mayfield, E. B.

    1981-01-01

    Starting with the integrated emission measure distributions of solar active regions, the distribution of the maximum temperature parameter which characterizes individual plasma loops is determined. The observed emission measure distributions were determined by combining EUV and X-ray data from two separate experiments on ATM/Skylab. The present work sets some limits on such an approach. It is found that the distribution of maximum temperature has approximately the same shape as the integrated emission measure distributions, a result which is expected since most of the loop emission measure is near their maximum temperatures.

  7. Substrate-emitting semiconductor laser with a trapezoidal active region

    SciTech Connect

    Dikareva, N V; Nekorkin, S M; Karzanova, M V; Zvonkov, B N; Aleshkin, V Ya; Dubinov, A A; Afonenko, A A

    2014-04-28

    Semiconductor lasers with a narrow (∼2°) directional pattern in the planes both parallel and perpendicular to the p–n junction are fabricated. To achieve a low radiation divergence in the p–n junction plane, the active region in this plane was designed in the form of a trapezium. The narrow directional pattern in the plane perpendicular to the p–n junction was ensured by the use of a leaky mode, through which more than 90% of laser power was coupled out. (lasers)

  8. Emission Measure Distribution and Heating of Two Active Region Cores

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2011-01-01

    Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM/T(exp 2.4) from log T = 5.55 up to a peak at log T = 6.57. The observations are explained extremely well by a simple nanoflare model. However, in the absence of additional constraints, the observations could possibly also be explained by steady heating.

  9. Past storminess recorded in the internal architecture of coastal formations of Estonia in the NE Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Tõnisson, Hannes; Vilumaa, Kadri; Kont, Are; Sugita, Shinya; Rosentau, Alar; Muru, Merle; Anderson, Agnes

    2016-04-01

    Over the past 50 years, storminess has increased in northern Europe because of the changes in cyclonic activity. The cyclone season in the Baltic Sea area has shifted from autumn to winter; this has led to intensification of shore processes (erosion, sediment transport and accumulation) and has increased pressure to the economy (land use, coastal protection measures) of the coastal regions in the Baltic states. Therefore, studing the effects of such changes on shore processes in the past is critical for prediction of the future changes along the Baltic coasts. Beach ridge plains are found worldwide, where cyclones and storm surges affect accumulation forms. These sandy shores are highly susceptible to erosion. Due to the isostatic uplift on the NE coast of the Baltic Sea, the signs of major past events are well-preserved in the internal architecture of old coastal formations (dune ridge-swale complexes). Wave-eroded scarps in beach deposits are visible in subsurface ground-penetrating radar (GPR) records, indicating the past high-energy events. Several study areas and transects were selected on the NW coast of Estonia, using high-resolution topographic maps (LiDAR). Shore-normal subsurface surveys have been conducted with a digital GSSI SIR-3000 georadar with a 270 MHz antenna at each transect. Interpretation of GPR facies was based on hand auger and window sampler coring, which provided accurate depths of key stratigraphic boundaries and bounding surfaces. Several samples for luminescence and 14C dating were collected to determine the approximate chronology of the coastal formations along the Estonian coast. We have found that changes in storminess, including the periods of high and low intensity of storms in late Holocene, are clearly reflected in the internal patterns of ancient coastal formations. The sections with small ridges with short seaward-dipped layers (interface between wave-built and aeolian deposits) in deeper horizons are probably formed during

  10. Peptides of the Constant Region of Antibodies Display Fungicidal Activity

    PubMed Central

    Polonelli, Luciano; Ciociola, Tecla; Magliani, Walter; Zanello, Pier Paolo; D'Adda, Tiziana; Galati, Serena; De Bernardis, Flavia; Arancia, Silvia; Gabrielli, Elena; Pericolini, Eva; Vecchiarelli, Anna; Arruda, Denise C.; Pinto, Marcia R.; Travassos, Luiz R.; Pertinhez, Thelma A.; Spisni, Alberto; Conti, Stefania

    2012-01-01

    Synthetic peptides with sequences identical to fragments of the constant region of different classes (IgG, IgM, IgA) of antibodies (Fc-peptides) exerted a fungicidal activity in vitro against pathogenic yeasts, such as Candida albicans, Candida glabrata, Cryptococcus neoformans, and Malassezia furfur, including caspofungin and triazole resistant strains. Alanine-substituted derivatives of fungicidal Fc-peptides, tested to evaluate the critical role of each residue, displayed unaltered, increased or decreased candidacidal activity in vitro. An Fc-peptide, included in all human IgGs, displayed a therapeutic effect against experimental mucosal and systemic candidiasis in mouse models. It is intriguing to hypothesize that some Fc-peptides may influence the antifungal immune response and constitute the basis for devising new antifungal agents. PMID:22470523

  11. EXPLORING THE CONNECTION BETWEEN STAR FORMATION AND ACTIVE GALACTIC NUCLEUS ACTIVITY IN THE LOCAL UNIVERSE

    SciTech Connect

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.; Schiminovich, D.; Bertincourt, B.; O'Dowd, M.

    2012-10-10

    We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from the Sloan Digital Sky Survey (SDSS) and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic contributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [Ne II] 12.8 {mu}m emission line is well correlated with the star formation rate measured from the SDSS spectra, and this holds for the star-forming, composite, and AGN-dominated systems. AGNs show a clear excess of [Ne III] 15.6 {mu}m emission relative to star-forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including the mid-IR spectral slope, the ratio of the [Ne V] 14.3 {mu}m to [Ne II] {mu}m 12.8 fluxes, the equivalent widths of the 7.7 {mu}m, 11.3 {mu}m, and 17 {mu}m polycyclic aromatic hydrocarbon (PAH) features, and the optical 'D' parameter which measures the distance at which a source lies from the locus of star-forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN dominance. We find that the PAH 11.3 {mu}m feature is significantly suppressed in the most AGN-dominated systems.

  12. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. II - NOAA active region 5747 (1989 October)

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Canfield, Richard C.; Mcclymont, A. N.; De La Beaujardiere, J.-F.; Fan, Yuhong; Tang, F.

    1993-01-01

    The paper describes October 1989 observations in NOAA Active Region 5747 of the morphology of energetic electron precipitation and high-pressure coronal flare plasmas of three flares and their relation to the vector magnetic field and vertical electric currents. The H-alpha spectroheliograms were coaligned with the vector magnetograms using continuum images of sunspots, enabling positional accuracy of a few arcsec. It was found that, during the gradual phase, the regions of the H-alpha flare that show the effects of enhanced pressure in the overlying corona often encompass extrema of the vertical current density, consistent with earlier work showing a close relationship between H-alpha emission and line-of-sight currents. The data are also consistent with the overall morphology and evolution described by erupting-filament models such as those of Kopp and Pneuman (1976) and Sturrock (1989).

  13. Active Region Magnetic Structure Observed in the Photosphere and Chromosphere

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Metcalf, Thomas R.

    2001-01-01

    The magnetic flux above sunspots and plage in NOAA (National Oceanic and Atmospheric Administration) Active Region 8299 has been measured in the photosphere and the chromosphere. We investigate the vertical magnetic structure above the umbrae, penumbrae and plage regions using quantitative statistical comparisons of the photospheric and chromospheric vector magnetic flux data. The results include: (1) a decrease in flux with height, (2) the direct detection of the superpenumbral canopy in the chromosphere, (3) values for dB/dz which are consistent with earlier investigations when derived from a straight difference between the two datasets but quite low when derived from the delta x B = 0 condition, (4) a monolithic structure in the umbra which extends well into the upper chromosphere with a very complex and varied structure in the penumbra and plage, as evidenced by (5) a uniform magnetic scale height in the umbrae with an abrupt jump to widely varying scale heights in the penumbral and plage regions. Further, we find (6) evidence for a very large (delta z approximately equals 3Mm) height difference between the atmospheric layers sampled in the two magnetograms, almost a factor of three larger than that implied by atmospheric models. We additionally test the apropriateness of using photospheric magnetic flux as a boundary for field-line extrapolations, and find a better agreement with observed coronal structure when the chromospheric flux is used as a boundary.

  14. Plasma Beta Above a Solar Active Region: Rethinking the Paradigm

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    In this paper, we present a model of the plasma beta above an active region and discuss its consequences in terms of coronal magnetic field modeling. The beta-plasma model is representative and derived from a collection of sources. The resulting beta variation with height is used to emphasize the assumption that the magnetic pressure dominates over the plasma pressure must be carefully considered depending on what part of the solar atmosphere is being considered. This paper points out (1) that the paradigm that the coronal magnetic field can be constructed from a force-free magnetic field must be used in the correct context, since the forcefree region is sandwiched between two regions which have beta greater than 1, (2) that the chromospheric MgIICIV magnetic measurements occur near the beta-minimum, and (3) that, moving from the photosphere upwards, beta can return to 1 at relatively low coronal heights, e.g. R approximately 1.2R(sub)s.

  15. The strength of an Ig switch region is determined by its ability to drive R loop formation and its number of WGCW sites.

    PubMed

    Zhang, Zheng Z; Pannunzio, Nicholas R; Han, Li; Hsieh, Chih-Lin; Yu, Kefei; Lieber, Michael R

    2014-07-24

    R loops exist at the murine IgH switch regions and possibly other locations, but their functional importance is unclear. In biochemical systems, R loop initiation requires DNA sequence regions containing clusters of G nucleotides, but cellular studies have not been done. Here, we vary the G-clustering, total switch region length, and the number of target sites (WGCW sites for the activation-induced deaminase) at synthetic switch regions in a murine B cell line to determine the effect on class switch recombination (CSR). G-clusters increase CSR regardless of their immediate proximity to the WGCW sites. This increase is accompanied by an increase in R loop formation. CSR efficiency correlates better with the absolute number of WGCW sites in the switch region rather than the total switch region length or density of WGCW sites. Thus, the overall strength of the switch region depends on G-clusters, which initiate R loop formation, and on the number of WGCW sites. PMID:25017067

  16. The Strength of an Ig Switch Region is Determined by its Ability to Drive R-loop Formation and its Number of WGCW Sites

    PubMed Central

    Zhang, Zheng Z.; Pannunzio, Nicholas R.; Han, Li; Hsieh, Chih-Lin; Yu, Kefei; Lieber, Michael R.

    2014-01-01

    SUMMARY R-loops exist at the murine IgH switch regions and possibly other locations, but their functional importance is unclear. In biochemical systems, R-loop initiation requires DNA sequence regions containing clusters of G nucleotides, but cellular studies have not been done. Here, we vary the G-clustering, total switch region length, and the number of target sites (WGCW sites for the activation-induced deaminase) at synthetic switch regions in a murine B cell line to determine the effect on class switch recombination (CSR). G-clusters increase CSR, regardless of their immediate proximity to the WGCW sites. This increase is accompanied by an increase in R-loop formation. CSR efficiency correlates better with the absolute number of WGCW sites in the switch region rather than the total switch region length or density of WGCW sites. Thus, the overall strength of the switch region depends on G-clusters, which initiate R-loop formation, and on the number of WGCW sites. PMID:25017067

  17. Magnetic helicity and free energy in solar active regions

    NASA Astrophysics Data System (ADS)

    Moraitis, K.; Georgoulis, M.; Tziotziou, K.; Archontis, V.

    2013-09-01

    We study the evolution of the non-potential free magnetic energy and relative magnetic helicity budgets in solar active regions (ARs). For this we use a time-series of a three-dimensional, synthetic AR produced by magnetohydrodynamical (MHD) simulations. As a first step, we calculate the potential magnetic field that has the same normal components with the MHD field along all boundaries of the AR, by solving Laplace's equation. The free magnetic energy of the AR is then easily derived. From the two fields, MHD and potential one, we calculate the corresponding vector potentials with a recently proposed integration method. The knowledge of both fields and their respective vector potentials throughout the AR, allows us to estimate the relative magnetic helicity budget of the AR. Following this procedure for each snapshot of the AR, we reconstruct the evolution of free energy and helicity in the AR. Our method reproduces, for a synthetic AR, the energy/helicity relations known to hold in real active regions.

  18. Multi-Wavelength Study of Active Region Loop Dynamics

    NASA Astrophysics Data System (ADS)

    Banerjee, D.

    2006-11-01

    Observations have revealed the existence of weak transient disturbances in extended coronal loop systems. These propagating disturbances (PDs) originate from small scale brightenings at the footpoints of the loops and propagate upward along the loops. In all cases observed, the projected propagation speed is close to, but below the expected sound speed in the loops. This suggests that the PDs could be interpreted as slow mode MHD waves. Interpreting the oscillation in terms of different wave modes and/or plasma motions always depend on the line of sight as we observe in the limb or on the center of the disk. The JOP 165 campaign will address some of these questions. MDI and TRACE photospheric and UV imaging of TRACE and SPIRIT have been acquired simultaneously with high temporal and spatial coverage along with the spectroscopic data from CDS. EIT was operated in the shutter-less mode to achieve high Cadence. Some of the off- limb active region dynamics and oscillations observed during this JOP campaign will be focused in this presentation. Plasma condensations and temporal variations in active region loops will be also addressed.

  19. Magnetic field measurements in and above a limb active region

    NASA Astrophysics Data System (ADS)

    Philip, Judge

    2013-07-01

    We analyze spectropolarimetric data of a limb active region (NOAA 11302) obtained on September 22nd 2011 using the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Stokes profiles including lines of Si I 1028.7 nm and He I 1083 nm were obtained in three scans over a 45"x75" area. Simultaneous narrow band Ca II K and G-band intensity data were acquired with a cadence of 5s at the DST. The He I data show not only typical active region polarization signatures, but also signatures in plumes -- cool post flare loops -- which extend many Mm into the corona across the visible limb. The plumes have remarkably uniform brightness, and the plume plasma is significantly Doppler shifted as it drains from the corona. Using carefully constructed observing and calibration sequences and applying Principal Component Analysis to remove instrumental artifacts, we achieved a polarization sensitivity approaching 0.02%. With this sensitivity we attempt to diagnose the vector magnetic fields and plasma properties of chromospheric and cool coronal material in and above NOAA 11302. Inversions using various radiative transfer models in the HAZEL code are remarkably consistent with the idea that plume spectra are formed in a simple, slab-like geometry, but that the ``disk'' spectra are formed under more traditional models (Milne-Eddington). The inverted magnetic data of He I lines are compared with photospheric inversions of DST Si I and Fe I data from the Solar Dynamics Observatory.

  20. Active Region Filaments Might Harbor Weak Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Díaz Baso, C. J.; Martínez González, M. J.; Asensio Ramos, A.

    2016-05-01

    Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and Hanle effect signatures was then pointed out by some authors. This was interpreted as either a signature of mixed “turbulent” field components or as a result of optical thickness. In this article, we present a natural scenario to explain these Zeeman-only spectropolarimetric observations of active region (AR) filaments. We propose a two-component model, one on top of the other. Both components have horizontal fields, with the azimuth difference between them being close to 90°. The component that lies lower in the atmosphere is permeated by a strong field of the order of 600 G, while the upper component has much weaker fields, of the order of 10 G. The ensuing scattering polarization signatures of the individual components have opposite signs, so its combination along the line of sight reduces—and even can cancel out—the Hanle signatures, giving rise to an apparent Zeeman-only profile. This model is also applicable to other chromospheric structures seen in absorption above ARs.

  1. Photospheric electric current and transition region brightness within an active region

    NASA Technical Reports Server (NTRS)

    Deloach, A. C.; Hagyard, M. J.; Rabin, D.; Moore, R. L.; Smith, B. J., Jr.; West, E. A.; Tandberg-Hanssen, E.

    1984-01-01

    Distributions of vertical electrical current density J(z) calculated from vector measurements of the photospheric magnetic field are compared with ultraviolet spectroheliograms to investigate whether resistive heating is an important source of enhanced emission in the transition region. The photospheric magnetic fields in Active Region 2372 were measured on April 6 and 7, 1980 with the Marshall Space Flight Center vector magnetograph; ultraviolet wavelength spectroheliograms (L-alpha and N V 1239 A) were obtained with the UV Spectrometer and Polarimeter experiment aboard the Solar Maximum Mission satellite. Spatial registration of the J(z) (5 arcsec resolution) and UV (3 arcsec resolution) maps indicates that the maximum current density is cospatial with a minor but persistent UV enhancement, but there is little detected current associated with other nearby bright areas. It is concluded that, although resistive heating may be important in the transition region, the currents responsible for the heating are largely unresolved in the present measurements and have no simple correlation with the residual current measured on 5-arcsec scales.

  2. CHP REGIONAL APPLICATION CENTERS: ACTIVITIES AND SELECTED RESULTS

    SciTech Connect

    Schweitzer, Martin

    2010-08-01

    Between 2001 and 2005, the U.S. Department of Energy (DOE) created a set of eight Regional Application Centers (RACs) to facilitate the development and deployment of Combined Heat and Power (CHP) technologies. By utilizing the thermal energy that is normally wasted when electricity is produced at central generating stations, Combined Heat and Power installations can save substantial amounts of energy compared to more traditional technologies. In addition, the location of CHP facilities at or near the point of consumption greatly reduces or eliminates electric transmission and distribution losses. The regional nature of the RACs allows each one to design and provide services that are most relevant to the specific economic and market conditions in its particular geographic area. Between them, the eight RACs provide services to all 50 states and the District of Columbia. Through the end of the federal 2009 fiscal year (FY 2009), the primary focus of the RACs was on providing CHP-related information to targeted markets, encouraging the creation and adoption of public policies and incentives favorable to CHP, and providing CHP users and prospective users with technical assistance and support on specific projects. Beginning with the 2010 fiscal year, the focus of the regional centers broadened to include district energy and waste heat recovery and these entities became formally known as Clean Energy Application Centers, as required by the Energy Independence and Security Act (EISA) of 2007. In 2007, ORNL led a cooperative effort to establish metrics to quantify the RACs accomplishments. That effort began with the development of a detailed logic model describing RAC operations and outcomes, which provided a basis for identifying important activities and accomplishments to track. A data collection spreadsheet soliciting information on those activities for FY 2008 and all previous years of RAC operations was developed and sent to the RACs in the summer of 2008. This

  3. Active Geodesics: Region-based Active Contour Segmentation with a Global Edge-based Constraint.

    PubMed

    Appia, Vikram; Yezzi, Anthony

    2011-11-01

    We present an active geodesic contour model in which we constrain the evolving active contour to be a geodesic with respect to a weighted edge-based energy through its entire evolution rather than just at its final state (as in the traditional geodesic active contour models). Since the contour is always a geodesic throughout the evolution, we automatically get local optimality with respect to an edge fitting criterion. This enables us to construct a purely region-based energy minimization model without having to devise arbitrary weights in the combination of our energy function to balance edge-based terms with the region-based terms. We show that this novel approach of combining edge information as the geodesic constraint in optimizing a purely region-based energy yields a new class of active contours which exhibit both local and global behaviors that are naturally responsive to intuitive types of user interaction. We also show the relationship of this new class of globally constrained active contours with traditional minimal path methods, which seek global minimizers of purely edge-based energies without incorporating region-based criteria. Finally, we present some numerical examples to illustrate the benefits of this approach over traditional active contour models.

  4. Characteristics, location and origin of flare activity in a complex active region

    NASA Technical Reports Server (NTRS)

    Machado, M. E.; Gary, G. A.; Hagyard, M. J.; Hernandez, A. M.; Rovira, M. G.

    1986-01-01

    The observational characteristics of series of multiple-loop flares from a complex active region are summarized. The location of the highest observed photospheric magnetic shear is found to be the commonly observed site of flare onset, but not, in many cases, the magnetic region where the largest time-integrated energy release is observed. The observations thus reveal a consistent pattern of energy-release processes related to the magnetic-field topology.

  5. Dynamics mechanism on fault basin formation in the Lower Yangtze region

    NASA Astrophysics Data System (ADS)

    Xu, X.; Wang, W.; Xu, C.

    2013-12-01

    It is one of the critical issues of the rift basin to study the specific dynamical mechanism of the basin formulation in the Lower Yangtze Region. There still exist controversies on the genetical mechanism, although some previous studies have revealed various formulation models, such as rift basin model related to the Pacific subduction, continental rift basin model, transtensional basin model related to the dextral slip of TanLu fault, simple shear inherited thin skin basin model, basin mode related to extension and detachment of basement, pull-apart basin model related to Mekenzie(1978) pure shear. Among these various tectonic models, the dynamics of formation of fault basin in the Lower Yangtze block is not yet fully understood. Our purpose is to explain comprehensively the formation of the fault basin by an integrated approach, drawing conclusions from our geological field investigation, seismic interpretation and literatures and using the numerical modeling. By contributing a two-dimensional finite element model of the Lower Yangtze block and its environs in the Paleogene, we are able to estimate the surface velocity, stress field and strain rate field of model. The results reveal that there is the nearly southwestward movement of the northeast part of block in an equilibrium of the nearly NEE-SWW trending displacement field with the reference velocity of 100 mm/a, and crustal plastic flow from north to south in internal model, dragging the upper crust to produce nearly N-S striking tension. Displacement and deformation, associated with current seismologic correlation analysis, can be extended to the depth of at least 30KM. Consequently, The deformation of the Lower Yangtze block and its environs is not influenced by the dextral movement of Tan-Lu fault, but the regional extension and strain in the Subei-Southern South Yellow Sea area which has the extensional stress filed in the upper crust. The observations of modeling and evidence from our data and the

  6. Irradiated interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 massive star formation regions

    NASA Astrophysics Data System (ADS)

    Hartigan, P.; Palmer, J.; Cleeves, L. I.

    2012-12-01

    Regions of massive star formation offer some of the best and most easily-observed examples of radiation hydrodynamics. Boundaries where fully-ionized H II regions transition to neutral/molecular photodissociation regions (PDRs) are of particular interest because marked temperature and density contrasts across the boundaries lead to evaporative flows and fluid dynamical instabilities that can evolve into spectacular pillar-like structures. When detached from their parent clouds, pillars become ionized globules that often harbor one or more young stars. H2 molecules at the interface between a PDR and an H II region absorb ultraviolet light from massive stars, and the resulting fluoresced infrared emission lines are an ideal way to trace this boundary independent of obscuring dust. This paper presents H2 images of four regions of massive star formation that illustrate different types of PDR boundaries. The Ara OB1 star formation region contains a striking long wall that has several wavy structures which are present in H2, but the emission is not particularly bright because the ambient UV fluxes are relatively low. In contrast, the Carina star formation region shows strong H2 fluorescence both along curved walls and at the edges of spectacular pillars that in some cases have become detached from their parent clouds. The less-spectacular but more well-known Eagle Nebula has two regions that have strong fluorescence in addition to its pillars. While somewhat older than the other regions, Cyg OB2 has the highest number of massive stars of the regions surveyed and contains many isolated, fluoresced globules that have head-tail morphologies which point towards the sources of ionizing radiation. These images provide a collection of potential astrophysical analogs that may relate to ablated interfaces observed in laser experiments of radiation hydrodynamics.

  7. New results of studying of the Devonian shale formation in the Volga-Ural region

    NASA Astrophysics Data System (ADS)

    Plotnikova, Irina; Pronin, Nikita; Morozov, Vladimir; Nosova, Fidania

    2015-04-01

    The objects of the study are Upper Devonian carbonate rocks in the territory of South-Tatar arch and Melekess basin in the Volga- Urals region. We studied core material and organic matter of Domanicoid facies from the sediments of Semilukskiy and Rechitskiy (Domanik) horizons of the Upper Devonian. Basic analytical research methods included the following: study of the composition, structural and textural features of the rocks, the structure of their voids, filter and reservoir properties and composition of the fluid. The complex research consisted of macroscopic description of the core material, optical microscopy analysis, radiographical analysis, thermal analysis, x-ray tomography, electron microscopy, gas-liquid chromatography, chromate-mass spectrometry, isotopic analysis of oil and organic matter, light hydrocarbons analysis using paraphase assay, adsorbed gases analysis, and thermal vacuum degassing method. In addition, we performed isotopic studies of hydrocarbons saturating shale rocks. The study of biomarkers was carried out with the help of chromato-mass spectrometry in the Laboratory of Geochemistry of Fossil Fuels, Kazan Federal University. GC/MS method was used in oil to investigate the individual composition of naphthenic hydrocarbons, primarily steranes and terpanes and another new biological markers. In this study we used several informative parameters characterizing the depositional environment, the type of source OM and its maturity. In the evaluation of the facial conditions of sedimentation and the degree of catagenetic conversion of the OM, the quantitative characteristics based not only on the distribution of steranes and terpanes, which are related to the lithology and maturity of the OM.New biomarkers parameters (carotenoids) were used to study the conditions of formation of shale strata. Based on these new data, a new model of geological and environmental conditions for the formation of shale strata saturated bituminous matter (organic

  8. Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

    NASA Astrophysics Data System (ADS)

    Timms, W. A.; Crane, R.; Anderson, D. J.; Bouzalakos, S.; Whelan, M.; McGeeney, D.; Rahman, P. F.; Acworth, R. I.

    2016-01-01

    Evaluating the possibility of leakage through low-permeability geological strata is critically important for sustainable water supplies, the extraction of fuels from coal and other strata, and the confinement of waste within the earth. The current work demonstrates that relatively rapid and realistic vertical hydraulic conductivity (Kv) measurements of aquitard cores using accelerated gravity can constrain and compliment larger-scale assessments of hydraulic connectivity. Steady-state fluid velocity through a low-K porous sample is linearly related to accelerated gravity (g level) in a centrifuge permeameter (CP) unless consolidation or geochemical reactions occur. A CP module was custom designed to fit a standard 2 m diameter geotechnical centrifuge (550 g maximum) with a capacity for sample dimensions up to 100 mm diameter and 200 mm length, and a total stress of ˜ 2 MPa at the base of the core. Formation fluids were used as influent to limit any shrink-swell phenomena, which may alter the permeability. Kv results from CP testing of minimally disturbed cores from three sites within a clayey-silt formation varied from 10-10 to 10-7 m s-1 (number of samples, n = 18). Additional tests were focussed on the Cattle Lane (CL) site, where Kv within the 99 % confidence interval (n = 9) was 1.1 × 10-9 to 2.0 × 10-9 m s-1. These Kv results were very similar to an independent in situ Kv method based on pore pressure propagation though the sequence. However, there was less certainty at two other core sites due to limited and variable Kv data. Blind standard 1 g column tests underestimated Kv compared to CP and in situ Kv data, possibly due to deionised water interactions with clay, and were more time-consuming than CP tests. Our Kv results were compared with the set-up of a flow model for the region, and considered in the context of heterogeneity and preferential flow paths at site and

  9. DETAILED NUMERICAL SIMULATIONS ON THE FORMATION OF PILLARS AROUND H II REGIONS

    SciTech Connect

    Gritschneder, Matthias; Burkert, Andreas; Naab, Thorsten; Walch, Stefanie

    2010-11-10

    We study the structural evolution of turbulent molecular clouds under the influence of ionizing radiation emitted from a nearby massive star by performing a high-resolution parameter study with the iVINE code. The temperature is taken to be 10 K or 100 K, the mean number density is either 100 cm{sup -3} or 300 cm{sup -3}. Furthermore, the turbulence is varied between Mach 1.5 and Mach 12.5, the main driving scale of the turbulence is varied between 1 pc and 8 pc. We vary the ionizing flux by an order of magnitude, corresponding to allowing between 0.5% and 5% of the mass in the domain to be ionized immediately. In our simulations, the ionizing radiation enhances the initial turbulent density distribution and thus leads to the formation of pillar-like structures observed adjacent to H II regions in a natural way. Gravitational collapse occurs regularly at the tips of the structures. We find a clear correlation between the initial state of the turbulent cold cloud and the final morphology and physical properties of the structures formed. The most favorable regime for the formation of pillars is Mach 4-10. Structures and therefore stars only form if the initial density contrast between the high-density unionized gas and the gas that is going to be ionized is lower than the temperature contrast between the hot and the cold gas. The density of the resulting pillars is determined by a pressure equilibrium between the hot and the cold gas. A thorough analysis of the simulations shows that the complex kinematical and geometrical structure of the formed elongated filaments reflects that of observed pillars to an impressive level of detail. In addition, we find that the observed line-of-sight velocities allow for a distinct determination of different formation mechanisms. Comparing the current simulations to previous results and recent observations, we conclude that, e.g., the pillars of creation in M16 formed by the mechanism proposed here and not by the radiation driven

  10. Activity of pyrrolizidine alkaloids against biofilm formation and Trichomonas vaginalis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crotalaria genus belongs to the subfamily Papilionoideae comprising about 600 species spread throughout tropical, neotropical and subtropical regions. In this study, seeds of Crolatalaria pallida were used to the isolation of usaramine, a pyrrolizidine alkaloid. Thus, Pseudomonas aeruginosa and Stap...

  11. Star Formation near Photodissociation Regions: Detection of a Peculiar Protostar near Cederblad 201

    NASA Astrophysics Data System (ADS)

    Goicoechea, Javier R.; Berné, Olivier; Gerin, Maryvonne; Joblin, Christine; Teyssier, David

    2008-06-01

    We present the detection and characterization of a peculiar low-mass protostar (IRAS 22129+7000) located ~0.4 pc from the Cederblad 201 photodissociation region (PDR) and ~0.2 pc from the HH 450 jet. The cold circumstellar envelope surrounding the object has been mapped through its 1.2 mm dust continuum emission with IRAM 30 m/MAMBO. The deeply embedded protostar is clearly detected with Spitzer MIPS (70 μm), IRS (20-35 μm), and IRAC (4.5, 5.8, and 8 μm), but also in the Ks band (2.15 μm). Given the large near- and mid-IR excess in its spectral energy distribution, but large submillimeter-to-bolometric luminosity ratio (simeq2%), IRAS 22129+7000 must be a transition Class 0/I source and/or a multiple stellar system. Targeted observations of several molecular lines from CO,13CO, C18O, HCO+, and DCO+ have been obtained. The presence of a collimated molecular outflow mapped with the CSO telescope in the CO J = 3-2 line suggests that the protostar/disk system is still accreting material from its natal envelope. Indeed, optically thick line profiles from high-density tracers such as HCO+ J = 1-0 show a redshifted absorption asymmetry reminiscent of inward motions. We construct a preliminary physical model of the circumstellar envelope (including radial density and temperature gradients, velocity field, and turbulence) that reproduces the observed line profiles and estimates the ionization fraction. The presence of both mechanical and (nonionizing) far-ultraviolet (FUV) radiative input makes the region an interesting case to study triggered star formation.

  12. CIRCUMSTELLAR STRUCTURE AROUND EVOLVED STARS IN THE CYGNUS-X STAR FORMATION REGION

    SciTech Connect

    Kraemer, Kathleen E.; Price, Stephan D.

    2010-06-15

    We present observations of newly discovered 24 {mu}m circumstellar structures detected with MIPS around three evolved stars in the Cygnus-X star-forming region. One of the objects, BD+43 3710, has a bipolar nebula, possibly due to an outflow or a torus of material. A second, HBHA 4202-22, a Wolf-Rayet candidate, shows a circular shell of 24 {mu}m emission suggestive of either a limb-brightened shell or disk seen face-on. No diffuse emission was detected around either of these two objects in the Spitzer 3.6-8 {mu}m IRAC bands. The third object is the luminous blue variable candidate G79.29+0.46. We resolved the previously known inner ring in all four IRAC bands. The 24 {mu}m emission from the inner ring extends {approx}1.'2 beyond the shorter wavelength emission, well beyond what can be attributed to the difference in resolutions between MIPS and IRAC. Additionally, we have discovered an outer ring of 24 {mu}m emission, possibly due to an earlier episode of mass loss. For the two shell stars, we present the results of radiative transfer models, constraining the stellar and dust shell parameters. The shells are composed of amorphous carbon grains, plus polycyclic aromatic hydrocarbons in the case of G79.29+0.46. Both G79.29+0.46 and HBHA 4202-22 lie behind the main Cygnus-X cloud. Although G79.29+0.46 simply may be on the far side of the cloud, HBHA 4202-22 is unrelated to the Cygnus-X star formation region.

  13. Repetitive Transcranial Magnetic Stimulation Activates Specific Regions in Rat Brain

    NASA Astrophysics Data System (ADS)

    Ji, Ru-Rong; Schlaepfer, Thomas E.; Aizenman, Carlos D.; Epstein, Charles M.; Qiu, Dike; Huang, Justin C.; Rupp, Fabio

    1998-12-01

    Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique to induce electric currents in the brain. Although rTMS is being evaluated as a possible alternative to electroconvulsive therapy for the treatment of refractory depression, little is known about the pattern of activation induced in the brain by rTMS. We have compared immediate early gene expression in rat brain after rTMS and electroconvulsive stimulation, a well-established animal model for electroconvulsive therapy. Our result shows that rTMS applied in conditions effective in animal models of depression induces different patterns of immediate-early gene expression than does electroconvulsive stimulation. In particular, rTMS evokes strong neural responses in the paraventricular nucleus of the thalamus (PVT) and in other regions involved in the regulation of circadian rhythms. The response in PVT is independent of the orientation of the stimulation probe relative to the head. Part of this response is likely because of direct activation, as repetitive magnetic stimulation also activates PVT neurons in brain slices.

  14. On the continuing stellar formation in the central regions of some globular clusters and their relation to the pulsars

    NASA Technical Reports Server (NTRS)

    Komberg, B. V.

    1979-01-01

    The discrepancy between the predicted and observed quantities of gas in the central regions of massive globular clusters is discussed. It is hypothesized that star formation continues in the central regions by means of gas released during stellar evolution or trapped by the central region when the globular clusters pass through the center of the galaxy. Nine globular clusters are indicated at distances less than 1000 ps from which radio pulsars or X-ray sources are observed. It is argued that they could have formed relatively recently in closed pairs in the central regions and then ejected at the stage of supernova bursts with velocities over 100 ks/s.

  15. 12 CFR Appendix I to Part 27 - Monthly Home Loan Activity Format

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Monthly Home Loan Activity Format I Appendix I to Part 27 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY FAIR HOUSING HOME LOAN DATA SYSTEM Pt. 27, App. I Appendix I to Part 27—Monthly Home Loan Activity Format...

  16. 12 CFR Appendix I to Part 27 - Monthly Home Loan Activity Format

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Monthly Home Loan Activity Format I Appendix I to Part 27 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY FAIR HOUSING HOME LOAN DATA SYSTEM Pt. 27, App. I Appendix I to Part 27—Monthly Home Loan Activity Format...

  17. Terrace Formation in the Upper Headwater Region of the Mattole River Watershed Across the Mendocino Triple Junction, Northwest California

    NASA Astrophysics Data System (ADS)

    Robinson, M.; Flanagan, S., II; Hemphill-Haley, M. A.

    2015-12-01

    The Mattole River, in northwestern California, is located in a tectonically active and geologically complex area, the Mendocino triple junction (MTJ), where the North American, Pacific and Gorda plates meet. The Mattole River does not follow the classic river "concave-up" profile. Instead, the river headwaters have wide valleys of low gradient fill, cut and strath terraces with deeply incised active channels. In fact, the river has a "convex-up" profile with a low gradient headwater leading to a higher gradient midcourse. Terrace formation in the upper headwater region of the Mattole River records times of disequilibrium of channel profile and incision as the river responds to changes that are, in large part, due to the passage of the northwardly migrating, thermally buoyant MTJ. In order to investigate the distribution and relative ages of terraces, detailed surveys of terrace surfaces and bedrock strath positions were conducted along four headwater tributaries: Thompson Creek, Baker Creek, Lost River and Ancestor Creek. Additionally, across the terraces, hand borings were excavated to bedrock to provide a three dimensional image of terrace thickness. Terrace morphology and stratigraphy provide information on terrace forming mechanisms and timing. This study includes high-resolution geomorphic data regarding the relation of Mattole headwater terraces to the MTJ, as well as provides more temporal information about the fluvial system's response to the ongoing northward migration of the MTJ.

  18. Unique SMAD1/5/8 activity at the phalanx-forming region determines digit identity

    PubMed Central

    Suzuki, Takayuki; Hasso, Sean M.; Fallon, John F.

    2008-01-01

    The zone of polarizing activity is the primary signaling center controlling anterior–posterior patterning of the amniote limb bud. The autopodial interdigits (IDs) are secondary signaling centers proposed to determine digit identity by acting on the cells of the digital ray. Here, we focus on events accompanying digital fate determination and define a region of the digital ray that expresses Sox9 and Bmpr1b and is phosphorylated-SMAD1/5/8 (p-SMAD1/5/8) positive. We name this region the phalanx-forming region (PFR), and show that the PFR cells arise from the distal subridge mesenchyme of digital ray. This phalanx-forming cell lineage is subsequently committed to the cartilage lineage; the fate of these cells is initially labile but becomes fixed as they are incorporated into the condensed cartilage of the digit primordium. Using an in vivo reporter assay, we establish that each digital PFR has a unique p-SMAD1/5/8 activity signature. In addition, we show that changes in this activity correlate with the identity of the digit that forms after experimental manipulation, supporting the idea that threshold signaling levels can lead to different developmental outcomes in a morphogenetic field. Our data define the molecular profile of the PFR, and we propose a model for understanding formation and variation of digits during autopodial development. PMID:18334652

  19. Enhancement effect of relative humidity on the formation and regional respiratory deposition of secondary organic aerosol.

    PubMed

    Yu, Kuo-Pin; Lin, Chi-Chi; Yang, Shang-Chun; Zhao, Ping

    2011-07-15

    In this study, we investigated the effect of relative humidity (RH) on the formation of secondary organic aerosol (SOA) generated from the ozonolysis of d-limonene in an environmental chamber. The mass yield and the number concentration of SOA increased seven and eight times, respectively, when the RH increased from 18% to 82%. The measured total loss rates (apparent loss rates) of the number and mass concentration of SOA in the chamber ranged from 1.70 to 1.77 h(-1) and from 2.51 to 2.61 h(-1), respectively, at a controlled ventilation rate of 0.72±0.04 h(-1). The wall-deposition-loss-rate coefficient observed (1.00±0.02 h(-1)) was approximate to the estimated value based on Zhao and Wu's model which includes the factors of turbulence, Brownian diffusion, turbophoresis and surface roughness. According to the ICRP (International Commission on Radiological Protection) model, the inhaled SOA particles are deposited primarily in the alveoli of the lung. The integrated alveolar deposited dose of the mass (surface area) of SOA over 3h accounted for 74.0-74.8% (74.3-74.9%) of the total deposited dose at the investigated RH. Raising the RH resulted in the growth of SOA particle sizes and increment of the deposition dose but did not cause significant changes in the ratio of regional to the total respiratory deposition of SOA. PMID:21570180

  20. TRIGGERED STAR FORMATION AROUND MID-INFRARED BUBBLES IN THE G8.14+0.23 H II REGION

    SciTech Connect

    Dewangan, L. K.; Ojha, D. K.; Chakraborti, S.; Anandarao, B. G.; Ghosh, S. K.

    2012-09-10

    Mid-infrared shells or bubbles around expanding H II regions have received much attention due to their ability to initiate a new generation of star formation. We present multi-wavelength observations around two bubbles associated with a southern massive star-forming region G8.14+0.23, to investigate the triggered star formation signature on the edges of the bubbles by the expansion of the H II region. We have found observational signatures of the collected molecular and cold dust material along the bubbles and the {sup 12}CO(J = 3-2) velocity map reveals that the molecular gas in the bubbles is physically associated around the G8.14+0.23 region. We have detected 244 young stellar objects (YSOs) in the region and about 37% of these YSOs occur in clusters. Interestingly, these YSO clusters are associated with the collected material on the edges of the bubbles. We have found good agreement between the dynamical age of the H II region and the kinematical timescale of bubbles (from the {sup 12}CO(J = 3-2) line data) with the fragmentation time of the accumulated molecular materials to explain possible 'collect and collapse' process around the G8.14+0.23 region. However, one cannot entirely rule out the possibility of triggered star formation by compression of the pre-existing dense clumps by the shock wave. We have also found two massive embedded YSOs (about 10 and 22 M{sub Sun }) which are associated with the dense fragmented clump at the interface of the bubbles. We conclude that the expansion of the H II region is also leading to the formation of these two young massive embedded YSOs in the G8.14+0.23 region.

  1. Cores, filaments, and bundles: hierarchical core formation in the L1495/B213 Taurus region

    NASA Astrophysics Data System (ADS)

    Hacar, A.; Tafalla, M.; Kauffmann, J.; Kovács, A.

    2013-06-01

    Context. Core condensation is a critical step in the star-formation process, but it is still poorly characterized observationally. Aims: We have studied the 10 pc-long L1495/B213 complex in Taurus to investigate how dense cores have condensed out of the lower density cloud material. Methods: We observed L1495/B213 in C18O(1-0), N2H+(1-0), and SO(JN = 32-21) with the 14 m FCRAO telescope, and complemented the data with dust continuum observations using APEX (870 μm) and IRAM 30 m (1200 μm). Results: From the N2H+ emission, we identify 19 dense cores, some starless and some protostellar. They are not distributed uniformly, but tend to cluster with relative separations on the order of 0.25 pc. From the C18O emission, we identify multiple velocity components in the gas. We have characterized them by fitting Gaussians to the spectra and by studying the distribution of the fits in position-position-velocity space. In this space, the C18O components appear as velocity-coherent structures, and we identify them automatically using a dedicated algorithm (FIVE: Friends In VElocity). Using this algorithm, we identify 35 filamentary components with typical lengths of 0.5 pc, sonic internal velocity dispersions, and mass-per-unit length close to the stability threshold of isothermal cylinders at 10 K. Core formation seems to have occurred inside the filamentary components via fragmentation, with few fertile components with higher mass-per-unit length being responsible for most cores in the cloud. On large scales, the filamentary components appear grouped into families, which we refer to as bundles. Conclusions: Core formation in L1495/B213 has proceeded by hierarchical fragmentation. The cloud fragmented first into several pc-scale regions. Each of these regions later fragmented into velocity-coherent filaments of about 0.5 pc in length. Finally, a small number of these filaments fragmented quasi-statically and produced the individual dense cores we see today. Based on

  2. Comparison of Solar Active Region Complexity Andgeomagnetic Activity from 1996 TO 2014

    NASA Astrophysics Data System (ADS)

    Tanskanen, E. I.; Nikbakhsh, S.; Perez-Suarez, D.; Hackman, T.

    2015-12-01

    We have studied the influence of magnetic complexity of solar Active Regions (ARs)on geomagnetic activity from 1996 to 2014. Sunspots are visual indicators of ARswhere the solar magnetic field is disturbed. We have used International, American,Space Environment Service Center (SESC) and Space Weather Prediction Center(SWPC) sunspot numbers to examine ARs. Major manifestations of solar magneticactivity, such as flares and Coronal Mass Ejections (CMEs), are associated withARs. For this study we chose the Mount Wilson scheme. It classifies ARs in terms oftheir magnetic topology from the least complex (?) to the most complex one ( ?).Several cases have been found where the more complex structures produce strongerflares and CMEs than the less complex ones. We have a list of identified substormsavailable with different phases and their durations. This will be compared to ourmagnetic complexity data to analyse the effects of active region magnetic complexityto the magnetic activity on the vicinity of the Earth.

  3. Modeling Ozone Formation and Transport in the Cascadia Region of the Pacific Northwest.

    NASA Astrophysics Data System (ADS)

    Barna, Mike; Lamb, Brian; O'Neill, Susan; Westberg, Hal; Figueroa-Kaminsky, Cris; Otterson, Sally; Bowman, Clint; Demay, Jennifer

    2000-03-01

    The rapidly growing Cascadia region of the Pacific Northwest, consisting of western Washington, Oregon, and southwestern British Columbia, has experienced surface ozone concentrations that exceed federally mandated standards. A modeling system consisting of the prognostic meteorological model known as the Fifth-Generation Pennsylvania State University-National Center for Atmospheric Research Mesosale Model (MM5), the diagnostic meteorological model CALMET, and the photochemical air quality model CALGRID was developed to investigate ozone formation and transport in this region. To address both the complex topography within the model domain and the relatively sparse network of surface and upper-air meteorological observations, MM5 simulations were performed using 4D data assimilation and a relatively high-resolution inner domain (5-km grid). The MM5 results, however, failed to reproduce the observed wind patterns in some portions of the domain. As a result, it was necessary to employ the MM5 solution as the initial-guess wind field for CALMET (also with a 5-km grid). Objective analysis was applied within CALMET to interpolate the predicted winds with available surface observations. This method involved an iterative approach to find the optimal set of weighting factors within CALMET to merge the MM5 solution with the available meteorological observations.The predicted ozone concentration patterns for a July 1996 event were very complex but generally showed areas of maximum ozone (130 ppb) occurring to the south and east of Puget Sound and within and to the south of the Portland area (170 ppb). Widespread ozone buildup does not occur over the course of the episode; rather, the maximum ozone concentration occurs each day downwind of each urban center. There was no evidence for recirculation of pollutants from one day to the next within an urban area. It also does not appear that emissions from one urban center influence the neighboring downwind urban area. The predicted

  4. Massive Star Formation of the SGR a East H (sub II) Regions Near the Galactic Center

    NASA Technical Reports Server (NTRS)

    Yusef-Zadeh, F.; Lacy, J. H.; Wardle, M.; Whitney, B.; Bushouse, H.; Roberts, D. A.; Arendt, R. G.

    2010-01-01

    A group of four compact H II regions associated with the well-known 50 km/s molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of approximately 6 pc. We present a study of ionized gas based on the [Ne II] (12.8 micron) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa alpha, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 =/- 3 solar mass star with a luminosity of 8 +/- 3 x 10(exp 4) Solar luminosity . The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3x (exp 4) years giving a mass flux approximately 3 x 10(exp -5) Solar Mass / year and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

  5. MASSIVE STAR FORMATION OF THE SGR A EAST H II REGIONS NEAR THE GALACTIC CENTER

    SciTech Connect

    Yusef-Zadeh, F.; Lacy, J. H.; Wardle, M.; Whitney, B.; Bushouse, H.; Roberts, D. A.; Arendt, R. G.

    2010-12-20

    A group of four compact H II regions associated with the well-known 50 km s{sup -1} molecular cloud is the closest site of on-going star formation to the dynamical center of the Galaxy, at a projected distance of {approx}6 pc. We present a study of ionized gas based on the [Ne II] (12.8 {mu}m) line, as well as multi-frequency radio continuum, Hubble Space Telescope Pa{alpha}, and Spitzer Infrared Array Camera observations of the most compact member of the H II group, Sgr A East H II D. The radio continuum image at 6 cm shows that this source breaks up into two equally bright ionized features, D1 and D2. The spectral energy distribution of the D source is consistent with it being due to a 25 {+-} 3 M{sub sun} star with a luminosity of 8 {+-} 3 x 10{sup 4} L{sub sun}. The inferred mass, effective temperature of the UV source, and the ionization rate are compatible with a young O9-B0 star. The ionized features D1 and D2 are considered to be ionized by UV radiation collimated by an accretion disk. We consider that the central massive star photoevaporates its circumstellar disk on a timescale of 3 x 10{sup 4} years giving a mass flux {approx}3 x 10{sup -5} M{sub sun} yr{sup -1} and producing the ionized material in D1 and D2 expanding in an inhomogeneous medium. The ionized gas kinematics, as traced by the [Ne II] emission, is difficult to interpret, but it could be explained by the interaction of a bipolar jet with surrounding gas along with what appears to be a conical wall of lower velocity gas. The other H II regions, Sgr A East A-C, have morphologies and kinematics that more closely resemble cometary flows seen in other compact H II regions, where gas moves along a paraboloidal surface formed by the interaction of a stellar wind with a molecular cloud.

  6. On the modified active region design of interband cascade lasers

    SciTech Connect

    Motyka, M.; Ryczko, K.; Dyksik, M.; Sęk, G.; Misiewicz, J.; Weih, R.; Dallner, M.; Kamp, M.; Höfling, S.

    2015-02-28

    Type II InAs/GaInSb quantum wells (QWs) grown on GaSb or InAs substrates and designed to be integrated in the active region of interband cascade lasers (ICLs) emitting in the mid infrared have been investigated. Optical spectroscopy, combined with band structure calculations, has been used to probe their electronic properties. A design with multiple InAs QWs has been compared with the more common double W-shaped QW and it has been demonstrated that it allows red shifting the emission wavelength and enhancing the transition oscillator strength. This can be beneficial for the improvements of the ICLs performances, especially when considering their long-wavelength operation.

  7. Investigating Molecular Hydrogen in Active Regions with IRIS

    NASA Astrophysics Data System (ADS)

    Jaeggli, Sarah A.; Saar, Steven H.; Daw, Adrian N.; Innes, Davina

    2014-06-01

    Molecular hydrogen should be the most abundant molecular species in sunspots, but recent observations with IRIS show that its florescent signature is absent from above the sunspot umbra, but appears brightly during flares. In this poster we continue the analysis of FUV observations of H2 in active regions, examining the correlation between the intensity of the H2 lines and the lines of C II and Si IV which are responsible for their excitation. We particularly focus on differentiating places where H2 is abundant, holes in the chromospheric opacity where FUV photons can enter more deeply into the solar atmosphere, and places where the FUV radiation field is intense, as in flares.

  8. Observational analysis of active region on June, 2000

    NASA Astrophysics Data System (ADS)

    Rovira, M. G.; Luoni, M. L.

    In the recent inaugurated German-Argentinian Solar-Observatory at El Leoncito, a H-alpha Telescope (HASTA) and a mirror coronograph (MICA) are obtained daily images of the solar disk and the inner corona. Since its installation on August 1997, MICA has been imaging the inner corona with high temporal and spatial resolution. Its field-of-view ranges 1.05 to 2.0 solar radii above the sun center. HASTA started operations on May 1998. It has a tunable ( [+1,-1] Å) Lyot-filter with a bandwith of 0.3 Å. In high speed mode full frames can be taken every 2 sec. We study the evolution of an Active Region (AR 9026) and we compare different images as taken in defferent wavelengths. These studies tend to relate flares with coronal mass ejection (CME).

  9. DO MOST ACTIVE GALACTIC NUCLEI LIVE IN HIGH STAR FORMATION NUCLEAR CUSPS?

    SciTech Connect

    Mushotzky, Richard F.; Shimizu, T. Taro; Meléndez, Marcio; Koss, Michael

    2014-02-01

    We present early results of the Herschel PACS (70 and 160 μm) and SPIRE (250, 350, and 500 μm) survey of 313 low redshift (z < 0.05), ultra-hard X-ray (14-195 keV) selected active galactic nuclei (AGNs) from the 58 month Swift/Burst Alert Telescope catalog. Selection of AGNs from ultra-hard X-rays avoids bias from obscuration, providing a complete sample of AGNs to study the connection between nuclear activity and star formation in host galaxies. With the high angular resolution of PACS, we find that >35% and >20% of the sources are ''point-like'' at 70 and 160 μm respectively and many more have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFRs) of 0.1-100 M {sub ☉} yr{sup –1} using the 70 and 160 μm flux densities as SFR indicators are consistent with those inferred from Spitzer Ne II fluxes, but we find that 11.25 μm polycyclic aromatic hydrocarbon data give ∼3× lower SFR. Using GALFIT to measure the size of the far-infrared emitting regions, we determined the SFR surface density (M {sub ☉} yr{sup –1} kpc{sup –2}) for our sample, finding that a significant fraction of these sources exceed the threshold for star formation driven winds (0.1 M {sub ☉} yr{sup –1} kpc{sup –2})

  10. Slow Magnetosonic Waves and Fast Flows in Active Region Loops

    NASA Technical Reports Server (NTRS)

    Ofman, L.; Wang, T. J.; Davila, J. M.

    2012-01-01

    Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (approx 100-300 km/s) quasiperiodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow.We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

  11. SLOW MAGNETOSONIC WAVES AND FAST FLOWS IN ACTIVE REGION LOOPS

    SciTech Connect

    Ofman, L.; Wang, T. J.; Davila, J. M.

    2012-08-01

    Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast ({approx}100-300 km s{sup -1}) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

  12. Sunspot waves and triggering of homologous active region jets

    NASA Astrophysics Data System (ADS)

    Chandra, R.; Gupta, G. R.; Mulay, Sargam; Tripathi, Durgesh

    2015-02-01

    We present and discuss multiwavelength observations of five homologous recurrent solar jets that occurred in active region NOAA 11133 on 2010 December 11. These jets were well observed by the Solar Dynamic observatory (SDO) with high spatial and temporal resolution. The speed of the jets ranged between 86 and 267 km s-1. A type III radio burst was observed in association with all the five jets. The investigation of the overall evolution of magnetic field in the source regions suggested that the flux was continuously emerging on longer term. However, all the jets but J5 were triggered during a local dip in the magnetic flux, suggesting the launch of the jets during localized submergence of magnetic flux. Additionally, using the PFSS modelling of the photospheric magnetic field, we found that all the jets were ejected in the direction of open field lines. We also traced sunspot oscillations from the sunspot interior to foot-point of jets and found presence of ˜3 min oscillations in all the SDO/AIA (Atmospheric Imaging Assembly) passbands. The wavelet analysis revealed an increase in amplitude of the oscillations just before the trigger of the jets, that decreased after the jets were triggered. The observations of increased amplitude of the oscillation and its subsequent decrease provides evidence of wave-induced reconnection triggering the jets.

  13. Effect of phosphate activating group on oligonucleotide formation on montmorillonite: the regioselective formation of 3',5'-linked oligoadenylates

    NASA Technical Reports Server (NTRS)

    Prabahar, K. J.; Cole, T. D.; Ferris, J. P.

    1994-01-01

    The effects of amine structure on the montmorillonite-catalyzed oligomerization of the 5'-phosphoramidates of adenosine are investigated. 4-Aminopyridine derivatives yielded oligoadenylates as long as dodecamers with a regioselectivity for 3',5'-phosphodiester bond formation averaging 88%. Linear and cyclic oligomers are obtained and no A5'ppA-containing products are detected. Oligomers as long as the hexanucleotide are obtained using 2-aminobenzimidazole as the activating group. A predominance of pA2'pA is detected in the dimer fraction along with cyclic 3',5'-trimer; no A5'ppA-containing oligomers were detected. Little or no oligomer formation was observed when morpholine, piperidine, pyrazole, 1,2,4-triazole, and 2-pyridone are used as phosphate-activating groups. The effects of the structure of the phosphate activating group on the oligomer structure and chain lengths are discussed.

  14. Stratigraphy of the Morrison and related formations, Colorado Plateau region, a preliminary report

    USGS Publications Warehouse

    Craig, Lawrence C.; ,

    1955-01-01

    Three subdivisions of the Jurassic rocks of the Colorado Plateau region are: the Glen Canyon group, mainly eolian and fluvial sedimentary rocks; the San Rafael group, marine and marginal marine sedimentary rocks; and the Morrison formation, fluvial and lacustrine sedimentary rocks. In central and eastern Colorado the Morrison formation has not been differ- entiated into members. In eastern Utah, northeastern Arizona, northwestern New Mexico, and in part of western Colorado, the Morrison may be divided into a lower part and an upper part; each part has two members which are di1Ierentiated on a lithologic basis. Where differentiated, the lower part of the Morrison consists either of the Salt Wash member or the Recapture member or both; these are equivalent in age and inter tongue and intergrade over a broad area in the vicinity of the Four Corners area of New Mexico, Colorado, Arizona, and Utah. The Salt Wash member is present in eastern Utah and parts of western Colorado, north- eastern Arizona, and northwestern New Mexico. It was formed as a large alluvial plain or 'fan' by an aggrading system of braided streams diverging to the north and east from an apex in south-central Utah. The major source area of the Salt Wash was to the southwest of south-central Utah, probably in west-central Arizona and southeastern California. The member was derived mainly from sedimentary rocks. The Salt Wash deposits grade from predomi- nantly coarse texture at the apex of the 'fan' to predominantly flne texture at the margin of the 'fan'. The Salt Wash member has been arbitrarily divided into four facies: a con- glomera tic sandstone facies, a sandstone and mudstone facies, a claystone and lenticular sandstone facies, and a claystone and limestone facies. The Recapture member of the Morrison formation is present in northeastern Arizona, northwestern New Mexico, and small areas of southeastern Utah and southwestern Colorado near the Four Corners. It was formed as a large alluvial plain

  15. Mineral ecophysiological evidence for microbial activity in banded iron formation

    SciTech Connect

    Li, Dr. Yi-Liang; Konhauser, Dr, Kurt; Cole, David R; Phelps, Tommy Joe

    2011-01-01

    The phosphorus composition of banded-iron formations (BIFs) has been used as a proxy for Precambrian seawater composition and the paleoeredox state of Earth's surface environment. However, it is unclear whether the phosphorus in BIFs originally entered the sediment as a sorbed component of the iron oxyhydroxide particles, or whether it was incorporated into the biomass of marine phytoplankton. We conducted high-resolution mineral analyses and report here the first detection of an Fe(III) acetate salt, as well as nanocrystals of apatite in association with magnetite, in the 2.48 Ga Dales Gorge Member of the Brockman Iron Formation (a BIF), Hamersley, Western Australia. The clusters of apatite are similar in size and morphology to biogenic apatite crystals resulting from biomass decay in Phanerozoic marine sediments, while the formation of an Fe(III) acetate salt and magnetite not only implies the original presence of biomass in the BIF sediments, but also that organic carbon likely served as an electron donor during bacterial Fe(III) reduction. This study is important because it suggests that phytoplankton may have played a key role in the transfer of phosphorus (and other trace elements) from the photic zone to the seafloor.

  16. Aminergic and cholinergic afferents to REM sleep induction regions of the pontine reticular formation in the rat.

    PubMed

    Semba, K

    1993-04-22

    Microinjection of cholinergic agonists in a dorsolateral part of the mesopontine tegmentum has been shown to induce a rapid eye movement (REM) sleep-like state. Physiological evidence indicates that not only acetylcholine but also various amine transmitters, including those implicated in behavioral state regulation, affect neuronal activity in this region of the pontine reticular formation. In the present study, sources of select aminergic and cholinergic inputs to this REM sleep induction zone were identified and quantitatively analyzed by using fluorescence retrograde tracing combined with immunofluorescence in the rat. In addition to previously demonstrated cholinergic projections from the pedunculopontine and laterodorsal tegmental nuclei, the REM sleep induction zone received various aminergic inputs that originated in widely distributed regions of the brainstem and hypothalamus. Serotoninergic afferents represented a mean of 44% of all aminergic/cholinergic source neurons projecting to the REM sleep induction zone, which was comparable to the mean percentage of 39% represented by cholinergic afferent neurons. The serotoninergic afferents originated from the raphe nuclei at all brainstem levels, with heavier projections from the pontine than from the medullary raphe nuclei. Unexpectedly, an additional major serotoninergic input was provided by serotoninergic neurons in the nucleus prosupralemniscus (B9). Noradrenergic afferent neurons represented a mean of 14% of all aminergic/cholinergic source neurons, which was only about one-third of the mean percentage of either cholinergic or serotoninergic source neurons. These noradrenergic projection neurons were located not only in the locus ceruleus (8%) but also in the lateral tegmentum, including the A5 (4%) and A7 (2%) cell groups. Histaminergic neurons in the tuberomammillary hypothalamic nucleus represented a minor group of afferent neurons (3%), and a still smaller input came from adrenergic C1 neurons. The

  17. Thermodynamic calculation and interatomic potential to predict the favored composition region for the Cu-Zr-Al metallic glass formation.

    PubMed

    Cui, Y Y; Wang, T L; Li, J H; Dai, Y; Liu, B X

    2011-03-01

    For the Cu-Zr-Al system, the glass forming compositions were firstly calculated based on the extended Miedema's model, suggesting that the amorphous phase could be thermodynamically favored over a large composition region. An n-body potential was then constructed under the smoothed and long-range second-moment-approximation of tight-binding formulism. Applying the constructed Cu-Zr-Al potential, molecular dynamics simulations were conducted using solid solution models to compare relative stability of crystalline solid solution versus its disordered counterpart. Simulations reveal that the physical origin of metallic glass formation is crystalline lattice collapsing while solute concentration exceeding the critical value, thus predicting a hexagonal composition region, within which the Cu-Zr-Al ternary metallic glass formation is energetically favored. The molecular dynamics simulations predicted composition region is defined as the quantitative glass-forming-ability or glass-forming-region of the Cu-Zr-Al system. PMID:21229150

  18. Modification of the activity of cell wall-bound peroxidase by hypergravity in relation to the stimulation of lignin formation in azuki bean epicotyls

    NASA Astrophysics Data System (ADS)

    Wakabayashi, Kazuyuki; Nakano, Saho; Soga, Kouichi; Hoson, Takayuki

    Lignin is a component of cell walls of terrestrial plants, which provides cell walls with the mechanical rigidity. Lignin is a phenolic polymer with high molecular mass and formed by the polymerization of phenolic substances on a cellulosic matrix. The polymerization is catalyzed by cell wall-bound peroxidase, and thus the activity of this enzyme regulates the rate of formation of lignin. In the present study, the changes in the lignin content and the activity of cell wall peroxidase were investigated along epicotyls of azuki bean seedlings grown under hypergravity conditions. The endogenous growth occurred primarily in the upper regions of the epicotyl and no growth was detected in the middle or basal regions. The amounts of acetyl bromide-soluble lignin increased from the upper to the basal regions of epicotyls. The lignin content per unit length in the basal region was three times higher than that in the upper region. Hypergravity treatment at 300 g for 6 h stimulated the increase in the lignin content in all regions of epicotyls, particularly in the basal regions. The peroxidase activity in the protein fraction extracted from the cell wall preparation with a high ionic strength buffer also increased gradually toward the basal region, and hypergravity treatment clearly increased the activity in all regions. There was a close correlation between the lignin content and the enzyme activity. These results suggest that gravity stimuli modulate the activity of cell wall-bound peroxidase, which, in turn, causes the stimulation of the lignin formation in stem organs.

  19. Long-Period ULF Wave Activity in the Cusp Region

    NASA Astrophysics Data System (ADS)

    Pilipenko, V.; Belakhovsky, V.; Engebretson, M. J.; Kozlovsky, A.

    2013-12-01

    We compare simultaneous observations of long-period ULF wave activity from the Svalbard/IMAGE and Greenland fluxgate magnetometer profiles covering the expected cusp geomagnetic latitudes. Irregular Pulsations at Cusp Latitudes (IPCL) and narrow-band Pc5 waves are found to be a ubiquitous element of ULF activity in the dayside high-latitude region. To identify the ionospheric projections of the cusp, we use the width of the return signal of the SuperDARN radar covering the Svalbard archipelago, predictions of empirical cusp models, and augmented whenever possible by DMSP identification of magnetospheric boundary domains. The meridional spatial structure of IPCL/Pc5 pulsation spectral power has been found to have a localized latitudinal peak, but not under the cusp proper as was previously thought, but several degrees southward from the equatorward cusp boundary. Possible mechanisms and their relevance to observational data are discussed. The occurrence of IPCL and Pc5 waves in the dayside boundary layers is a challenge to modelers, because so far their mechanism has not been firmly identified.

  20. The Pliocene Yafo Formation in Israel: Hydrogeologically inert or active?

    NASA Astrophysics Data System (ADS)

    Avisar, D.; Rosenthal, E.; Shulman, H.; Zilberbrand, M.; Flexer, A.; Kronfeld, J.; Ben Avraham, Z.; Fleischer, L.

    For several decades the ``Saqiye beds'' (later renamed Yafo Formation) underlying the Coastal Plain aquifer (Kurkar Group) aquifer of Israel, were regarded as an extremely thick, tectonically undisturbed, and absolutely impervious aquiclude. Following intensive groundwater exploitation from the overlying Kurkar Group aquifer, brackish and saline waters were locally encountered in the lower parts of this aquifer and always at the contact with the underlying Yafo Formation aquiclude. The present study revealed that this aquiclude is not a uniform and impervious rock unit, but rather an alternation of pervious and impervious strata within the Yafo Formation containing highly pressured fluids of different - mostly high - salinities. The permeable beds are at an angular unconformity and in direct contact with the overlying Kurkar Group aquifer. The Yafo Formation and the underlying and overlying rock units are dislocated by numerous fault systems, which facilitate accessibility of brines into the Kurkar Group aquifer. The mobilization of the saline fluids and their injection into the Kurkar Group aquifer could be due either to diffusion of saline fluids occurring in the permeable horizons of the Petah Tiqva Member through the clays of the Yafo Formation or to their upconing following intensive pumping in the Coastal Plain aquifer. It could have also been caused by up-dip movement of saline water as the result of overpressure generated by major accumulation of gas in the permeable horizons. Another possible mechanism could be hydraulic contact with pressurized brines up-flowing along fault zones from deep-seated Jurassic or Cretaceous reservoirs. The squeezing of saline interstitial water from the clays of the Yafo Formation into the overlying Kurkar Group aquifer, is of secondary importance for groundwater salinization (its input is comparable with salt input from rain). Depuis longtemps, les «couches de Saqiye», nommées maintenant formation de Yafo, constituant le

  1. Type Region of the Ione Formation (Eocene), Central California: Stratigraphy, Paleogeography, and Relation to Auriferous Gravels

    USGS Publications Warehouse

    Creely, Scott; Force, Eric R.

    2007-01-01

    The middle Eocene Ione Formation extends over 200 miles (320 km) along the western edge of the Sierra Nevada. Our study was concentrated in the type region, 30 miles (48 km) along strike. There a bedrock ridge forms the seaward western side of the Ione depositional tract, defining a subbasin margin. The eastern limit of the type Ione is locally defined by high-angle faults. Ione sediments were spread over Upper Mesozoic metamorphic and plutonic bedrock, fed by gold-bearing streams dissecting the western slope of the ancestral Sierra Nevada. By middle Eocene time, a tropical or subtropical climate prevailed, leading to deep chemical weathering (including laterization) and a distinctively mature mineral assemblage was fed to and generated within Ione deposits. The Ione is noted for its abundant kaolinitic clay, some of it coarsely crystalline; the clay is present as both detrital grains and authigenic cement. Quartz is abundant, mostly as angular grains. Heavy mineral fractions are dominated by altered ilmenite and zircon. Distribution of feldspar is irregular, both stratigraphically and areally. Non-marine facies are most voluminous, and include conglomerates, especially at the base and along the eastern margins of the formation where they pass into Sierran auriferous gravels. Clays, grading into lignites, and gritty sands are also common facies. Both braided and meandering fluvial facies have been recognized. Shallow marine waters flooded the basin probably twice. Tongues of sediment exhibiting a variety of estuarine to marine indicators are underlain and overlain by fluvial deposits. Marine body fossils are found at only a few localities, but burrows identified as Ophiomorpha and cf. Thalassinoides are abundant in many places. Other clues to marginal marine deposition are the occurrence of glauconite in one bed, typical relations of lagoonal to beach (locally heavy-mineral-rich) lithofacies, closed-basin three-dimensional morphology of basinal facies, and high

  2. Regional Triggering of Volcanic Activity Following Large Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Hill-Butler, Charley; Blackett, Matthew; Wright, Robert

    2015-04-01

    There are numerous reports of a spatial and temporal link between volcanic activity and high magnitude seismic events. In fact, since 1950, all large magnitude earthquakes have been followed by volcanic eruptions in the following year - 1952 Kamchatka M9.2, 1960 Chile M9.5, 1964 Alaska M9.2, 2004 & 2005 Sumatra-Andaman M9.3 & M8.7 and 2011 Japan M9.0. While at a global scale, 56% of all large earthquakes (M≥8.0) in the 21st century were followed by increases in thermal activity. The most significant change in volcanic activity occurred between December 2004 and April 2005 following the M9.1 December 2004 earthquake after which new eruptions were detected at 10 volcanoes and global volcanic flux doubled over 52 days (Hill-Butler et al. 2014). The ability to determine a volcano's activity or 'response', however, has resulted in a number of disparities with <50% of all volcanoes being monitored by ground-based instruments. The advent of satellite remote sensing for volcanology has, therefore, provided researchers with an opportunity to quantify the timing, magnitude and character of volcanic events. Using data acquired from the MODVOLC algorithm, this research examines a globally comparable database of satellite-derived radiant flux alongside USGS NEIC data to identify changes in volcanic activity following an earthquake, February 2000 - December 2012. Using an estimate of background temperature obtained from the MODIS Land Surface Temperature (LST) product (Wright et al. 2014), thermal radiance was converted to radiant flux following the method of Kaufman et al. (1998). The resulting heat flux inventory was then compared to all seismic events (M≥6.0) within 1000 km of each volcano to evaluate if changes in volcanic heat flux correlate with regional earthquakes. This presentation will first identify relationships at the temporal and spatial scale, more complex relationships obtained by machine learning algorithms will then be examined to establish favourable

  3. Clustering and Pattern Formation in Chemorepulsive Active Colloids

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  4. Clustering and Pattern Formation in Chemorepulsive Active Colloids.

    PubMed

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

    2015-12-18

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

  5. Clustering and Pattern Formation in Chemorepulsive Active Colloids.

    PubMed

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

    2015-12-18

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

  6. 77 FR 24952 - Agency Information Collection Activities; Proposed Collection; Comment Request; Regional Haze...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-26

    ... ICR (August 26, 2009; 74 FR 43118). The last collection request anticipated the program progressing... AGENCY Agency Information Collection Activities; Proposed Collection; Comment Request; Regional Haze... organizations and facilities potentially regulated under the regional haze rule. Title: Regional...

  7. Sejong Open Cluster Survey (SOS) - V. The Active Star Forming Region SH 2-255-257

    NASA Astrophysics Data System (ADS)

    Lim, Beomdu; Sung, Hwankyung; Hur, Hyeonoh; Lee, Byeong-Cheol; Bessell, Michael S.; Kim, Jinyoung S.; Lee, Kang Hwan; Park, Byeong-Gon; Jeong, Gwanghui

    2015-12-01

    There is much observational evidence that active star formation is taking place in the H II regions Sh 2-255-257. We present a photometric study of this star forming region (SFR) using imaging data obtained in passbands from the optical to the mid-infrared, in order to study the star formation process. A total of 218 members were identified using various selection criteria based on their observational properties. The SFR is reddened by at least E(B-V) = 0.8 mag, and the reddening law toward the region is normal (R_V = 3.1). From the zero-age main sequence fitting method it is confirmed that the SFR is 2.1 ± 0.3 kpc from the Sun. The median age of the identified members is estimated to be about 1.3 Myr from a comparison of the Hertzsprung-Russell diagram (HRD) with stellar evolutionary models. The initial mass function (IMF) is derived from the HRD and the near-infrared (J, J-H) color-magnitude diagram. The slope of the IMF is about Γ = -1.6 ± 0.1, which is slightly steeper than that of the Salpeter/Kroupa IMF. It implies that low-mass star formation is dominant in the SFR. The sum of the masses of all the identified members provides the lower limit of the cluster mass (169 M_{⊙}). We also analyzed the spectral energy distribution (SED) of pre-main sequence stars using the SED fitting tool of Robitaille et al., and confirm that there is a significant discrepancy between stellar mass and age obtained from two different methods based on the SED fitting tool and the HRD.

  8. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. III - NOAA active region 6233 (1990 August)

    NASA Technical Reports Server (NTRS)

    De La Beaujardiere, J.-F.; Canfield, Richard C.; Leka, K. D.

    1993-01-01

    We investigate the spatial relationship between vertical electric currents and flare phenomena in NOAA Active Region 6233, which was observed 1990, August 28-31 at Mees Solar Observatory. The two flares studied are the 1N/M1.8 flare on August 28, 22:30 UT and the 1N/M1.6 flare on August 29, 20:35 UT. Using Stokes polarimetry we make magnetograms of the region and compute the vertical current density. Using H-alpha imaging spectroscopy we identify sites of intense nonthermal electron precipitation or of high coronal pressure. The precipitation in these flares is barely strong enough to be detectable. We find that both precipitation and high pressure tend to occur near vertical currents, but that neither phenomenon is cospatial with current maxima. In contrast with the conclusion of other authors, we argue that these observations do not support a current-interruption model for flares, unless the relevant currents are primarily horizontal. The magnetic morphology and temporal evolution of these flares suggest that an erupting filament model may be relevant, but this model does not explicitly predict the relationship between precipitation, high pressure, and vertical currents.

  9. Local Luminous Infrared Galaxies. III. Co-evolution of Black Hole Growth and Star Formation Activity?

    NASA Astrophysics Data System (ADS)

    Alonso-Herrero, Almudena; Pereira-Santaella, Miguel; Rieke, George H.; Diamond-Stanic, Aleksandar M.; Wang, Yiping; Hernán-Caballero, Antonio; Rigopoulou, Dimitra

    2013-03-01

    Local luminous infrared (IR) galaxies (LIRGs) have both high star formation rates (SFR) and a high AGN (Seyfert and AGN/starburst composite) incidence. Therefore, they are ideal candidates to explore the co-evolution of black hole (BH) growth and star formation (SF) activity, not necessarily associated with major mergers. Here, we use Spitzer/IRS spectroscopy of a complete volume-limited sample of local LIRGs (distances of <78 Mpc). We estimate typical BH masses of 3 × 107 M ⊙ using [Ne III] 15.56 μm and optical [O III] λ5007 gas velocity dispersions and literature stellar velocity dispersions. We find that in a large fraction of local LIRGs, the current SFR is taking place not only in the inner nuclear ~1.5 kpc region, as estimated from the nuclear 11.3 μm PAH luminosities, but also in the host galaxy. We next use the ratios between the SFRs and BH accretion rates (BHAR) to study whether the SF activity and BH growth are contemporaneous in local LIRGs. On average, local LIRGs have SFR to BHAR ratios higher than those of optically selected Seyferts of similar active galactic nucleus (AGN) luminosities. However, the majority of the IR-bright galaxies in the revised-Shapley-Ames Seyfert sample behave like local LIRGs. Moreover, the AGN incidence tends to be higher in local LIRGs with the lowest SFRs. All of this suggests that in local LIRGs there is a distinct IR-bright star-forming phase taking place prior to the bulk of the current BH growth (i.e., AGN phase). The latter is reflected first as a composite and then as a Seyfert, and later as a non-LIRG optically identified Seyfert nucleus with moderate SF in its host galaxy. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407.

  10. LOCAL LUMINOUS INFRARED GALAXIES. III. CO-EVOLUTION OF BLACK HOLE GROWTH AND STAR FORMATION ACTIVITY?

    SciTech Connect

    Alonso-Herrero, Almudena; Hernan-Caballero, Antonio; Pereira-Santaella, Miguel; Rieke, George H.; Diamond-Stanic, Aleksandar M.; Wang Yiping; Rigopoulou, Dimitra

    2013-03-10

    Local luminous infrared (IR) galaxies (LIRGs) have both high star formation rates (SFR) and a high AGN (Seyfert and AGN/starburst composite) incidence. Therefore, they are ideal candidates to explore the co-evolution of black hole (BH) growth and star formation (SF) activity, not necessarily associated with major mergers. Here, we use Spitzer/IRS spectroscopy of a complete volume-limited sample of local LIRGs (distances of <78 Mpc). We estimate typical BH masses of 3 Multiplication-Sign 10{sup 7} M{sub Sun} using [Ne III] 15.56 {mu}m and optical [O III] {lambda}5007 gas velocity dispersions and literature stellar velocity dispersions. We find that in a large fraction of local LIRGs, the current SFR is taking place not only in the inner nuclear {approx}1.5 kpc region, as estimated from the nuclear 11.3 {mu}m PAH luminosities, but also in the host galaxy. We next use the ratios between the SFRs and BH accretion rates (BHAR) to study whether the SF activity and BH growth are contemporaneous in local LIRGs. On average, local LIRGs have SFR to BHAR ratios higher than those of optically selected Seyferts of similar active galactic nucleus (AGN) luminosities. However, the majority of the IR-bright galaxies in the revised-Shapley-Ames Seyfert sample behave like local LIRGs. Moreover, the AGN incidence tends to be higher in local LIRGs with the lowest SFRs. All of this suggests that in local LIRGs there is a distinct IR-bright star-forming phase taking place prior to the bulk of the current BH growth (i.e., AGN phase). The latter is reflected first as a composite and then as a Seyfert, and later as a non-LIRG optically identified Seyfert nucleus with moderate SF in its host galaxy.

  11. Development prospects for Bazhenov formation bituminous claystones in the southeast of the West Siberian Plate (Tomsk Region)

    NASA Astrophysics Data System (ADS)

    Belozerov, V. B.; Baranov, V. E.; Dmitriev, A. Y.

    2015-02-01

    The article considers the use of time-tested bituminous shale development technologies in the southeast of the West Siberian Plate (Tomsk Region). A research target is the bituminous claystones of the Bazhenov formation. The Bazhenov formation was divided into stratigraphic units, and the sequence of forming these units within the territory under study was restored on the basis of the peculiarities of the Bazhenov formation section structure with gamma-ray logging data. The joint analysis of logs (gamma-ray logging, resistivity logging, SP logging, neutron gamma-ray logging, induction logging) and core data revealed the wide development of carbonatization processes in the lower stratigraphic units of the Bazhenov formation, whereas the upper, most bituminous units do not have the signs of carbonatization. It is a favorable factor for using the existing technologies of producing hydrocarbons from analogous sedimentary deposits. Considering the degree of lithological disconnection of an oilbearing object from adjacent reservoir formations allows making a conclusion that the application of the existing technologies for developing bituminous claystones can be implemented only in the insignificant territory of the area under study where the Bazhenov formation overlies Georgiev formation claystones being over 8 meters thick. To develop the oil and gas potential of the Bazhenov formation in other territories, there will be a need for new technologies that allow forming a fracture-cavernous matrix in a carbonate rock.

  12. Contribution of regional brain melanocortin receptor subtypes to elevated activity energy expenditure in lean, active rats.

    PubMed

    Shukla, C; Koch, L G; Britton, S L; Cai, M; Hruby, V J; Bednarek, M; Novak, C M

    2015-12-01

    Physical activity and non-exercise activity thermogenesis (NEAT) are crucial factors accounting for individual differences in body weight, interacting with genetic predisposition. In the brain, a number of neuroendocrine intermediates regulate food intake and energy expenditure (EE); this includes the brain melanocortin (MC) system, consisting of MC peptides as well as their receptors (MCR). MC3R and MC4R have emerged as critical modulators of EE and food intake. To determine how variance in MC signaling may underlie individual differences in physical activity levels, we examined behavioral response to MC receptor agonists and antagonists in rats that show high and low levels of physical activity and NEAT, that is, high- and low-capacity runners (HCR, LCR), developed by artificial selection for differential intrinsic aerobic running capacity. Focusing on the hypothalamus, we identified brain region-specific elevations in expression of MCR 3, 4, and also MC5R, in the highly active, lean HCR relative to the less active and obesity-prone LCR. Further, the differences in activity and associated EE as a result of MCR activation or suppression using specific agonists and antagonists were similarly region-specific and directly corresponded to the differential MCR expression patterns. The agonists and antagonists investigated here did not significantly impact food intake at the doses used, suggesting that the differential pattern of receptor expression may by more meaningful to physical activity than to other aspects of energy balance regulation. Thus, MCR-mediated physical activity may be a key neural mechanism in distinguishing the lean phenotype and a target for enhancing physical activity and NEAT.

  13. Large Solar Energetic Particle Events Associated With Filament Eruptions Outside Active Regions

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds approx. 1000 km/s) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of approx.2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ?4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  14. Large Solar Energetic Particle Events Associated with Filament Eruptions Outside of Active Regions

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-06-01

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ˜ 1000 km s-1) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2-3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ˜2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10-100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  15. LARGE SOLAR ENERGETIC PARTICLE EVENTS ASSOCIATED WITH FILAMENT ERUPTIONS OUTSIDE ACTIVE REGIONS

    SciTech Connect

    Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie, H.; Thakur, N.; Kahler, S. W.

    2015-06-10

    We report on four large filament eruptions (FEs) from solar cycles 23 and 24 that were associated with large solar energetic particle (SEP) events and interplanetary type II radio bursts. The post-eruption arcades corresponded mostly to C-class soft X-ray enhancements, but an M1.0 flare was associated with one event. However, the associated coronal mass ejections (CMEs) were fast (speeds ∼ 1000 km s{sup −1}) and appeared as halo CMEs in the coronagraph field of view. The interplanetary type II radio bursts occurred over a wide wavelength range, indicating the existence of strong shocks throughout the inner heliosphere. No metric type II bursts were present in three events, indicating that the shocks formed beyond 2–3 Rs. In one case, there was a metric type II burst with low starting frequency, indicating a shock formation height of ∼2 Rs. The FE-associated SEP events did have softer spectra (spectral index >4) in the 10–100 MeV range, but there were other low-intensity SEP events with spectral indices ≥4. Some of these events are likely FE-SEP events, but were not classified as such in the literature because they occurred close to active regions. Some were definitely associated with large active region flares, but the shock formation height was large. We definitely find a diminished role for flares and complex type III burst durations in these large SEP events. Fast CMEs and shock formation at larger distances from the Sun seem to be the primary characteristics of the FE-associated SEP events.

  16. Warm dust and aromatic bands as quantitative probes of star-formation activity

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; Roussel, H.; Sauvage, M.; Charmandaris, V.

    2004-05-01

    We combine samples of spiral galaxies and starburst systems observed with ISOCAM on board ISO to investigate the reliability of mid-infrared dust emission as a quantitative tracer of star formation activity. The total sample covers very diverse galactic environments and probes a much wider dynamic range in star formation rate density than previous similar studies. We find that both the monochromatic 15 μm continuum and the 5-8.5 μm emission constitute excellent indicators of the star formation rate as quantified by the Lyman continuum luminosity LLyc, within specified validity limits which are different for the two tracers. Normalized to projected surface area, the 15 μm continuum luminosity Σ15 μm,ct is directly proportional to ΣLyc over several orders of magnitude. Two regimes are distinguished from the relative offsets in the observed relationship: the proportionality factor increases by a factor of ≈5 between quiescent disks in spiral galaxies, and moderate to extreme star-forming environments in circumnuclear regions of spirals and in starburst systems. The transition occurs near ΣLyc ˜ 102 L⊙ pc-2 and is interpreted as due to very small dust grains starting to dominate the emission at 15 μm over aromatic species above this threshold. The 5-8.5 μm luminosity per unit projected area is also directly proportional to the Lyman continuum luminosity, with a single conversion factor from the most quiescent objects included in the sample up to ΣLyc ˜ 104 L⊙ pc-2, where the relationship then flattens. The turnover is attributed to depletion of aromatic band carriers in the harsher conditions prevailing in extreme starburst environments. The observed relationships provide empirical calibrations useful for estimating star formation rates from mid-infrared observations, much less affected by extinction than optical and near-infrared tracers in deeply embedded H II regions and obscured starbursts, as well as for theoretical predictions from evolutionary

  17. Active zones of mammalian neuromuscular junctions: formation, density, and aging

    PubMed Central

    Nishimune, Hiroshi

    2012-01-01

    Presynaptic active zones are synaptic vesicle release sites that playessential roles in the function and pathology of mammalian neuromuscular junctions (NMJs). The molecular mechanisms of active zone organization utilize presynaptic voltage-dependent calcium channels (VDCCs) in NMJs as scaffolding proteins. VDCCs interact extracellularly with the muscle-derived synapse organizer, laminin β2, and interact intracellularly with active zone-specific proteins, such as Bassoon, CAST/Erc2/ELKS2alpha, ELKS, Piccolo, and RIMs. These molecular mechanisms are supported by studies in P/Q- and N-type VDCCs double-knockout mice, and they are consistent with the pathological conditions of Lambert-Eaton myasthenic syndrome and Pierson syndrome, which are caused by autoantibodies against VDCCs or by a laminin β2 mutation. During normal postnatal maturation, NMJs maintain the density of active zones, while NMJs triple their size. However, active zones become impaired during aging. Propitiously, muscle exercise ameliorates the active zone impairment in aged NMJs, which suggests the potential for therapeutic strategies. PMID:23252894

  18. Mapping of Sand Types and Dune Morphologies in the Aeolis Dorsa Region, Western Medusae Fossae Formation, Mars

    NASA Astrophysics Data System (ADS)

    Boyd, A. S.; Burr, D. M.

    2016-06-01

    Preliminary mapping of low- and high-albedo sand deposits in the Aeolis Dorsa region, Medusae Fossae Formation (MFF), suggests sand transport from the north, consistent with sand source(s) in Elysium Mons, the Cerberus plains, or the MFF itself.

  19. Distinct Roles for the N- and C-terminal Regions of M-Sec in Plasma Membrane Deformation during Tunneling Nanotube Formation.

    PubMed

    Kimura, Shunsuke; Yamashita, Masami; Yamakami-Kimura, Megumi; Sato, Yusuke; Yamagata, Atsushi; Kobashigawa, Yoshihiro; Inagaki, Fuyuhiko; Amada, Takako; Hase, Koji; Iwanaga, Toshihiko; Ohno, Hiroshi; Fukai, Shuya

    2016-01-01

    The tunneling nanotube (TNT) is a structure used for intercellular communication, and is a thin membrane protrusion mediating transport of various signaling molecules and cellular components. M-Sec has potent membrane deformation ability and induces TNT formation in cooperation with the Ral/exocyst complex. Here, we show that the N-terminal polybasic region of M-Sec directly binds phosphatidylinositol (4,5)-bisphosphate for its localization to the plasma membrane during the initial stage of TNT formation. We further report a crystal structure of M-Sec, which consists of helix bundles arranged in a straight rod-like shape, similar to the membrane tethering complex subunits. A positively charged surface in the C-terminal domains is required for M-Sec interaction with active RalA to extend the plasma membrane protrusions. Our results suggest that the membrane-associated M-Sec recruits active RalA, which directs the exocyst complex to form TNTs.

  20. Biomineral formation as a biosignature for microbial activities Precambrian cherts

    NASA Astrophysics Data System (ADS)

    Rincón Tomás, Blanca; Mühlen, Dominik; Hoppert, Michael; Reitner, Joachim

    2015-04-01

    In recent anoxic sediments manganese(II)carbonate minerals (e.g., rhodochrosite, kutnohorite) derive mainly from the reduction of manganese(IV) compounds by microbial anaerobic respiration. Small particles of rhodochrosite in stromatolite-like features in the Dresser chert Fm (Pilbara supergroup, W-Australia), associated with small flakes of kerogen, account for biogenic formation of the mineral in this early Archaean setting. Contrastingly, the formation of huge manganese-rich (carbonate) deposits requires effective manganese redox cycling, also conducted by various microbial processes, mainly requiring conditions of the early and late Proterozoic (Kirschvink et al., 2000; Nealson and Saffrani 1994). However, putative anaerobic pathways like microbial nitrate-dependent manganese oxidation (Hulth et al., 1999), anoxygenic photosynthesis (Johnson et al., 2013) and oxidation in UV light may facilitate manganese cycling even in a reducing atmosphere. Thus manganese redox cycling might have been possible even before the onset of oxygenic photosynthesis. Hence, there are several ways how manganese carbonates could have been formed biogenically and deposited in Precambrian sediments. Thus, the minerals may be suitable biosignatures for microbial redox processes in many respects. The hyperthermophilic archaeon Pyrobaculum islandicum produces rhodochrosite during growth on hydrogen and organic compounds and may be a putative model organism for the reduction of Mn(IV). References Hulth S, Aller RC, Gilbert F. (1999) Geochim Cosmochim Acta, 63, 49-66. Johnson JE, Webb SM, Thomas K, Ono S, Kirschvink JL, Fischer WW. (2013) Proc Natl Acad Sci USA, 110, 11238-11243. Kirschvink JL, Gaidos EJ, Bertani LE, Beukes NJ, Gutzmer J, Maepa LN, Steinberger LE. (2000) Proc Natl Acad Sci USA, 97, 1400-1405. Nealson KH, Saffarini D. (1994). Annu Rev Microbiol, 48, 311-343.

  1. Sulfation mediates activity of zosteric acid against biofilm formation.

    PubMed

    Kurth, Caroline; Cavas, Levent; Pohnert, Georg

    2015-01-01

    Zosteric acid (ZA), a metabolite from the marine sea grass Zostera marina, has attracted much attention due to its attributed antifouling (AF) activity. However, recent results on dynamic transformations of aromatic sulfates in marine phototrophic organisms suggest potential enzymatic desulfation of metabolites like ZA. The activity of ZA was thus re-investigated using biofilm assays and simultaneous analytical monitoring by liquid chromatography/mass spectrometry (LC/MS). Comparison of ZA and its non-sulfated form para-coumaric acid (CA) revealed that the active substance was in all cases the non-sulfated CA while ZA was virtually inactive. CA exhibited a strong biofilm inhibiting activity against Escherichia coli and Vibrio natriegens. The LC/MS data revealed that the apparent biofilm inhibiting effects of ZA on V. natriegens can be entirely attributed to CA released from ZA by sulfatase activity. In the light of various potential applications, the (a)biotic transformation of ZA to CA has thus to be considered in future AF formulations.

  2. Foreign Body Giant Cell Formation Is Preceded by Lamellipodia Formation and Can Be Attenuated by Inhibition of Rac1 Activation

    PubMed Central

    Jay, Steven M.; Skokos, Eleni; Laiwalla, Farah; Krady, Marie-Marthe; Kyriakides, Themis R.

    2007-01-01

    Macrophages that are recruited to the site of implanted biomaterials undergo fusion to form surface-damaging foreign body giant cells. Exposure of peripheral blood monocytes to interleukin-4 can recapitulate the fusion process in vitro. In this study, we used interleukin-4 to induce multinucleation of murine bone marrow-derived macrophages and observed changes in cell shape, including elongation and lamellipodia formation, before fusion. Because cytoskeletal rearrangements are regulated by small GTPases, we examined the effects of inhibitors of Rho kinase (Y-32885) and Rac activation (NSC23766) on fusion. Y-32885 did not prevent cytoskeletal changes or fusion but limited the extent of multinucleation. NSC23766, on the other hand, inhibited lamellipodia formation and fusion in a dose-dependent manner. In addition, we found that in control cells, these changes were preceded by Rac1 activation. However, NSC23766 did not block the uptake of polystyrene microspheres. Likewise, short interfering RNA knockdown of Rac1 limited fusion without limiting phagocytosis. Thus, phagocytosis and fusion can be partially decoupled based on their susceptibility to NSC23766. Furthermore, poly(ethylene-co-vinyl acetate) scaffolds containing NSC23766 attenuated foreign body giant cell formation in vivo. These observations suggest that targeting Rac1 activation could protect biomaterials without compromising the ability of macrophages to perform beneficial phagocytic functions at implantation sites. PMID:17556592

  3. Foreign body giant cell formation is preceded by lamellipodia formation and can be attenuated by inhibition of Rac1 activation.

    PubMed

    Jay, Steven M; Skokos, Eleni; Laiwalla, Farah; Krady, Marie-Marthe; Kyriakides, Themis R

    2007-08-01

    Macrophages that are recruited to the site of implanted biomaterials undergo fusion to form surface-damaging foreign body giant cells. Exposure of peripheral blood monocytes to interleukin-4 can recapitulate the fusion process in vitro. In this study, we used interleukin-4 to induce multinucleation of murine bone marrow-derived macrophages and observed changes in cell shape, including elongation and lamellipodia formation, before fusion. Because cytoskeletal rearrangements are regulated by small GTPases, we examined the effects of inhibitors of Rho kinase (Y-32885) and Rac activation (NSC23766) on fusion. Y-32885 did not prevent cytoskeletal changes or fusion but limited the extent of multinucleation. NSC23766, on the other hand, inhibited lamellipodia formation and fusion in a dose-dependent manner. In addition, we found that in control cells, these changes were preceded by Rac1 activation. However, NSC23766 did not block the uptake of polystyrene microspheres. Likewise, short interfering RNA knockdown of Rac1 limited fusion without limiting phagocytosis. Thus, phagocytosis and fusion can be partially decoupled based on their susceptibility to NSC23766. Furthermore, poly(ethylene-co-vinyl acetate) scaffolds containing NSC23766 attenuated foreign body giant cell formation in vivo. These observations suggest that targeting Rac1 activation could protect biomaterials without compromising the ability of macrophages to perform beneficial phagocytic functions at implantation sites.

  4. Megacity impacts on regional ozone formation: observations and WRF-Chem modeling for the MIRAGE-Shanghai field campaign

    NASA Astrophysics Data System (ADS)

    Tie, X.; Geng, F.; Guenther, A.; Cao, J.; Greenberg, J.; Zhang, R.; Apel, E.; Li, G.; Weinheimer, A.; Chen, J.; Cai, C.

    2013-06-01

    The MIRAGE-Shanghai experiment was designed to characterize the factors controlling regional air pollution near a Chinese megacity (Shanghai) and was conducted during September 2009. This paper provides information on the measurements conducted for this study. In order to have some deep analysis of the measurements, a regional chemical/dynamical model (version 3 of Weather Research and Forecasting Chemical model - WRF-Chemv3) is applied for this study. The model results are intensively compared with the measurements to evaluate the model capability for calculating air pollutants in the Shanghai region, especially the chemical species related to ozone formation. The results show that the model is able to calculate the general distributions (the level and the variability) of air pollutants in the Shanghai region, and the differences between the model calculation and the measurement are mostly smaller than 30%, except the calculations of HONO (nitrous acid) at PD (Pudong) and CO (carbon monoxide) at DT (Dongtan). The main scientific focus is the study of ozone chemical formation not only in the urban area, but also on a regional scale of the surrounding area of Shanghai. The results show that during the experiment period, the ozone photochemical formation was strongly under the VOC (volatile organic compound)-limited condition in the urban area of Shanghai. Moreover, the VOC-limited condition occurred not only in the city, but also in the larger regional area. There was a continuous enhancement of ozone concentrations in the downwind of the megacity of Shanghai, resulting in a significant enhancement of ozone concentrations in a very large regional area in the surrounding region of Shanghai. The sensitivity study of the model suggests that there is a threshold value for switching from VOC-limited condition to NOx (nitric oxide and nitrogen dioxide)-limited condition. The threshold value is strongly dependent on the emission ratio of NOx / VOCs. When the ratio is about

  5. Megacity impacts on regional ozone formation: observations and WRF-Chem modeling for the MIRAGE-Shanghai field campaign

    NASA Astrophysics Data System (ADS)

    Tie, X.; Geng, F.; Guenther, A.; Cao, J.; Greenberg, J.; Zhang, R.; Apel, E.; Li, G.; Weinheimer, A.; Chen, J.; Cai, C.

    2013-01-01

    The MIRAGE-Shanghai experiment was designed to characterize the factors controlling regional air pollution near a Chinese Megacity (Shanghai) and was conducted during September 2009. This paper provides an overview of the measurements conducted for this study. In addition to the measurements, a regional chemical/dynamical model (version 3 of Weather Research and Forecasting Chemical model - WRF-Chemv3) is applied for this study. The model results are intensively compared with the measurements to evaluate the model capability for calculating air pollutants in the Shanghai region, especially the chemical species related to ozone formation. The results show that the model is able to calculate the general distributions (the level and the variability) of air pollutants in the Shanghai region, and the difference between the model calculation and the measurement are mostly smaller than 30%, except the calculations of HONO at PD (Pudong) and CO at DT (Dongtan). The main scientific focus is the study of ozone chemical formation not only in the urban area, but also on a regional scale of the surrounding area of Shanghai. The results show that during the experiment period, the ozone photochemical formation was strongly under the VOC-limited condition in the urban area of Shanghai. Moreover, the VOC-limited condition occurred not only in the city, but also in the larger regional area. There was a continuous enhancement of ozone concentrations in the downwind of the megacity of Shanghai, resulting in a significant enhancement of ozone concentrations in a very large regional area in the surrounding region of Shanghai. The sensitivity study of the model suggests that there is a threshold value for switching from VOC-limited condition to NOx-limited condition. The threshold value is strongly dependent on the emission ratio of NOx/VOCs. When the ratio is about 0.4, the Shanghai region is under a strong VOC-limited condition over the regional scale. In contrast, when the ratio is

  6. Seismic activity of the San Francisco Bay region

    USGS Publications Warehouse

    Bakun, W.H.

    1999-01-01

    Moment magnitude M with objective confidence-level uncertainties are estimated for felt San Francisco Bay region earthquakes using Bakun and Wentworth's (1997) analysis strategy for seismic intensity observations. The frequency-magnitude distribution is well described for M ???5.5 events since 1850 by a Gutenberg-Richter relation with a b-value of 0.90. The seismic moment rate ??M0/yr since 1836 is 2.68 X 1018 N-m/yr (95% confidence range = 1.29 X 1018 N-m/yr to 4.07 X 1018 N-m/yr); the seismic moment rate since 1850 is nearly the same. ??M0/yr in the 56 years before 1906 is about 10 times that in the 70 years after 1906. In contrast, ??M0/yr since 1977 is about equal that in the 56 years before 1906. 80% (1?? = 14%) of the plate-motion moment accumulation rate is available for release in earthquakes. The historical ??M0/yr and the portion of the plate-motion moment accumulation rate available for release in earthquakes are used in a seismic cycle model to estimate the rate of seismic activity in the twenty-first century. High and low rates of future seismic activity are both permissible given the range of possible seismic-cycle recurrence times T and the uncertainties in the historical ??M0 and in the percentage of plate motion available for release in earthquakes. If the historical seismic moment rate is not greater than the estimated 2.68 X 1018 N-m/yr and the percentage of the plate-motion moment accumulation available for release in earthquakes is not less than the estimated 80%, then for all T, the rate of seismic moment release from now until the next 1906-sized shock will be comparable to the rate from 1836 to 1905 when M 6 1/2 shocks occurred every 15 to 20 years.

  7. FIP BIAS EVOLUTION IN A DECAYING ACTIVE REGION

    SciTech Connect

    Baker, D.; Yardley, S. L.; Driel-Gesztelyi, L. van; Long, D. M.; Green, L. M.; Brooks, D. H.; Démoulin, P.

    2015-04-01

    Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode’s EUV Imaging Spectrometer instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR)11389. The composition maps show how FIP bias evolves within the decaying AR during the period 2012 January 4–6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR’s decay phase, small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing timescales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Finally, the FIP bias still remains dominantly coronal only in a part of the AR’s high-flux density core. We conclude that in the decay phase of an AR’s lifetime, the FIP bias is becoming increasingly modulated by episodes of small-scale flux emergence, i.e., decreasing the AR’s overall FIP bias. Our results show that magnetic field evolution plays an important role in compositional changes during AR development, revealing a more complex relationship than expected from previous well-known Skylab results showing that FIP bias increases almost linearly with age in young ARs.

  8. Star formation and AGN activity in the most luminous LINERs in the local universe

    NASA Astrophysics Data System (ADS)

    Pović, Mirjana; Márquez, Isabel; Netzer, Hagai; Masegosa, Josefa; Nordon, Raanan; Pérez, Enrique; Schoenell, William

    2016-11-01

    This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate (SFR) low-ionization nuclear emission-line regions (LINERs) at z = 0.04-0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and IRAS) for 13 of them. We measured emission-line intensities, extinction, stellar populations, stellar masses, ages, active galactic nuclei (AGN) luminosities, and SFRs. We find considerable differences from other low-redshift LINERs, in terms of extinction, and general similarity to star-forming galaxies. We confirm the existence of such luminous LINERs in the local universe, after being previously detected at z ˜ 0.3 by Tommasin et al. The median stellar mass of these LINERs corresponds to 6-7 × 1010 M⊙ which was found in previous work to correspond to the peak of relative growth rate of stellar populations and therefore for the highest SFRs. Other LINERs although showing similar AGN luminosities have lower SFR. We find that most of these sources have LAGN ˜ LSF suggesting co-evolution of black hole and stellar mass. In general, the fraction of local LINERs on the main sequence of star-forming galaxies is related to their AGN luminosity.

  9. Acetylcholine activity in selective striatal regions supports behavioral flexibility.

    PubMed

    Ragozzino, Michael E; Mohler, Eric G; Prior, Margaret; Palencia, Carlos A; Rozman, Suzanne

    2009-01-01

    Daily living often requires individuals to flexibly respond to new circumstances. There is considerable evidence that the striatum is part of a larger neural network that supports flexible adaptations. Cholinergic interneurons are situated to strongly influence striatal output patterns which may enable flexible adaptations. The present experiments investigated whether acetylcholine actions in different striatal regions support behavioral flexibility by measuring acetylcholine efflux during place reversal learning. Acetylcholine efflux selectively increased in the dorsomedial striatum, but not dorsolateral or ventromedial striatum during place reversal learning. In order to modulate the M2-class of autoreceptors, administration of oxotremorine sesquifumurate (100 nM) into the dorsomedial striatum, concomitantly impaired reversal learning and an increase in acetylcholine output. These effects were reversed by the m(2) muscarinic receptor antagonist, AF-DX-116 (20 nM). The effects of oxotremorine sesquifumurate and AF-DX-116 on acetylcholine efflux were selective to behaviorally-induced changes as neither treatment affected acetylcholine output in a resting condition. In contrast to reversal learning, acetylcholine efflux in the dorsomedial striatum did not change during place acquisition. The results reveal an essential role for cholinergic activity and define its locus of control to the dorsomedial striatum in cognitive flexibility.

  10. Plasma composition in a sigmoidal anemone active region

    SciTech Connect

    Baker, D.; Van Driel-Gesztelyi, L.; Green, L. M.; Carlyle, J.; Brooks, D. H.; Démoulin, P.; Steed, K.

    2013-11-20

    Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

  11. Optical Properties of Active Regions in Terahertz Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, M.; Motyka, M.; Rudno-Rudziński, W.; Sęk, G.; Misiewicz, J.; Pucicki, D.; Kosiel, K.; Sankowska, I.; Kubacka-Traczyk, J.; Bugajski, M.

    2016-07-01

    In this work, AlGaAs/GaAs superlattice, with layers' sequence and compositions imitating the active and injector regions of a quantum cascade laser designed for emission in the terahertz spectral range, was investigated. Three independent absorption-like optical spectroscopy techniques were employed in order to study the band structure of the minibands formed within the conduction band. Photoreflectance measurements provided information about interband transitions in the investigated system. Common transmission spectra revealed, in the target range of intraband transitions, mainly a number of lines associated with the phonon-related processes, including two-phonon absorption. In contrast, differential transmittance realized by means of Fourier-transform spectroscopy was utilized to probe the confined states of the conduction band. The obtained energy separation between the second and third confined electron levels, expected to be predominantly contributing to the lasing, was found to be ~9 meV. The optical spectroscopy measurements were supported by numerical calculations performed in the effective mass approximation and XRD measurements for layers' width verification. The calculated energy spacings are in a good agreement with the experimental values.

  12. Plasma Composition in a Sigmoidal Anemone Active Region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Green, L. M.; Steed, K.; Carlyle, J.

    2013-11-01

    Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

  13. Active region emission measure distributions and implications for nanoflare heating

    SciTech Connect

    Cargill, P. J.

    2014-03-20

    The temperature dependence of the emission measure (EM) in the core of active regions coronal loops is an important diagnostic of heating processes. Observations indicate that EM(T) ∼ T{sup a} below approximately 4 MK, with 2 < a < 5. Zero-dimensional hydrodynamic simulations of nanoflare trains are used to demonstrate the dependence of a on the time between individual nanoflares (T{sub N} ) and the distribution of nanoflare energies. If T{sub N} is greater than a few thousand seconds, a < 3. For smaller values, trains of equally spaced nanoflares cannot account for the observed range of a if the distribution of nanoflare energies is either constant, randomly distributed, or a power law. Power law distributions where there is a delay between consecutive nanoflares proportional to the energy of the second nanoflare do lead to the observed range of a. However, T{sub N} must then be of the order of hundreds to no more than a few thousand seconds. If a nanoflare leads to the relaxation of a stressed coronal field to a near-potential state, the time taken to build up the required magnetic energy is thus too long to account for the EM measurements. Instead, it is suggested that a nanoflare involves the relaxation from one stressed coronal state to another, dissipating only a small fraction of the available magnetic energy. A consequence is that nanoflare energies may be smaller than previously envisioned.

  14. The distribution of maximum temperatures of coronal active region loops

    NASA Technical Reports Server (NTRS)

    Mayfield, E. B.; Teske, R. G.

    1980-01-01

    The emission measure distribution across the range 4.5 log T 6.5 was derived for several coronal active regions by combining EUV line fluxes with broadband X-ray fluxes. The distributions of the maximum temperature was then derived using a numerical model. It is shown that the emission measure distribution can be represented over the full range 5.6 log Tm 6.5 by the superposition of simple loop models, if the models incorporate a substantial rise in their individual emission measure distributions near the maximum temperature. The unresolved loops may have substantial area ratios, since it is this ratio that fixes the extent of the rise in the emission measure distribution. Since the bulk of the emission measure is then contributed from the loop tops, the distribution of maximum temperatures has approximately the same shape as does the integrated emission measure distributions. The EUV and X-ray data used were obtained by from two separate experiments on ATM/Skylab.

  15. Geometry of Broad Line Regions of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Lü, Xiao-Rong

    2008-02-01

    It has long remained an open question as to the geometry of the broad line region (BLR) in active galactic nuclei (AGNs). The reverberation mapping technique which measures the response of the broad emission lines to the ionizing continuum, when combined with multiwavelength continuum fitted by sophisticated accretion disks, provides a way of probing the BLR geometry. We analyze a sample of 35 AGNs, which have been monitored by the reverberation mapping campaign. In view of energy budget, the reverberation-based BH masses are found to be in agreement with those obtained by accretion disk models in two thirds of the present sample while the reverberation mapping methods underestimate the BH masses in about one third of objects, as also suggested by Collin et al. in a recent work. We point out that there are obviously two kinds of BLR geometry, which are strongly dependent on the Eddington ratio, and separated by the value LBol/LEdd~0.1. These results prefer a scenario of the disk and wind configuration of the BLR and identify the Eddington ratio as the physical driver regulating the wind in the BLR.

  16. THE ORIGIN OF NET ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Dalmasse, K.; Kliem, B.; Török, T.

    2015-09-01

    There is a recurring question in solar physics regarding whether or not electric currents are neutralized in active regions (ARs). This question was recently revisited using three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetic flux emergence into the solar atmosphere. Such simulations showed that flux emergence can generate a substantial net current in ARs. Other sources of AR currents are photospheric horizontal flows. Our aim is to determine the conditions for the occurrence of net versus neutralized currents with this second mechanism. Using 3D MHD simulations, we systematically impose line-tied, quasi-static, photospheric twisting and shearing motions to a bipolar potential magnetic field. We find that such flows: (1) produce both direct and return currents, (2) induce very weak compression currents—not observed in 2.5D—in the ambient field present in the close vicinity of the current-carrying field, and (3) can generate force-free magnetic fields with a net current. We demonstrate that neutralized currents are in general produced only in the absence of magnetic shear at the photospheric polarity inversion line—a special condition that is rarely observed. We conclude that  photospheric flows, as magnetic flux emergence, can build up net currents in the solar atmosphere, in agreement with recent observations. These results thus provide support for eruption models based on pre-eruption magnetic fields that possess a net coronal current.

  17. Fear Appeals and the Formation of Active Publics.

    ERIC Educational Resources Information Center

    Roser, Connie; Thompson, Margaret

    1995-01-01

    Examines the process through which a fear appeal transforms low-involvement audiences into active publics. Analyzes cognitive and emotional responses of uninvolved viewers to a film on environmental contamination, together with coping strategies used to deal with the threat. Concludes that cognition and affect mediate viewers' responses to a…

  18. Formation of continuous activated carbon fibers for barrier fabrics

    NASA Astrophysics Data System (ADS)

    Liang, Ying

    1997-08-01

    Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained

  19. Lithofacies, depositional environments, regional biostratigraphy and age of the Chitarwata Formation in the Bugti Hills, Balochistan, Pakistan

    NASA Astrophysics Data System (ADS)

    Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, S. R. Hassan; Crochet, Jean-Yves; De Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

    2009-02-01

    The Oligocene-early Miocene Chitarwata Formation records a critical interval of terrestrial sedimentation that predates the Siwalik deposits on the Potwar Plateau of north-central Pakistan. This Oligocene-early Miocene time interval has long been considered as lacking in the entire Indo-Pakistan region. The Chitarwata Formation is widely exposed in the Sulaiman Range, but has never been described in detail in the Sulaiman Lobe, where the famous fossiliferous strata called 'Bugti Bone Beds' have been known for over a century and half. The Chitarwata Formation represents coastal-delta at the base, and plain and fluvial environments at the top. Lithofacies and sedimentary structures of the Chitarwata Formation in the Bugti area are described in detail, and show a clearly distinct lithologic pattern, different from that reported from the Zinda Pir area. The Chitarwata Formation also records an important transition in the evolution of the drainage systems in the area during the late Paleogene and early Neogene. This transition from the west-flowing paleo-Indus fluvial system to the development of the ancestral Indus drainage system may explain the numerous hiatuses that characterize the Chitarwata Formation. The abundance of fossil mammals from the Chitarwata and overlying Vihowa formation in the Bugti Hills provides critical biochronologic information that sheds new light on biostratigraphic correlation with the Zinda Pir area and for the entire Sulaiman Range.

  20. 78 FR 38739 - Standard Format and Content for Post-Shutdown Decommissioning Activities Report

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-27

    ..., DG-1272, in the Federal Register on December 19, 2012 (77 FR 75198), for a 60-day public comment... COMMISSION Standard Format and Content for Post-Shutdown Decommissioning Activities Report AGENCY: Nuclear... (NRC) is issuing Revision 1 of Regulatory Guide (RG) 1.185, ``Standard Format and Content for...

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

    PubMed

    Greulich, P; Santen, L

    2010-06-01

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

  2. Psycho-Pedagogical Conditions of Formation of Professional Creative Activity of Future Professionals

    ERIC Educational Resources Information Center

    Askarovna, Uzakbayeva Sakypzhamal; Yertaevna, Abeltayeva Zhanel; Erhanovna, Sadykova Ayzhan; Rysbekova, R.

    2015-01-01

    Organizational, psychological and pedagogical conditions (the position of student in the educational process, the inclusion of students in active and independent activities, the creation of a positive creative environment and psychological climate, the active use of the forms, methods, technologies, adequate formation of professional creative…

  3. Comparing the validity of 2 physical activity questionnaire formats in African-American and Hispanic women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to compare the validity of 2 physical activity questionnaire formats—one that lists activities (Checklist questionnaire) and one that assesses overall activities (Global questionnaire) by domain. Two questionnaire formats were validated among 260 African-American and Hi...

  4. Comparative internal kinematics of the H II regions in interacting and isolated galaxies: implications for massive star formation modes

    NASA Astrophysics Data System (ADS)

    Zaragoza-Cardiel, Javier; Beckman, John E.; Font, Joan; García-Lorenzo, Begoña; Camps-Fariña, Artemi; Fathi, Kambiz; James, Philip A.; Erroz-Ferrer, Santiago; Barrera-Ballesteros, Jorge; Cisternas, Mauricio

    2015-08-01

    We have observed 12 interacting galaxy pairs using the Fabry-Perot interferometer GH αFaS (Galaxy H α Fabry-Perot system) on the 4.2-m William Herschel Telescope at the Observatorio del Roque de los Muchachos, La Palma. We present here the Hα surface brightness, velocity and velocity dispersion maps for the 10 systems we have not previously observed using this technique, as well as the physical properties (sizes, Hα luminosities and velocity dispersion) of 1259 H II regions from the full sample. We also derive the physical properties of 1054 H II regions in a sample of 28 isolated galaxies observed with the same instrument in order to compare the two populations of H II regions. We find a population of the brightest H II regions for which the scaling relations, for example the relation between the Hα luminosity and the radius, are clearly distinct from the relations for the regions of lower luminosity. The regions in this bright population are more frequent in the interacting galaxies. We find that the turbulence, and also the star formation rate (SFR), are enhanced in the H II regions in the interacting galaxies. We have also extracted the Hα equivalent widths for the H II regions of both samples, and we have found that the distribution of H II region ages coincides for the two samples of galaxies. We suggest that the SFR enhancement is brought about by gas flows induced by the interactions, which give rise to gravitationally bound gas clouds which grow further by accretion from the flowing gas, producing conditions favourable to star formation.

  5. MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION

    SciTech Connect

    Zhang, Hongqi; Brandenburg, Axel; Sokoloff, D. D.

    2014-04-01

    We compute for the first time the magnetic helicity and energy spectra of the solar active region NOAA 11158 during 2011 February 11-15 at 20° southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of the magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The magnetic helicity normalized to its theoretical maximum value, here referred to as relative helicity, is around 4% and strongest at intermediate wavenumbers of k ≈ 0.4 Mm{sup –1}, corresponding to a scale of 2π/k ≈ 16 Mm. The same sign and a similar value are also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The modulus of the magnetic helicity spectrum shows a k {sup –11/3} power law at large wavenumbers, which implies a k {sup –5/3} spectrum for the modulus of the current helicity. A k {sup –5/3} spectrum is also obtained for the magnetic energy. The energy spectra evaluated separately from the horizontal and vertical fields agree for wavenumbers below 3 Mm{sup –1}, corresponding to scales above 2 Mm. This gives some justification to our assumption of isotropy and places limits resulting from possible instrumental artifacts at small scales.

  6. CONTRACTING AND ERUPTING COMPONENTS OF SIGMOIDAL ACTIVE REGIONS

    SciTech Connect

    Liu Rui; Wang Yuming; Liu Chang; Wang Haimin; Toeroek, Tibor

    2012-10-01

    It has recently been noted that solar eruptions can be associated with the contraction of coronal loops that are not involved in magnetic reconnection processes. In this paper, we investigate five coronal eruptions originating from four sigmoidal active regions, using high-cadence, high-resolution narrowband EUV images obtained by the Solar Dynamic Observatory (SDO). The magnitudes of the flares associated with the eruptions range from GOES class B to class X. Owing to the high-sensitivity and broad temperature coverage of the Atmospheric Imaging Assembly (AIA) on board SDO, we are able to identify both the contracting and erupting components of the eruptions: the former is observed in cold AIA channels as the contracting coronal loops overlying the elbows of the sigmoid, and the latter is preferentially observed in warm/hot AIA channels as an expanding bubble originating from the center of the sigmoid. The initiation of eruption always precedes the contraction, and in the energetically mild events (B- and C-flares), it also precedes the increase in GOES soft X-ray fluxes. In the more energetic events, the eruption is simultaneous with the impulsive phase of the nonthermal hard X-ray emission. These observations confirm that loop contraction is an integrated process in eruptions with partially opened arcades. The consequence of contraction is a new equilibrium with reduced magnetic energy, as the contracting loops never regain their original positions. The contracting process is a direct consequence of flare energy release, as evidenced by the strong correlation of the maximal contracting speed, and strong anti-correlation of the time delay of contraction relative to expansion, with the peak soft X-ray flux. This is also implied by the relationship between contraction and expansion, i.e., their timing and speed.

  7. Identifying the Main Driver of Active Region Outflows

    NASA Astrophysics Data System (ADS)

    Baker, D.; van Driel-Gesztelyi, L.; Mandrini, C. H.; Démoulin, P.; Murray, M. J.

    2012-08-01

    Hinode's EUV Imaging Spectrometer (EIS) has discovered ubiquitous outflows of a few to 50 km s-1 from active regions (ARs). The characteristics of these outflows are very curious in that they are most prominent at the AR boundary and appear over monopolar magnetic areas. They are linked to strong non-thermal line broadening and are stronger in hotter EUV lines. The outflows persist for at least several days. Whereas red-shifted down flows observed in AR closed loops are well understood, to date there is no general consensus for the mechanism(s) driving blue-shifted AR-related outflows. We use Hinode EIS and X-Ray Telescope observations of AR 10942 coupled with magnetic modeling to demonstrate for the first time that the outflows originate from specific locations of the magnetic topology where field lines display strong gradients of magnetic connectivity, namely quasi-separatrix layers (QSLs), or in the limit of infinitely thin QSLs, separatrices. The strongest AR outflows were found to be in the vicinity of QSL sections located over areas of strong magnetic field. We argue that magnetic reconnection at QSLs, separating closed field lines of the AR and either large-scale externally connected or ‘open’ field lines, is a viable mechanism for driving AR outflows which are potentially sources of the slow solar wind. In fact, magnetic reconnection along QSLs (including separatricies) is the first theory to explain the most puzzling characteristics of the outflows, namely their occurrence over monopolar areas at the periphery of ARs and their longevity.

  8. ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS

    SciTech Connect

    Petrie, G. J. D.; Sudol, J. J.

    2010-12-01

    We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65{sup 0} of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of {approx}10 G to as high as {approx}450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65{sup 0} of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

  9. Minimal continuum theories of structure formation in dense active fluids

    NASA Astrophysics Data System (ADS)

    Dunkel, Jörn; Heidenreich, Sebastian; Bär, Markus; Goldstein, Raymond E.

    2013-04-01

    Self-sustained dynamical phases of living matter can exhibit remarkable similarities over a wide range of scales, from mesoscopic vortex structures in microbial suspensions and motility assays of biopolymers to turbulent large-scale instabilities in flocks of birds or schools of fish. Here, we argue that, in many cases, the phenomenology of such active states can be efficiently described in terms of fourth- and higher-order partial differential equations. Structural transitions in these models can be interpreted as Landau-type kinematic transitions in Fourier (wavenumber) space, suggesting that microscopically different biological systems can share universal long-wavelength features. This general idea is illustrated through numerical simulations for two classes of continuum models for incompressible active fluids: a Swift-Hohenberg-type scalar field theory, and a minimal vector model that extends the classical Toner-Tu theory and appears to be a promising candidate for the quantitative description of dense bacterial suspensions. We discuss how microscopic symmetry-breaking mechanisms can enter macroscopic continuum descriptions of collective microbial motion near surfaces, and conclude by outlining future applications.

  10. Active plasma source formation in the MAP diode

    SciTech Connect

    Lamppa, K.P.; Stinnett, R.W.; Renk, T.J.

    1995-07-01

    The Ion Beam Surface Treatment (IBEST) program is exploring using ion beams to treat the surface of a wide variety of materials. These experiments have shown that improved corrosion resistance, surface hardening, grain size modification, polishing and surface cleaning can all be achieved using a pulsed 0.4-0.8 MeV ion beam delivering 1-10 J/cm{sup 2}. The Magnetically-confined Anode Plasma (MAP) diode, developed at Cornell University, produces an active plasma which can be used to treat the surfaces of materials. The diode consists of a fast puff valve as the source of gas to produce the desired ions and two capacitively driven B-fields. A slow magnetic field is used for electron insulation and a fast field is used to both ionize the puffed gas and to position the plasma in the proper spatial location in the anode prior to the accelerator pulse. The relative timing between subsystems is an important factor in the effective production of the active plasma source for the MAP diode system. The MAP diode has been characterized using a Langmuir probe to measure plasma arrival times at the anode annulus for hydrogen gas. This data was then used to determine the optimum operating point for the MAP diode on RHEPP-1 accelerator shots. Operation of the MAP diode system to produce an ion beam of 500 kV, 12 kA with 40% efficiency (measured at the diode) has been demonstrated.

  11. Fab-based bispecific antibody formats with robust biophysical properties and biological activity.

    PubMed

    Wu, Xiufeng; Sereno, Arlene J; Huang, Flora; Lewis, Steven M; Lieu, Ricky L; Weldon, Caroline; Torres, Carina; Fine, Cody; Batt, Micheal A; Fitchett, Jonathan R; Glasebrook, Andrew L; Kuhlman, Brian; Demarest, Stephen J

    2015-01-01

    A myriad of innovative bispecific antibody (BsAb) platforms have been reported. Most require significant protein engineering to be viable from a development and manufacturing perspective. Single-chain variable fragments (scFvs) and diabodies that consist only of antibody variable domains have been used as building blocks for making BsAbs for decades. The drawback with Fv-only moieties is that they lack the native-like interactions with CH1/CL domains that make antibody Fab regions stable and soluble. Here, we utilize a redesigned Fab interface to explore 2 novel Fab-based BsAbs platforms. The redesigned Fab interface designs limit heavy and light chain mixing when 2 Fabs are co-expressed simultaneously, thus allowing the use of 2 different Fabs within a BsAb construct without the requirement of one or more scFvs. We describe the stability and activity of a HER2×HER2 IgG-Fab BsAb, and compare its biophysical and activity properties with those of an IgG-scFv that utilizes the variable domains of the same parental antibodies. We also generated an EGFR × CD3 tandem Fab protein with a similar format to a tandem scFv (otherwise known as a bispecific T cell engager or BiTE). We show that the Fab-based BsAbs have superior biophysical properties compared to the scFv-based BsAbs. Additionally, the Fab-based BsAbs do not simply recapitulate the activity of their scFv counterparts, but are shown to possess unique biological activity.

  12. ON THE ROLE OF ROTATING SUNSPOTS IN THE ACTIVITY OF SOLAR ACTIVE REGION NOAA 11158

    SciTech Connect

    Vemareddy, P.; Ambastha, A.; Maurya, R. A. E-mail: ambastha@prl.res.in

    2012-12-10

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, {alpha}{sub av}, {alpha}{sub best}, derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity.

  13. The Maximum Free Magnetic Energy Allowed in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Moore, Ronald L.; Falconer, D. A.

    2009-05-01

    Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are LWLSG, a gauge of the total free energy in an active region's magnetic field, and LΦ, a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 RSun central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size LΦ of the active region, (2) in (Log LWLSG, Log LΦ) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active-region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: áBñ ≡ ΦA ≈ 300 G, where Φ is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (< 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division, NSF's Division of Atmospheric Sciences, and AFOSR's MURI Program.

  14. The Maximum Free Magnetic Energy Allowed in a Solar Active Region

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Falconer, David A.

    2009-01-01

    Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (less than 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

  15. Cooperative magnetographic and radioastronomical investigations of the active solar region AR 3804 in July 1982.

    NASA Astrophysics Data System (ADS)

    Akhmedov, Sh. B.; Borovik, V. N.; Gel'Frejkh, G. B.; Bogod, V. M.; Korzhavin, A. N.; Petrov, Z. E.; Hofmann, A.; Bachmann, G.

    An analysis of the radiation peculiar source in the active solar region AR 3804 is presented using the magnetograms obtained at ZIAP AW DDR in Potsdam. The source is on the border line of polarities of the photospheric magnetic field above the filament and has the flux spectrum increasing with the wavelength, the brightness temperature at 4 cm being above 6×106K, and the logarithm spectrum slope in the shortwave region (λ = 2 cm) being about n = 10. The polarization degree within 2 - 4 cm is close to 30%. An analysis of magnetograms of the total field vector showed that in the source region there is observed a density increase of the longitudinal current in the photosphere, this increase having different signs on different sides from the zero magnetic line. Near the source there is observed a magnetic field hill of the reverse polarity relative to the background field. It is suggested to relate the source with the magnetic loop of the "twisted" field in the corona in which the local energy emission and corona heating due to dissipation of magnetic fields of complex configuration occur (apparently, with the current sheet formation).

  16. MID-INFRARED SPECTRAL INDICATORS OF STAR FORMATION AND ACTIVE GALACTIC NUCLEUS ACTIVITY IN NORMAL GALAXIES

    SciTech Connect

    Treyer, Marie; Martin, Christopher D.; Wyder, Ted; Schiminovich, David; O'Dowd, Matt; Johnson, Benjamin D.; Charlot, Stephane; Heckman, Timothy; Martins, Lucimara; Seibert, Mark; Van der Hulst, J. M.

    2010-08-20

    We investigate the use of mid-infrared (MIR) polycyclic aromatic hydrocarbon (PAH) bands, the continuum, and emission lines as probes of star formation (SF) and active galactic nucleus (AGN) activity in a sample of 100 'normal' and local (z {approx} 0.1) emission-line galaxies. The MIR spectra were obtained with the Spitzer Space Telescope Infrared Spectrograph as part of the Spitzer-SDSS-GALEX Spectroscopic Survey, which includes multi-wavelength photometry from the ultraviolet to the far-infrared and optical spectroscopy. The continuum and features were extracted using PAHFIT, a decomposition code which we find to yield PAH equivalent widths (EWs) up to {approx}30 times larger than the commonly used spline methods. Despite the lack of extreme objects in our sample (such as strong AGNs, low-metallicity galaxies, or ULIRGs), we find significant variations in PAH, continuum, and emission-line properties, and systematic trends between these MIR properties and optically derived physical properties, such as age, metallicity, and radiation field hardness. We revisit the diagnostic diagram relating PAH EWs and [Ne II]12.8 {mu}m/[O IV]25.9 {mu}m line ratios and find it to be in much better agreement with the standard optical SF/AGN classification than when spline decompositions are used, while also potentially revealing obscured AGNs. The luminosity of individual PAH components, of the continuum, and, with poorer statistics, of the neon emission lines and molecular hydrogen lines are found to be tightly correlated to the total infrared (TIR) luminosity, making individual MIR components good gauges of the total dust emission in SF galaxies. Like the TIR luminosity, these individual components can be used to estimate dust attenuation in the UV and in H{alpha} lines based on energy balance arguments. We also propose average scaling relations between these components and dust-corrected, H{alpha}-derived SF rates.

  17. DIFFRACTION, REFRACTION, AND REFLECTION OF AN EXTREME-ULTRAVIOLET WAVE OBSERVED DURING ITS INTERACTIONS WITH REMOTE ACTIVE REGIONS

    SciTech Connect

    Shen Yuandeng; Liu Yu; Zhao Ruijuan; Tian Zhanjun; Su Jiangtao; Li Hui; Ichimoto, Kiyoshi; Shibata, Kazunari

    2013-08-20

    We present observations of the diffraction, refraction, and reflection of a global extreme-ultraviolet (EUV) wave propagating in the solar corona. These intriguing phenomena are observed when the wave interacts with two remote active regions, and together they exhibit properties of an EUV wave. When the wave approached AR11465, it became weaker and finally disappeared in the active region, but a few minutes later a new wavefront appeared behind the active region, and it was not concentric with the incoming wave. In addition, a reflected wave was also simultaneously observed on the wave incoming side. When the wave approached AR11459, it transmitted through the active region directly and without reflection. The formation of the new wavefront and the transmission could be explained with diffraction and refraction effects, respectively. We propose that the different behaviors observed during the interactions may be caused by different speed gradients at the boundaries of the two active regions. We find that the EUV wave formed ahead of a group of expanding loops a few minutes after the start of the loops' expansion, which represents the initiation of the associated coronal mass ejection (CME). Based on these results, we conclude that the EUV wave should be a nonlinear magnetosonic wave or shock driven by the associated CME, which propagated faster than the ambient fast mode speed and gradually slowed down to an ordinary linear wave. Our observations support the hybrid model that includes both fast wave and slow non-wave components.

  18. FLARE ENERGY BUILD-UP IN A DECAYING ACTIVE REGION NEAR A CORONAL HOLE

    SciTech Connect

    Su Yingna; Van Ballegooijen, Adriaan; Golub, Leon; Schmieder, Brigitte; Berlicki, Arkadiusz; Guo, Yang; Huang Guangli

    2009-10-10

    A B1.7 two-ribbon flare occurred in a highly non-potential decaying active region near a coronal hole at 10:00 UT on 2008 May 17. This flare is 'large' in the sense that it involves the entire region, and it is associated with both a filament eruption and a coronal mass ejection. We present multi-wavelength observations from EUV (TRACE, STEREO/EUVI), X-rays (Hinode/XRT), and Halpha (THEMIS, BBSO) prior to, during and after the flare. Prior to the flare, the region contained two filaments. The long J-shaped sheared loops corresponding to the southern filament were evolved from two short loop systems, which happened around 22:00 UT after a filament eruption on May 16. Formation of highly sheared loops in the southeastern part of the region was observed by STEREO 8 hr before the flare. We also perform nonlinear force-free field (NLFFF) modeling for the region at two times prior to the flare, using the flux rope insertion method. The models include the non-force-free effect of magnetic buoyancy in the photosphere. The best-fit NLFFF models show good fit to observations both in the corona (X-ray and EUV loops) and chromosphere (Halpha filament). We find that the horizontal fields in the photosphere are relatively insensitive to the present of flux ropes in the corona. The axial flux of the flux rope in the NLFFF model on May 17 is twice that on May 16, and the model on May 17 is only marginally stable. We also find that the quasi-circular flare ribbons are associated with the separatrix between open and closed fields. This observation and NLFFF modeling suggest that this flare may be triggered by the reconnection at the null point on the separatrix surface.

  19. A SINFONI view of the nuclear activity and circumnuclear star formation in NGC 4303

    NASA Astrophysics Data System (ADS)

    Riffel, Rogemar A.; Colina, L.; Storchi-Bergmann, T.; Piqueras López, J.; Arribas, S.; Riffel, R.; Pastoriza, M.; Sales, Dinalva A.; Dametto, N. Z.; Labiano, A.; Davies, R. I.

    2016-10-01

    We present new maps of emission-line flux distributions and kinematics in both ionized (traced by H I and [Fe II] lines) and molecular (H2) gas of the inner 0.7 × 0.7 kpc2 of the galaxy NGC 4303, with a spatial resolution 40-80 pc and velocity resolution 90-150 km s- 1 obtained from near-IR integral field spectroscopy using the Very Large Telescope instrument SINFONI. The most prominent feature is a 200-250 pc ring of circumnuclear star-forming regions. The emission from ionized and molecular gas shows distinct flux distributions: while the strongest H I and [Fe II] emission comes from regions in the west side of the ring (ages ˜ 4 Myr), the H2 emission is strongest at the nucleus and in the east side of the ring (ages > 10 Myr). We find that regions of enhanced hot H2 emission are anti-correlated with those of enhanced [Fe II] and H I emission, which can be attributed to post-starburst regions that do not have ionizing photons anymore but still are hot enough (≈2000 K) to excite the H2 molecule. The line ratios are consistent with the presence of an active galactic nucleus at the nucleus. The youngest regions have stellar masses in the range 0.3-1.5 × 105 M⊙ and ionized and hot molecular gas masses of ˜0.25-1.2 × 104 M⊙ and ˜2.5-5 M⊙, respectively. The stellar and gas velocity fields show a rotation pattern, with the gas presenting larger velocity amplitudes than the stars, with a deviation observed for the H2 along the nuclear bar, where increased velocity dispersion is also observed, possibly associated with non-circular motions along the bar. The stars in the ring show smaller velocity dispersion than the surroundings, which can be attributed to a cooler dynamics due to their recent formation from cool gas.

  20. Titanium nanotubes activate genes related to bone formation in vitro

    PubMed Central

    Pozio, Alfonso; Palmieri, Annalisa; Girardi, Ambra; Cura, Francesca; Carinci, Francesco

    2012-01-01

    Background: Titanium is used worldwide to make osseointegrable devices, thanks to its favorable characteristics as mechanical proprieties and biocompatibility, demonstrated by in vivo studies with animal models and clinical trials over a forty-year period. However, the exact genetic effect of the titanium layer on cells is still not well characterized. Materials and Methods: To investigate how titanium nanotubes stimulate osteoblasts differentiation and proliferation, some osteoblast genes (SP7, RUNX2, COL3A1, COL1A1, ALPL, SPP1 and FOSL1) were analyzed by quantitative Real Time RT- PCR. Results: After 15 days, osteoblasts cultivated on titanium naotube showed the up-regulation of bone related genes SP7, ENG, FOSL1 and SPP1 and the down-regulation of RUNX2, COL3A1, COL1A1, and ALPL. After 30 days of treatment, the bone related genes SP7, ENG, FOSL1 and RUNX2 were up-regulated while COL3A1, COL1A1, ALPL and SPP1 were down-regulated. Conclusions: Our results, demonstrates that titanium nanotubes can lead to osteoblast differentiation and extracellular matrix deposition and mineralization in dental pulp stem cells by the activation of osteoblast related genes SPP1, FOSL1 and RUNX2. PMID:23814577

  1. Studies of the Permian Phosphoria Formation and related rocks, Great Basin-Rocky Mountain region

    USGS Publications Warehouse

    Wardlaw, Bruce R.

    1979-01-01

    PART A: The transgression of the Permian Retort Phosphatic Shale Member of the Phosphoria Formation is dated by the occurrence of diagnostic brachiopods. The complex pattern of this transgression reflects the paleogeography and indicates two initial basins of deposition: one in southwestern Montana and one in southeastern Idaho. PART B: A new formation is proposed for middle Permian rocks of a transitional facies positioned laterally between the Rex Chert Member of the Phosphoria Formation in northeastern Utah and southeastern Idaho and the Plympton Formation in northeastern Nevada and northwestern Utah. PART C: The relationships of the Permian Park City Group to the Phosphoria and Park City Formations are clarified by the stratigraphy of four sections in northwestern Utah, northeastern Nevada, and southern Idaho. PART D: Five biostratigraphic zones based on the distribution of brachiopods and conodonts are proposed for the Park City Group. They are: the Peniculauris ivesi-Neostreptognathodus prayi Zone, the Peniculauris bassi-Neostreptognathodus sulcoplicatus Zone, the Peniculauris bassi-Neostreptognathodus sp. C Zone, the Thamnosia depressa Zone, and the Yakovlevia. multistriata-Neogondolella bitteri Zone. They range in age from Leonardian to Wordian.

  2. Lithofacies, depositional environments, and regional stratigraphy of the lower Eocene Ghazij Formation, Balochistan, Pakistan

    USGS Publications Warehouse

    Johnson, Edward A.; Warwick, P.D.; Roberts, S.B.; Khan, I.H.

    1999-01-01

    A regional stratigraphic investigation of one of the most important coal-bearing lithostratigraphic units in Pakistan, the report includes sedimentologic observations taken from outcrops and measured sections, information derived from petrographic and paleontologic analyses, depositional interpretations, and descriptions of regional trends.

  3. 76 FR 58533 - Powder River Regional Coal Team Activities; Notice of Public Meeting in Casper, WY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-21

    ... Bureau of Land Management Powder River Regional Coal Team Activities; Notice of Public Meeting in Casper... River Regional Coal Team (RCT) has scheduled a public meeting for October 26, 2011, to review coal management activities in the Powder River Coal Production Region. DATES: The RCT meeting will begin at 9...

  4. MASSIVE CLUSTERS IN THE INNER REGIONS OF NGC 1365: CLUSTER FORMATION AND GAS DYNAMICS IN GALACTIC BARS

    SciTech Connect

    Elmegreen, Bruce G.; Galliano, Emmanuel; Alloin, Danielle E-mail: egallian@on.b

    2009-10-01

    Cluster formation and gas dynamics in the central regions of barred galaxies are not well understood. This paper reviews the environment of three 10{sup 7} M {sub sun} clusters near the inner Lindblad resonance (ILR) of the barred spiral NGC 1365. The morphology, mass, and flow of H I and CO gas in the spiral and barred regions are examined for evidence of the location and mechanism of cluster formation. The accretion rate is compared with the star formation rate to infer the lifetime of the starburst. The gas appears to move from inside corotation in the spiral region to looping filaments in the interbar region at a rate of approx6 M {sub sun} yr{sup -1} before impacting the bar dustlane somewhere along its length. The gas in this dustlane moves inward, growing in flux as a result of the accretion to approx40 M {sub sun} yr{sup -1} near the ILR. This inner rate exceeds the current nuclear star formation rate by a factor of 4, suggesting continued buildup of nuclear mass for another approx0.5 Gyr. The bar may be only 1-2 Gyr old. Extrapolating the bar flow back in time, we infer that the clusters formed in the bar dustlane outside the central dust ring at a position where an interbar filament currently impacts the lane. The ram pressure from this impact is comparable to the pressure in the bar dustlane, and both are comparable to the pressure in the massive clusters. Impact triggering is suggested. The isothermal assumption in numerical simulations seems inappropriate for the rarefaction parts of spiral and bar gas flows. The clusters have enough lower-mass counterparts to suggest they are part of a normal power-law mass distribution. Gas trapping in the most massive clusters could explain their [Ne II] emission, which is not evident from the lower-mass clusters nearby.

  5. A FORMATION SCENARIO OF YOUNG STELLAR GROUPS IN THE REGION OF THE SCORPIO CENTAURUS OB ASSOCIATION

    SciTech Connect

    Ortega, V. G.; Jilinski, E.; De la Reza, R.; Bazzanella, B.

    2009-04-15

    The main objective of this work is to investigate the role played by Lower Centaurus Crux (LCC) and Upper Centaurus Lupus (UCL), both subcomponents of the Scorpio Centaurus OB association (Sco-Cen), in the formation of the groups {beta} Pictoris, TW Hydrae, and the {eta} Chamaeleontis cluster. The dynamical evolution of all the stellar groups involved and of the bubbles and shells blown by LCC and UCL are calculated, and followed from the past to the present. This leads to a formation scenario in which (1) the groups {beta} Pictoris, TW Hydrae were formed in the wake of the shells created by LCC and UCL, (2) the young cluster {eta} Chamaeleontis was born as a consequence of the collision of the shells of LCC and UCL, and (3) the formation of Upper Scorpius (US), the other main subcomponent of the Sco-Cen association, may have been started by the same process that created {eta} Chamaeleontis.

  6. Detection of neural activity in the brains of Japanese honeybee workers during the formation of a "hot defensive bee ball".

    PubMed

    Ugajin, Atsushi; Kiya, Taketoshi; Kunieda, Takekazu; Ono, Masato; Yoshida, Tadaharu; Kubo, Takeo

    2012-01-01

    Anti-predator behaviors are essential to survival for most animals. The neural bases of such behaviors, however, remain largely unknown. Although honeybees commonly use their stingers to counterattack predators, the Japanese honeybee (Apis cerana japonica) uses a different strategy to fight against the giant hornet (Vespa mandarinia japonica). Instead of stinging the hornet, Japanese honeybees form a "hot defensive bee ball" by surrounding the hornet en masse, killing it with heat. The European honeybee (A. mellifera ligustica), on the other hand, does not exhibit this behavior, and their colonies are often destroyed by a hornet attack. In the present study, we attempted to analyze the neural basis of this behavior by mapping the active brain regions of Japanese honeybee workers during the formation of a hot defensive bee ball. First, we identified an A. cerana homolog (Acks = Apis cerana kakusei) of kakusei, an immediate early gene that we previously identified from A. mellifera, and showed that Acks has characteristics similar to kakusei and can be used to visualize active brain regions in A. cerana. Using Acks as a neural activity marker, we demonstrated that neural activity in the mushroom bodies, especially in Class II Kenyon cells, one subtype of mushroom body intrinsic neurons, and a restricted area between the dorsal lobes and the optic lobes was increased in the brains of Japanese honeybee workers involved in the formation of a hot defensive bee ball. In addition, workers exposed to 46°C heat also exhibited Acks expression patterns similar to those observed in the brains of workers involved in the formation of a hot defensive bee ball, suggesting that the neural activity observed in the brains of workers involved in the hot defensive bee ball mainly reflects thermal stimuli processing. PMID:22431987

  7. A Multi-wavelength Study of Star Formation Activity in the S235 Complex

    NASA Astrophysics Data System (ADS)

    Dewangan, L. K.; Ojha, D. K.; Luna, A.; Anandarao, B. G.; Ninan, J. P.; Mallick, K. K.; Mayya, Y. D.

    2016-03-01

    We have carried out an extensive multi-wavelength study to investigate the star formation process in the S235 complex. The S235 complex has a spherelike shell appearance at wavelengths longer than 2 μm and harbors an O9.5V type star approximately at its center. A near-infrared extinction map of the complex traces eight subregions (having AV > 8 mag), and five of them appear to be distributed in an almost regularly spaced manner along the spherelike shell surrounding the ionized emission. This picture is also supported by the integrated 12CO and 13CO intensity maps and by Bolocam 1.1 mm continuum emission. The position-velocity analysis of CO reveals an almost semi-ringlike structure, suggesting an expanding H ii region. We find that the Bolocam clump masses increase as we move away from the location of the ionizing star. This correlation is seen only for those clumps that are distributed near the edges of the shell. Photometric analysis reveals 435 young stellar objects (YSOs), 59% of which are found in clusters. Six subregions (including five located near the edges of the shell) are very well correlated with the dust clumps, CO gas, and YSOs. The average values of Mach numbers derived using NH3 data for three (East 1, East 2, and Central E) out of these six subregions are 2.9, 2.3, and 2.9, indicating these subregions are supersonic. The molecular outflows are detected in these three subregions, further confirming the ongoing star formation activity. Together, all these results are interpreted as observational evidence of positive feedback of a massive star.

  8. Mechanisms for quenching star formation activities in green valley galaxies and its depends on morphologies

    NASA Astrophysics Data System (ADS)

    Kong, Xu; Pan, Zhizheng; Lian, Jianhui

    2015-08-01

    Galaxies are categorized into two main populations, red quiescent galaxies and blue star-forming galaxies. One of the key questions is which physical mechanisms are responsible for quenching star formation activities in blue galaxies and the resulting transformation? In this talk, we present research on the morphologies, spectra, and environments of "green valley" galaxies in the COSMOS field and low redshift "green valley" galaxies in SDSS. Our findings suggest that environmental conditions, most likely starvation and harassment, significantly affect the transformation of M* < 10^10.0 Msun blue galaxies into red galaxies, especially at z < 0.5. Using image from SDSS and GALEX, we analyze the radial ultraviolet-optical color distributions in a sample of low redshift green valley galaxies, and investigate how quenching is processing in a galaxy. The early-type "green valley" galaxies (ETGs) have dramatically different radial NUV-r color distributions compared to late-type "green valley" galaxies (LTGs), most of ETGs have blue cores, nearly all LTGs have uniform color profiles that can be well-interpreted as red bulges plus blue disk components. These results suggest that the LTGs follow a general model by which quenching first occurs in the core regions, and then finally extend to the rest of the galaxy; for ETGs, their star formations are centrally concentrated. Our results can be re-examined and have important implications for the IFU surveys, such as MaNGA and SAMI (2013ApJ...776...14P, 2014ApJ...792L...4P, 2015MNRAS.446.1449L).

  9. The Limit of Magnetic-Shear Energy in Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Falconer, David A.; Sterling, Alphonse C.

    2013-01-01

    It has been found previously, by measuring from active ]region magnetograms a proxy of the free energy in the active region fs magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main ]sequence path bordering the free ]energy ]limit line in (flux content, free ]energy proxy) phase space. Here we present evidence that specifies the underlying magnetic condition that gives rise to the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free ]energy limit, the ratio of magnetic ]shear free energy to the non ]free magnetic energy the potential field would have is of order 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. Evidently, most active regions in which this core ]field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1, most active regions are compelled to explode.

  10. The Limit of Magnetic-Shear Energy in Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ronald; Falconer, David; Sterling, Alphonse

    2012-01-01

    It has been found previously, by measuring from active-region magnetograms a proxy of the free energy in the active region's magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region's magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a coronal mass ejection/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy-limit line in (flux content, free-energy proxy) phase space. Here, we present evidence that specifies the underlying magnetic condition that gives rise to the free-energy limit and the accompanying main sequence of explosive active regions. Using a suitable free-energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free-energy limit, the ratio of magnetic-shear free energy to the non-free magnetic energy the potential field would have is of the order of one in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free-energy limit. Evidently, most active regions in which this core-field energy ratio is much less than one cannot be triggered to explode; as this ratio approaches one, most active regions become capable of exploding; and when this ratio is one, most active regions are compelled to explode.

  11. THE LIMIT OF MAGNETIC-SHEAR ENERGY IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Moore, Ronald L.; Falconer, David A.; Sterling, Alphonse C.

    2012-05-01

    It has been found previously, by measuring from active-region magnetograms a proxy of the free energy in the active region's magnetic field, (1) that there is a sharp upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region's magnetic flux content, and (2) that most active regions are near this limit when their field explodes in a coronal mass ejection/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy-limit line in (flux content, free-energy proxy) phase space. Here, we present evidence that specifies the underlying magnetic condition that gives rise to the free-energy limit and the accompanying main sequence of explosive active regions. Using a suitable free-energy proxy measured from vector magnetograms of 44 active regions, we find evidence that (1) in active regions at and near their free-energy limit, the ratio of magnetic-shear free energy to the non-free magnetic energy the potential field would have is of the order of one in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free-energy limit. Evidently, most active regions in which this core-field energy ratio is much less than one cannot be triggered to explode; as this ratio approaches one, most active regions become capable of exploding; and when this ratio is one, most active regions are compelled to explode.

  12. Rapid Conversion of Traditional Introductory Physics Sequences to an Activity-Based Format

    ERIC Educational Resources Information Center

    Yoder, Garett; Cook, Jerry

    2014-01-01

    The Department of Physics at EKU [Eastern Kentucky University] with support from the National Science Foundations Course Curriculum and Laboratory Improvement Program has successfully converted our entire introductory physics sequence, both algebra-based and calculus-based courses, to an activity-based format where laboratory activities,…

  13. Analysis of body calcium (regional changes in body calcium by in vivo neutron activation analysis)

    NASA Technical Reports Server (NTRS)

    Suki, W.; Johnson, P. C.; Leblanc, A.; Evans, H. J.

    1981-01-01

    The effect of space flight on urine and fecal calcium loss was documented during the three long-term Skylab flights. Neutron activation analysis was used to determine regional calcium loss. Various designs for regional analysis were investigated.

  14. Effect of viscous macromolecules on peritoneal plasminogen activator activity: a potential mechanism for their ability to reduce postoperative adhesion formation.

    PubMed

    Mayer, M; Yedgar, S; Hurwitz, A; Palti, Z; Finzi, Z; Milwidsky, A

    1988-10-01

    Activity of peritoneal plasminogen activator and its regulation by dextran and other macromolecules that clinically suppress postoperative adhesions was studied. Plasminogen activator activity was assayed by a two-stage globinolytic assay that monitors formation of plasmin, as well as by cleavage of a chromogenic peptide substrate (S-2444) in the presence of aprotinin (Trasylol). Plasminogen activator activity was located on the outer surface of human peritoneum. Incubation of peritoneal tissue with buffer in vitro (conditioning) prompted release of plasminogen activator into the conditioning medium. The released plasminogen activator formed a single band on sodium dodecyl sulfate-gel electrophoresis at an apparent molecular weight of 174,000 and was markedly suppressed by antiserum raised against human melanoma tissue-type plasminogen activator. Nonspecific proteolytic activity did not accumulate in the medium during conditioning. The presence of dextran 80 during conditioning of peritoneum reversibly suppressed tissue-bound plasminogen activator activity and reduced plasminogen activator activity in the spent medium. A similar inhibition of peritoneal plasminogen activator was induced by dextran 500, methyl cellulose, and polyvinylpyrrolidone. Dextran, when added to the medium after conditioning, had no direct inhibitory effect on plasminogen activator activity. Dextran did not induce peritoneal production of inhibitor(s) of trypsin, chymotrypsin, or urokinase. On the basis of these findings, two possible mechanisms for the effect of viscous polymers in the reduction of adhesion formation are proposed. These mechanisms consider the importance of peritoneal tissue-type plasminogen activator for removal of fibrin clots and suggest that polymer coating either prevents the shedding of plasminogen activator into the abdominal cavity or reduces the access of fibrin clots to the serosal surfaces. PMID:2459968

  15. An active carbon catalyst prevents coke formation from asphaltenes during the hydrocracking of vacuum residue

    SciTech Connect

    Fukuyama, H.; Terai, S.

    2007-07-01

    Active carbons were prepared by the steam activation of a brown coal char. The active carbon with mesopores showed greater adsorption selectivity for asphaltenes. The active carbon was effective at suppressing coke formation, even with the high hydrocracking conversion of vacuum residue. The analysis of the change in the composition of saturates, aromatics, resins, and asphaltenes in the cracked residue with conversion demonstrated the ability of active carbon to restrict the transformation of asphaltenes to coke. The active carbon that was richer in mesopores was presumably more effective at providing adsorption sites for the hydrocarbon free-radicals generated initially during thermal cracking to prevent them from coupling and polycondensing.

  16. Enhancement of CO(3-2)/CO(1-0) ratios and star formation efficiencies in supergiant H II regions

    SciTech Connect

    Miura, Rie E.; Espada, Daniel; Komugi, Shinya; Nakanishi, Kouichiro; Sawada, Tsuyoshi; Fujii, Kosuke; Kawabe, Ryohei; Kohno, Kotaro; Tosaki, Tomoka; Hirota, Akihiko; Minamidani, Tetsuhiro; Okumura, Sachiko K.; Kuno, Nario; Muraoka, Kazuyuki; Onodera, Sachiko; Kaneko, Hiroyuki

    2014-06-20

    We present evidence that super giant H II regions (GHRs) and other disk regions of the nearby spiral galaxy, M33, occupy distinct locations in the correlation between molecular gas, Σ{sub H{sub 2}}, and the star formation rate surface density, Σ{sub SFR}. This result is based on wide-field and high-sensitivity CO(3-2) observations at 100 pc resolution. Star formation efficiencies (SFEs), defined as Σ{sub SFR}/Σ{sub H{sub 2}}, in GHRs are found to be ∼1 dex higher than in other disk regions. The CO(3-2)/CO(1-0) integrated intensity ratio, R {sub 3-2/1-0}, is also higher than the average over the disk. Such high SFEs and R {sub 3-2/1-0} can reach the values found in starburst galaxies, which suggests that GHRs may be the elements building up a larger-scale starburst region. Three possible contributions to high SFEs in GHRs are investigated: (1) the I {sub CO}-N(H{sub 2}) conversion factor, (2) the dense gas fraction traced by R {sub 3-2/1-0}, and (3) the initial mass function (IMF). We conclude that these starburst-like properties in GHRs can be interpreted by a combination of both a top-heavy IMF and a high dense gas fraction, but not by changes in the I {sub CO}-N(H{sub 2}) conversion factor.

  17. Eruption of the magnetic flux rope in a fast decayed active region

    NASA Astrophysics Data System (ADS)

    Yang, Shangbin

    2012-07-01

    An isolated and fast decayed active region was observed when passing through solar disk. There is only one CME related with it that give us a good opportunity to investigate the whole process of the CME. Filament in this active region rises up rapidly and then hesitates and disintegrates into flare loops. The rising filament from EIT images separates into two parts just before eruption. It is interesting that this filament rises up with positive kink which is opposite to the negative helicity according to the inverse S-shaped X-ray sigmoid and accumulated magnetic helicity. A new filament reforms several hours later after CME and the axis of this new one rotates clockwise about 22° comparing with that of the former one. We also observed a bright transient J-shaped X-ray sigmoid immediately appears after filament eruption. It quickly develops into a soft X-ray cusp and rises up firstly then drops down. We propose that field lines underneath bald-patch sparatrix surface (BPSS) where for the formation of a magnetic tangential discontinuity are locally rooted to the photosphere near the bald-patch (BP) inversion line. Field lines above the surface are detached from the photosphere to form this CME and partially open the field which make the filament loses equilibrium to rise quickly and then be drawn back by the tension force of magnetic field after eruption to form a new filament. Two magnetic cancelation regions have been observed clearly just before filament eruption that reflect the existence of BPs. On the other hand, the values of total magnetic helicity to the corona taken by emergence and differential rotation normalized by the square total magnetic flux implies the possibility of upper bound on the total magnetic helicity that a force-free field can contain.

  18. Sulfate Aerosol Formation and Oxidation Pathways on Haze Event over East Asia Region Focusing on Korea.

    NASA Astrophysics Data System (ADS)

    Choi, D.; Koo, Y. S.

    2014-12-01

    The aerosol transports from China largely contribute to high PM (Particulate Matter) concentration in Korea. Especially, secondary inorganic aerosol (SIA) such as nitrate, sulfate and ammonium are largely transported from China to Korea during haze event. The measured PM2.5 (Particle Matter with aerodynamic diameters less than 2.5㎛) concentrations at the supersite monitoring stations in Korea are normally over 100 ug/m3 and SIAs are major chemical species with more than 70% of PM2.5 during the event. According to our air quality forecast model, sulfate concentrations are largely under-predicted in winter and slightly over-predicted in summer. Those discrepancies between model predicted and observed sulfate concentrations are mainly due to uncertainties of precursor emissions of NOx, SO2, and VOCs (Volatile Organic Compounds) and chemical mechanism of the sulfate formation in the chemical forecast model of CMAQ (Community Multiscale Air Quality Model). Formation of sulfate is chemically linked to primary emissions of sulfur dioxide and to be abundancy of atmospheric oxidants such as hydroxyl radical, hydrogen peroxide, ozone, methyl hydroperoxide, and peroxyacetic acid. All of these oxidant species are formed via photochemical reactions with NOx and VOCs. The aim of this work is to investigate the dependency of sulfate formation on oxidant levels in winter and summer during episode event using CMAQ and its sulfate tracking probing tool. The sensitivity of the precursor emissions of SO2, NOx, VOCs and NH3 was also tested to understand the pathways of the sulfate formation. The results show that long range transport from China is a major factor to determine sulfate level in Korea during haze events and dominant mechanisms in the sulfate formation are the gas-phase OH and aqueous phase H2O2 reactions. NOx-SO2-VOCs chemical regimes for the sulfate formation is the VOCs limited regimes in Korea. The further details of the sensitivity run of the precursor emissions and

  19. Kinetics of acrylamide formation/elimination reactions as affected by water activity.

    PubMed

    De Vleeschouwer, Kristel; Van der Plancken, Iesel; Van Loey, Ann; Hendrickx, Marc E

    2007-01-01

    The influence of water activity on the kinetics of acrylamide formation and elimination reaction was investigated using low-moisture equimolar asparagine-glucose model systems, which were heated at temperatures between 120 and 200 degrees C for variable heating times. To determine the water content corresponding to the water activities tested, a sorption moisture isotherm was constructed experimentally. The acrylamide concentrations measured at different water activities could be modeled on the basis of a reaction scheme including not only acrylamide formation and elimination reactions but also an alternative Maillard reaction between both reactants. The corresponding rate constants and activation energies were estimated using nonlinear regression analysis. Whereas the rate constant for acrylamide formation varied only slightly with the initial water activity of the model system, the elimination rate constant showed a clear minimum around a water activity of 0.82. The opposite trend, namely, a maximum at a water activity of 0.82, was found for the Maillard reaction rate constant as a function of water activity, which confirms data from literature. The activation energies for the different reactions changed in a comparable way as the corresponding rate constant with water activity. PMID:17503764

  20. The Formation of Glycine in Hot Cores: New Gas-grain Chemical Simulations of Star-forming Regions

    NASA Astrophysics Data System (ADS)

    Garrod, Robin

    2012-07-01

    Organic molecules of increasing complexity have been detected in the warm envelopes of star-forming cores, commonly referred to as "hot cores". Spectroscopic searches at mm/sub-mm wavelengths have uncovered both amines and carboxylic acids in these regions, as well as a range of other compounds including alcohols, ethers, esters, and nitriles. However, the simplest amino acid, glycine (NH2CH2COOH), has not yet been reliably detected in the ISM. There has been much interest in this molecule, due to its importance to the formation of proteins, and to life, while the positive identification of interstellar molecules of similar or greater complexity suggests that its existence in star-forming regions is plausible. I will present the results of recent models of hot-core chemistry that simulate the formation of both simple and complex molecules on the surfaces or within the ice mantles of dust grains. I will also present results from the first gas-grain astrochemical model to approach the question of amino-acid formation in hot cores. The formation of glycine in moderate abundance is found to be as efficient as that for similarly complex species, while its sublimation from the grains occurs at somewhat higher temperatures. However, simulated emission spectra based on the model results show that the degree of compactness of high-abundance regions, and the density and temperature profiles of the cores may be the key variables affecting the future detection of glycine, as well as other amino acids, and may explain its non-detection to date.

  1. Leveraging Regional Exploration to Develop Geologic Framework for CO2 Storage in Deep Formations in Midwestern United States

    SciTech Connect

    Neeraj Gupta

    2009-09-30

    Obtaining subsurface data for developing a regional framework for geologic storage of CO{sub 2} can require drilling and characterization in a large number of deep wells, especially in areas with limited pre-existing data. One approach for achieving this objective, without the prohibitive costs of drilling costly standalone test wells, is to collaborate with the oil and gas drilling efforts in a piggyback approach that can provide substantial cost savings and help fill data gaps in areas that may not otherwise get characterized. This leveraging with oil/gas drilling also mitigates some of the risk involved in standalone wells. This collaborative approach has been used for characterizing in a number of locations in the midwestern USA between 2005 and 2009 with funding from U.S. Department of Energy's National Energy Technology Laboratory (DOE award: DE-FC26-05NT42434) and in-kind contributions from a number of oil and gas operators. The results are presented in this final technical report. In addition to data collected under current award, selected data from related projects such as the Midwestern Regional Carbon Sequestration Partnership (MRCSP), the Ohio River Valley CO{sub 2} storage project at and near the Mountaineer Plant, and the drilling of the Ohio Stratigraphic well in Eastern Ohio are discussed and used in the report. Data from this effort are also being incorporated into the MRCSP geologic mapping. The project activities were organized into tracking and evaluation of characterization opportunities; participation in the incremental drilling, basic and advanced logging in selected wells; and data analysis and reporting. Although a large number of opportunities were identified and evaluated, only a small subset was carried into the field stage. Typical selection factors included reaching an acceptable agreement with the operator, drilling and logging risks, and extent of pre-existing data near the candidate wells. The region of study is primarily along the

  2. Antibody Constant Region Peptides Can Display Immunomodulatory Activity through Activation of the Dectin-1 Signalling Pathway

    PubMed Central

    Cenci, Elio; Monari, Claudia; Magliani, Walter; Ciociola, Tecla; Conti, Stefania; Gatti, Rita; Bistoni, Francesco; Polonelli, Luciano; Vecchiarelli, Anna

    2012-01-01

    We previously reported that a synthetic peptide with sequence identical to a CDR of a mouse monoclonal antibody specific for difucosyl human blood group A exerted an immunomodulatory activity on murine macrophages. It was therapeutic against systemic candidiasis without possessing direct candidacidal properties. Here we demonstrate that a selected peptide, N10K, putatively deriving from the enzymatic cleavage of the constant region (Fc) of human IgG1, is able to induce IL-6 secretion and pIkB-α activation. More importantly, it causes an up-regulation of Dectin-1 expression. This leads to an increased activation of β-glucan-induced pSyk, CARD9 and pIkB-α, and an increase in the production of pro-inflammatory cytokines such as IL-6, IL-12, IL-1β and TNF-α. The increased activation of this pathway coincides with an augmented phagocytosis of non opsonized Candida albicans cells by monocytes. The findings suggest that some Fc-peptides, potentially deriving from the proteolysis of immunoglobulins, may cause an unexpected immunoregulation in a way reminiscent of innate immunity molecules. PMID:22952831

  3. Effect of acicular ferrite formation on grain refinement in the coarse-grained region of heat-affected zone

    SciTech Connect

    Wan, X.L.; Wei, R.; Wu, K.M.

    2010-07-15

    The microstructure of acicular ferrite and its formation for the grain refinement of coarse-grained region of heat-affected zone of high strength low-alloy bainite steels were studied using three-dimensional reconstruction technique. Crystallographic grain size was analyzed by means of electron backscatter diffraction. It was revealed that the microstructure in the coarse-grained region of the heat-affected zone consisted of predominantly bainite packets and a small proportion of acicular ferrite. Acicular ferrite was of lath or plate-like rather than needle or rod-like morphology. Tempering of the coarse-grained region of heat-affected zone showed that the acicular ferrite was more stable than the bainite, indicating that the acicular ferrite was formed prior to bainite. The acicular ferrite laths or plates divided the prior austenite grains into smaller and separate regions, and confining the bainite transformed at lower temperatures in the smaller regions and hence leading to the grain refinement in the coarse-grained region of the heat-affected zone.

  4. Active diagnostic of the eigenmode formation in the ion-cyclotron frequency range in the GAMMA10 central cell

    SciTech Connect

    Yamaguchi, Y.; Ichimura, M.; Higaki, H.; Kakimoto, S.; Nakagome, K.; Nemoto, K.; Katano, M.; Nakajima, H.; Fukuyama, A.; Cho, T.

    2006-10-15

    A wide-band radio-frequency (rf) probe system was constructed for the active diagnostic of the eigenmode formations in the ion-cyclotron range of frequency (ICRF) in GAMMA10. An antenna was installed in the peripheral region in the central cell. The low power rf pulse with the frequency sweep is applied to the antenna. The waves excited in the plasma are detected with a magnetic probe. The excitation of eigenmodes is described by using the antenna-plasma-probe transfer function. The transfer function can be obtained from the antenna current signal and the magnetic probe signal. When the real and imaginary parts of the transfer function are plotted on the complex plane, the resultant curves are approximately circular, indicating an eigenmode formation. The results of the measurement show that several eigenmodes can be excited in the present experimental condition.

  5. Earthquake Model of the Middle East (EMME) Project: Active Fault Database for the Middle East Region

    NASA Astrophysics Data System (ADS)

    Gülen, L.; Wp2 Team

    2010-12-01

    The Earthquake Model of the Middle East (EMME) Project is a regional project of the umbrella GEM (Global Earthquake Model) project (http://www.emme-gem.org/). EMME project region includes Turkey, Georgia, Armenia, Azerbaijan, Syria, Lebanon, Jordan, Iran, Pakistan, and Afghanistan. Both EMME and SHARE projects overlap and Turkey becomes a bridge connecting the two projects. The Middle East region is tectonically and seismically very active part of the Alpine-Himalayan orogenic belt. Many major earthquakes have occurred in this region over the years causing casualties in the millions. The EMME project will use PSHA approach and the existing source models will be revised or modified by the incorporation of newly acquired data. More importantly the most distinguishing aspect of the EMME project from the previous ones will be its dynamic character. This very important characteristic is accomplished by the design of a flexible and scalable database that will permit continuous update, refinement, and analysis. A digital active fault map of the Middle East region is under construction in ArcGIS format. We are developing a database of fault parameters for active faults that are capable of generating earthquakes above a threshold magnitude of Mw≥5.5. Similar to the WGCEP-2007 and UCERF-2 projects, the EMME project database includes information on the geometry and rates of movement of faults in a “Fault Section Database”. The “Fault Section” concept has a physical significance, in that if one or more fault parameters change, a new fault section is defined along a fault zone. So far over 3,000 Fault Sections have been defined and parameterized for the Middle East region. A separate “Paleo-Sites Database” includes information on the timing and amounts of fault displacement for major fault zones. A digital reference library that includes the pdf files of the relevant papers, reports is also being prepared. Another task of the WP-2 of the EMME project is to prepare

  6. In Vitro Evaluation of Bacteriocins Activity Against Listeria monocytogenes Biofilm Formation.

    PubMed

    Camargo, Anderson Carlos; de Paula, Otávio Almeida Lino; Todorov, Svetoslav Dimitrov; Nero, Luís Augusto

    2016-03-01

    The present study aimed to assess the activity of cell-free supernatant (CFS) containing bacteriocins on the formation and maintenance of biofilms developed by Listeria monocytogenes, and the associated effect of bacteriocins and ethylene-diamine-tetra-acetic acid (EDTA) on the formed biofilm. CFS from 9 lactic acid bacteria (LAB) strains was tested for inhibitory activity against 85 L. monocytogenes isolates and 21 LAB strains. Then, 12 L. monocytogenes strains were selected based on genetic profiles and sensitivity to CFS and were subjected to an in vitro assay to assess biofilm formation in microtiter plates, considering different culture media and incubation conditions. Based on these results, 6 L. monocytogenes strains were subjected to the same in vitro procedure to assess biofilm formation, being co-inoculated with CFS. In addition, these strains were subjected to the same in vitro procedure, modified by adding the CFS after biofilm formation. Relevant decrease in biofilm formation was observed in the first experiment, but CFS added after biofilm formation did not eliminate them. CFS from Lactobacillus curvatus ET31 were selected due to its anti-biofilm activity, being associated to EDTA at different concentrations and tested for biofilm control of three strains of L. monocytogenes, using the same in vitro procedure described previously. Concentrated bacteriocin presented poor performance in eliminating formed biofilms, and EDTA concentration presented no evident interference on biofilm elimination. Twelve selected L. monocytogenes strains were positive for investigated virulence makers and negative for luxS gene, recognized as being involved in biofilm formation. Selected L. monocytogenes strains were able to produce biofilms under different conditions. CFSs have the potential to prevent biofilm formation, but they were not able to destroy already formed biofilms. Nevertheless, low concentrations of CFS combined with EDTA caused a relevant reduction in

  7. A Tale of Two Super-Active Active Regions: On the Magnetic Origin of Flares and CMEs

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Dhakal, Suman; Chintzoglou, Georgios

    2015-04-01

    From a comparative study of two super-active active regions, we find that the magnetic origin of CMEs is different from that of flares. NOAA AR 12192 is one of the largest active regions in the recorded history with a sunspot number of 66 and area of 2410 millonths. During its passage through the front disk from Oct. 14-30, 2014, the active region produced 93 C-class, 30 M-class and 6 X-class flares. However, all six X-class flares are confined; in other words, none of them are associated with CMEs; most other flares are also confined. This behavior of low-CME production rate for such as a super active region is rather peculiar, given the usual hand-on-hand occurrence of CMEs with flares. To further strengthen this point, we also investigated the super-active NOAA AR 11429, which had a sunspot number of 28 and area of 1270 millionths. During its passage from March 02-17, 2012, the active region produced 47 C-class, 15 M-class and 3 X-class flares. In this active region, all three X-class flares were accompanied by CMEs, and the same for most M-class flares. Given the relative sizes of the two active regions, the production rates of flares are comparable. But the CME production rates are not. Through a careful study of the magnetic configuration on the surface and the extrapolated magnetic field in the corona, we argue that the generation of flares largely depends on the amount of free energy in the active region. On the other hand, the generation of CMEs largely depends on the complexity, such as measured by magnetic helicity. In particular, we argue that the high CME generation rate in the smaller active region is caused by the emergence and continuous generation of magnetic flux ropes in the region.

  8. Regional impacts of oil and gas development on ozone formation in the western United States.

    PubMed

    Rodriguez, Marco A; Barna, Michael G; Moore, Tom

    2009-09-01

    The Intermountain West is currently experiencing increased growth in oil and gas production, which has the potential to affect the visibility and air quality of various Class I areas in the region. The following work presents an analysis of these impacts using the Comprehensive Air Quality Model with extensions (CAMx). CAMx is a state-of-the-science, "one-atmosphere" Eulerian photochemical dispersion model that has been widely used in the assessment of gaseous and particulate air pollution (ozone, fine [PM2.5], and coarse [PM10] particulate matter). Meteorology and emissions inventories developed by the Western Regional Air Partnership Regional Modeling Center for regional haze analysis and planning are used to establish an ozone baseline simulation for the year 2002. The predicted range of values for ozone in the national parks and other Class I areas in the western United States is then evaluated with available observations from the Clean Air Status and Trends Network (CASTNET). This evaluation demonstrates the model's suitability for subsequent planning, sensitivity, and emissions control strategy modeling. Once the ozone baseline simulation has been established, an analysis of the model results is performed to investigate the regional impacts of oil and gas development on the ozone concentrations that affect the air quality of Class I areas. Results indicate that the maximum 8-hr ozone enhancement from oil and gas (9.6 parts per billion [ppb]) could affect southwestern Colorado and northwestern New Mexico. Class I areas in this region that are likely to be impacted by increased ozone include Mesa Verde National Park and Weminuche Wilderness Area in Colorado and San Pedro Parks Wilderness Area, Bandelier Wilderness Area, Pecos Wilderness Area, and Wheeler Peak Wilderness Area in New Mexico.

  9. Regional impacts of oil and gas development on ozone formation in the western United States.

    PubMed

    Rodriguez, Marco A; Barna, Michael G; Moore, Tom

    2009-09-01

    The Intermountain West is currently experiencing increased growth in oil and gas production, which has the potential to affect the visibility and air quality of various Class I areas in the region. The following work presents an analysis of these impacts using the Comprehensive Air Quality Model with extensions (CAMx). CAMx is a state-of-the-science, "one-atmosphere" Eulerian photochemical dispersion model that has been widely used in the assessment of gaseous and particulate air pollution (ozone, fine [PM2.5], and coarse [PM10] particulate matter). Meteorology and emissions inventories developed by the Western Regional Air Partnership Regional Modeling Center for regional haze analysis and planning are used to establish an ozone baseline simulation for the year 2002. The predicted range of values for ozone in the national parks and other Class I areas in the western United States is then evaluated with available observations from the Clean Air Status and Trends Network (CASTNET). This evaluation demonstrates the model's suitability for subsequent planning, sensitivity, and emissions control strategy modeling. Once the ozone baseline simulation has been established, an analysis of the model results is performed to investigate the regional impacts of oil and gas development on the ozone concentrations that affect the air quality of Class I areas. Results indicate that the maximum 8-hr ozone enhancement from oil and gas (9.6 parts per billion [ppb]) could affect southwestern Colorado and northwestern New Mexico. Class I areas in this region that are likely to be impacted by increased ozone include Mesa Verde National Park and Weminuche Wilderness Area in Colorado and San Pedro Parks Wilderness Area, Bandelier Wilderness Area, Pecos Wilderness Area, and Wheeler Peak Wilderness Area in New Mexico. PMID:19785277

  10. The membrane-active amphibian peptide caerin 1.8 inhibits fibril formation of amyloid β1-42.

    PubMed

    Liu, Yanqin; Wang, Tianfang; Calabrese, Antonio N; Carver, John A; Cummins, Scott F; Bowie, John H

    2015-11-01

    The amphibian host-defense peptide caerin 1.8 [(1)GLFKVLGSV(10)AKHLLPHVVP(20)VIAEKL(NH2)] inhibits fibril formation of amyloid β 1-42 [(1)DAEFRHDSG(10)YEVHHQKLVF(20)FAEDVGSNKG(30)AIIGLMVGGV(40)VIA] [Aβ42] (the major precursor of the extracellular fibrillar deposits of Alzheimer's disease). Some truncated forms of caerin 1.8 also inhibit fibril formation of Aβ42. For example, caerin 1.8 (1-13) [(1)GLFKVLGSV(10)AKHL(NH2) and caerin 1.8 (22-25) [KVLGSV(10)AKHLLPHVVP(20)VIAEKL(NH2)] show 85% and 75% respectively of the inhibition activity of the parent caerin 1.8. The synthetic peptide KLVFFKKKKKK is a known inhibitor of Aβ42 fibril formation, and was used as a standard in this study. Caerin 1.8 is the more effective fibril inhibitor. IC50 values (± 15%) are caerin 1.8 (75 μM) and KLVFFKKKKKK (370 μM). MALDI mass spectrometry shows the presence of a small peak corresponding to a protonated 1:1 adduct [caerin 1.8/Aβ42]H(+). Molecular dynamics simulation suggests that both hydrogen bonding and hydrophobic interactions between Aβ42 and caerin 1.8 facilitate the formation of a 1:1 complex in water. Fibril formation from Aβ42 has been proposed to be based around the (16)KLVF(20)F region of Aβ42; this region in the 1:1 complex is partially blocked from attachment of a further molecule of Aβ42.

  11. Modeling volcanic deformation in a regional stress field: Implications for the formation of graben structures on Alba Patera, Mars

    NASA Astrophysics Data System (ADS)

    Cailleau, Beatrice; Walter, Thomas R.; Janle, Peter; Hauber, Ernst

    2003-12-01

    Abundant grabens transect the volcano Alba Patera. Their complex geometry and formation mechanisms are still poorly understood. Tectonic processes and magmatic intrusions are responsible for these long surface features. Cross-cutting relationships of the grabens show radial fractures that were formed during early stages and were progressively overprinted by concentric fractures on the mid and upper flanks of the volcano. Two modeling methods are used to understand the formation of the observed structures and to evaluate their implications for hidden subvolcanic processes. Surface deformation and fault arrangements predicted in finite element models are compared to the graben systems observed in Viking images. The orientation and position of the concentric grabens are found to be best reproduced by local crustal subsidence, superimposed on a regional NW-SE oriented extension with decreasing magnitude from south to north. In analogue sandbox models we also simulate surface structures of arrangements that almost perfectly mimic the observed lineaments on Alba Patera. Formation of the grabens spans a period on the order of a billion years, suggesting long-term geodynamic processes to be responsible for the subsidence of the central Alba Patera area. The progressive change toward higher concentricity is likely resultant from an increase in density in the crust by accumulation of intrusive material and cooling, thus causing subsidence of the region above this volcanic root.

  12. Cortisol's effects on hippocampal activation in depressed patients are related to alterations in memory formation.

    PubMed

    Abercrombie, Heather C; Jahn, Allison L; Davidson, Richard J; Kern, Simone; Kirschbaum, Clemens; Halverson, Jerry

    2011-01-01

    Many investigators have hypothesized that brain response to cortisol is altered in depression. However, neural activation in response to exogenously manipulated cortisol elevations has not yet been directly examined in depressed humans. Animal research shows that glucocorticoids have robust effects on hippocampal function, and can either enhance or suppress neuroplastic events in the hippocampus depending on a number of factors. We hypothesized that depressed individuals would show 1) altered hippocampal response to exogenous administration of cortisol, and 2) altered effects of cortisol on learning. In a repeated-measures design, 19 unmedicated depressed and 41 healthy individuals completed two fMRI scans. Fifteen mg oral hydrocortisone (i.e., cortisol) or placebo (order randomized and double-blind) was administered 1 h prior to encoding of emotional and neutral words during fMRI scans. Data analysis examined the effects of cortisol administration on 1) brain activation during encoding, and 2) subsequent free recall for words. Cortisol affected subsequent recall performance in depressed but not healthy individuals. We found alterations in hippocampal response to cortisol in depressed women, but not in depressed men (who showed altered response to cortisol in other regions, including subgenual prefrontal cortex). In both depressed men and women, cortisol's effects on hippocampal function were positively correlated with its effects on recall performance assessed days later. Our data provide evidence that in depressed compared to healthy women, cortisol's effects on hippocampal function are altered. Our data also show that in both depressed men and women, cortisol's effects on emotional memory formation and hippocampal function are related.

  13. Staphylokinase Control of Staphylococcus aureus Biofilm Formation and Detachment Through Host Plasminogen Activation.

    PubMed

    Kwiecinski, Jakub; Peetermans, Marijke; Liesenborghs, Laurens; Na, Manli; Björnsdottir, Halla; Zhu, Xuefeng; Jacobsson, Gunnar; Johansson, Bengt R; Geoghegan, Joan A; Foster, Timothy J; Josefsson, Elisabet; Bylund, Johan; Verhamme, Peter; Jin, Tao

    2016-01-01

    Staphylococcus aureus biofilms, a leading cause of persistent infections, are highly resistant to immune defenses and antimicrobial therapies. In the present study, we investigated the contribution of fibrin and staphylokinase (Sak) to biofilm formation. In both clinical S. aureus isolates and laboratory strains, high Sak-producing strains formed less biofilm than strains that lacked Sak, suggesting that Sak prevents biofilm formation. In addition, Sak induced detachment of mature biofilms. This effect depended on plasminogen activation by Sak. Host-derived fibrin, the main substrate cleaved by Sak-activated plasminogen, was a major component of biofilm matrix, and dissolution of this fibrin scaffold greatly increased susceptibility of biofilms to antibiotics and neutrophil phagocytosis. Sak also attenuated biofilm-associated catheter infections in mouse models. In conclusion, our results reveal a novel role for Sak-induced plasminogen activation that prevents S. aureus biofilm formation and induces detachment of existing biofilms through proteolytic cleavage of biofilm matrix components.

  14. Seismic activity monitoring in the Izvorul Muntelui dam region

    NASA Astrophysics Data System (ADS)

    Borleanu, Felix; Otilia Placinta, Anca; Popa, Mihaela; Adelin Moldovan, Iren; Popescu, Emilia

    2016-04-01

    Earthquakes occurrences near the artificial water reservoirs are caused by stress variation due to the weight of water, weakness of fractures or faults and increasing of pore pressure in crustal rocks. In the present study we aim to investigate how Izvorul Muntelui dam, located in the Eastern Carpathians influences local seismicity. For this purpose we selected from the seismic bulletins computed within National Data Center of National Institute for Earth Physics, Romania, crustal events occurred between 984 and 2015 in a range of 0.3 deg around the artificial lake. Subsequently to improve the seismic monitoring of the region we applied a cross-correlation detector on the continuous recordings of Bicaz (BIZ) seismic stations. Besides the tectonic events we detected sources within this region that periodically generate artificial evens. We couldn't emphasize the existence of a direct correlation between the water level variations and natural seismicity of the investigated area.

  15. Automatic Tracking of Active Regions and Detection of Solar Flares in Solar EUV Images

    NASA Astrophysics Data System (ADS)

    Caballero, C.; Aranda, M. C.

    2014-05-01

    Solar catalogs are frequently handmade by experts using a manual approach or semi-automated approach. The appearance of new tools is very useful because the work is automated. Nowadays it is impossible to produce solar catalogs using these methods, because of the emergence of new spacecraft that provide a huge amount of information. In this article an automated system for detecting and tracking active regions and solar flares throughout their evolution using the Extreme UV Imaging Telescope (EIT) on the Solar and Heliospheric Observatory (SOHO) spacecraft is presented. The system is quite complex and consists of different phases: i) acquisition and preprocessing; ii) segmentation of regions of interest; iii) clustering of these regions to form candidate active regions which can become active regions; iv) tracking of active regions; v) detection of solar flares. This article describes all phases, but focuses on the phases of tracking and detection of active regions and solar flares. The system relies on consecutive solar images using a rotation law to track the active</