Sample records for quasi-periodic pulsatory non-thermal

  1. Pulsatory Patterns in Active Fluids

    NASA Astrophysics Data System (ADS)

    Kumar, K. Vijay; Bois, Justin S.; Jülicher, Frank; Grill, Stephan W.

    2014-05-01

    We show that pulsatory patterns arise in thin active films in which two chemical species regulate active stress. The regulating species diffuse within the film and are advected by self-generated flows resulting from active stress gradients. Spontaneous pulsatory patterns emerge when the following conditions are met: (i) the fast-diffusing species up-regulates and the slow-diffusing species down-regulates active stress, or (ii) the active stress up-regulator turns over faster compared to the active stress down-regulator. Our study, motivated by pulsatory patterns in the actomyosin cortex in cells and tissues, provides a simple generic mechanism for oscillatory patterns in active fluids.

  2. Quasi-Periodic Pulsations in Solar Flares

    NASA Astrophysics Data System (ADS)

    Nakariakov, V. M.; Melnikov, V. F.

    2009-12-01

    Quasi-periodic pulsations (QPP) are a common feature of flaring energy releases in the solar atmosphere, observed in all bands, from radio to hard X-ray. In this review we concentrate on QPP with the periods longer than one second. Physical mechanisms responsible for the generation of long QPP split into two groups: “load/unload” mechanisms and MHD oscillations. Load/unload mechanisms are repetitive regimes of flaring energy releases by magnetic reconnection or by other means. MHD oscillations can affect all elements of the flaring emission generation: triggering of reconnection and modulation of its rate, acceleration and dynamics of non-thermal electrons, and physical conditions in the emitting plasmas. In the case of MHD oscillations, the periodicity of QPP is determined either by the presence of some resonances, e.g. standing modes of plasma structures, or by wave dispersion. Periods and other parameters of QPP are linked with properties of flaring plasmas and their morphology. Observational investigation of the QPP generation mechanisms based upon the use of spatial information, broadband spectral coverage and multi-periodicity is discussed.

  3. The quasi-periodic Hamiltonian Hopf bifurcation

    NASA Astrophysics Data System (ADS)

    Broer, Henk W.; Hanßmann, Heinz; Hoo, Jun

    2007-02-01

    We consider the quasi-periodic dynamics of non-integrable perturbations of a family of integrable Hamiltonian systems with normally 1 : -1 resonant invariant tori. In particular, we focus on the supercritical quasi-periodic Hamiltonian Hopf bifurcation and address the persistence problem of the singular foliation into invariant quasi-periodic tori near the bifurcation point. With the help of KAM theory, we show that the singular torus foliation survives a small perturbation and that the persisting tori in this foliation form Cantor families. A leading example is the Lagrange top near gyroscopic stabilization weakly coupled with a quasi-periodic oscillator.

  4. Imaging and Spectral Observations of Quasi-periodic Pulsations in a Solar Flare

    NASA Astrophysics Data System (ADS)

    Li, D.; Ning, Z. J.; Zhang, Q. M.

    2015-07-01

    We explore the quasi-periodic pulsations (QPPs) in a solar flare observed by Fermi Gamma-ray Burst Monitor, Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, and Interface Region Imaging Spectrograph (IRIS) on 2014 September 10. QPPs are identified as the regular and periodic peaks on the rapidly varying components, which are the light curves after removing the slowly varying components. The QPPs display only three peaks at the beginning on the hard X-ray emissions, but 10 peaks on the chromospheric and coronal line emissions, and more than seven peaks (each peak corresponds to a type III burst on the dynamic spectra) at the radio emissions. A uniform quasi-period of about 4 minutes is detected among them. AIA imaging observations exhibit that the 4-minute QPPs originate from the flare ribbon and tend to appear on the ribbon front. IRIS spectral observations show that each peak of the QPPs tends to a broad line width and a red Doppler velocity at C i, O iv, Si iv, and Fe xxi lines. Our findings indicate that the QPPs are produced by the non-thermal electrons that are accelerated by the induced quasi-periodic magnetic reconnections in this flare.

  5. Quasi-periodic oscillations in superfluid magnetars

    NASA Astrophysics Data System (ADS)

    Passamonti, A.; Lander, S. K.

    2014-02-01

    We study the time evolution of axisymmetric oscillations of superfluid magnetars with a poloidal magnetic field and an elastic crust, working in Newtonian gravity. Extending earlier models, we study the effects of composition gradients and entrainment on the magneto-elastic wave spectrum and on the potential identification of the observed quasi-periodic oscillations (QPOs). We use two-fluid polytropic equations of state to construct our stellar models, which mimic realistic composition gradient configurations. The basic features of the axial axisymmetric spectrum of normal fluid stars are reproduced by our results and in addition we find several magneto-elastic waves with a mixed character. In the core, these oscillations mimic the shear mode pattern of the crust as a result of the strong dynamical coupling between these two regions. Incorporating the most recent entrainment configurations in our models, we find that they have a double effect on the spectrum: the magnetic oscillations of the core have a frequency enhancement, while the mixed magneto-elastic waves originating in the crust are moved towards the frequencies of the single-fluid case. The distribution of lower frequency magneto-elastic oscillations for our models is qualitatively similar to the observed magnetar QPOs with ? < 155 Hz. In particular, some of these QPOs could represent mixed magneto-elastic oscillations with frequencies not greatly different from the crustal modes of an unmagnetized star. We find that many QPOs could even be accounted for using a model with a relatively weak polar field of Bp ? 3 × 1014 G, because of the superfluid enhancement of magnetic oscillations. Finally, we discuss the possible identification of 625 and 1837 Hz QPOs either with non-axisymmetric modes or with high-frequency axisymmetric QPOs excited by crustal mode overtones.

  6. Wannier functions for quasi-periodic finite-gap potentials

    E-print Network

    E. D. Belokolos; V. Z. Enolskii; M. Salerno

    2004-12-22

    In this paper we consider Wannier functions of quasi-periodic g-gap ($g\\geq 1$) potentials and investigate their main properties. In particular, we discuss the problem of averaging underlying the definition of Wannier functions for both periodic and quasi-periodic potentials and express Bloch functions and quasi-momenta in terms of hyperelliptic $\\sigma$ functions. Using this approach we derive a power series expansion of the Wannier function for quasi-periodic potentials valid at $|x|\\simeq 0$ and an asymptotic expansion valid at large distance. These functions are important for a number of applied problems.

  7. Formal averaging of quasi-periodic vector fields Ander Murua

    E-print Network

    Murua, Ander

    the quasi-periodic vector field d dt y = f (y, t) = kZ d ei(k·)t fk(y). there exists a formal quasi-periodic change of variables y = K(Y , t) that transforms the QP system into d dt Y = F1(Y ) + 2 F2(Y·)tfk(y), y(t) = y(0) + uT u(t) u Fu(y(0)), T is the set of rooted trees labelled by k Z d , and for each u

  8. Pressure-driven reconnection and quasi periodical oscillations in plasmas

    SciTech Connect

    Paccagnella, R., E-mail: roberto.paccagnella@igi.cnr.it [Consorzio RFX and Istituto Gas Ionizzati del Consiglio Nazionale delle Ricerche (CNR), Padova (Italy)

    2014-03-15

    This paper presents a model for an ohmically heated plasma in which a feedback exists between thermal conduction and transport, on one side, and the magneto-hydro-dynamical stability of the system, on the other side. In presence of a reconnection threshold for the magnetic field, a variety of periodical or quasi periodical oscillations for the physical quantities describing the system are evidenced. The model is employed to interpret the observed quasi periodical oscillations of electron temperature and perturbed magnetic field around the so called “Single Helical” state in the reversed field pinch, but its relevance for other periodical phenomena observed in magnetic confinement systems, especially in tokamaks, is suggested.

  9. Band nonparabolicity in quasi-periodic Fibonacci heterostructures

    NASA Astrophysics Data System (ADS)

    Palomino-Ovando, M.; Cocoletzi, Gregorio H.; Pérez-López, C.

    1996-02-01

    Nonparabolic dispersion relations of electrons in the reformulated Schrödinger equation and a 2 × 2 transfer matrix approach are applied to the study of quasi-periodic Fibonacci semiconductor heterostructures. Energy minibands and resonant tunneling amplitudes are investigated and compared with the parabolic case to show the importance of nonparabolic deviations in {AlxGa1-xAs}/{GaAs} superlattices.

  10. Quasi-periodic oscillations from Rossby Wave instability

    E-print Network

    Gourgoulhon, Eric

    QPO Rossby Quasi-periodic oscillations from Rossby Wave instability Frédéric VINCENT1 P. Varnière/16 Frédéric VINCENT Rossby wave QPO #12;QPO Rossby Credit R. Hynes Microquasars Stellar-mass BH + accretion disk + jet 2/16 Frédéric VINCENT Rossby wave QPO #12;QPO Rossby GC flare light curve (Hamaus+09

  11. Quasi-periodic oscillations from Rossby Wave instability

    E-print Network

    Gourgoulhon, Eric

    QPO Rossby Quasi-periodic oscillations from Rossby Wave instability Frédéric VINCENT1 P. Varnière/13 Frédéric VINCENT Rossby wave QPO #12;QPO Rossby Credit R. Hynes Microquasars Stellar-mass BH + accretion disk + jet 2/13 Frédéric VINCENT Rossby wave QPO #12;QPO Rossby GC flare light curve (Hamaus+09

  12. Quasi-periodic continuation along a continuous symmetry

    NASA Astrophysics Data System (ADS)

    Salomone, Matthew David

    Given a system of differential equations which admits a continuous group of symmetries and possesses a periodic solution, we show that under certain nondegeneracy assumptions there always exists a continuous family containing infinitely many periodic and quasi-periodic trajectories. This generalizes the continuation method of Poincaré to orbits which are not necessarily periodic. We apply these results in the setting of the Lagrangian N -body problem of homogeneous potential to characterize an infinite family of rotating nonplanar "hip-hop" orbits in the four-body problem of equal masses, and show how some other trajectories in the N -body theory may be extended to infinite families of periodic and quasi-periodic trajectories.

  13. Development of A Modified Quasi-periodic Undulator for HLS

    E-print Network

    Yang, Yufeng; chen, Wan; Jia, Qika; Sun, Shuchen; Li, Zhiqiang

    2013-01-01

    A modified quasi periodic undulator (QPU) is developed and to be installed at Hefei Light Source (HLS).Magnet dimensions optimization is applied. High harmonics contamination is eliminated from the fundamental emission effectively according to the field tests. The depression ratio of 3rd harmonic is increased by an order of magnitude than the current device with other harmonics well reduced simultaneously. The significance of the modification measure is verified practically. The design, measurement and commissioning of the device is described.

  14. QUASI-PERIODIC OSCILLATIONS IN LASCO CORONAL MASS EJECTION SPEEDS

    SciTech Connect

    Shanmugaraju, A. [Department of Physics, Arul Anandar College, Karumathur-625 514 (India); Moon, Y.-J. [School of Space Research, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Cho, K.-S.; Bong, S. C. [Korea Astronomy and Space Science Institute (KASI), Whaamdong, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Gopalswamy, N.; Akiyama, S.; Yashiro, S. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Umapathy, S. [School of Physics, Madurai Kamaraj University, Madurai (India); Vrsnak, B., E-mail: shanmugaraju_a@yahoo.co, E-mail: moonyj@khu.ac.k [Hvar Observatory, Faculty of Geodesy, Zagreb (Croatia)

    2010-01-01

    Quasi-periodic oscillations in the speed profile of coronal mass ejections (CMEs) in the radial distance range 2-30 solar radii are studied. We considered the height-time data of the 307 CMEs recorded by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005 January-March. In order to study the speed-distance profile of the CMEs, we have used only 116 events for which there are at least 10 height-time measurements made in the LASCO field of view. The instantaneous CME speed is estimated using a pair of height-time data points, providing the speed-distance profile. We found quasi-periodic patterns in at least 15 speed-distance profiles, where the speed amplitudes are larger than the speed errors. For these events we have determined the speed amplitude and period of oscillations. The periods of quasi-periodic oscillations are found in the range 48-240 minutes, tending to increase with height. The oscillations have similar properties as those reported by Krall et al., who interpreted them in terms of the flux-rope model. The nature of forces responsible for the motion of CMEs and their oscillations are discussed.

  15. Cassini and Galileo Observations of Quasi-periodic Radio Bursts

    NASA Astrophysics Data System (ADS)

    Hospodarsky, G. B.; Kurth, W. S.; Gurnett, D. A.; Kaiser, M. L.; Zarka, P.; Krupp, N.; Waite, J. H.

    Simultaneous measurements of many Jovian plasma and radio emissions were ob- tained by the Cassini and Galileo spacecraft during the Cassini flyby of Jupiter (clos- est approach was on December 30, 2000). Jovian type III radio emissions, also known as quasi-periodic (QP) emissions, were often detected by both spacecraft. This type of emission has been detected by Voyager, Ulysses, Galileo, and Cassini, with pe- riodicities ranging from about a minute to many tens of minutes (often around 40 minutes). Other quasi-periodic events have been detected in the energetic particle data of Ulysses, Galileo and Cassini and in the x-ray spectrum obtained by the Chandra spacecraft, usually with periodicities around 40 minutes. The multiple observations of similar quasi-periodic events suggests that there may be a common source for these phenomena. Many examples of simultaneous detection of the QP radio emissions were obtained by the Cassini and Galileo plasma wave and radio instruments. The charac- teristics of the QP emissions observed by each spacecraft are very similar, and when the difference in the travel time of a radio emission from Jupiter to each spacecraft is taken into account, the QP bursts are observed to occur simultaneously at each space- craft. These similar characteristics of the emissions, even when the two spacecraft are separated by many hours in local time and many degrees of system III longitude, sug- gest a broadly beamed 'strobe light' source for the emission, and not a narrow beam which rotates with the planet. The implications of these simultaneous observations will be discussed.

  16. Development of a Quasi-Periodic Undulator for the HLS

    E-print Network

    Yufeng Yang; Huihua Lu; Wan Chen; Qika Jia; Shuchen Sun; Zhiqiang Li

    2014-03-11

    China's first quasi-periodic undulator (QPU) has been developed for the Hefei Light Source (HLS). It uses a magnetic configuration with varied thicknesses of NdFeB blocks, based on the QPU of European Synchrotron Radiation Facility (ESRF). Depression of 3rd harmonic radiation is significantly improved over the ESRF QPU, as deduced from the measured magnetic fields. A method of configuring shims of different geometries and sizes, based on a symmetric principle to correct multi-pole field integrals, was demonstrated.

  17. Development of a quasi-periodic undulator for the HLS

    NASA Astrophysics Data System (ADS)

    Yang, Yu-Feng; Lu, Hui-Hua; Chen, Wan; Jia, Qi-Ka; Sun, Shu-Chen; Li, Zhi-Qiang

    2014-07-01

    China's first quasi-periodic undulator (QPU) has been developed for the Hefei Light Source (HLS). It uses a magnetic configuration with varied thicknesses of NdFeB blocks, which is based on the QPU of European Synchrotron Radiation Facility (ESRF). The depression of 3rd harmonic radiation is significantly improved over the ESRF QPU, as deduced from the measured magnetic fields. A method of configuring shims of different geometries and sizes, based on a symmetric principle to correct multi-pole field integrals, is demonstrated.

  18. Development of a Quasi-Periodic Undulator for the HLS

    E-print Network

    Yang, Yufeng; Chen, Wan; Jia, Qika; Sun, Shuchen; Li, Zhiqiang

    2014-01-01

    China's first quasi-periodic undulator (QPU) has been developed for the Hefei Light Source (HLS). It uses a magnetic configuration with varied thicknesses of NdFeB blocks, based on the QPU of European Synchrotron Radiation Facility (ESRF). Depression of 3rd harmonic radiation is significantly improved over the ESRF QPU, as deduced from the measured magnetic fields. A method of configuring shims of different geometries and sizes, based on a symmetric principle to correct multi-pole field integrals, was demonstrated.

  19. Quasi-periodic compressive waves in polar plumes

    NASA Technical Reports Server (NTRS)

    DeForest, C. E.; Gurman, J. B.

    1997-01-01

    The observation of polar plumes in the south polar coronal hole, carried out on 7 March 1996 by the Solar and Heliospheric Observatory (SOHO), are analyzed. These polar plumes are cool density structures that arise from morphologically unipolar magnetic footpoints. Data from the extreme ultraviolet imaging telescope show quasi-periodic perturbations in the brightness of the Fe IX and X line emissions at 171 A from polar plumes. The perturbations have periods of 10 to 15 min, and repeat for several cycles suggesting that they are compressive waves propagating through the plume at or near the Alfven speed. Possible explanations for the observed phenomenon are proposed.

  20. Analytic quasi-periodic Schrödinger operators and rational frequency approximants

    E-print Network

    S. Jitomirskaya; C. A. Marx

    2012-02-13

    Consider a quasi-periodic Schr\\"odinger operator $H_{\\alpha,\\theta}$ with analytic potential and irrational frequency $\\alpha$. Given any rational approximating $\\alpha$, let $S_+$ and $S_-$ denote the union, respectively, the intersection of the spectra taken over $\\theta$. We show that up to sets of zero Lebesgue measure, the absolutely continuous spectrum can be obtained asymptotically from $S_-$ of the periodic operators associated with the continued fraction expansion of $\\alpha$. This proves a conjecture of Y. Last in the analytic case. Similarly, from the asymptotics of $S_+$, one recovers the spectrum of $H_{\\alpha,\\theta}.$

  1. Quasi-periodic oscillations, charge and the gravitomagnetic theory

    E-print Network

    Jacob Biemond

    2009-03-20

    A new model for the explanation of the high frequency quasi-periodic oscillations (QPOs) in pulsars, black holes and white dwarfs is presented. Three circular tori are assumed to be present around the star: an inner torus with charge $Q_i$, an outer torus with charge $Q_o$ and a torus with electrically neutral mass $m_m$ in the middle, whereas the star bears a charge $Q_s$ ($Q_o$ and $Q_s$ have the same sign, $Q_i$ the opposite one). The frequency $\

  2. Quasi-periodic Oscillation of a Coronal Bright Point

    NASA Astrophysics Data System (ADS)

    Samanta, Tanmoy; Banerjee, Dipankar; Tian, Hui

    2015-06-01

    Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Imager magnetogram on board the Solar Dynamics Observatory, and spectroscopic data from the newly launched Interface Region Imaging Spectrograph (IRIS). The detailed analysis shows that the BP evolves throughout our observing period along with changes in underlying photospheric magnetic flux and shows periodic brightenings in different EUV and far-UV images. With the highest possible spectral and spatial resolution of IRIS, we attempted to identify the sources of these oscillations. IRIS sit-and-stare observation provided a unique opportunity to study the time evolution of one footpoint of the BP as the slit position crossed it. We noticed enhanced line profile asymmetry, enhanced line width, intensity enhancements, and large deviation from the average Doppler shift in the line profiles at specific instances, which indicate the presence of sudden flows along the line-of-sight direction. We propose that transition region explosive events originating from small-scale reconnections and the reconnection outflows are affecting the line profiles. The correlation between all these parameters is consistent with the repetitive reconnection scenario and could explain the quasi-periodic nature of the brightening.

  3. Quasi-periodic Solutions of the Kaup-Kupershmidt Hierarchy

    NASA Astrophysics Data System (ADS)

    Geng, Xianguo; Wu, Lihua; He, Guoliang

    2013-08-01

    Based on solving the Lenard recursion equations and the zero-curvature equation, we derive the Kaup-Kupershmidt hierarchy associated with a 3×3 matrix spectral problem. Resorting to the characteristic polynomial of the Lax matrix for the Kaup-Kupershmidt hierarchy, we introduce a trigonal curve {K}_{m-1} and present the corresponding Baker-Akhiezer function and meromorphic function on it. The Abel map is introduced to straighten out the Kaup-Kupershmidt flows. With the aid of the properties of the Baker-Akhiezer function and the meromorphic function and their asymptotic expansions, we arrive at their explicit Riemann theta function representations. The Riemann-Jacobi inversion problem is achieved by comparing the asymptotic expansion of the Baker-Akhiezer function and its Riemann theta function representation, from which quasi-periodic solutions of the entire Kaup-Kupershmidt hierarchy are obtained in terms of the Riemann theta functions.

  4. Quasi-Periodic Oscillation of a Coronal Bright Point

    E-print Network

    Samanta, Tanmoy; Tian, Hui

    2015-01-01

    Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underneath magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly (AIA) images, the Helioseismic and Magnetic Imager (HMI) magnetogram on board the Solar Dynamics Observatory (SDO) and spectroscopic data from the newly launched Interface Region Imaging Spectrograph (IRIS). The detailed analysis shows that the BP evolves throughout our observing period along with changes in underlying photospheric magnetic flux and shows periodic brightenings in different EUV and FUV images. With highest possible spectral and spatial resolution of IRIS, we attempted to identify the sources of these oscillations. IRIS sit and stare observation provided a unique opportunity to study the time evolution of one foot point of the BP as the slit position crossed it. We noticed enhanced line prof...

  5. Quasi-Periodic Pulsations in a Solar Microwave Burst

    NASA Technical Reports Server (NTRS)

    Kundu, Mukul R.; Grechnev, V. V.; White, S. M.

    2003-01-01

    We studied a microwave burst that showed deep quasi-periodic pulsations using imaging observations at 17 and 34 GHz. Strongly modulated pul sations appear in radio images from the eastern end of a long loop an d in hard X-rays from the western end of the loop. Radio modulations are seen at the western end of the loop but at a level some 20 times weaker than at the eastern end; these radio modulations at the western end of the loop, like the hard X-ray modulations at the same locatio n, appear to lead the modulations at the eastern end by about 0.5 s, but all have the same period. The period of the modulation can be exp lained by MHD oscillations of the loop approximately 120" long connecting the sources.

  6. Quasi Periodic Oscillations (QPOs) in Blazars on Diverse Time Scales

    NASA Astrophysics Data System (ADS)

    Gupta, A. C.

    2010-12-01

    Blazars, including BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs), are subclass of radio-loud active galactic nuclei (AGN) with relativistic jets aligned nearly with the line of sight. Blazar emission extends across the entire electromagnetic (EM) spectrum and they show detectable flux variations on diverse timescales ranging from a few minutes through days and months to decades through all EM bands. The presence of quasi-periodic oscillations (QPOs) is fairly common in both black hole and neutron star binaries in our and nearby galaxies. Recently we have reported claims of QPOs detection on diverse timescales ranging from a few tens of minutes to hours to days and even months by using X-ray and optical time series data of blazars in a series of papers by my group. How to detect QPOs in time series data? What causes QPOs? What are likely the explanation of QPO detection in blazars? I will discuss these in my talk.

  7. Quasi-periodic modulation of equatorial noise intensity

    NASA Astrophysics Data System (ADS)

    Nemec, Frantisek; Santolik, Ondrej; Hrbackova, Zuzana; Pickett, Jolene S.; Cornilleau-Wehrlin, Nicole

    2015-04-01

    Equatorial noise (EN) emissions are electromagnetic waves at frequencies between the proton cyclotron frequency and the lower hybrid frequency observed routinely in the equatorial region of the inner magnetosphere. They propagate in the extraordinary mode nearly perpendicular to the ambient magnetic field. Although their harmonic structure, which is characteristic of the proton cyclotron frequency in the source region has been known for a couple of decades, they were generally believed to be continuous in time. The analysis of more than 2000 EN events observed by the STAFF-SA and WBD instruments on board the Cluster spacecraft reveals that this is not always the case, with about 5% of events exhibiting a clear quasi-periodic (QP) modulation of the wave intensity. We perform a systematic analysis of these events, and we discuss possible mechanisms of the QP intensity modulation. It is shown that the events occur usually in the noon-to-dawn magnetic local time sector, and their occurrence seems to be related to the periods of increased geomagnetic activity. The modulation period of these events is on the order of minutes. Compressional ULF magnetic field pulsations with periods about double the modulation periods of EN were identified in about half of the events. These ULF pulsations might modulate the EN wave intensity, similarly as they modulate the intensity of formerly reported VLF whistler-mode QP events.

  8. Quasi-periodic oscillations in black-hole binaries

    NASA Astrophysics Data System (ADS)

    Motta, S.

    2015-07-01

    Fast time variability is an important characteristic of black hole (BH) binaries and a key ingredient in understanding the physical processes in these systems. Fast time variability is generally studied through the inspection of power density spectra, whose component are either broad distributed over several decades in frequency or fairly narrow, in the form of localised peak (quasi-periodic oscillations, QPOs). It is now clear that QPOs are a common characteristic of accreting systems: they have been observed in accreting stellar mass BHs and neutron stars in X-ray binaries, in CVs, in ULXs and even in AGN. Even though their origin and nature is still debated, the study of QPOs provides a way to explore the inner accretion flow around accreting objects. Various models have been proposed to explain the origin of QPOs in black hole binaries, but only a few have been proved to be promising so far, having shown good agreement with observations. I will describe how timing is done in X-rays and how QPOs are usually studied. I will briefly review some of the proposed models and I will finally show the most recent results obtained on QPOs.

  9. Omnidirectional reflection from Fibonacci quasi-periodic one-dimensional photonic crystal

    Microsoft Academic Search

    D. Lusk; I. Abdulhalim; F. Placido

    2001-01-01

    It is shown that omnidirectional reflection (ODR) is possible from quasi-periodic isotropic dielectric stacks following a Fibonacci sequence (FS). The transition from truly periodic to fully quasi-periodic structure is investigated by building periodic structures having unit cells made of FS of order j. The number of periods required to achieve ODR decreases as j increases until only a single period

  10. Quasi-periodic electron bursts in the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Steffl, A. J.; Shinn, A. B.

    2012-12-01

    In early 2007, the New Horizons spacecraft flew through the Jovian magnetosphere on the dusk side. During the flyby, the Alice FUV spectrograph proved that in addition to detecting FUV photons, it was also quite effective at detecting MeV electrons, which can penetrate the relatively thin instrument housing and interact with the microchannel plate detector. Radiation modeling shows that Alice is sensitive primarily to electrons with energies between 1-8 MeV. Alice cannot determine the spatial distribution of these MeV electrons, nor does it have any energy resolution, but it does have large count rates (up to 15000 counts/s) and a time resolution of 1s—the highest of any electron detector yet flown to Jupiter. Along New Horizons' trajectory from 60 R_J upstream of Jupiter to closest approach at 32 R_J on the dusk side to 60 R_J downstream of Jupiter, we find the flux of MeV electrons to be highly variable on timescales of minutes to hours. There are numerous factor of two changes in electron flux (both increases and decreases) that occur over 50-100s. Frequently, though not always, the MeV electron flux exhibits quasi-periodic variations with timescales of 1-3 minutes. The amplitude of these bursts can vary, sometimes abruptly, from a few percent to factors of several. We also see evidence of larger amplitude 20-45 minute QP bursts with smaller amplitude 1-3 minute bursts superimposed. During two incidences of particularly strong 1-3 minute QP bursts, we find the magnetic field lines passing through the spacecraft map back to Jupiter's ionosphere just inside the main auroral oval to the same location where 1-3 minute QP flares have been seen in the FUV aurora. We therefore suggest that these auroral flares are not caused by pulsed reconnection at the dayside magnetopause, as has been proposed, but rather by some acceleration mechanism internal to the magnetosphere.

  11. Quasi-Periodic Electron Bursts in the Jovian Magnetosphere

    NASA Astrophysics Data System (ADS)

    Steffl, Andrew J.; Shinn, A. B.

    2013-10-01

    In early 2007, the New Horizons spacecraft flew through the Jovian magnetosphere on the dusk side. During the flyby, the Alice FUV spectrograph proved that in addition to detecting FUV photons, it was also quite effective at detecting MeV electrons, which can penetrate the relatively thin instrument housing and interact with the microchannel plate detector. Radiation modeling shows that Alice is sensitive primarily to electrons with energies between 1-8 MeV. Alice cannot determine the spatial distribution of these MeV electrons, nor does it have any energy resolution, but it does have large count rates (up to 15000 counts/s) and a time resolution of 1s--among the highest of any electron detector flown to Jupiter. Along New Horizons’ trajectory from 60 R_J upstream of Jupiter to closest approach at 32 R_J on the dusk side to 60 R_J downstream of Jupiter, we find the flux of MeV electrons to be highly variable on timescales of minutes to hours. There are numerous factor of two changes in electron flux (both increases and decreases) that occur over 50-100s. Frequently, though not always, the MeV electron flux exhibits quasi-periodic variations with timescales of 1-3 minutes. The amplitude of these bursts can vary, sometimes abruptly, from a few percent to factors of several. We also see evidence of larger amplitude 20-45 minute QP bursts with smaller amplitude 1-3 minute bursts superimposed. During two incidences of particularly strong 1-3 minute QP bursts, we find the magnetic field lines passing through the spacecraft map back to Jupiter’s ionosphere just inside the main auroral oval to the same location where 1-3 minute QP flares have been seen in the FUV aurora. We therefore suggest that these auroral flares are not caused by magnetic reconnection at the dayside magnetopause, but rather by some acceleration mechanism internal to the magnetosphere.

  12. Effects of quasi-periodicity on defect modes of photonic crystals

    Microsoft Academic Search

    Xiao-Ming Shen; Xian-Feng Chen; Mei-Ping Jiang; Xiao-Gang Chao; Du-Fang Shi

    2006-01-01

    In this letter, the effects of Bragg-mirror quasi-periodicity on the shifts and quality factor in defect modes of photonic\\u000a crystals are studied by using the transfer matrix method. Furthermore the influence of the quasi-periodicity on electric field\\u000a enhancement effect inside the defect layer is studied, which is similar to that on the quality factor.

  13. Three-dimensional analysis of a noise barrier using a quasi-periodic boundary element method.

    PubMed

    Fard, Samaneh M B; Peters, Herwig; Kessissoglou, Nicole; Marburg, Steffen

    2015-06-01

    Two-dimensional (2D) numerical models are often used to estimate the environmental noise attenuation of a roadside barrier. The prediction of noise barrier attenuation using a 2D boundary element model assumes an infinitely long barrier with constant cross section. However, for barrier geometries that do not have constant cross section in the third dimension, three-dimensional (3D) models should be used for greater accuracy of noise reduction due to the barrier. The size of a numerical model and hence its computational cost can be significantly reduced using a 3D quasi-periodic structure, whereby the structure is truncated using a finite number of periodic sections. In this study, a quasi-periodic model developed using the boundary element method is used to predict the acoustic performance of 3D noise barriers. The convergence behavior of the quasi-periodic model is discussed. Results from the quasi-periodic model are compared with results from both a 3D analytical model and a 2D finite element model, showing good agreement. Quasi-periodic models of different noise barrier designs are developed and their acoustic performances in terms of frequency and receiver positions are discussed. The quasi-periodic boundary element method provides a computationally efficient tool to examine the acoustic performance of 3D noise barrier designs. PMID:26093402

  14. THE SPECTROSCOPIC SIGNATURE OF QUASI-PERIODIC UPFLOWS IN ACTIVE REGION TIMESERIES

    SciTech Connect

    Tian Hui; McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 8037 (United States); De Pontieu, Bart, E-mail: htian@ucar.edu, E-mail: mscott@ucar.edu, E-mail: bdp@lmsal.com [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States)

    2011-02-01

    Quasi-periodic propagating disturbances are frequently observed in coronal intensity image sequences. These disturbances have historically been interpreted as being the signature of slow-mode magnetoacoustic waves propagating into the corona. The detailed analysis of Hinode EUV Imaging Spectrometer (EIS) timeseries observations of an active region (known to contain propagating disturbances) shows strongly correlated, quasi-periodic, oscillations in intensity, Doppler shift, and line width. No frequency doubling is visible in the latter. The enhancements in the moments of the line profile are generally accompanied by a faint, quasi-periodically occurring, excess emission at {approx}100 km s{sup -1} in the blue wing of coronal emission lines. The correspondence of quasi-periodic excess wing emission and the moments of the line profile indicates that repetitive high-velocity upflows are responsible for the oscillatory behavior observed. Furthermore, we show that the same quasi-periodic upflows can be directly identified in a simultaneous image sequence obtained by the Hinode X-Ray Telescope. These results are consistent with the recent assertion of De Pontieu and McIntosh that the wave interpretation of the data is not unique. Indeed, given that several instances are seen to propagate along the direction of the EIS slit that clearly shows in-phase, quasi-periodic variations of intensity, velocity, width (without frequency doubling), and blue wing enhanced emission, this data set would appear to provide a compelling example that upflows are more likely to be the main cause of the quasi-periodicities observed here, as such correspondences are hard to reconcile in the wave paradigm.

  15. Dipolar mode localization and spectral gaps in quasi-periodic arrays of ferromagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Forestiere, Carlo; Miano, Giovanni; Serpico, Claudio; D'Aquino, Massimiliano; Dal Negro, Luca

    2009-06-01

    In this paper we study the spectral, localization, and dispersion properties of the ferromagnetic dipolar modes around a stable, saturated, and spatially uniform equilibrium in quasi-periodically modulated arrays of ferromagnetic nanoparticles based on the Fibonacci sequence. The Fibonacci sequence is the chief example of deterministic quasi-periodic order. The problem is reduced to the study of a linear-generalized eigenvalue equation for a suitable Hermitian operator connected to the micromagnetic effective field, which accounts for the magnetostatic, anisotropy, and Zeeman interactions. The coupling with a weak applied magnetic field, varying sinusoidally in time, is dealt with and the role of the losses is highlighted. By calculating the resonance frequencies and eigenmodes of the Fibonacci arrays we demonstrate the presence of large spectral gaps and strongly localized modes and we evaluate the pseudodispersion diagrams. The magnetization oscillation modes in quasi-periodic arrays of magnetic nanoparticles show, at microwave frequencies, behaviors that are very similar to those shown, at optical frequencies, by plasmon modes in quasi-periodic arrays of metal nanoparticles. The presence of band gaps and strongly localized states in magnetic nanoparticle arrays based on quasi-periodic order may have an impact in the design and fabrication of new microwave nanodevices and magnetic nanosensors.

  16. Invariant tori for a derivative nonlinear Schrödinger equation with quasi-periodic forcing

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Si, Jianguo

    2015-03-01

    This paper is concerned with a one dimensional derivative nonlinear Schrödinger equation with quasi-periodic forcing under periodic boundary conditions i u t + u x x + i g ( ? t ) ( f ( |u|2 ) u ) x = 0 , x ? T ? R / 2 ? Z , where g(?t) is real analytic and quasi-periodic on t with frequency vector ? = (?1, ?2, …, ?m). f is real analytic in some neighborhood of the origin in ?, f(0) = 0 and f'(0) ? 0. We show that the above equation admits Cantor families of smooth quasi-periodic solutions of small amplitude. The proof is based on an abstract infinite dimensional Kolmogorov-Arnold-Moser theorem for unbounded perturbation vector fields and partial Birkhoff normal form.

  17. Exciton photoluminescence in resonant quasi-periodic Thue-Morse quantum wells.

    PubMed

    Hsueh, W J; Chang, C H; Lin, C T

    2014-02-01

    This Letter investigates exciton photoluminescence (PL) in resonant quasi-periodic Thue-Morse quantum wells (QWs). The results show that the PL properties of quasi-periodic Thue-Morse QWs are quite different from those of resonant Fibonacci QWs. The maximum and minimum PL intensities occur under the anti-Bragg and Bragg conditions, respectively. The maxima of the PL intensity gradually decline when the filling factor increases from 0.25 to 0.5. Accordingly, the squared electric field at the QWs decreases as the Thue-Morse QW deviates from the anti-Bragg condition. PMID:24487847

  18. Acoustic lens: A thin plate with quasi-periodic array of holes

    NASA Astrophysics Data System (ADS)

    Ye, Yangtao; Ke, Manzhu; Li, Chunhui; Wang, Tian; Qiu, Chunyin; Liu, Zhengyou

    2014-05-01

    A thin steel plate with quasi-periodic array of holes is fabricated, which is demonstrated to be able to function as an acoustic lens. With either a plane wave or a point source in object space, hotspots with the smallest size up to one-fifth wavelength are observed in the post-evanescent field regime in image space. Imaging of a point source with good resolution at different positions is also exhibited. The singular field distributions originate from the interference of the diffractive beams specific to quasi-periodic structures, which generates distinct and plentiful diffractive patterns.

  19. The quasi-periodic nature of wall slip for molten plastics in large amplitude oscillatory shear

    E-print Network

    Adrian, David Warren

    1992-01-01

    THE QUASI-PERIODIC NATURE OF WALL SLIP FOR MOLTEN PLASTICS IN LARGE AMPLITUDE OSCILLATORY SHEAR A Thesis by DAVID WARREN ADRIAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 1992 Major Subject: Mechanical Engineering THE QUASI-PERIODIC NATURE OF WALL SLIP FOR MOLTEN PLASTICS IN LARGE AMPLITUDE OSCILLATORY SHEAR A Thesis by DAVID WARREN ADRIAN Approved as to style and content by: A. J...

  20. Pseudo resonance induced quasi-periodic behavior in stochastic threshold dynamics

    E-print Network

    Peter D. Ditlevsen; Holger Braun

    2011-06-07

    Here we present a simple stochastic threshold model consisting of a deterministic slowly decaying term and a fast stochastic noise term. The process shows a pseudo-resonance, in the sense that for small and large intensities of the noise the signal is irregular and the distribution of threshold crossings is broad, while for a tuned intermediate value of noise intensity the signal becomes quasi-periodic and the distribution of threshold crossings is narrow. The mechanism captured by the model might be relevant for explaining apparent quasi-periodicity of observed climatic variations where no internal or external periodicities can be identified.

  1. Non thermal small black holes

    E-print Network

    Xavier Calmet; Dionysios Fragkakis; Nina Gausmann

    2012-01-21

    In this chapter we review the current theoretical state of the art of small black holes at the LHC. We discuss the production mechanism for small non thermal black holes at the LHC and discuss new signatures due to a possible discrete mass spectrum of these black holes.

  2. Remarks about bifurcation and stability of quasi-periodic solutions which bifurcate from periodic solutions of the Navier Stokes equations

    Microsoft Academic Search

    Daniel D. Joseph

    L. D. Landau (1944) and E. Hopf (1948) have conjectured that the transition to turbulence may be described as repeated branching\\u000a of quasi-periodic solutions into quasi-periodic solutions with more frequencies. The simplest case is the bifurcation of periodic\\u000a solutions from steady solutions. The next hardest problem is the bifurcation of quasi-periodic solutions from basic time periodic\\u000a solutions of fixed frequency.

  3. Pure Point Spectrum of the Floquet Hamiltonian for the Quantum Harmonic Oscillator Under Time Quasi- Periodic Perturbations

    E-print Network

    W. -M. Wang

    2008-05-24

    We prove that the $1-d$ quantum harmonic oscillator is stable under spatially localized, time quasi-periodic perturbations on a set of Diophantine frequencies of positive measure. This proves a conjecture raised by Enss-Veselic in their 1983 paper \\cite{EV} in the general quasi-periodic setting. The motivation of the present paper also comes from construction of quasi-periodic solutions for the corresponding nonlinear equation.

  4. Hölder continuity of the integrated density of states for quasi-periodic Jacobi operators

    E-print Network

    Kai Tao; Mircea Voda

    2015-01-29

    We show H\\"older continuity for the integrated density of states of a quasi-periodic Jacobi operator with analytic coefficients, in the regime of positive Lyapunov exponent and with a strong Diophantine condition on the frequency. In particular, when the coefficients are trigonometric polynomials we express the H\\"older exponent in terms of the degrees of the coefficients.

  5. WEAKLY CONNECTED QUASI-PERIODIC OSCILLATORS, FM INTERACTIONS, AND MULTIPLEXING IN THE BRAIN

    Microsoft Academic Search

    EUGENE M. IZHIKEVICHy; SIAM J. APPL

    We prove that weakly connected networks of quasi-periodic (multifrequency) oscil- lators can be transformed into a phase model by a continuous change of variables. The phase model has the same form as the one for periodic oscillators with the exception that each phase variable is a vector. When the oscillators have mutually nonresonant frequency (rotation) vectors, the phase model uncouples.

  6. Dominated splittings and the spectrum of singular quasi-periodic Jacobi operators

    E-print Network

    C. A. Marx

    2014-07-18

    We prove that the resolvent set of any, possibly singular, quasi periodic Jacobi operator is characterized as the set of all energies whose associated Jacobi cocycles induce a dominated splitting. This extends a well-known result by R. A. Johnson for Schr\\"odinger operators.

  7. Faster and Parameter-Free Discord Search in Quasi-Periodic Time Series

    E-print Network

    Gallagher, Marcus

    Faster and Parameter-Free Discord Search in Quasi-Periodic Time Series Wei Luo and Marcus Gallagher The University of Queensland, Australia {luo,marcusg}@itee.uq.edu.au Abstract. Time series discord has proven to be a useful concept for time- series anomaly identification. To search for discords, various algorithms have

  8. Superstable periodic orbits of 1d maps under quasi-periodic forcing and reducibility loss

    E-print Network

    Barcelona, Universitat de

    Superstable periodic orbits of 1d maps under quasi-periodic forcing and reducibility loss `Angel of period doubling bifurcations. Between each of these bifurcations, a superstable periodic orbit is known parameter. It is known that, if is small enough, the superstable periodic orbits of the unperturbed map

  9. Understanding Quasi-Periodic Fieldlines and Their Topology in Toroidal Magnetic Fields

    E-print Network

    Chen, Guoning

    Understanding Quasi-Periodic Fieldlines and Their Topology in Toroidal Magnetic Fields Allen) surfaces that form within the magnetic field. Among the two distinct topological structures, we approach for classifying and characterizing different magnetic surfaces in the toroidal magnetic fields. 1

  10. Dripping handrails and the quasi-periodic oscillations of the AM Herculis objects

    NASA Technical Reports Server (NTRS)

    Steiman-Cameron, Thomas Y.; Young, Karl; Scargle, Jeffrey D.; Crutchfield, James P.; Imamura, James N.; Wolff, Michael T.; Wood, Kent S.

    1994-01-01

    AM Her objects exhibit periodic, quasi-periodic, and aperiodic variability on timescales ranging from seconds to years. Here, we investigate a process for the production of aperiodic and quasi-periodic accretion rate fluctuations. We consider the nonlinear dynamical model known as the dripping handrail (DHR). The DHR, basically a model for certain types of spatially extended systems and loosely based on water condensing on and dripping off a handrail, has recently been used as a model for the quasi-periodic oscillations (QPO) and very low frequency noise of the low-mass X-ray binary Sco X-1. Here, we show that (1) the DHR is a robust QPO generation process in that it leads to QPO production under a wide range of conditions and assumptions; (2) the phenomenology of the DHR is consistent with the observed aperiodic and quasi-periodic varibility of the AM Her QPO source VV Pup over timescales ranging from 16 ms to 20 s; and (3) a single DHR model can produce both broadband QPOs and features with quality Q greater than 20 as observed in several AM Her QPO sources.

  11. Dominated splittings and the spectrum of quasi-periodic Jacobi operators

    NASA Astrophysics Data System (ADS)

    Marx, C. A.

    2014-12-01

    We prove that the resolvent set of any, possibly singular, quasi- periodic Jacobi operator is characterized as the set of all energies whose associated Jacobi cocycles induce a dominated splitting. This extends a well-known result by Johnson for Schrödinger operators.

  12. Fabrication and characteristics of two-dimensional quasi-periodic photonic crystal lasers

    Microsoft Academic Search

    Feng-Mao Tsai; Po-Tsung Lee; Tsan-Wen Lu; Tien-Chang Lu; Hao-Chung Kuo

    2006-01-01

    Lasing characteristics of 12-fold quasi-periodic photonic crystal micro-cavity lasers are obtained and compared with triangular lattice photonic crystal lasers. An ultra-low threshold is observed and tolerance of fabrication imperfection in QPC lasers is investigated.

  13. The effect of quasi-periodicity on the resonant tunneling lifetimes of states in electrically biased semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Panchadhyayee, P.; Biswas, R.; Sinha, C.; Mahapatra, P. K.

    2008-11-01

    The tunneling lifetimes of quasi-resonant states for electrons in various kinds of generalized Fibonacci and generalized Thue-Morse GaAs-AlxGa1-xAs superlattices have been evaluated numerically under variable dc bias conditions. All the quasi-periodic systems have been framed using the generalized block model. The variation of the lifetime at different quasi-resonant levels with respect to the external dc field undergoes a remarkable change due to the effect of quasi-periodicity. The occurrence of a minimum value of the average lifetime and its dependence on quasi-periodicity have been analyzed. It is shown that the low-order quasi-periodicity in the case of the generalized Fibonacci superlattice and the high-order quasi-periodicity for the generalized Thue-Morse superlattice hold promise for potential device applications. The impact of an increase in the number of barriers on the tunneling lifetime has also been studied exhaustively.

  14. LOW-FREQUENCY OBSERVATIONS OF TRANSIENT QUASI-PERIODIC RADIO EMISSION FROM THE SOLAR ATMOSPHERE

    SciTech Connect

    Sasikumar Raja, K.; Ramesh, R., E-mail: sasikumar@iiap.res.in [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034 (India)

    2013-09-20

    We report low-frequency observations of quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was ?5.2 s, and their average degree of circular polarization (dcp) was ?0.12. We calculated the associated magnetic field B (1) using the empirical relationship between the dcp and B for the harmonic type III emission, and (2) from the observed quasi-periodicity of the bursts. Both the methods result in B ? 4.2 G at the location of the 80 MHz plasma level (radial distance r ? 1.3 R{sub ?}) in the active region corona.

  15. Narrowband DWDM filters based on Fibonacci-class quasi-periodic structures.

    PubMed

    Golmohammadi, S; Moravvej-Farshi, M K; Rostami, A; Zarifkar, A

    2007-08-20

    In this paper, we propose a narrowband DWDM filter structure, whose reflection band characteristics, meets the ITU-T standard. The proposed filter structure is based on Fibonacci quasi-periodic structures composed of multilayers with large index differences. Studying the effects of the optical and geometrical parameters of Fibonacci quasi-periodic structures on its filtering properties, we have realized that to achieve the ITU-T standard, we need to cascade two successive structures both with the same generation numbers j=4 and orders n=25 and apodized refractive indices. The apodization process helps to minimize the stop band sidelobes. We have also demonstrated that beside Fibonacci's order, n, the layers dimensions, and their refractive index ratios are the main design parameters. PMID:19547405

  16. Quasi-Periodic Oscillations and broadband variability in short magnetar bursts

    E-print Network

    Huppenkothen, Daniela; Uttley, Phil; van der Horst, Alexander J; van der Klis, Michiel; Kouveliotou, Chryssa; Gogus, Ersin; Granot, Jonathan; Vaughan, Simon; Finger, Mark H

    2012-01-01

    The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. However, with only three giant flares ever recorded, and only two with data of sufficient quality to search for QPOs, such analysis is seriously data limited. We set out a procedure for doing QPO searches in the far more numerous, short, less energetic magnetar bursts. The short, transient nature of these bursts requires the implementation of sophisticated statistical techniques to make reliable inferences. Using Bayesian statistics, we model the periodogram as a combination of red noise at low frequencies and white noise at high frequencies, which we show is a conservative approach to the problem. We use empirical models to make inferences about the potential signature of periodic and quasi-periodic oscillations at these frequencies. We compare our method with previously used techniques and find that although it is on the whole more conservative, it is also more reliable in ...

  17. Broadband asymmetric acoustic transmission by a plate with quasi-periodic surface ridges

    SciTech Connect

    Li, Chunhui; Ke, Manzhu, E-mail: mzke@whu.edu.cn; Ye, Yangtao; Xu, Shengjun; Qiu, Chunyin; Liu, Zhengyou [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

    2014-07-14

    In this paper, an acoustic system with broadband asymmetric transmission is designed and fabricated, which consists of a water-immersed aluminum plate engraved with quasi-periodically-patterned ridges on single surface. It demonstrates that when the acoustic waves are launched into the system from the structured side, they can couple into the Lamb modes in the plate efficiently and attain a high transmission; on the contrary, when the waves are incident from the opposite flat side, the coupling is weak, and the transmission is low. Superior to systems with periodic patterning, this quasi-periodically-patterned system has a broad working frequency range due to the collective contributions from the multiple diffractions specific to the structure.

  18. Modeling quasi-periodic signals by a non-parametric model: Application on fetal ECG extraction.

    PubMed

    Noorzadeh, Saman; Niknazar, Mohammad; Rivet, Bertrand; Fontecave-Jallon, Julie; Gumery, Pierre-Yves; Jutten, Christian

    2014-08-01

    Quasi-periodic signals can be modeled by their second order statistics as Gaussian process. This work presents a non-parametric method to model such signals. ECG, as a quasi-periodic signal, can also be modeled by such method which can help to extract the fetal ECG from the maternal ECG signal, using a single source abdominal channel. The prior information on the signal shape, and on the maternal and fetal RR interval, helps to better estimate the parameters while applying the Bayesian principles. The values of the parameters of the method, among which the R-peak instants, are accurately estimated using the Metropolis-Hastings algorithm. This estimation provides very precise values for the R-peaks, so that they can be located even between the existing time samples. PMID:25570347

  19. Quasi-periodic hard X-ray oscillations before impulsive phase of solar flares

    NASA Astrophysics Data System (ADS)

    Tomczak, Michal; Jakimiec, Jerzy

    Using observations from the YOHKOH Hard X-ray Telescope and Compton Gamma Ray Ob-servatory spectrometer we have found small-amplitude quasi-periodic hard X-ray oscillations before impulsive phase (OBIP) of solar flares. We have been investigating properties of the oscillations and transition from the OBIP to impulsive phase. Our results support the model of electron acceleration in oscillating magnetic traps (Jakimiec and Tomczak 2010, Solar Physics, 261, 233).

  20. Quasi-periodic solutions of nonlinear beam equation with prescribed frequencies

    NASA Astrophysics Data System (ADS)

    Chang, Jing; Gao, Yixian; Li, Yong

    2015-05-01

    Consider the one dimensional nonlinear beam equation utt + uxxxx + mu + u3 = 0 under Dirichlet boundary conditions. We show that for any m > 0 but a set of small Lebesgue measure, the above equation admits a family of small-amplitude quasi-periodic solutions with n-dimensional Diophantine frequencies. These Diophantine frequencies are the small dilation of a prescribed Diophantine vector. The proofs are based on an infinite dimensional Kolmogorov-Arnold-Moser iteration procedure and a partial Birkhoff normal form.

  1. Transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals containing indefinite metamaterials

    Microsoft Academic Search

    Liwei Zhang; Kai Fang; Guiqiang Du; Haitao Jiang; Junfang Zhao

    2011-01-01

    The transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals (1DPCs) containing indefinite metamaterials are theoretically studied. It is found that 1DPCs can possess an omnidirectional zero average index (zero-n?) gap which exists in all Fibonacci sequences. In contrast to Bragg gaps, such zero-n? gap is less sensitive to the incidence angle, the scale length and the polarizations of electromagnetic waves.

  2. On quasi-periodic solutions for generalized Boussinesq equation with quadratic nonlinearity

    NASA Astrophysics Data System (ADS)

    Shi, Yanling; Xu, Junxiang; Xu, Xindong

    2015-02-01

    In this paper, one-dimensional generalized Boussinesq equation: utt - uxx + (u2 + uxx)xx = 0 with boundary conditions ux(0, t) = ux(?, t) = uxxx(0, t) = uxxx(?, t) = 0 is considered. It is proved that the equation admits a Whitney smooth family of small-amplitude quasi-periodic solutions with 2-dimensional Diophantine frequencies. The proof is based on an infinite dimensional Kolmogorov-Arnold-Moser theorem and Birkhoff normal form.

  3. A minimal 2-D quadratic map with quasi-periodicity route to chaos

    E-print Network

    Sprott, Julien Clinton

    -dimensional quadratic map given by f(x, y) = 1 - ay2 + bx x , (3) where a and b are bifurcation parameters. Equation (3] but not extensively studied. Equation (4) reduces to the time-delayed quadratic map for b = 0, much as the H´enon mapA minimal 2-D quadratic map with quasi-periodicity route to chaos Zeraoulia Elhadj1 , J. C. Sprott2

  4. Lifetime distribution of spontaneous emission from line antennas in two-dimensional quasi-periodic photonic crystals

    NASA Astrophysics Data System (ADS)

    Xu, Xingsheng; Hu, Haiyang; Yamada, Toshiki; Chen, Hongda; Wang, Yiquan

    2008-03-01

    We investigate the lifetime distribution functions of spontaneous emission from line antennas embedded in finite-size two-dimensional 12-fold quasi-periodic photonic crystals. Our calculations indicate that two-dimensional quasi-periodic crystals lead to the coexistence of both accelerated and inhibited decay processes. The decay behaviors of line antennas are drastically changed as the locations of the antennas are varied from the center to the edge in quasi-periodic photonic crystals and the location of transition frequency is varied.

  5. Quasi-periodic synchronisation of self-modulation oscillations in a ring chip laser by an external periodic signal

    SciTech Connect

    Aulova, T V; Kravtsov, Nikolai V; Lariontsev, E G; Chekina, S N [D.V. Skobel'tsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2011-06-30

    The synchronisation of periodic self-modulation oscillations in a ring Nd:YAG chip laser under an external periodic signal modulating the pump power has been experimentally investigated. A new quasi-periodic regime of synchronisation of self-modulation oscillations is found. The characteristic features of the behaviour of spectral and temporal structures of synchronised quasi-periodic oscillations with a change in the external signal frequency are studied. (control of laser radiation parameters)

  6. Lifetime distribution of spontaneous emission from line antennas in two-dimensional quasi-periodic photonic crystals

    Microsoft Academic Search

    Xingsheng Xu; Haiyang Hu; Toshiki Yamada; Hongda Chen; Yiquan Wang

    2008-01-01

    We investigate the lifetime distribution functions of spontaneous emission from line antennas embedded in finite-size two-dimensional 12-fold quasi-periodic photonic crystals. Our calculations indicate that two-dimensional quasi-periodic crystals lead to the coexistence of both accelerated and inhibited decay processes. The decay behaviors of line antennas are drastically changed as the locations of the antennas are varied from the center to the

  7. Matter-wave interferometry in periodic and quasi-periodic arrays

    NASA Astrophysics Data System (ADS)

    Eksioglu, Y.; Vignolo, P.; Tosi, M. P.

    2004-12-01

    We calculate within a Bose-Hubbard tight-binding model the matter-wave flow driven by a constant force through a Bose-Einstein condensate of 87Rb atoms in various types of quasi-onedimensional arrays of potential wells. Interference patterns are obtained when beam splitting is induced by creating energy minigaps either through period doubling or through quasi-periodicity governed by the Fibonacci series. The generation of such condensate modulations by means of optical-laser structures is also discussed.

  8. Electronic band gap and transport in Fibonacci quasi-periodic graphene superlattice

    NASA Astrophysics Data System (ADS)

    Zhao, Pei-Liang; Chen, Xi

    2011-10-01

    We investigate electronic band gap and transport in Fibonacci quasi-periodic graphene superlattice. It is found that such structure can possess a zero-k¯ gap which exists in all Fibonacci sequences. Different from Bragg gap, zero-k¯ gap associated with Dirac point is less sensitive to the incidence angle and lattice constants. The defect mode appeared inside the zero-k¯ gap has a great effect on transmission, conductance, and shot noise, which can be applicable to control the electron transport.

  9. Transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals containing indefinite metamaterials

    NASA Astrophysics Data System (ADS)

    Zhang, Liwei; Fang, Kai; Du, Guiqiang; Jiang, Haitao; Zhao, Junfang

    2011-02-01

    The transmission properties of Fibonacci quasi-periodic one-dimensional photonic crystals (1DPCs) containing indefinite metamaterials are theoretically studied. It is found that 1DPCs can possess an omnidirectional zero average index (zero- n?) gap which exists in all Fibonacci sequences. In contrast to Bragg gaps, such zero- n? gap is less sensitive to the incidence angle, the scale length and the polarizations of electromagnetic waves. When an impurity is introduced, a defect mode appears inside the zero- n? gap with a very weak dependence on the incidence angle and scaling.

  10. Analysis of quasi-periodic pore-network structure of centric marine diatom frustules

    NASA Astrophysics Data System (ADS)

    Cohoon, Gregory A.; Alvarez, Christine E.; Meyers, Keith; Deheyn, Dimitri D.; Hildebrand, Mark; Kieu, Khanh; Norwood, Robert A.

    2015-03-01

    Diatoms are a common type of phytoplankton characterized by their silica exoskeleton known as a frustule. The diatom frustule is composed of two valves and a series of connecting girdle bands. Each diatom species has a unique frustule shape and valves in particular species display an intricate pattern of pores resembling a photonic crystal structure. We used several numerical techniques to analyze the periodic and quasi-periodic valve pore-network structure in diatoms of the Coscinodiscophyceae order. We quantitatively identify defect locations and pore spacing in the valve and use this information to better understand the optical and biological properties of the diatom.

  11. Quasi-Periodic Solutions of (3+1) Generalized BKP Equation By Using Riemann Theta Functions

    E-print Network

    Seçil Demiray; Filiz Ta?can Güney

    2014-09-24

    This paper is focused on quasi-periodic wave solutions of (3+1) generalized BKP equation. Because of some difficulties in calculations of N=3 periodic solutions, hardly ever has there been a study on these solutions by using Rieamann theta function. In this study, we obtain one and two periodic wave solutions as well as three periodic wave solutions for (3+1) generalized BKP equation. Moreover we analyse the asymptotic behavior of the periodic wave solutions tend to the known soliton solutions under a small amplitude limit.

  12. Quasi-periodic oscillations as a probe of galactic-bulge X-ray sources

    NASA Technical Reports Server (NTRS)

    Lamb, F. K.

    1986-01-01

    Quasi-periodic oscillations (QPOs) with frequencies in the range 5-50 Hz have recently been discovered in X-rays from two bright galactic-bulge sources and from Sco X-1. A shot-noise model that provides a mathematical framework for analyzing the constraints imposed on physical models by the observed power density spectra is described. A variety of physical models are then examined briefly. One of the most promising, the beat-frequency-modulated accretion model, is adopted as a working hypothesis to consider the clues it may provide concerning the galactic-bulge sources. Finally, some key observations are noted.

  13. Electronic spectra of one-dimensional nano-quasi-periodic systems under bias

    NASA Astrophysics Data System (ADS)

    Pérez-Maldonado, M. T.; Monsivais, G.; Velasco, V.; Rodríguez-Ramos, R.; Stern, C.

    2010-06-01

    We investigate the properties of the energy spectra of quantum one-dimensional nano-quasi-crystals in the presence of external electric fields. These systems are modelled by means of finite sequences, ordered according to a Fibonacci rule which constituted of two blocks A (constant potentials of different heights defined on finite intervals) and B (delta potentials of different intensities). We use the electric field ability of producing Stark ladders in periodic systems to obtain well separated energy levels and to study the evolution of these levels when disorder is introduced. We show that this effect also allows us to predict the approximate position of the levels in the disordered system, in spite of its chaotic appearance at first view. We show, against the usual belief, that the nth Stark ladder in general is not formed exclusively from the levels of the nth band. The disorder is introduced in two different ways: by changing the distribution of the blocks or by changing the values of the delta potential intensities. In both cases we start from electrified periodic structures which are gradually perturbed to obtain electrified quasi-periodic structures. We show that the use of Fibonacci sequences as a particular case is not crucial and one can use the electric field to analyze any other type of quasi-periodic systems.

  14. GENERATION OF QUASI-PERIODIC WAVES AND FLOWS IN THE SOLAR ATMOSPHERE BY OSCILLATORY RECONNECTION

    SciTech Connect

    McLaughlin, J. A.; Verth, G. [School of Computing, Engineering and Information Sciences, Northumbria University, Newcastle Upon Tyne, NE1 8ST (United Kingdom); Fedun, V.; Erdelyi, R., E-mail: james.a.mclaughlin@northumbria.ac.uk, E-mail: gary.verth@northumbria.ac.uk, E-mail: v.fedun@sheffield.ac.uk, E-mail: robertus@sheffield.ac.uk [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield, S3 7RH (United Kingdom)

    2012-04-10

    We investigate the long-term evolution of an initially buoyant magnetic flux tube emerging into a gravitationally stratified coronal hole environment and report on the resulting oscillations and outflows. We perform 2.5-dimensional nonlinear numerical simulations, generalizing the models of McLaughlin et al. and Murray et al. We find that the physical mechanism of oscillatory reconnection naturally generates quasi-periodic vertical outflows, with a transverse/swaying aspect. The vertical outflows consist of both a periodic aspect and evidence of a positively directed flow. The speed of the vertical outflow (20-60 km s{sup -1}) is comparable to those reported in the observational literature. We also perform a parametric study varying the magnetic strength of the buoyant flux tube and find a range of associated periodicities: 1.75-3.5 minutes. Thus, the mechanism of oscillatory reconnection may provide a physical explanation to some of the high-speed, quasi-periodic, transverse outflows/jets recently reported by a multitude of authors and instruments.

  15. On the self-averaging of dispersion for transport in quasi-periodic random media

    NASA Astrophysics Data System (ADS)

    Eberhard, J. P.; Suciu, N.; Vamos, C.

    2007-01-01

    In this study we present a numerical analysis for the self-averaging of the longitudinal dispersion coefficient for transport in heterogeneous media. This is done by investigating the mean-square sample-to-sample fluctuations of the dispersion for finite times and finite numbers of modes for a random field using analytical arguments as well as numerical simulations. We consider transport of point-like injections in a quasi-periodic random field with a Gaussian correlation function. In particular, we focus on the asymptotic and pre-asymptotic behaviour of the fluctuations with the aid of a probability density function for the dispersion, and we verify the logarithmic growth of the sample-to-sample fluctuations as earlier reported in Eberhard (2004 J. Phys. A: Math. Gen. 37 2549-71). We also comment on the choice of the relevant parameters to generate quasi-periodic realizations with respect to the self-averaging of transport in statistically homogeneous Gaussian velocity fields.

  16. Dynamics and spectral theory of quasi-periodic Schrödinger-type operators

    E-print Network

    S. Jitomirskaya; C. A. Marx

    2015-03-19

    Quasi-periodic Schr\\"odinger-type operators naturally arise in solid state physics, describing the influence of an external magnetic field on the electrons of a crystal. In the late 1970s, numerical studies for the most prominent model, the almost Mathieu operator (AMO), produced the first example of a fractal in physics known as "Hofstadter's butterfly," marking the starting point for the ongoing strong interest in such operators in both mathematics (several of B. Simon's problems) and physics (e.g. Graphene, quantum Hall effect). Whereas research in the first three decades was focused mainly on unraveling the unusual properties of the AMO and operators with similar structure of potential, in recent years a combination of techniques from dynamical systems with those from spectral theory has allowed for a more "global," model-independent point of view. Intriguing phenomena first encountered for the AMO, notably the appearance of criticality corresponding to purely singular continuous spectrum for a measure theoretically typical realization of the phase, could be tested for prevalence in general models. The intention of this article is to survey the theory of quasi-periodic Schr\\"odinger-type operators attaining this "global" view-point with an emphasis on dynamical aspects of the spectral theory of such operators.

  17. Topological incommensurate magnetization plateaus in quasi-periodic quantum spin chains

    PubMed Central

    Hu, Hai-Ping; Cheng, Chen; Luo, Hong-Gang; Chen, Shu

    2015-01-01

    Uncovering topologically nontrivial states in nature is an intriguing and important issue in recent years. While most studies are based on the topological band insulators, the topological state in strongly correlated low-dimensional systems has not been extensively explored due to the failure of direct explanation from the topological band insulator theory on such systems and the origin of the topological property is unclear. Here we report the theoretical discovery of strongly correlated topological states in quasi-periodic Heisenberg spin chain systems corresponding to a series of incommensurate magnetization plateaus under the presence of the magnetic field, which are uniquely determined by the quasi-periodic structure of exchange couplings. The topological features of plateau states are demonstrated by the existence of non-trivial spin-flip edge excitations, which can be well characterized by nonzero topological invariants defined in a two-dimensional parameter space. Furthermore, we demonstrate that the topological invariant of the plateau state can be read out from a generalized Streda formula and the spin-flip excitation spectrum exhibits a similar structure of the Hofstadter's butterfly spectrum for the two-dimensional quantum Hall system on a lattice. PMID:25678145

  18. Topological incommensurate magnetization plateaus in quasi-periodic quantum spin chains.

    PubMed

    Hu, Hai-Ping; Cheng, Chen; Luo, Hong-Gang; Chen, Shu

    2015-01-01

    Uncovering topologically nontrivial states in nature is an intriguing and important issue in recent years. While most studies are based on the topological band insulators, the topological state in strongly correlated low-dimensional systems has not been extensively explored due to the failure of direct explanation from the topological band insulator theory on such systems and the origin of the topological property is unclear. Here we report the theoretical discovery of strongly correlated topological states in quasi-periodic Heisenberg spin chain systems corresponding to a series of incommensurate magnetization plateaus under the presence of the magnetic field, which are uniquely determined by the quasi-periodic structure of exchange couplings. The topological features of plateau states are demonstrated by the existence of non-trivial spin-flip edge excitations, which can be well characterized by nonzero topological invariants defined in a two-dimensional parameter space. Furthermore, we demonstrate that the topological invariant of the plateau state can be read out from a generalized Streda formula and the spin-flip excitation spectrum exhibits a similar structure of the Hofstadter's butterfly spectrum for the two-dimensional quantum Hall system on a lattice. PMID:25678145

  19. Topological incommensurate magnetization plateaus in quasi-periodic quantum spin chains

    NASA Astrophysics Data System (ADS)

    Hu, Hai-Ping; Cheng, Chen; Luo, Hong-Gang; Chen, Shu

    2015-02-01

    Uncovering topologically nontrivial states in nature is an intriguing and important issue in recent years. While most studies are based on the topological band insulators, the topological state in strongly correlated low-dimensional systems has not been extensively explored due to the failure of direct explanation from the topological band insulator theory on such systems and the origin of the topological property is unclear. Here we report the theoretical discovery of strongly correlated topological states in quasi-periodic Heisenberg spin chain systems corresponding to a series of incommensurate magnetization plateaus under the presence of the magnetic field, which are uniquely determined by the quasi-periodic structure of exchange couplings. The topological features of plateau states are demonstrated by the existence of non-trivial spin-flip edge excitations, which can be well characterized by nonzero topological invariants defined in a two-dimensional parameter space. Furthermore, we demonstrate that the topological invariant of the plateau state can be read out from a generalized Streda formula and the spin-flip excitation spectrum exhibits a similar structure of the Hofstadter's butterfly spectrum for the two-dimensional quantum Hall system on a lattice.

  20. Wideband absorption in fibonacci quasi-periodic graphene-based hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Ning, Renxia; Liu, Shaobin; Zhang, Haifeng; Kong, Xiangkun; Bian, Borui; Bao, Jie

    2014-12-01

    A heterostructure containing a Fibonacci quasi-periodic layer and a resonant metal back reflector is proposed, which can realize wideband absorption. The Fibonacci layer is composed of graphene-based hyperbolic metamaterials and isotropic media to obtain wideband absorption. To enhance absorption, an impedance-matching layer is put on top of the Fibonacci layer. It is shown to absorb roughly 90% of all available electromagnetic waves in an 11 terahertz absorption bandwidth for a transverse magnetic mode at normal angle incidence. The absorption bandwidth is affected by the reflection band gap. Compared with some previous designs, our proposed structure has a larger absorption bandwidth and higher absorption in the mid-infrared range. The results should be valuable in the design of infrared stealth and broadband optoelectronic devices.

  1. Delayed feedback control and phase reduction of unstable quasi-periodic orbits

    NASA Astrophysics Data System (ADS)

    Ichinose, Natsuhiro; Komuro, Motomasa

    2014-09-01

    The delayed feedback control (DFC) is applied to stabilize unstable quasi-periodic orbits (QPOs) in discrete-time systems. The feedback input is given by the difference between the current state and a time-delayed state in the DFC. However, there is an inevitable time-delay mismatch in QPOs. To evaluate the influence of the time-delay mismatch on the DFC, we propose a phase reduction method for QPOs and construct a phase response curve (PRC) from unstable QPOs directly. Using the PRC, we estimate the rotation number of QPO stabilized by the DFC. We show that the orbit of the DFC is consistent with the unstable QPO perturbed by a small state difference resulting from the time-delay mismatch, implying that the DFC can certainly stabilize the unstable QPO.

  2. Growth of Sobolev Norms in Linear Schrödinger Equations with Quasi-Periodic Potential

    NASA Astrophysics Data System (ADS)

    Bourgain, J.

    In this paper, we consider the following problem. Let iut+?u+V(x,t)u= 0 be a linear Schrödinger equation ( periodic boundary conditions) where V is a real, bounded, real analytic potential which is periodic in x and quasi periodic in t with diophantine frequency vector ?. Denote S(t) the corresponding flow map. Thus S(t) preserves the L2-norm and our aim is to study its behaviour on Hs(TD), s> 0. Our main result is the growth in time is at most logarithmic; thus if ??Hs, then More precisely, (*) is proven in 1D and 2D when V is small. We also exhibit examples showing that a growth of higher Sobolev norms may occur in this context and (*) is thus essentially best possible.

  3. Tunability of acoustic phonon transmission and thermal conductance in three dimensional quasi-periodically stubbed waveguides

    NASA Astrophysics Data System (ADS)

    Xie, Zhong-Xiang; Liu, Jing-Zhong; Yu, Xia; Wang, Hai-Bin; Deng, Yuan-Xiang; Li, Ke-Min; Zhang, Yong

    2015-03-01

    We investigate acoustic phonon transmission and thermal conductance in three dimensional (3D) quasi-periodically stubbed waveguides according to the Fibonacci sequence. Results show that the transmission coefficient exhibits the periodic oscillation upon varying the length of stub/waveguide at low frequency, and the period of such oscillation is tunably decreased with increasing the Fibonacci number N. Interestingly, there also exist some anti-resonant dips that gradually develop into wide stop-frequency gaps with increasing N. As the temperature goes up, a transition of the thermal conductance from the decrease to the increase occurs in these systems. When N is increased, the thermal conductance is approximately decreased with a linear trend. Moreover, the decreasing degree sensitively depends on the variation of temperature. A brief analysis of these results is given.

  4. Periodic and quasi-periodic solutions for multi-instabilities involved in brake squeal

    NASA Astrophysics Data System (ADS)

    Coudeyras, N.; Nacivet, S.; Sinou, J.-J.

    2009-12-01

    This paper is devoted to the computation of nonlinear dynamic steady-state solutions of autonomous systems subjected to multi-instabilities and proposes a new nonlinear method for predicting periodic and quasi-periodic solutions intended for application to the disc brake squeal phenomenon. Firstly, finite element models of a pad and a disc are reduced to include only their contact nodes by using a Craig and Bampton strategy. Secondly, a complex eigenvalue analysis is performed showing two unstable modes for a wide range of friction coefficients, after which a Generalized Constrained Harmonic Balance Method (GCHBM) is presented. This method can compute nonlinear periodic or pseudo-periodic responses depending on the number of unstable frequencies. The numerical results are in good agreement with those of time marching methods.

  5. Ergodic theory and visualization. II. Fourier mesochronic plots visualize (quasi)periodic sets.

    PubMed

    Levnaji?, Zoran; Mezi?, Igor

    2015-05-01

    We present an application and analysis of a visualization method for measure-preserving dynamical systems introduced by I. Mezi? and A. Banaszuk [Physica D 197, 101 (2004)], based on frequency analysis and Koopman operator theory. This extends our earlier work on visualization of ergodic partition [Z. Levnaji? and I. Mezi?, Chaos 20, 033114 (2010)]. Our method employs the concept of Fourier time average [I. Mezi? and A. Banaszuk, Physica D 197, 101 (2004)], and is realized as a computational algorithms for visualization of periodic and quasi-periodic sets in the phase space. The complement of periodic phase space partition contains chaotic zone, and we show how to identify it. The range of method's applicability is illustrated using well-known Chirikov standard map, while its potential in illuminating higher-dimensional dynamics is presented by studying the Froeschlé map and the Extended Standard Map. PMID:26026317

  6. On quasi-periodic variations of low-energy cosmic rays observed near earth.

    PubMed

    Kudela, Karel; Langer, Ronald

    2015-06-01

    Cosmic ray (CR) may partially, especially at high altitudes, contribute to the dosimetric characteristics. Along with irregular CR variations as Forbush decreases and solar particle events are, the quasi-periodic variations may be of some relevance too. A very short review (with references to original papers) of the present knowledge of various types of such variations is presented, namely (i) diurnal wave, (ii) ?27 d variability due to the solar rotation, (iii) Rieger-type periodicity, and (iv) quasi-biennial oscillations as well as waves on longer time scales related to solar activity and to polarity of magnetic field of the Sun. Variability is illustrated in measurements of secondary CR on the ground including the high-altitude observations at Lomnický štít. PMID:25979741

  7. The Upper Kilohertz Quasi-periodic Oscillation: A Gravitationally Lensed Vertical Oscillation

    NASA Astrophysics Data System (ADS)

    Bursa, M.; Abramowicz, M. A.; Karas, V.; Klu?niak, W.

    2004-12-01

    We show that a luminous torus orbiting a Schwarzschild black hole gives rise to a periodically varying flux of radiation when oscillating along its own axis, even though the source of radiation is steady and perfectly axisymmetric. This implies that the simplest oscillation mode in an accretion flow, axisymmetric up and down motion at the meridional epicyclic frequency, may be directly observable when it occurs in the inner parts of accretion flow around neutron stars and black holes. The high-frequency modulations of the X-ray flux observed in low-mass X-ray binaries at two frequencies (twin kilohertz quasi-periodic oscillations) could then be a signature of strong gravity both because radial and meridional oscillations have different frequencies in non-Newtonian gravity and because strong gravitational deflection of light rays causes the flux of radiation to be modulated at the higher frequency.

  8. Quasi-Periodic Variations of the Pulsation Frequencies of Three White Dwarfs

    NASA Astrophysics Data System (ADS)

    Dalessio, James; Provencal, Judith L.; Shipman, Harry L.

    2015-06-01

    We report on variations of the normal mode frequencies of the pulsating DB white dwarfs EC 20058-5234 and KIC 8626021 and the pulsating DA white dwarf GD 66. We discover periodic and quasi-periodic variations of multiple normal mode frequencies that cannot be due to the presence of planetary companions. We note the possible signature of a planetary companion to EC 20058-5234 and now know that GD 66 cannot have a planet in a several AU orbit down to half a Jupiter mass. We also announce secular variations of the normal mode frequencies of all three stars that are inconsistent with cooling alone. Periodic variations in the amplitudes of many of these modes is also noted. We hypothesize that these frequency variations are caused by complex variations of the magnetic field strength and geometry, analogous to behavior observed in the Sun.

  9. Wegner-type bounds for a two-particle lattice model with a generic "rough" quasi-periodic potential

    E-print Network

    Martin Gaume

    2009-05-28

    In this paper, we consider a class of two-particle tight-binding Hamiltonians, describing pairs of interacting quantum particles on the lattice $\\Z^d$, $d\\ge 1$ subject to a common external potential $V(x)$ which we assume quasi-periodic and depending on an auxiliary parameter. Such parametric families of ergodic deterministic potentials ("grand ensembles") have been introduced earlier in \\cite{C07}, in the framework of single-particle lattice systems, where it was proved that a non-uniform analog of the Wegner bound holds true for a class of quasi-periodic grand ensembles. Using the approach proposed in \\cite{CS08}, we establish volume-dependent Wegner-type bounds for a class of quasi-periodic two-particle lattice systems with a non-random short-range interaction.

  10. Experimental realization of broadband parametric generation in a quasi-periodically poled LiTaO3.

    PubMed

    Pan, S D; Yuan, Y; Zhao, L N; Lv, X J; Zhu, S N

    2008-11-10

    We have achieved broadband parametric generation by using a quasi-periodically poled LiTaO(3) crystal as frequency converter. Tuning wavelength rang from 0.609 microm to 5.208 microm, which covered three quasi-phase-matching processes, was obtained by means of changing the pump wavelength from 0.530 microm to 1.184 microm. The experiment results are in good agreement with theory. The maximum conversion efficiency is 62% with a 10 Hz-5 ns pump source, at the average pump power of 0.5 mW. Our results exhibit a possible application of quasi-periodic superlattice in laser technology. PMID:19581947

  11. GB6 J1058+5628: A NEW QUASI-PERIODIC BL LAC OBJECT FROM THE ASIAGO PLATE ARCHIVE

    SciTech Connect

    Nesci, R., E-mail: roberto.nesci@uniroma1.i [Physics Department, University of Roma La Sapienza, Piazzale A. Moro 2, I-00185 Roma (Italy)

    2010-06-15

    We present the historic photographic light curves of three little known blazars (two BL Lac objects and one FSRQ), GB6 J1058+5628, GB6 J1148+5254, and GB6 J1209+4119, spanning a time interval of about 50 years, mostly built using the Asiago plate archive. All objects show evident long-term variability, over which short-term variations are superposed. One source, GB6 J1058+5628, showed a marked quasi-periodic variability of 1 mag on timescale of about 6.3 years, making it one of the few BL Lac objects with a quasi-periodic behavior.

  12. Periodic and Quasi -Periodic Motions of a Solar Sail Close to SL1 in the Earth -Sun System

    E-print Network

    Barcelona, Universitat de

    Periodic and Quasi - Periodic Motions of a Solar Sail Close to SL1 in the Earth - Sun System with the Sun - sail direction) the system has five equilibrium points. When we add the effect of the solar sail Abstract Solar sails are a proposed form of spacecraft propulsion using large membrane mirrors to propel

  13. Superconducting fluctuations in one-dimensional quasi-periodic ``metallic'' chains.

    NASA Astrophysics Data System (ADS)

    Grant, Paul M.

    2010-03-01

    It is well known that a purely periodic chain of odd-electron atoms, nominally expected to exhibit metallic behavior, is unstable to charge/spin spatial displacement which lowers its ground state energy by gapping its multi-degenerate Fermi surface, in this case consisting of nesting parallel sheets. It is largely for these reasons that superconductivity is not observed in highly one-dimensional metals -- it is simply energetically more favorable for CDW/SDW gaps to form, rather than a BCS state, at least one mediated by electron-phonon coupling. In this talk, we explore the hypothetical electronic properties of a nominally ``metallic'' quasi-periodic chain using both an analytical approach and computationally with density functional theory, searching for configurations which yield ``gap-lets'' sufficiently small to permit the formation of BCS pairs as the new energetically favored ground state. The particular embodiment we examine is a string of aluminum atoms with interatomic spacings determined by a Fibonacci sequence. We propose a path to attempt synthesis of such a structure for experimental examinationand perhaps leading to an entirely new class of higher temperature superconductors.

  14. Where are the X-ray quasi-periodic oscillations in active galaxies?

    NASA Astrophysics Data System (ADS)

    Vaughan, S.; Uttley, P.

    2005-09-01

    In this paper, we address the question of whether existing X-ray observations of Seyfert galaxies are sufficiently sensitive to detect quasi-periodic oscillations (QPOs) similar to those observed in the X-ray variations of Galactic black holes (GBHs). We use data from XMM-Newton and simulated data based on the best Rossi X-ray Timing Explorer (RXTE) long-term monitoring light curves to show that if X-ray QPOs are present in Seyfert X-ray light curves - with similar shapes and strengths to those observed in GBHs, but at lower frequencies commensurate with their larger black hole masses - they would be exceedingly difficult to detect. Our results offer a simple explanation for the present lack of QPO detections in Seyferts. We discuss the improvements in telescope size and monitoring patterns needed to make QPO detections feasible. The most efficient type of future observatory for searching for X-ray QPOs in active Galactic nuclei (AGN) is an X-ray All-Sky Monitor (ASM). A sufficiently sensitive ASM would be ideally suited to detect low-frequency QPOs in nearby AGN. The detection of AGN QPOs would strengthen the AGN-GBH connection, and could serve as powerful diagnostics of the black hole mass and the structure of the X-ray emitting region in AGN.

  15. Quasi-Periodic Oscillations from Low-Mass X-Ray Binaries with Neutron Stars

    E-print Network

    Jean Swank

    2004-02-21

    Before the launch of the Rossi X-ray Timing Explorer (RXTE) it was recognized that neutron star accretion disks could extend inward to very near the neutron star surface, and thus be governed by millisecond timescales. Previous missions lacked the sensitivity to detect them. The kilohertz quasi-periodic oscillations (QPO) that RXTE discovered are often, but not always, evident in the X-ray flux. In 8 years RXTE has found kilohertz signals in about a fourth of 100 low-mass X-ray binaries (LMXB) containing neutron stars. The observed power spectra have simple dominant features, the two kilohertz oscillations, a low frequency oscillation, and band-limited white noise. They vary systematically with changes in other source properties and offer the possibility of comparison with model predictions. New information from the millisecond pulsars resolves some questions about the relations of the QPO and the spin. Coherence, energy spectrum and time lag measurements have indicated systematic behaviors, which should constrain mechanisms.

  16. Quasi-periodic Oscillations Associated with Spectral Branches in RXTE Observations of Circinus X-1

    E-print Network

    Robert E. Shirey; Hale V. Bradt; Alan M. Levine; Edward H. Morgan

    1998-05-12

    We present Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 which illustrate the variety of intensity profiles associated with the 16.55 d flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average intensity of the flaring state decreased gradually over ~12 days. Fourier power density spectra for these observations show a narrow quasi-periodic oscillation (QPO) peak which shifts in frequency between 6.8 Hz and 32 Hz, as well as a broad QPO peak that remains roughly stationary at ~4 Hz. We identify these as Z-source horizontal and normal branch oscillations (HBOs/NBOs) respectively. Color-color and hardness-intensity diagrams (CDs/HIDs) show curvilinear tracks for each of the observations. The properties of the QPOs and very low frequency noise allow us to identify segments of these tracks with Z-source horizontal, normal, and flaring branches which shift location in the CDs and HIDs over the course of the 16.55 d cycle. These results contradict a previous prediction, based on the hypothesis that Cir X-1 is a high-Mdot atoll source, that HBOs should never occur in this source (Oosterbroek et al. 1995; van der Klis 1994).

  17. Kilo-Second Quasi-Periodic Oscillations in the Cataclysmic Variable DW Cancri

    E-print Network

    M. Uemura; T. Kato; R. Ishioka; R. Novak; J. Pietz

    2002-03-15

    Our photometric monitoring revealed that DW Cnc, which was originally classified as a dwarf nova (V=15--17.5), remained at a bright state of Rc=14.68+/-0.07 for 61 days. In conjunction with optical spectra lacking a strong He II emission line, we propose that the object is not a dwarf nova, but a non-magnetic nova-like variable. Throughout our monitoring, the object showed strong quasi-periodic oscillations (QPOs) with amplitudes reaching about 0.3 mag. Our period analysis yielded a power spectrum with two peaks of QPOs, whose center periods are 37.5+/-0.1 and 73.4+/-0.4 min and, furthermore, with a significant power in frequencies lower than the QPOs. DW Cnc is a unique cataclysmic variable in which kilo-second QPOs were continuously detected for 61 days. We propose two possible interpretations of DW Cnc: (i) A permanent superhumper below the period minimum of hydrogen-rich cataclysmic variables. (ii) A nova-like variable having an orbital period over 3 hours. In this case, the QPOs may be caused by trapped disk oscillations.

  18. Kilohertz quasi-periodic oscillations in low-mass X-ray binaries

    E-print Network

    M. van der Klis

    1997-04-28

    In early 1996 a series of discoveries begun with NASA's Rossi X-ray Timing Explorer of a new, up to then unknown astrophysical phenomenon. It turned out that accreting low magnetic-field neutron stars show quasi-periodic oscillations in their X-ray flux at rates of up to more than a kilohertz. These kHz QPO, now reported from eleven different systems, are among the fastest phenomena in the sky and can provide us with new information about the fundamental properties of neutron stars and help testing general relativity in the strong-field regime. If, for example, their frequencies can be identified with the Keplerian frequencies of matter in orbit around a 1.4 Solar-mass neutron star, then the radius of the star would have to be less than 15 km, which directly constrains the equation of state of bulk nuclear-density matter, and for an only slightly tighter orbit or slightly more massive neutron star the orbital radius would equal the Schwarzschild-geometry general-relativistic marginally stable orbit (12.5 km for a 1.4 Solar mass object). So far all models that have been put forward for explaining the new phenomenon have encountered problems. In this paper I review the relatively simple and highly suggestive phenomenology as it has emerged from the data up to now, and discuss some of the proposed models.

  19. Quasi-periodic oscillations discovered in the X-ray pulsar XTE J1858+034

    NASA Astrophysics Data System (ADS)

    Paul, B.; Rao, A. R.

    1998-12-01

    We have discovered low frequency quasi-periodic oscillations at 0.11 Hz in the 221 s X-ray pulsar XTE J1858+034. Among about 30 known transient X-ray pulsars this is the sixth source in which QPOs have been observed. If the QPOs are produced because of inhomogeneities in the accretion disk at the magnetospheric boundary, the low frequency of the QPOs indicate a large magnetosphere for this pulsar. Both the Keplerian frequency model and the beat frequency model are applicable for production of QPOs in this source. The QPOs and regular pulsations are found to be stronger at higher energy which favours the beat frequency model. A detailed analysis, of the QPO feature as a function of pulse phase and energy will be presented which will help in firmly deciding one of the two alternatives for the QPO phenomenon. The spectrum is hard, consisting of two components, a cut-off power law and an iron fluorescence line.

  20. SGR 1806-20: Evidence for a Superstrong Magnetic Field from Quasi-Periodic Oscillations

    NASA Astrophysics Data System (ADS)

    Vietri, Mario; Stella, Luigi; Israel, Gian Luca

    2007-06-01

    Fast quasi-periodic oscillations (QPOs; frequencies of ~20-1840 Hz) have recently been discovered in the ringing tail of giant flares from soft gamma repeaters (SGRs) when the luminosity is of order 1041-1041.5 ergs s-1. These oscillations persisted for many tens of seconds, remained coherent for up to hundreds of cycles, and were observed over a wide range of rotational phases of the neutron stars believed to host SGRs. Therefore, these QPOs must have originated from a compact, virtually nonexpanding region inside the star's magnetosphere, emitting with a very moderate degree of beaming (if at all). The fastest QPOs imply a luminosity variation of ?L/?t~=6×1043 ergs s-2, the largest luminosity variation ever observed from a compact source. It exceeds by over an order of magnitude the usual Cavallo-Fabian-Rees (CFR) luminosity variability limit for a matter-to-radiation conversion efficiency of 100%. We show that such an extreme variability can be reconciled with the CFR limit if the emitting region is immersed in a magnetic field >~1015 G at the star surface, providing independent evidence for the superstrong magnetic fields of magnetars.

  1. OBSERVABLE QUASI-PERIODIC OSCILLATIONS PRODUCED BY STEEP PULSE PROFILES IN MAGNETAR FLARES

    SciTech Connect

    D'Angelo, C. R.; Watts, A. L., E-mail: c.r.dangelo@uva.nl [Instituut Anton Pannekoek, University of Amsterdam, Amsterdam 1098 XH (Netherlands)

    2012-06-01

    Strong quasi-periodic oscillations (QPOs) in the tails of the giant gamma-ray flares seen in SGR 1806-20 and SGR 1900+14 are thought to be produced by starquakes in the flaring magnetar. However, the large fractional amplitudes (up to {approx}20%) observed are difficult to reconcile with predicted amplitudes of starquakes. Here, we demonstrate that the steeply pulsed emission profile in the tail of the giant flare can enhance the observed amplitude of the underlying oscillation, analogous to a beam of light oscillating in and out of the line of sight. This mechanism will also broaden the feature in the power spectrum and introduce power at harmonics of the oscillation. The observed strength of the oscillation depends on the amplitude of the underlying starquake, the orientation and location of the emission on the surface of the star, and the gradient of the light curve profile. While the amplification of the signal can be significant, we demonstrate that, even with uncertainties in the emission geometry, this effect is not sufficient to produce the observed QPOs. This result excludes the direct observation of a starquake and suggests that the observed variations come from modulations in the intensity of the emission.

  2. Quasi-phase-matched generation of tunable blue light in a quasi-periodic structure.

    PubMed

    Xu, Ping; Li, Kun; Zhao, Gang; Zhu, Shi-ning; Du, Yan; Ji, Shuai-hua; Zhu, Yong-yuan; Ming, Nai-ben; Luo, L; Li, K F; Cheah, K W

    2004-01-01

    We present what is to our knowledge a new approach to generating tunable blue light by cascaded nonlinear frequency conversion in a single LiTaO3 crystal. Simultaneous quasi-phase matching of an optical parametric generation process and a sum-frequency mixing process is achieved by means of structuring the crystal with a quasi-periodic optical superlattice. The spectral (wavelength tuning and bandwidth) and power characteristics of the blue-light generation are studied with a fixed-wavelength 532-nm picosecond laser and a wavelength-tunable nanosecond optical parametric oscillator (OPO) as the pump sources. By tuning the OPO wavelength, we could tune the blue output over approximately 20 nm. Temperature tuning of the blue output at a fixed pump wavelength of 532 nm was limited to approximately 1.5 nm. A maximum blue power of 15 microW was generated at a pump power of 0.5 mW, corresponding to an efficiency of 3%. PMID:14719672

  3. Quasi-periodic recurrence of large earthquakes on the southern San Andreas fault

    USGS Publications Warehouse

    Scharer, Katherine M.; Biasi, Glenn P.; Weldon, Ray J., II; Fumal, Tom E.

    2010-01-01

    It has been 153 yr since the last large earthquake on the southern San Andreas fault (California, United States), but the average interseismic interval is only ~100 yr. If the recurrence of large earthquakes is periodic, rather than random or clustered, the length of this period is notable and would generally increase the risk estimated in probabilistic seismic hazard analyses. Unfortunately, robust characterization of a distribution describing earthquake recurrence on a single fault is limited by the brevity of most earthquake records. Here we use statistical tests on a 3000 yr combined record of 29 ground-rupturing earthquakes from Wrightwood, California. We show that earthquake recurrence there is more regular than expected from a Poisson distribution and is not clustered, leading us to conclude that recurrence is quasi-periodic. The observation of unimodal time dependence is persistent across an observationally based sensitivity analysis that critically examines alternative interpretations of the geologic record. The results support formal forecast efforts that use renewal models to estimate probabilities of future earthquakes on the southern San Andreas fault. Only four intervals (15%) from the record are longer than the present open interval, highlighting the current hazard posed by this fault.

  4. An Extension of Spectral Methods to Quasi-Periodic and Multiscale Problems

    NASA Astrophysics Data System (ADS)

    Wirth, A.

    1997-04-01

    For efficiently treating quasi-periodic and multiscale problems numerically, it is here proposed to change the number of space dimensions which is then multiplied by the number of different (incommensurable or widely separated) scales occurring in the problem. Then, all calculations are performed in this higher-dimensional space. In the higher-dimensional space the problem is a standard periodic problem where, in the presence of dissipation, only the lower-order harmonics are relevant and one can thus use all the standard spectral methods for periodic functions with a relatively small number of modes. The method is validated, using the Burgers equation, and the two-dimensional linearized Navier-Stokes equation, by comparison with standard spectral or pseudo-spectral methods (in which the dimensionality of the space is not changed but very high resolution is used). For physical problems of interest in which different widely separated scales occur, standard methods require very large computer resources; the gain in storage and CPU resources, when using the "higher dimension" method, is typically proportional to the ratio of scales.

  5. SGR1806-20: evidence for a superstrong Magnetic Field from Quasi Periodic Oscillations

    E-print Network

    M. Vietri; L. Stella; G. Israel

    2007-02-22

    Fast Quasi-Periodic Oscillations (QPOs, frequencies of $\\sim 20 - 1840$ Hz) have been recently discovered in the ringing tail of giant flares from Soft Gamma Repeaters (SGRs), when the luminosity was of order $10^{41}-10^{41.5}$ erg/s. These oscillations persisted for many tens of seconds, remained coherent for up to hundreds of cycles and were observed over a wide range of rotational phases of the neutron stars believed to host SGRs. Therefore these QPOs must have originated from a compact, virtually non-expanding region inside the star's magnetosphere, emitting with a very moderate degree of beaming (if at all). The fastest QPOs imply a luminosity variation of $\\Delta L/\\Delta t \\simeq 6 \\times 10^{43}$ erg s$^{-2}$, the largest luminosity variation ever observed from a compact source. It exceeds by over an order of magnitude the usual Cavallo-Fabian-Rees (CFR) luminosity variability limit for a matter-to-radiation conversion efficiency of 100%. We show that such an extreme variability can be reconciled with the CFR limit if the emitting region is immersed in a magnetic field $\\gtrsim 10^{15}$ G at the star surface, providing independent evidence for the superstrong magnetic fields of magnetars.

  6. Probing Neutron Star Physics with Quasi-Periodic Oscillations in Magnetar Bursts

    NASA Astrophysics Data System (ADS)

    Huppenkothen, Daniela

    2015-04-01

    Neutron stars, the remnants of massive stellar explosions, are prime candidates for studying dense matter physics in conditions not accessible in the laboratory. Among the zoo of neutron star phenomena, magnetars, neutron stars with an extremely high magnetic field, are of particular interest for their spectacular bursting behaviour in X-rays and gamma-rays. They show thousands of recurrent short, bright bursts as well as some of the brightest gamma-ray events, called giant flares, ever observed on earth. The detection of quasi-periodic oscillations (QPOs) in giant flares and, more recently, in small recurrent bursts, is generally interpreted as the observable signature of global oscillations of the neutron star following a star quake. This detection has opened up the potential of neutron star seismology: probing the physical conditions in the interior of the star via the information conveyed in star quakes. In this talk, I will give an overview of observational studies of these sources, focusing on recent detections of QPOs in smaller bursts as well as results from the giant flares. I will then tie these observational results to theoretical models of the star quakes that tie observations to the neutron star interior and crust, and I will finish with an outlook of the future of magnetar seismology. DH is supported by the Moore-Sloan Data Science Environment at NYU.

  7. DISCOVERY OF QUASI-PERIODIC OSCILLATIONS IN THE RECURRENT BURST EMISSION FROM SGR 1806-20

    SciTech Connect

    El-Mezeini, Ahmed M.; Ibrahim, Alaa I., E-mail: amezeini@aucegypt.ed, E-mail: ai@aucegypt.ed, E-mail: amiae2@cam.ac.u, E-mail: ai@space.mit.ed [Department of Physics, American University in Cairo, New Cairo 11835 (Egypt)

    2010-10-01

    We present evidence for quasi-periodic oscillations (QPOs) in the recurrent outburst emission from the soft gamma repeater SGR 1806-20 using NASA's Rossi X-ray Timing Explorer (RXTE) observations. By searching a sample of 30 bursts for timing signals at the frequencies of the QPOs discovered in the 2004 December 27 giant flare from the source, we find three QPOs at 84, 103, and 648 Hz in three different bursts. The first two QPOs lie within {approx}1{sigma} from the 92 Hz QPO detected in the giant flare. The third QPO lies within {approx}9{sigma} from the 625 Hz QPO also detected in the same flare. The detected QPOs are found in bursts with different durations, morphologies, and brightness, and are vindicated by Monte Carlo simulations, which set a lower limit confidence interval {>=}4.3{sigma}. We also find evidence for candidate QPOs at higher frequencies in other bursts with lower statistical significance. The fact that we can find evidence for QPOs in the recurrent bursts at frequencies relatively close to those found in the giant flare is intriguing and can offer insight about the origin of the oscillations. We confront our finding against the available theoretical models and discuss the connection between the QPOs we report and those detected in the giant flares. The implications to the neutron star properties are also discussed.

  8. Drift-Free Position Estimation of Periodic or Quasi-Periodic Motion Using Inertial Sensors

    PubMed Central

    Latt, Win Tun; Veluvolu, Kalyana Chakravarthy; Ang, Wei Tech

    2011-01-01

    Position sensing with inertial sensors such as accelerometers and gyroscopes usually requires other aided sensors or prior knowledge of motion characteristics to remove position drift resulting from integration of acceleration or velocity so as to obtain accurate position estimation. A method based on analytical integration has previously been developed to obtain accurate position estimate of periodic or quasi-periodic motion from inertial sensors using prior knowledge of the motion but without using aided sensors. In this paper, a new method is proposed which employs linear filtering stage coupled with adaptive filtering stage to remove drift and attenuation. The prior knowledge of the motion the proposed method requires is only approximate band of frequencies of the motion. Existing adaptive filtering methods based on Fourier series such as weighted-frequency Fourier linear combiner (WFLC), and band-limited multiple Fourier linear combiner (BMFLC) are modified to combine with the proposed method. To validate and compare the performance of the proposed method with the method based on analytical integration, simulation study is performed using periodic signals as well as real physiological tremor data, and real-time experiments are conducted using an ADXL-203 accelerometer. Results demonstrate that the performance of the proposed method outperforms the existing analytical integration method. PMID:22163935

  9. Relativistic Non-Thermal Bremsstrahlung Radiation

    NASA Astrophysics Data System (ADS)

    Zekovi?, Vladimir; Arbutina, Bojan; Dobardži?, Aleksandra; Pavlovi?, Marko Z.

    2013-11-01

    By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution N(p)dp = k p-qdp. We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.

  10. Drifting Quasi-Periodic Modulation of the Fast Magnetosonic Mode: Van Allen Probe Observations

    NASA Astrophysics Data System (ADS)

    Boardsen, S. A.; Hospodarsky, G. B.; Kletzing, C.; Pfaff, R. F., Jr.; Kurth, W. S.; Wygant, J. R.; MacDonald, E.

    2014-12-01

    The fast magnetosonic mode is one of the dominant wave modes in the Earth's radiation belts. These waves influence the ring current by scattering ions in energy in the 10's of keV range, and are believed to be a heat source for radiation belt electrons. The fast magnetosonic mode observed around the Earth's inner equatorial magnetosphere sometimes exhibits quasi-periodic modulation as detected by the Van Allen probes. During each modulation the wave frequency exhibits a strong drifting (dispersive) signature characterized by a rising tone. Each tone is composed of harmonics with spacing close to the proton cyclotron frequency. The tones are band limited in frequency and mainly observed above the 20th harmonic of the local proton cyclotron frequency. We observe this modulation mainly outside the plasmapause, but it has also been observed to penetrate down to 1.5 RE. The modulation is observed up to magnetic latitudes of ±17º, at all magnetic local times, but its signatures are more pronounced on the dayside. For events where lower frequency ULF waves are detected, the period of the ULF wave is about twice the modulation period of the fast magnetosonic mode, suggesting strong wave-wave interactions. The modulation period varies from 50 to 200 s and its duration ranges from 0.2 to 3 h, with the maximum duration limited by the spacecraft orbit. We hypothesize that the rising tone is produced by changing Alfven velocities created by steepened density fluctuations due to plasma modification by an underlying ULF wave.

  11. ON THE HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS FROM BLACK HOLES

    SciTech Connect

    Erkut, M. Hakan, E-mail: m.erkut@iku.edu.tr [Department of Physics, Istanbul Kueltuer University, Atakoey Campus, Bak Latin-Small-Letter-Dotless-I rkoey 34156, Istanbul (Turkey)

    2011-12-10

    We apply the global mode analysis, which has been recently developed for the modeling of kHz quasi-periodic oscillations (QPOs) from neutron stars, to the inner region of an accretion disk around a rotating black hole. Within a pseudo-Newtonian approach that keeps the ratio of the radial epicyclic frequency {kappa} to the orbital frequency {Omega} the same as the corresponding ratio for a Kerr black hole, we determine the innermost disk region where the hydrodynamic modes grow in amplitude. We find that the radiation flux emerging from the inner disk has the highest values within the same region. Using the flux-weighted averages of the frequency bands over this region we identify the growing modes with highest frequency branches {Omega} + {kappa} and {Omega} to be the plausible candidates for the high-frequency QPO pairs observed in black hole systems. The observed frequency ratio around 1.5 can therefore be understood naturally in terms of the global free oscillations in the innermost region of a viscous accretion disk around a black hole without invoking a particular resonance to produce black hole QPOs. Although the frequency ratio ({Omega} + {kappa})/({Omega}) is found to be not sensitive to the black hole's spin which is good for explaining the high-frequency QPOs, it may work as a limited diagnostic of the spin parameter to distinguish black holes with very large spin from the slowly rotating ones. Within our model we estimate the frequency ratio of a high-frequency QPO pair to be greater than 1.5 if the black hole is a slow rotator. For fast rotating black holes, we expect the same ratio to be less than 1.5.

  12. MASS-ANGULAR-MOMENTUM RELATIONS IMPLIED BY MODELS OF TWIN PEAK QUASI-PERIODIC OSCILLATIONS

    SciTech Connect

    Toeroek, Gabriel; Bakala, Pavel; Sramkova, Eva; Stuchlik, Zdenek; Urbanec, Martin; Goluchova, Katerina, E-mail: pavel.bakala@fpf.slu.cz, E-mail: martin.urbanec@fpf.slu.cz, E-mail: zdenek.stuchlik@fpf.slu.cz, E-mail: terek@volny.cz, E-mail: sram_eva@centrum.cz [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezrucovo nam. 13, CZ-746 01 Opava (Czech Republic)

    2012-12-01

    Twin peak quasi-periodic oscillations (QPOs) appear in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. Observations of the peculiar Z-source Circinus X-1 display unusually low QPO frequencies. Using these observations, we have previously considered the relativistic precession (RP) twin peak QPO model to estimate the mass of the central NS in Circinus X-1. We have shown that such an estimate results in a specific mass-angular-momentum (M - j) relation rather than a single preferred combination of M and j. Here we confront our previous results with another binary, the atoll source 4U 1636-53 that displays the twin peak QPOs at very high frequencies, and extend the consideration to various twin peak QPO models. In analogy to the RP model, we find that these imply their own specific M - j relations. We explore these relations for both sources and note differences in the {chi}{sup 2} behavior that represent a dichotomy between high- and low-frequency sources. Based on the RP model, we demonstrate that this dichotomy is related to a strong variability of the model predictive power across the frequency plane. This variability naturally comes from the radial dependence of characteristic frequencies of orbital motion. As a consequence, the restrictions on the models resulting from observations of low-frequency sources are weaker than those in the case of high-frequency sources. Finally we also discuss the need for a correction to the RP model and consider the removing of M - j degeneracies, based on the twin peak QPO-independent angular momentum estimates.

  13. IS COMPTON COOLING SUFFICIENT TO EXPLAIN EVOLUTION OF OBSERVED QUASI-PERIODIC OSCILLATIONS IN OUTBURST SOURCES?

    SciTech Connect

    Mondal, Santanu; Chakrabarti, Sandip K.; Debnath, Dipak, E-mail: santanu@csp.res.in, E-mail: chakraba@bose.res.in, E-mail: dipak@csp.res.in [Indian Center for Space Physics, 43 Chalantika, Garia Station Road, Kolkata 700084 (India)

    2015-01-01

    In outburst sources, quasi-periodic oscillation (QPO) frequency is known to evolve in a certain way: in the rising phase, it monotonically goes up until a soft intermediate state is achieved. In the propagating oscillatory shock model, oscillation of the Compton cloud is thought to cause QPOs. Thus, in order to increase QPO frequency, the Compton cloud must collapse steadily in the rising phase. In decline phases, the exact opposite should be true. We investigate cause of this evolution of the Compton cloud. The same viscosity parameter that increases the Keplerian disk rate also moves the inner edge of the Keplerian component, thereby reducing the size of the Compton cloud and reducing the cooling timescale. We show that cooling of the Compton cloud by inverse Comptonization is enough for it to collapse sufficiently so as to explain the QPO evolution. In the two-component advective flow configuration of Chakrabarti-Titarchuk, centrifugal force-induced shock represents the boundary of the Compton cloud. We take the rising phase of 2010 outburst of Galactic black hole candidate H 1743-322 and find an estimation of variation of the ? parameter of the sub-Keplerian flow to be monotonically rising from 0.0001 to 0.02, well within the range suggested by magnetorotational instability. We also estimate the inward velocity of the Compton cloud to be a few meters per second, which is comparable to what is found in several earlier studies of our group by empirically fitting the shock locations with the time of observations.

  14. On the High-frequency Quasi-periodic Oscillations from Black Holes

    NASA Astrophysics Data System (ADS)

    Erkut, M. Hakan

    2011-12-01

    We apply the global mode analysis, which has been recently developed for the modeling of kHz quasi-periodic oscillations (QPOs) from neutron stars, to the inner region of an accretion disk around a rotating black hole. Within a pseudo-Newtonian approach that keeps the ratio of the radial epicyclic frequency ? to the orbital frequency ? the same as the corresponding ratio for a Kerr black hole, we determine the innermost disk region where the hydrodynamic modes grow in amplitude. We find that the radiation flux emerging from the inner disk has the highest values within the same region. Using the flux-weighted averages of the frequency bands over this region we identify the growing modes with highest frequency branches ? + ? and ? to be the plausible candidates for the high-frequency QPO pairs observed in black hole systems. The observed frequency ratio around 1.5 can therefore be understood naturally in terms of the global free oscillations in the innermost region of a viscous accretion disk around a black hole without invoking a particular resonance to produce black hole QPOs. Although the frequency ratio lang? + ?rang/lang?rang is found to be not sensitive to the black hole's spin which is good for explaining the high-frequency QPOs, it may work as a limited diagnostic of the spin parameter to distinguish black holes with very large spin from the slowly rotating ones. Within our model we estimate the frequency ratio of a high-frequency QPO pair to be greater than 1.5 if the black hole is a slow rotator. For fast rotating black holes, we expect the same ratio to be less than 1.5.

  15. Measuring mass and angular momentum of black holes with high-frequency quasi-periodic oscillations

    E-print Network

    B. Aschenbach

    2004-06-24

    3:2 and/or 3:1 twin high frequency quasi-periodic oscillations (HFQPOs) have been measured for the three microquasars GRO J1655-40, XTE J1550-564 and GRS 1915+105. For a test particle orbiting a rotating black on a stable circular orbit there exist two different orbits at which the vertical and radial epicyclic oscillations are in either a 3:1 or 3:2 parametric resonance for any choice of the black hole angular momentum $a$. If the two orbits are required to be frequency commensurable Keplerian orbits there is only one solution for the two orbit radii and $a$. This model predicts that the microquasars have the same $a$, and it predicts their black hole masses on the basis of the measured HFQPOs in agreement with the dynamically determined masses. Application of this model to the Galactic Center black hole Sgr A* using the recently measured QPOs (Genzel et al., 2003, Aschenbach et al., 2004) leads to a black hole mass of (3.28 +/- 0.13) x 10^6 M_odot, and the same $a$ as for the microquasars. The possibility that all four sources have $a$=0.99616 suggests that this value is the upper limit of $a$ imposed by general relativity. The same value for the lower orbit radius and the same value for $a$ are also suggested by an analysis of the general relativistic expression for the radial gradient of the orbital velocity, which changes sign in a narrow annular region around the lower orbit when $a$>0.9953.

  16. On the high coherence of kilo-Hz Quasi-Periodic Oscillations

    E-print Network

    D. Barret; W. Kluzniak; J. F. Olive; S. Paltani; G. K. Skinner

    2004-12-16

    We have carried out a systematic study of the properties of the kilo-Hertz quasi-periodic oscillations (QPO) observed in the X-ray emission of the neutron star low-mass X-ray binary 4U1608-52, using archival data obtained with the Rossi X-ray Timing Explorer. We have investigated the quality factor, Q, of the oscillations (defined as the ratio of the frequency of the QPO peak to its full width at half maximum). In order to minimise the effect of long-term frequency drifts, power spectra were computed over the shortest times permitted by the data statistics. We show that the high Q of ~200 reported by Berger et al. (1996) for the lower frequency kilo-Hz QPO in one of their observations is by no means exceptional, as we observe a mean Q value in excess of 150 in 14 out of the 21 observations analysed and Q can remain above 200 for thousands of seconds. The frequency of the QPO varies over the wide range 560--890 Hz and we find a systematic trend for the coherence time of the QPO, estimated as tau=Q /(pi nu), to increase with the frequency, up to a maximum level at ~ 800 Hz, beyond which it appears to decrease, at frequencies where the QPO weakens. There is a more complex relationship between tau and the QPO root mean squared amplitude (RMS), in which positive and negative correlations can be found. A higher-frequency QPO, revealed by correcting for the frequency drift of the 560-890 Hz one, has a much lower Q (~10) which does not follow the same pattern. We discuss these results in the framework of competing QPO models and show that those involving clumps orbiting within or above the accretion disk are ruled out.

  17. STEREO observations of quasi-periodically driven high velocity outflows in polar plumes

    NASA Astrophysics Data System (ADS)

    McIntosh, S. W.; Innes, D. E.; de Pontieu, B.; Leamon, R. J.

    2010-02-01

    Context. Plumes are one of the most ubiquitous features seen at the limb in polar coronal holes and are considered to be a source of high density plasma streams to the fast solar wind. Aims: We analyze STEREO observations of plumes and aim to reinterpret and place observations with previous generations of EUV imagers within a new context that was recently developed from Hinode observations. Methods: We exploit the higher signal-to-noise, spatial and temporal resolution of the EUVI telescopes over that of SOHO/EIT to study the temporal variation of polar plumes in high detail. We employ recently developed insight from imaging (and spectral) diagnostics of active region, plage, and quiet Sun plasmas to identify the presence of apparent motions as high-speed upflows in magnetic regions as opposed to previous interpretations of propagating waves. Results: In almost all polar plumes observed at the limb in these STEREO sequences, in all coronal passbands, we observe high speed jets of plasma traveling along the structures with a mean velocity of 135 km s-1 at a range of temperatures from 0.5-1.5 MK. The jets have an apparent brightness enhancement of ~5% above that of the plumes they travel on and repeat quasi-periodically, with repeat-times ranging from five to twenty-five minutes. We also notice a very weak, fine scale, rapidly evolving, but ubiquitous companion of the plumes that covers the entire coronal hole limb. Conclusions: The observed jets are remarkably similar in intensity enhancement, periodicity and velocity to those observed in other magnetic regions of the solar atmosphere. They are multi-thermal in nature. We infer that the jets observed on the plumes are a source of heated mass to the fast solar wind. Further, based on the previous results that motivated this study, we suggest that these jets originated in the upper chromosphere. Five movies are only available in electronic form at http://www.aanda.org

  18. QUASI-PERIODIC PROPAGATING SIGNALS IN THE SOLAR CORONA: THE SIGNATURE OF MAGNETOACOUSTIC WAVES OR HIGH-VELOCITY UPFLOWS?

    SciTech Connect

    De Pontieu, Bart [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States); McIntosh, Scott W., E-mail: bdp@lmsal.co, E-mail: mscott@ucar.ed [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States)

    2010-10-20

    Since the discovery of quasi-periodic propagating oscillations with periods of order 3-10 minutes in coronal loops with TRACE and SOHO/EIT (and later with STEREO/EUVI and Hinode/EIS), they have been almost universally interpreted as evidence for propagating slow-mode magnetoacoustic waves in the low plasma {beta} coronal environment. Here we show that this interpretation is not unique, and that for coronal loops associated with plage regions (as opposed to sunspots), the presence of magnetoacoustic waves may not be the only cause for the observed quasi-periodicities. We focus instead on the ubiquitous, faint upflows at 50-150 km s{sup -1} that were recently discovered as blueward asymmetries of spectral line profiles in footpoint regions of coronal loops, and as faint disturbances propagating along coronal loops in EUV/X-ray imaging time series. These faint upflows are most likely driven from below and have been associated with chromospheric jets that are (partially) rapidly heated to coronal temperatures at low heights. These two scenarios (waves versus flows) are difficult to differentiate using only imaging data, but careful analysis of spectral line profiles indicates that faint upflows are likely responsible for some of the observed quasi-periodic oscillatory signals in the corona. We show that recent EIS measurements of intensity and velocity oscillations of coronal lines (which had previously been interpreted as direct evidence for propagating waves) are actually accompanied by significant oscillations in the line width that are driven by a quasi-periodically varying component of emission in the blue wing of the line. This faint additional component of blue-shifted emission quasi-periodically modulates the peak intensity and line centroid of a single Gaussian fit to the spectral profile with the same small amplitudes (respectively a few percent of background intensity and a few km s{sup -1}) that were previously used to infer the presence of slow-mode magnetoacoustic waves. Our results indicate that it is possible that a significant fraction of the quasi-periodicities observed with coronal imagers and spectrographs that have previously been interpreted as propagating magnetoacoustic waves are instead caused by these upflows. The different physical cause for coronal oscillations would significantly impact the prospects of successful coronal seismology using propagating disturbances in coronal loops.

  19. Phase-rectified signal averaging for the detection of quasi-periodicities and the prediction of cardiovascular risk

    NASA Astrophysics Data System (ADS)

    Kantelhardt, Jan W.; Bauer, Axel; Schumann, Aicko Y.; Barthel, Petra; Schneider, Raphael; Malik, Marek; Schmidt, Georg

    2007-03-01

    We present the phase-rectified signal averaging (PRSA) method as an efficient technique for the study of quasi-periodic oscillations in noisy, nonstationary signals. It allows the assessment of system dynamics despite phase resetting and noise and in relation with either increases or decreases of the considered signal. We employ the method to study the quasi-periodicities of the human heart rate based on long-term ECG recordings. The center deflection of the PRSA curve characterizes the average capacity of the heart to decelerate (or accelerate) the cardiac rhythm. It can be measured by a central wavelet coefficient which we denote as deceleration capacity (DC). We find that decreased DC is a more precise predictor of mortality in survivors of heart attack than left ventricular ejection fraction, the current "gold standard" risk predictor. In addition, we discuss the dependence of the DC parameter on age and on diabetes.

  20. Extracting multipole moments of neutron stars from quasi-periodic oscillations in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Boshkayev, Kuantay; Rueda, Jorge; Muccino, Marco

    2015-06-01

    We consider the kilohertz quasi-periodic oscillations of low-mass X-ray binaries within the Hartle-Thorne spacetime. We show that the interpretation of the epicyclic frequencies of this spacetime with the observed kilohertz quasi-periodic oscillations, within the Relativistic Precession Model, allows us to extract the total mass M, angular momentum J, and quadrupole moment Q of the compact object in a low-mass X-ray binary. We exemplify this fact by analyzing the data of the Z-source GX 5-1. We show that the extracted multipole structure of the compact component of this source deviates from the one expected from a Kerr black hole and instead it points to a neutron star explanation.

  1. Observations of quasi-periodic oscillations from GX 5 - 1 and Cygnus X-2 with the Einstein (HEAO 2) Observatory

    NASA Technical Reports Server (NTRS)

    Elsner, R. F.; Weisskopf, M. C.; Darbro, W.; Ramsey, B. D.; Williams, A. C.

    1986-01-01

    The bright galactic bulge X-ray source GX 5 - 1 was observed in April 1979 with the Monitor Proportional Counter on board the Einstein (HEAO 2) Observatory. Analysis of the high time resolution data from the Time Interval Processor confirms the recent Exosat discovery of quasi-periodic oscillations in the X-ray emission from GX 5 - 1. In addition, the summed 0.4 s power spectrum shows the low-frequency red noise component also discovered in the Exosat data. Low-frequency structure is also clearly present in data taken from the bright galaxtic X-ray source Cyg X-2 in December 1978. The expected power spectrum for quasi-periodic oscillations was calculated, including the low-frequency red noise component, using a simple shot noise model with oscillating shots.

  2. Kilohertz Quasi-periodic Oscillations in Neutron Star Binaries Modeled as Keplerian Oscillations in a Rotating Frame of Reference

    Microsoft Academic Search

    Vladimir Osherovich; Lev Titarchuk

    1999-01-01

    Since the discovery of kHz quasi-periodic oscillations (QPOs) in neutron star binaries, the difference between peak frequencies of two modes in the upper part of the spectrum, i.e., Deltaomega=omega_h-omega_K has been studied extensively. The idea that Deltaomega is constant and (as a beat frequency) is related to the rotational frequency of the neutron star has been tested previously. The observed

  3. The quasi-periodic behavior of rainfall variability in Africa and its relationship to the southern oscillation

    Microsoft Academic Search

    Sharon E. Nicholson; Dara Entekhabi

    1986-01-01

    The temporal characteristics of rainfall variability in Africa are examined using departure series for 84 regions of the continent and five larger-scale zones. The forms of non-randomness which are investigated include linear trends, persistence and quasi-periodic fluctuations. No long-term trends in African rainfall are evident. In some sectors, most noteably along the Benguela coast and equatorial Africa, rainfall anomalies tend

  4. Diffusive-Compression Acceleration and Turbulent Diffusion of Cosmic Rays in Quasi-periodic and Turbulent Flows

    Microsoft Academic Search

    G. M. Webb; C. M. Ko; G. P. Zank; J. R. Jokipii

    2003-01-01

    Multiple scale perturbation methods are used to study the transport and acceleration of energetic charged particles in quasi-periodic, fluid velocity structures in one, two, or three space dimensions, with spatial period lu, where lu is much less than the diffusion scale length ld=kappa0\\/u0 and kappa0 and u0 are characteristic values of the energetic particle diffusion coefficients and fluid speed, respectively.

  5. Electromagnetic properties of periodic and quasi-periodic one-dimensional, metallo-dielectric photonic band gap structures

    Microsoft Academic Search

    C. Sibilia; M. Scalora; M. Centini; M. Bertolotti; M. J. Bloemer; C. M. Bowden

    1999-01-01

    We discuss some of the electromagnetic properties of one-dimensional, metallo-dielectric photonic band gap structures. In our considerations, we include discussions of the transmissive and reflective properties of multilayer stacks, and the density of electromagnetic field modes for the structure. In particular, we highlight and contrast the role of quasi-periodic structures with respect to periodic structures, in the form of Cantor

  6. TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. III. QUASI-PERIODIC VARIABILITY

    SciTech Connect

    Johannsen, Tim [Physics Department, University of Arizona, 1118 East 4th Street, Tucson, AZ 85721 (United States); Psaltis, Dimitrios, E-mail: timj@physics.arizona.edu, E-mail: dpsaltis@email.arizona.edu [Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2011-01-01

    According to the no-hair theorem, astrophysical black holes are uniquely described by their masses and spins. An observational test of the no-hair theorem can be performed by measuring at least three different multipole moments of the spacetime of a black hole and verifying whether their values are consistent with the unique combinations of the Kerr solution. In this paper, we study quasi-periodic variability observed in the emission from black holes across the electromagnetic spectrum as a test of the no-hair theorem. We derive expressions for the Keplerian and epicyclic frequencies in a quasi-Kerr spacetime, in which the quadrupole moment is a free parameter in addition to mass and spin. We show that, for moderate spins, the Keplerian frequency is practically independent of small deviations of the quadrupole moment from the Kerr value, while the epicyclic frequencies exhibit significant variations. We apply this framework to quasi-periodic oscillations (QPOs) in black hole X-ray binaries in two different scenarios. In the case that a pair of QPOs can be identified as the fundamental g- and c-modes in the accretion disk, we show that the no-hair theorem can be tested in conjunction with an independent mass measurement. If pairs of oscillations are identified with non-parametric resonance of dynamical frequencies in the accretion disk, then testing the no-hair theorem also requires an independent measurement of the black hole spin. In addition, we argue that VLBI observations of Sgr A* may test the no-hair theorem through a combination of imaging observations and the detection of quasi-periodic variability.

  7. Analysis of continuously distorted quasi-periodic images: two-dimensional reconstruction of S layers of cyanobacteria

    NASA Astrophysics Data System (ADS)

    Krzyzanek, Vladislav

    2000-04-01

    Methods for the analysis of continuously distorted quasi- periodic images are improved. Especially techniques of 2D reconstruction are studied. The locally normalized correlation is used in the correlation-averaging method. To eliminate image distortion the function of the distortion is approximated step by step by the linear fractional function or by the Lagrange interpolation polynomials. The modification of the methods is illustrated in figures of cyanobacterial S layers, namely, on negatively strained S layers of Synechocystis aquatilis Kovacik 1990/8 and Microcystis aeruginosa Hindak 1971/1 and the metal-shadowed S layer of Microcystis cf. wesenbergii Bitov 1994.

  8. Intensity-dependent quasi-periodic oscillations in the X-ray flux of GX5 - 1

    NASA Technical Reports Server (NTRS)

    Van Der Klis, M.; Jansen, F.; Van Paradijs, J.; Van Den Heuvel, E. P. J.; Lewin, W. H. G.

    1985-01-01

    The X-ray flux of the bright galactic bulge source GX5 - 1 shows intensity-dependent quasi-periodic oscillations between 20 and 40 Hz, appearing as a broad peak in the power spectrum whose centroid frequency, width, and integrated excess power strongly depend on the source intensity. The strength and steepness of low-frequency noise present in the power spectra below 15 Hz also depend on the source intensity. No evidence is found for coherent X-ray pulsations between 0.5 and 2000 Hz. Possible mechanisms to explain these new phenomena are discussed.

  9. Foldover, quasi-periodicity, spin-wave instabilities in ultra-thin films subject to RF fields

    NASA Astrophysics Data System (ADS)

    d'Aquino, M.; Bertotti, G.; Serpico, C.; Mayergoyz, I. D.; Bonin, R.; Guida, G.

    2007-09-01

    We study magnetization dynamics in a uniaxial ultra-thin ferromagnetic disk subject to spatially uniform microwave external fields. The rotational invariance of the system is such that the only admissible spatially uniform steady states are periodic ( P-modes) and quasi-periodic ( Q-modes) modes. The stability of P-modes versus spatially uniform and nonuniform perturbations is studied by using spin-wave analysis and the instability diagram for all possible P-modes is computed. The predictions of the spin-wave analysis are compared with micromagnetic simulations.

  10. Omnidirectional photonic band gaps enlarged by Fibonacci quasi-periodic one-dimensional ternary superconductor photonic crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Liu, Shao-Bin; Kong, Xiang-Kun; Bian, Bo-Rui; Dai, Yi

    2012-12-01

    First two omnidirectional photonic band gaps (OBGs) realized by one-dimensional (1D) Fibonacci quasi-periodic structure which is composed of superconductor and two kinds of isotropic dielectric are theoretically studied by the transfer matrix method (TMM). From the numerical results, it has been shown that such OBGs are insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency ranges and central frequencies of OBGs cease to change with increasing Fibonacci order, but vary with the ambient temperature of system and the thickness of the superconductor, respectively. The bandwidths of OBGs can be notably enlarged. The damping coefficient of superconductor layers has no effect on the frequency ranges of OBGs. Those OBGs originate from a Bragg gap in contrast to zero-n˜ gap or single negative (negative permittivity or negative permeability) gap. It has been proved that Fibonacci quasi-periodic 1D ternary superconductor dielectric photonic crystals (SDPCs) have a superior feature in the enhancement of OBGs frequency ranges compared with the conventional binary dielectric photonic crystals (DPCs).

  11. Fuel injector utilizing non-thermal plasma activation

    DOEpatents

    Coates, Don M. (Santa Fe, NM); Rosocha, Louis A. (Los Alamos, NM)

    2009-12-01

    A non-thermal plasma assisted combustion fuel injector that uses an inner and outer electrode to create an electric field from a high voltage power supply. A dielectric material is operatively disposed between the two electrodes to prevent arcing and to promote the formation of a non-thermal plasma. A fuel injector, which converts a liquid fuel into a dispersed mist, vapor, or aerosolized fuel, injects into the non-thermal plasma generating energetic electrons and other highly reactive chemical species.

  12. Electronic properties of a quasi-periodic array of tight binding rings immersed in a magnetic field

    NASA Astrophysics Data System (ADS)

    Sengupta, Sheelan; Chakrabarti, Arunava

    2004-08-01

    Electronic properties of model mesoscopic rings of two different sizes placed in contact with each other in a quasi-periodic Fibonacci sequence have been examined within the tight binding framework. The array of the rings is immersed in a constant magnetic field. The resonant one electron transport is analysed for selected sizes of the rings. It is found that the resonance is a result of a subtle positional correlation, sometimes revealed only when the field assumes special values. The energy eigenvalues at resonance all correspond to a six-cycle of the full matrix map of the Fibonacci array of rings. Interestingly, we find that for a certain combination of the rings, the charge density at the band centre displays a cross-over, going from a perfectly extended (even periodic) character to a fractal behavior as a function of the external field.

  13. Coherent transport in linear arrays of quantum dots: The effects of period doubling and of quasi-periodicity

    NASA Astrophysics Data System (ADS)

    Bakhtiari, M. R.; Vignolo, P.; Tosi, M. P.

    2005-09-01

    We evaluate the phase-coherent transport of electrons along linear structures of varying length, which are made from two types of potential wells set in either a periodic or a Fibonacci quasi-periodic sequence. The array is described by a tight-binding Hamiltonian and is reduced to an effective dimer by means of a decimation-renormalization method, extended to allow for connection to external metallic leads, and the transmission coefficient is evaluated in a T-matrix-scattering approach. Parallel behaviors are found for the energy dependence of the density of electron states and of the transmittivity of the array. In particular, we explicitly show that on increasing its length the periodic array undergoes a metal-insulator transition near single occupancy per dot, whereas prominent pseudo-gaps emerge away from the band center in the Fibonacci-ordered array.

  14. Twin peak quasi-periodic oscillations and the kinematics of orbital motion in a curved space-time

    E-print Network

    Claudio Germanà

    2012-11-14

    Twin peak high frequency quasi-periodic oscillations (HF QPOs) observed in the power spectra of Low Mass X-ray Binaries (LMXBs), with either a black hole or a neutron star, have central frequencies that are typical of the orbital motion time-scale close to the compact object. Thus, twin HF QPOs might carry the fingerprint of physical effects in a strongly curved space-time. We study the azimuth phase \\phi(t) for orbital motion in the Schwarzschild metric and calculate the power spectra to check whether they display the features seen in the observed ones. We show that the timing of \\phi(t) on non-closed orbits can account for the observed twin peak HF QPOs. The uppermost couple of peaks in frequency has the lower peak that corresponds to the azimuthal frequency \

  15. Quasi-periodic oscillations discovered in the new X-ray pulsar XTE J1858+034

    NASA Astrophysics Data System (ADS)

    Paul, B.; Rao, A. R.

    1998-09-01

    We report the discovery of low frequency quasi-periodic oscillations centered at 0.11 Hz in the newly discovered 221 s X-ray pulsar XTE J1858+034. Among about 30 known transient X-ray pulsars this is the sixth source in which QPOs have been observed. If the QPOs are produced because of inhomogeneities in the accretion disk at the magnetospheric boundary, the low frequency of the QPOs indicate a large magnetosphere for this pulsar. Both the Keplerian frequency model and the beat frequency model are applicable for production of QPOs in this source. The QPOs and regular pulsations are found to be stronger at higher energy which favours the beat frequency model. The magnetic field of the pulsar is calculated as a function of its distance. The energy spectrum is found to be very hard, consisting of two components, a cut-off power law and an iron fluorescence line.

  16. NEAR-INFRARED AND X-RAY QUASI-PERIODIC OSCILLATIONS IN NUMERICAL MODELS OF Sgr A*

    SciTech Connect

    Dolence, Joshua C.; Gammie, Charles F.; Shiokawa, Hotaka [Astronomy Department, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Noble, Scott C., E-mail: jdolence@astro.princeton.edu [Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, 78 Lomb Memorial Dr, Rochester, NY 14623 (United States)

    2012-02-10

    We report transient quasi-periodic oscillations (QPOs) on minute timescales in relativistic, radiative models of the galactic center source Sgr A*. The QPOs result from nonaxisymmetric m = 1 structure in the accretion flow excited by MHD turbulence. Near-infrared (NIR) and X-ray power spectra show significant peaks at frequencies comparable to the orbital frequency at the innermost stable circular orbit (ISCO) f{sub o} . The excess power is associated with inward propagating magnetic filaments inside the ISCO. The amplitudes of the QPOs are sensitive to the electron distribution function. We argue that transient QPOs appear at a range of frequencies in the neighborhood of f{sub o} and that the power spectra, averaged over long times, likely show a broad bump near f{sub o} rather than distinct, narrow QPO features.

  17. Discovery of new quasi-periodic oscillations in the X-ray transient source V~0332+53

    E-print Network

    J. L. Qu; S. Zhang; L. Song; M. Falanga

    2005-08-25

    We report the discovery of a new quasi-period oscillation (QPO) at 0.22 Hz, centered on the source spin frequency of the high mass X-ray binary system V~0332+53 when the source was observed during its November 2004/March 2005 outburst by {\\em RXTE}. Besides this new QPO, we also detected the known 0.05 Hz QPO. Both the 0.22 and 0.05 Hz QPOs stand out clearly at a mid-flux level of the outburst within January 15--19 2005, and later at an even lower flux level as the width of 0.22 Hz QPO drops. No evolution of the centroid frequency with the flux is seen in either QPO. The rms value below 10 keV is around 4--6% for both QPOs and decreases at higher energies. We discuss our results in the context of current QPO models.

  18. High-Frequency Quasi-Periodic Oscillations in the Black Hole X-Ray Transient XTE J1650-500

    NASA Technical Reports Server (NTRS)

    Holman, Jeroen; Klein-Wolt, Marc; Rossi, Sabrina; Miller, Jon M.; Wijnands, Rudy; Belloni, Tomaso; VanDerKlis, Michiel; Lewin, Walter H. G.

    2003-01-01

    We report the detection of high-frequency variability in the black hole X-ray transient XTE 51650-500. A quasi-periodic oscillation (QPO) was found at 250 Hz during a transition from the hard to the soft state. We also detected less coherent variability around 50 Hz that disappeared when the 250 Hz QPO showed up. There are indications that when the energy spectrum hardened the QPO frequency increased from approx. 110 to approx. 270 Hz, although the observed frequencies are also consistent with being 1 : 2 : 3 harmonics of each other. Interpreting the 250 Hz as the orbital frequency at the innermost stable orbit around a Schwarzschild black hole leads to a mass estimate of 8.2 solar mass. The spectral results by Miller et al., which suggest considerable black hole spin, would imply a higher mass.

  19. Quasi-periodic motions in a special class of dynamical equations with dissipative effects: a pair of detection methods

    E-print Network

    Ugo Locatelli; Letizia Stefanelli

    2014-07-18

    We consider a particular class of equations of motion, generalizing to n degrees of freedom the "dissipative spin--orbit problem", commonly studied in Celestial Mechanics. Those equations are formulated in a pseudo-Hamiltonian framework with action-angle coordinates; they contain a quasi-integrable conservative part and friction terms, assumed to be linear and isotropic with respect to the action variables. In such a context, we transfer two methods determining quasi-periodic solutions, which were originally designed to analyze purely Hamiltonian quasi-integrable problems. First, we show how the frequency map analysis can be adapted to this kind of dissipative models. Our approach is based on a key remark: the method can work as usual, by studying the behavior of the angular velocities of the motions as a function of the so called "external frequencies", instead of the actions. Moreover, we explicitly implement the Kolmogorov's normalization algorithm for the dissipative systems considered here. In a previous article, we proved a theoretical result: such a constructing procedure is convergent under the hypotheses usually assumed in KAM theory. In the present work, we show that it can be translated to a code making algebraic manipulations on a computer, so to calculate effectively quasi-periodic solutions on invariant tori. Both the methods are carefully tested, by checking that their predictions are in agreement, in the case of the so called "dissipative forced pendulum". Furthermore, the results obtained by applying our adaptation of the frequency analysis method to the dissipative standard map are compared with some existing ones in the literature.

  20. Quasi-periodic oscillations in accreting magnetic white dwarfs. II. The asset of numerical modelling for interpreting observations

    NASA Astrophysics Data System (ADS)

    Busschaert, C.; Falize, É.; Michaut, C.; Bonnet-Bidaud, J.-M.; Mouchet, M.

    2015-07-01

    Context. Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. The high magnetic field strength leads to the formation of an accretion column instead of an accretion disk. High-energy radiation coming from those objects is emitted from the column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. Aims: We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. Methods: The radiation hydrodynamics code Hades was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. Synthetic light curves and X-ray spectra were extracted from numerical simulations. A fast Fourier analysis was performed on the simulated light curves. The oscillation frequencies and amplitudes in the X-ray and optical domains are studied to compare those numerical results to observational ones. Different dimensional formulae were developed to complete the numerical evaluations. Results: The complete characterization of the emitting region is described for the two main radiative regimes: when only the bremsstrahlung losses and when both cyclotron and bremsstrahlung losses are considered. The effect of the non-linear cooling instability regime on the accretion column behaviour is analysed. Variation in luminosity on short timescales (~1 s quasi-periodic oscillations) is an expected consequence of this specific dynamic. The importance of secondary shock instability on the quasi-periodic oscillation phenomenon is discussed. The stabilization effect of the cyclotron process is confirmed by our numerical simulations, as well as the power distribution in the various modes of oscillation.

  1. TOPICAL REVIEW: Non-thermal atmospheric pressure discharges

    Microsoft Academic Search

    A. Fridman; A. Chirokov; A. Gutsol

    2005-01-01

    There has been considerable interest in non-thermal atmospheric pressure discharges over the past decade due to the increased number of industrial applications. Diverse applications demand a solid physical and chemical understanding of the operational principals of such discharges. This paper focuses on the four most important and widely used varieties of non-thermal discharges: corona, dielectric barrier, gliding arc and spark

  2. Periodic and quasi-periodic solutions for multi-instabilities involved in brake squeal N. Coudeyrasa,b, S. Nacivetb and J-J. Sinoua

    E-print Network

    Paris-Sud XI, Université de

    to the disc brake squeal phenomenon. Firstly, finite element models of a pad and a disc are reduced to includePeriodic and quasi-periodic solutions for multi-instabilities involved in brake squeal N Citro¨en, 18 rue des Fauvelles, 92250 La Garenne Colombes, France. Keywords : Brake squeal, multi

  3. The effects of periodic and quasi-periodic orders on the photonic bandgap structures of microring coupled-resonator optical waveguides.

    PubMed

    Ang, Thomas Y L; Chin, Mee Koy

    2009-03-30

    We present a coupling matrix formalism to investigate the effects of periodic and quasi-periodic orders on the photonic bandgap (PBG) structures of coupled-resonator optical waveguides (CROWs) based on microring resonators. For the periodic order case, size-tuned defects are introduced at periodic locations among the regular rings, which are size-untuned, to form a periodic ordered CROW system. The periodic coupled defects result in multiple localization states that lead to the formation of mini-defect bands and mini-PBGs within the PBG of a defect-free CROW. The position and number of such mini-defect bands depend on the size tuning of the defects. For the quasi-periodic order case, the arrangement of the defects and the regular rings in the ring cascade is an intermediate between periodic order and randomness, thus forming a quasi-periodic ordered CROW system. The effects of quasi-periodicity on the PBG structures are illustrated using the Fibonacci sequences, which result in a single high-Q localized state to appear that gradually transits to a mini-band within a wide photonic stop band as the number of lattice cells increases. PMID:19333282

  4. Quasi-periodic oscillations in accreting magnetic white dwarfs I. Observational constraints in X-ray and optical

    E-print Network

    Bonnet-Bidaud, J M; Busschaert, C; Falize, E; Michaut, C

    2015-01-01

    Quasi-periodic oscillations (QPOs) are observed in the optical flux of some polars with typical periods of 1 to 3 s but none have been observed yet in X-rays where a significant part of the accreting energy is released. QPOs are expected and predicted from shock oscillations. Most of the polars have been observed by the XMM-Newton satellite. We made use of the homogeneous set of observations of the polars by XMM-Newton to search for the presence of QPOs in the (0.5-10 keV) energy range and to set significant upper limits for the brightest X-ray polars. We extracted high time-resolution X-ray light curves by taking advantage of the 0.07 sec resolution of the EPIC-PN camera. Among the 65 polars observed with XMM-Newton from 1998 to 2012, a sample of 24 sources was selected on the basis of their counting rate in the PN instrument to secure significant limits. We searched for QPOs using Fast Fourier Transform (FFT) methods and defined limits of detection using statistical tools. Among the sample surveyed, none sh...

  5. Detecting Long-Duration Narrow-Band Gravitational Wave Transients Associated with Soft Gamma Repeater Quasi-Periodic Oscillations

    E-print Network

    Murphy, David; Raffai, Peter; Bartos, Imre; Khan, Rubab; Marka, Zsuzsa; Matone, Luca; Redwine, Keith; Marka, Szabolcs

    2013-01-01

    We have performed an in-depth concept study of a gravitational wave data analysis method which targets repeated long quasi-monochromatic transients (triggers) from cosmic sources. The algorithm concept can be applied to multi-trigger data sets in which the detector-source orientation and the statistical properties of the data stream change with time, and does not require the assumption that the data is Gaussian. Reconstructing or limiting the energetics of potential gravitational wave emissions associated with quasi-periodic oscillations (QPOs) observed in the X-ray lightcurve tails of soft gamma repeater flares might be an interesting endeavour of the future. Therefore we chose this in a simplified form to illustrate the flow, capabilities, and performance of the method. We investigate performance aspects of a multi-trigger based data analysis approach by using O(100 s) long stretches of mock data in coincidence with the times of observed QPOs, and by using the known sky location of the source. We analytical...

  6. Quasi-periodic Fibonacci and periodic one-dimensional hypersonic phononic crystals of porous silicon: Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Aliev, Gazi N.; Goller, Bernhard

    2014-09-01

    A one-dimensional Fibonacci phononic crystal and a distributed Bragg reflector were constructed from porous silicon. The structures had the same number of layers and similar acoustic impedance mismatch, and were electrochemically etched in highly boron doped silicon wafers. The thickness of the individual layers in the stacks was approximately 2 ?m. Both types of hypersonic band gap structure were studied by direct measurement of the transmittance of longitudinal acoustic waves in the 0.1-2.6 GHz range. Acoustic band gaps deeper than 50 dB were detected in both structures. The experimental results were compared with model calculations employing the transfer matrix method. The acoustic properties of periodic and quasi-periodic structures in which half-wave retarding bi-layers do not consist of two quarter-wave retarding layers are discussed. The strong correlation between width and depth of gaps in the transmission spectra is demonstrated. The dominant mechanisms of acoustic losses in porous multilayer structures are discussed. The elastic constants remain proportional over our range of porosity, and hence, the Grüneisen parameter is constant. This simplifies the expression for the porosity dependence of the Akhiezer damping.

  7. Quasi-Periodic Oscillations in Short Recurring Bursts of the Soft-Gamma Repeater J1550-5418

    E-print Network

    Huppenkothen, Daniela; Watts, Anna L; Heil, Lucy; van der Klis, Michiel; van der Horst, Alexander J; Kouveliotou, Chryssa; Baring, Matthew G; Gogus, Ersin; Granot, Jonathan; Kaneko, Yuki; Lin, Lin; von Kienlin, Andreas; Younes, George

    2014-01-01

    The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. The scarcity of giant flares makes a search for QPOs in the shorter, far more numerous bursts from Soft Gamma Repeaters (SGRs) desirable. In Huppenkothen et al (2013), we developed a Bayesian method for searching for QPOs in short magnetar bursts, taking into account the effects of the complicated burst structure, and have shown its feasibility on a small sample of bursts. Here, we apply the same method to a much larger sample from a burst storm of 286 bursts from SGR J1550-5418. We report a candidate signal at 260 Hz in a search of the individual bursts, which is fairly broad. We also find two QPOs at 93 Hz and one at 127 Hz, when averaging periodograms from a number of bursts in individual triggers, at frequencies close to QPOs previously observed in magnetar giant flares. Finally, for the first time, we explore the overall burst variability in the sample, and report a weak...

  8. Cluster observations of quasi-periodic impulsive signatures in the dayside northern lobe: High-latitude flux transfer events?

    NASA Technical Reports Server (NTRS)

    Thompson, S. M.; Kivelson, M. G.; Khurana, K. K.; Balogh, A.; Reme, H.; Fazakerley, A. N.; Kistler, L. M.

    2004-01-01

    We report on a series of quasi-periodic reversals in GSM B(sub Z) observed by the four Cluster spacecraft in the northern dayside lobe poleward of the cusp on 23 February 2001. During an interval of about 35 min, multiple reversals (negative to positive) in B(sub Z) of approximately 1-min duration with an approximate 8-min recurrence time were observed. The individual structures do not resemble low-latitude flux transfer events (FTE) [Russell and Elphic, 1979] but the 8-min recurrence frequency suggests that intermittent reconnection may be occurring .Measurements (appropriately lagged) of the solar wind at ACE show that the IMF was southward-oriented with a strong B(sub X) and that a modest dynamic pressure increased as the events started. The multi-point observations afforded by the Cluster spacecraft were used to infer the motion (direction and speed) of the observed magnetic field reversals. The associated currents were also calculated and they are consistent with the spatial confinement of the observed magnetic field reversals. We propose that the observed reversals are due to flux tubes reconnecting with closed field lines on the dayside. Ancillary data from the Cluster Ion Spectrometry (CIS) and Plasma Electron And Current Experiment (PEACE) instruments were used to develop a physical picture of the reversals.

  9. The quasi-periodical VLF/ELF emissions detected onboard the DEMETER spacecraft: statistical and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Pasmanik, Dmitry; Hayosh, Mykhaylo; Demekhov, Andrei; Santolík, Ond?ej; Nemec, František; Parrot, Michel

    2015-04-01

    We present a statistical study of the quasi-periodic (QP) ELF/VLF emissions measured by the DEMETER spacecraft. Events with modulation period larger than 10 s and frequency bandwidth more than 200 Hz were visually selected among the six year of measurements. Selected QP-emissions events occur mostly at frequencies from about 750 Hz to 2 kHz, but they may be observed at frequencies as low as 500 Hz and as high as 8 kHz. The statistical analysis clearly shows that QP events with larger modulation periods have lower frequency drift and smaller wave amplitude. Intense QP events have higher frequency drifts and larger values of the frequency bandwiths. Numerical simulation of the QP emissions based on the theoretical model of the flow cyclotron maser is performed. Calculations were made for wide range of plasma parameters (i.e. cold plasma density, L-shell, energetic electron flux and etc.) The numerical results are in good agreement with the observed relationship between different parameters of the QP emissions. The comparison between theoretical results and observations allow us to estimate the typical properties of the source of the QP emissions observed by the DEMETER satellite.

  10. Quasi-periodic Fibonacci and periodic one-dimensional hypersonic phononic crystals of porous silicon: Experiment and simulation

    SciTech Connect

    Aliev, Gazi N., E-mail: g.aliev@bath.ac.uk; Goller, Bernhard [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)

    2014-09-07

    A one-dimensional Fibonacci phononic crystal and a distributed Bragg reflector were constructed from porous silicon. The structures had the same number of layers and similar acoustic impedance mismatch, and were electrochemically etched in highly boron doped silicon wafers. The thickness of the individual layers in the stacks was approximately 2??m. Both types of hypersonic band gap structure were studied by direct measurement of the transmittance of longitudinal acoustic waves in the 0.1–2.6?GHz range. Acoustic band gaps deeper than 50?dB were detected in both structures. The experimental results were compared with model calculations employing the transfer matrix method. The acoustic properties of periodic and quasi-periodic structures in which half-wave retarding bi-layers do not consist of two quarter-wave retarding layers are discussed. The strong correlation between width and depth of gaps in the transmission spectra is demonstrated. The dominant mechanisms of acoustic losses in porous multilayer structures are discussed. The elastic constants remain proportional over our range of porosity, and hence, the Grüneisen parameter is constant. This simplifies the expression for the porosity dependence of the Akhiezer damping.

  11. The applications of the MHD Alfven wave oscillation model for kHz quasi-periodic oscillations

    E-print Network

    C. M. Zhang; H. X. Yin; Y. H. Zhao; H. K. Chang; L. M. Song

    2007-01-30

    In this paper, we improve the previous work on the MHD Alfven wave oscillation model for the neutron star (NS) kHz quasi-periodic oscillations (QPOs), and compare the model with the updated twin kHz QPO data. For the 17 NS X-ray sources with the simultaneously detected twin kHz QPO frequencies, the stellar mass M and radius R constraints are given by means of the derived parameter A in the model, which is associated with the averaged mass density of star as ${\\rm \\lan \\rho \\ran = 3M/(4\\pi R^{3}) \\simeq 2.4\\times 10^{14} (g/cm^{3}) (A/0.7)^{2}}$, and we also compare the M-R constraints with the star equations of states. Moreover, we also discuss the theoretical maximum kHz QPO frequency and maximum twin peak separation, and some expectations on SAX J1808.4-3658 are mentioned, such as its highest kHz QPO frequency $\\sim$~870 (Hz), which is about 1.4-1.5 times less than those of the other known kHz QPO sources. The estimated magnetic fields for both Z sources (about Eddington accretion rate $\\med$) and Atoll sources ($ 1% \\med$) are approximately $10^9$ G and $10^8$ G respectively.

  12. High-Frequency Quasi-Periodic Oscillations in the 2000 Outburst of the Galactic Microquasar XTE J1550-564

    NASA Technical Reports Server (NTRS)

    Miller, J. M.; Wijnands, R.; Homan, J.; Belloni, T.; Pooley, D.; Kouveliotou, C.; vanderKlis, M.; Lewin, W. H. G.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We present an analysis of the high-frequency timing properties of the April-May 2000 outburst of the black hole candidate and Galactic microquasar XTE J1550-564, measured with the Rossi X-ray Timing Explorer, The rapid X-ray variability we measure is consistent with the source being in either the "very high" or "intermediate" canonical black hole state. A strong (5-8% RMS) quasi-periodic oscillation (QPO) is found between 249-278 Hz; this may represent the first recurrence of the same high-frequency QPO in subsequent outbursts of a transient black hole candidate. We also present possible evidence for a lower-frequency QPO at approximately 187 Hz, also reported previously and likely present simultaneously with the higher-frequency QPO. We discuss these findings within the context of the 1998 outburst of XTE J1550-564, and comment on implications for models of QPOs, accretion flows, and black hole spin.

  13. Variable Quasi Periodic Oscillations during an outburst of the transient X-ray pulsar XTE J1858+034

    E-print Network

    U. Mukherjee; S. Bapna; H. Raichur; B. Paul; S. N. A. Jaaffrey

    2006-02-25

    We have investigated the Quasi Periodic Oscillation (QPO) properties of the transient accreting X-ray pulsar XTE J1858+034 during the second outburst of this source in April-May 2004. We have used observations made with the Proportional Counter Array (PCA) of the Rossi X-ray Timing Explorer (RXTE) during May 14-18 2004, in the declining phase of the outburst. We detected the presence of low frequency QPOs in the frequency range of 140--185 mHz in all the RXTE-PCA observations. We report evolution of the QPO parameters with the time, X-ray flux, and X-ray photon energy. Though a correlation between the QPO centroid frequency and the instantaneous X-ray flux is not very clear from the data, we point out that the QPO frequency and the one day averaged X-ray flux decreased with time during these observations. We have obtained a clear energy dependence of the RMS variation in the QPOs, increasing from about 3% at 3 keV to 6% at 25 keV. The X-ray pulse profile is a single peaked sinusoidal, with pulse fraction increasing from 20% at 3 keV to 45% at 30 keV. We found that, similar to the previous outburst, the energy spectrum is well fitted with a model consisting of a cut-off power law along with an iron emission line.

  14. Phase-resolved spectroscopy of low-frequency quasi-periodic oscillations in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Ingram, Adam; van der Klis, Michiel

    2015-02-01

    X-ray radiation from black hole binary (BHB) systems regularly displays quasi-periodic oscillations (QPOs). In principle, a number of suggested physical mechanisms can reproduce their power spectral properties, thus more powerful diagnostics which preserve phase are required to discern between different models. In this paper, we first find for two Rossi X-ray Timing Explorer observations of the BHB GRS 1915+105 that the QPO has a well-defined average waveform. That is, the phase difference and amplitude ratios between the first two harmonics vary tightly around a well-defined mean. This enables us to reconstruct QPO waveforms in each energy channel, in order to constrain QPO phase-resolved spectra. We fit these phase-resolved spectra across 16 phases with a model including Comptonization and reflection (Gaussian and smeared edge components) to find strong spectral pivoting and a modulation in the iron line equivalent width. The latter indicates the observed reflection fraction is changing throughout the QPO cycle. This points to a geometric QPO origin, although we note that the data presented here do not entirely rule out an alternative interpretation of variable disc ionization state. We also see tentative hints of modulations in the iron line centroid and width which, although not statistically significant, could result from a non-azimuthally symmetric QPO mechanism.

  15. Spike-interval triggered averaging reveals a quasi-periodic spiking alternative for stochastic resonance in catfish electroreceptors.

    PubMed

    Lankheet, Martin J M; Klink, P Christiaan; Borghuis, Bart G; Noest, André J

    2012-01-01

    Catfish detect and identify invisible prey by sensing their ultra-weak electric fields with electroreceptors. Any neuron that deals with small-amplitude input has to overcome sensitivity limitations arising from inherent threshold non-linearities in spike-generation mechanisms. Many sensory cells solve this issue with stochastic resonance, in which a moderate amount of intrinsic noise causes irregular spontaneous spiking activity with a probability that is modulated by the input signal. Here we show that catfish electroreceptors have adopted a fundamentally different strategy. Using a reverse correlation technique in which we take spike interval durations into account, we show that the electroreceptors generate a supra-threshold bias current that results in quasi-periodically produced spikes. In this regime stimuli modulate the interval between successive spikes rather than the instantaneous probability for a spike. This alternative for stochastic resonance combines threshold-free sensitivity for weak stimuli with similar sensitivity for excitations and inhibitions based on single interspike intervals. PMID:22403709

  16. Quasi-periodic nanoripples in graphene grown by chemical vapor deposition and its impact on charge transport.

    PubMed

    Ni, Guang-Xin; Zheng, Yi; Bae, Sukang; Kim, Hye Ri; Pachoud, Alexandre; Kim, Young Soo; Tan, Chang-Ling; Im, Danho; Ahn, Jong-Hyun; Hong, Byung Hee; Ozyilmaz, Barbaros

    2012-02-28

    The technical breakthrough in synthesizing graphene by chemical vapor deposition methods (CVD) has opened up enormous opportunities for large-scale device applications. To improve the electrical properties of CVD graphene grown on copper (Cu-CVD graphene), recent efforts have focused on increasing the grain size of such polycrystalline graphene films to 100 ?m and larger. While an increase in grain size and, hence, a decrease of grain boundary density is expected to greatly enhance the device performance, here we show that the charge mobility and sheet resistance of Cu-CVD graphene is already limited within a single grain. We find that the current high-temperature growth and wet transfer methods of CVD graphene result in quasi-periodic nanoripple arrays (NRAs). Electron-flexural phonon scattering in such partially suspended graphene devices introduces anisotropic charge transport and sets limits to both the highest possible charge mobility and lowest possible sheet resistance values. Our findings provide guidance for further improving the CVD graphene growth and transfer process. PMID:22251076

  17. Quasi-periodic oscillations in short recurring bursts of the soft gamma repeater J1550–5418

    SciTech Connect

    Huppenkothen, D.; D'Angelo, C.; Watts, A. L.; Heil, L.; Van der Klis, M.; Van der Horst, A. J. [Astronomical Institute "Anton Pannekoek," University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Kouveliotou, C. [Astrophysics Office, ZP 12, NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Gö?ü?, E.; Kaneko, Y. [Sabanc?University, Orhanl?-Tuzla, ?stanbul 34956 (Turkey); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra'anana 43537 (Israel); Lin, L. [François Arago Centre, APC, 10 rue Alice Domon et Léonie Duquet, F-75205 Paris (France); Von Kienlin, A. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Younes, G., E-mail: D.Huppenkothen@uva.nl [NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2014-06-01

    The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. The scarcity of giant flares makes a search for QPOs in the shorter, far more numerous bursts from soft gamma repeaters (SGRs) desirable. In Huppenkothen et al., we developed a Bayesian method for searching for QPOs in short magnetar bursts, taking into account the effects of the complicated burst structure, and have shown its feasibility on a small sample of bursts. Here we apply the same method to a much larger sample from a burst storm of 286 bursts from SGR J1550–5418. We report a candidate signal at 260 Hz in a search of the individual bursts, which is fairly broad. We also find two QPOs at ?93 Hz, and one at 127 Hz, when averaging periodograms from a number of bursts in individual triggers, at frequencies close to QPOs previously observed in magnetar giant flares. Finally, for the first time, we explore the overall burst variability in the sample and report a weak anti-correlation between the power-law index of the broadband model characterizing aperiodic burst variability and the burst duration: shorter bursts have steeper power-law indices than longer bursts. This indicates that longer bursts vary over a broader range of timescales and are not simply longer versions of the short bursts.

  18. Non-thermal plasmas in flames and other inhomogeneous environments

    E-print Network

    Guerra García, Carmen

    2015-01-01

    Non-thermal plasmas in non-uniform gases appear in several technological applications (plasma assisted combustion and aerodynamics, and plasma jets), as well as in natural phenomena (sprites). Whereas in the case of plasma ...

  19. Application of non-thermal plasmas to pollution control

    Microsoft Academic Search

    B. M. Penetrante; G. E. Vogtlin; J. N. Bardsley; P. A. Vitello; P. H. Wallman

    1993-01-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (HâS), (2) removal of trichloroethylene (TCE), and (3) removal of nitric oxides (NOâ) Emphasis is placed on the energy

  20. Application of non-thermal plasmas to pollution control

    Microsoft Academic Search

    B. M. Penetrante; G. E. Vogtlin; J. N. Bardsley; P. A. Vitello; P. H. Wallman

    1993-01-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (H[sub 2]S), (2) removal of trichloroethylene (TCE), and (3) removal of nitric oxides (NO[sub x]) Emphasis is placed on

  1. Quasi-periodic Fast-mode Magnetosonic Wave Trains Inside and Outside CME Bubbles Detected by SDO/AIA

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Ofman, L.; Downs, C.; Title, A. M.

    2013-07-01

    Quasi-periodic fast-mode magnetosonic wave trains both inside and outside expanding CME bubbles have recently been discovered by SDO/AIA (Liu et al. 2011, 2012; Shen & Liu 2012). In general, a wave train inside a CME bubble originates from a flare site and propagates along a funnel of coronal loops at typically 1000-2000 km/s (Ofman et al. 2011). A wave train outside a CME usually originates from a CME flank and propagates in the low corona along the solar surface following the leading front of a global EUV wave at typically 500-1000 km/s. The former is primarily seen in the cooler 171 Angstrom channel with a characteristic temperature of 0.8 MK, while the latter is pronounced in the hotter 193 and 211 Angstrom channels of typically 1.6-2.0 MK. What is the relationship between the two types of wave trains? Why do they appear differently in location and wavelength (temperature)? To answer these questions, we report here for the first time the evidence that the wave train beyond the CME bubble is the continuation of the same wave train along the funnel within the CME. The continuous deceleration of the waves is consistent with the expected decrease of the local fast-mode speed with distance from the active region (e.g., Ofman et al. 2011; Downs et al. 2012). There is an abrupt change of the wave speed at the topological interface where the expanding CME flank is located, indicative of contrasting magnetic and plasma conditions, which can give rise to different (fast-mode) speeds and wavelength (temperature) dependent appearances of these wave trains.Abstract (2,250 Maximum Characters): Quasi-periodic fast-mode magnetosonic wave trains both inside and outside expanding CME bubbles have recently been discovered by SDO/AIA (Liu et al. 2011, 2012; Shen & Liu 2012). In general, a wave train inside a CME bubble originates from a flare site and propagates along a funnel of coronal loops at typically 1000-2000 km/s (Ofman et al. 2011). A wave train outside a CME usually originates from a CME flank and propagates in the low corona along the solar surface following the leading front of a global EUV wave at typically 500-1000 km/s. The former is primarily seen in the cooler 171 Angstrom channel with a characteristic temperature of 0.8 MK, while the latter is pronounced in the hotter 193 and 211 Angstrom channels of typically 1.6-2.0 MK. What is the relationship between the two types of wave trains? Why do they appear differently in location and wavelength (temperature)? To answer these questions, we report here for the first time the evidence that the wave train beyond the CME bubble is the continuation of the same wave train along the funnel within the CME. The continuous deceleration of the waves is consistent with the expected decrease of the local fast-mode speed with distance from the active region (e.g., Ofman et al. 2011; Downs et al. 2012). There is an abrupt change of the wave speed at the topological interface where the expanding CME flank is located, indicative of contrasting magnetic and plasma conditions, which can give rise to different (fast-mode) speeds and wavelength (temperature) dependent appearances of these wave trains.

  2. Discovery of a Second High-Frequency Quasi-Periodic Oscillation from the Microquasar GRS 1915+105

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We report the discovery in archival Rossi X-Ray Timing Explorer data of a approx. 40 Hz quasi-periodic oscillation QPO) in the hard X-ray flux from the Galactic microquasar GRS 1915+105. The QPO is detected only in the hard X-ray band above approx. 13 keV and was discovered in observations in which the previously known 67 Hz QPO is present. The 40 Hz QPO has a typical rms amplitude of approx. 2% in the 13-27 keV band and a width of approx. 5.5 Hz (FWHM). We show that the 67 and 40 Hz QPOs are detected in the same observations in 1997 July and November. However, the QPO is not detected in observations from 1996 April, May, and June in which the 67 Hz QPO was first discovered. The frequency of the 67 Hz QPO is significantly higher in the 1997 observations by about 5% compared with the 1996 data. The identification of the 40 Hz QPO makes GRS 1915 + 105 the second black hole binary to show a pair of simultaneous high-frequency QPOs (the other being GRO J1655-40). The similarities between the properties of the 67 Hz QPO in GRS 1915+105 and the recently discovered 450 Hz QPO in GRO J1655-40 suggest that the pairs of frequencies in these systems may be produced by the same physical mechanism, with the frequency differences between the two being likely due to different black hole masses in the two systems. We discuss the implications of our result for the mass and spin of GRS 1915+105 as well as for models of X-ray variability in black holes and neutron stars.

  3. Timing Spectroscopy of Quasi-Periodic Oscillations in the Low-Mass X-ray Neutron Star Binaries

    E-print Network

    Lev Titarchuk; Vladimir Osherovich; Sergey Kuznetsov

    1999-09-15

    Precise simultaneous measurements of the frequencies of the two kiloHertz quasi-periodic oscillations (referred in the literature as upper and lower kHz QPOs) cast doubts on the validity of the simple beat-frequency interpretation and some of the modifications introduced to explain the results of the varying frequency difference. A new model explains the variation of the frequency difference suggesting that the upper kHz QPO,namely nu_h is an upper hybrid frequency of the Keplerian oscillator under the influence of the Coriolis force and the lower kHz QPO is the Keplerian frequency nu_K. Such an oscillator has two branches characterized by high frequency nu_h (around 1 kHz) and by low frequency nu_L (around 50 Hz). The frequency nu_L depends strongly on the angle, delta between the normal to the neutron star disk and Omega - the angular velocity of the magnetosphere surrounding the neutron star. In the lower part of the QPO spectrum (around 10 Hz), this model identifies the frequency of radial viscous oscillations nu_v (previously called "extra noise component") and the break frequency nu_b, which is associated with the diffusive process in the transition region (the innermost part of the disk). According to this model, all frequencies (namely nu_h, nu_L, nu_b and nu_v) have specific dependences on nu_K. This paper focuses on the verification of the predicted relations. For the source 4U 1728-34, the best theoretical fit is obtained for delta=8.3+/-1.0^o, which is slightly larger than delta=5.5+/- 0.5^o previously found for Sco X-1. In addition, we show that the theoretically derived power law relation, nu_b proportional to nu_v^{1.61} is consistent with the recent observations of other atoll and Z-sources.

  4. Quasi-Periodic Oscillations in Black Hole Candidates as an Indicator of Transition Between Low and High States

    NASA Technical Reports Server (NTRS)

    Rutledge, Robert E.; Lewin, Walter H. G.; VanDerKlis, Michiel; vanParadijs, Jan; Dotani, Tadayasu; Vaughan, Brian; Belloni, Tomaso; Oosterbroek, Tim; Kouvewliotou, Chryssa

    1999-01-01

    By comparing positions on a spectral color-color diagram from 10 black hole candidates (BHCS) observed with Ginga (1354-64, 1826-24, 1630-47, LMC X-1, LMC X-3, GS 2000+25, GS 2023+33, GS 1124-68, Cyg X-1, and GX 339-4) with the observed broadband noise (BBN) (0.001-64 Hz) and quasi-periodic oscillation (QPO) variability, we find that the "very high state" is spectrally intermediate to the soft/high state and hard/low state. We find a transition point in spectral hardness where the dependence of the BHC QPO centroid frequency (of GS 1124-68 and GX 339-4) on spectral hardness switches from a correlation to an anticorrelation; where the BBN variability switches from high state to low state; and where the spectral hardness of the QPO relative to that of the BBN variability is a maximum. This coincidence of changing behavior in both the QPO and the broadband variability leads us to hypothesize that the QPO is due to interaction between the physical components which dominate the behaviors of BHCs when they occupy the hard/low and soft/high states. We conclude that these QPOs should be observed from BHCs during transition between these two states. Comparison with QPO and BBN behavior observed during the 1996 transition of Cyg X-1 supports this hypothesis. We also report 1-3 Hz QPOs observed in GS 2000+25 and Cyg X-1 in the hard/low state, and we compare these to the QPOs observed in GS 1124-68 and GX 339-4.

  5. Quasi-Periodic Oscillations in Black Hole Candidates as an Indicator of Transition Between Low and High States

    NASA Technical Reports Server (NTRS)

    Rutledge, Robert E; Lewin, Walter H. G.; vanderKlis, Michiel; vanParadijs, Jan; Dotani, Tadayasu; Vaughan, Brian; Belloni, Tomaso; Oosterbroek, Tim; Kouveliotou, Chryssa

    1998-01-01

    By comparing positions on a spectral color-color diagram from 10 black hole candidates (BHCS) observed with Ginga (1354-64, 1826-24, 1630-47, LMC X-1, LMC X-3, GS 2000+25, GS 2023+33, GS 1124-68, Cyg X-1, and GX 339-4) with the observed broad-band noise (0.001- 64 Hz; BBN) and quasi-periodic oscillation (QPO) variability, we find that the so-called "Very High State" is spectrally intermediate to the Soft/High-State and Hard/Low-State. We find a transition point in spectral hardness where the dependence of the BHC QPO centroid frequency (of GS 1124-68 and GX 339-4) on spectral hardness switches from a correlation to an anti-correlation; where the BBN variability switches from High-State to Low-State; and where the spectral hardness of the QPO relative to that of the BBN variability is a maximum. This coincidence of changing behavior in both the QPO and the broad-band variability leads us to hypothesize that the QPO is due to interaction between the physical components which dominate the behaviors of BHCs when they occupy the Hard/Low and Soft/High States. We conclude that these QPO should be observed from BHCs during transition between these two states. Comparison with QPO and BBN behavior observed during the 1996 transition of Cyg X-1 supports this hypothesis. We also report 1-3 Hz QPO observed in GS 2000+25 and Cyg X-1 in the Hard/Low State, and we compare these to the QPO observed in GS 1124-68 and GX 339-4.

  6. Acoustic-gravity waves in the nonisothermal atmosphere and its influence on the magnetospheric quasi-periodic vlf emissions

    NASA Astrophysics Data System (ADS)

    Savina, Olga; Bespalov, Peter; Misonova, Vera; Petrov, Kiril

    2014-05-01

    We examine two mutually complementing tasks related to the theoretical analysis of acoustic-gravity disturbances in the Earth's atmosphere and its influence on magnetosphere processes. Our research is based on modern atmospherical models. We study waves propagation, absorption, and filtration. The atmospheric nonisothermicity is taken into account, for example, by introduction of a two-layered atmosphere temperature model. For a study of more delicate effects, a piecewise-linear model, for which the analytical solution is written by the hypergeometric functions, is employed. Also we consider an influence of acoustic-gravity waves on VLF electromagnetic wave excitation in the magnetosphere. This influence occurs as a result of the following processes: a modulation of the plasma density by acoustic-gravity waves in the ionosphere, a modulation of reflection from the ionosphere for VLF waves, and a modification of the magnetospheric resonator Q-factor for VLF waves. Variation of the magnetospheric resonator Q-factor has an influence on the operation of the plasma magnetospheric maser, where the active substances are radiation belts particles and the working modes are electromagnetic VLF waves (whistler-type waves). The plasma magnetospheric maser can be responsible for an excitation of self-oscillations. These self-oscillations are frequently characterized by alternating stages of accumulation and precipitation of energetic particles into the ionosphere during a pulse of whistler emissions. Numerical and analytical investigations of the response of self-oscillations to harmonic oscillations of the whistler reflection coefficient shows that even a small modulation rate can significantly changes the magnetospheric VLF emissions. Our results can explain the causes of the modulation of energetic electron fluxes and whistler wave intensity with a time scale from 10 to 150 seconds in the day-side magnetosphere. Such quasi-periodic VLF emissions are often observed in the sub-auroral and auroral magnetosphere and have a noticeable effect on the formation of the space weather phenomena.

  7. An Abstract Nash-Moser Theorem and Quasi-Periodic Solutions for NLW and NLS on Compact Lie Groups and Homogeneous Manifolds

    NASA Astrophysics Data System (ADS)

    Berti, Massimiliano; Corsi, Livia; Procesi, Michela

    2015-03-01

    We prove an abstract implicit function theorem with parameters for smooth operators defined on scales of sequence spaces, modeled for the search of quasi-periodic solutions of PDEs. The tame estimates required for the inverse linearised operators at each step of the iterative scheme are deduced via a multiscale inductive argument. The Cantor-like set of parameters where the solution exists is defined in a non inductive way. This formulation completely decouples the iterative scheme from the measure theoretical analysis of the parameters where the small divisors non-resonance conditions are verified. As an application, we deduce the existence of quasi-periodic solutions for forced NLW and NLS equations on any compact Lie group or manifold which is homogeneous with respect to a compact Lie group, extending previous results valid only for tori. A basic tool of harmonic analysis is the highest weight theory for the irreducible representations of compact Lie groups.

  8. QUASI-PERIODIC OSCILLATIONS OF {approx}15 MINUTES IN THE OPTICAL LIGHT CURVE OF THE BL LAC S5 0716+714

    SciTech Connect

    Rani, Bindu; Gupta, Alok C. [Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263 129 (India); Joshi, U. C.; Ganesh, S. [Physical Research Laboratory, Navrangpura, Ahmedabad 380 009 (India); Wiita, Paul J., E-mail: binduphysics@gmail.co [Department of Physics, College of New Jersey, P.O. Box 7718, Ewing, NJ 08628 (United States)

    2010-08-20

    Over the course of 3 hr on 2008 December 27, we obtained optical (R band) observations of the blazar S5 0716+714 at a very fast cadence of 10 s. Using several different techniques, we find fluctuations with an approximately 15 minute quasi-period to be present in the first portion of these data at a >3{sigma} confidence level. This is the fastest quasi-periodic oscillation that has been claimed to be observed in any blazar at any wavelength. While these data are insufficient to strongly constrain models for such fluctuations, the presence of such a short timescale when the source is not in a very low state seems to favor the action of turbulence behind a shock in the blazar's relativistic jet.

  9. Effects of Non-Thermal Plasma on Mammalian Cells

    PubMed Central

    Kalghatgi, Sameer; Kelly, Crystal M.; Cerchar, Ekaterina; Torabi, Behzad; Alekseev, Oleg; Fridman, Alexander; Friedman, Gary; Azizkhan-Clifford, Jane

    2011-01-01

    Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces no heat, so its effects can be selective. In order to exploit the potential for clinical applications, including wound healing, sterilization, blood coagulation, and cancer treatment, a mechanistic understanding of the interaction of non-thermal plasma with living tissues is required. Using mammalian cells in culture, it is shown here that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects that range from increasing cell proliferation to inducing apoptosis. It is also shown that these effects are primarily due to formation of intracellular reactive oxygen species (ROS). We have utilized ?-H2AX to detect DNA damage induced by non-thermal plasma and found that it is initiated by production of active neutral species that most likely induce formation of organic peroxides in cell medium. Phosphorylation of H2AX following non-thermal plasma treatment is ATR dependent and ATM independent, suggesting that plasma treatment may lead to replication arrest or formation of single-stranded DNA breaks; however, plasma does not lead to formation of bulky adducts/thymine dimers. PMID:21283714

  10. Quasi-periodic Slipping Magnetic Reconnection During an X-class Solar Flare Observed by the Solar Dynamics Observatory and Interface Region Imaging Spectrograph

    NASA Astrophysics Data System (ADS)

    Li, Ting; Zhang, Jun

    2015-05-01

    We first report the quasi-periodic slipping motion of flare loops during an eruptive X-class flare on 2014 September 10. The slipping motion was investigated at a specific location along one of the two ribbons and can be observed throughout the impulsive phase of the flare. The apparent slipping velocity was 20–110 km s?1, and the associated period was 3–6 minutes. The footpoints of flare loops appeared as small-scale bright knots observed in 1400 Å, corresponding to fine structures of the flare ribbon. These bright knots were observed to move along the southern part of the longer ribbon and also exhibited a quasi-periodic pattern. The Si iv 1402.77 Å line was redshifted by 30–50 km s?1 at the locations of moving knots with a ?40–60 km s?1 line width, larger than other sites of the flare ribbon. We suggest that the quasi-periodic slipping reconnection is involved in this process and the redshift at the bright knots is probably indicative of reconnection downflow. The emission line of Si iv at the northern part of the longer ribbon also exhibited obvious redshifts of about 10–70 km s?1 in the impulsive phase of the flare, with the redshifts at the outer edges of the ribbon larger than those in the middle. The redshift velocities at post-flare loops reached about 80–100 km s?1 in the transition region.

  11. Statistical properties of twin kilohertz quasi-periodic oscillations neutron star low-mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Wang, D. H.; Chen, L.; Zhang, C. M.; Lei, Y. J.; Qu, J. L.

    2014-02-01

    We collect the data of twin kilohertz quasi-periodic oscillations (kHz QPOs) published before 2012 from 26 neutron star (NS) low-mass X-ray binary (LMXB) sources, then we analyze the centroid frequency (?) distribution of twin kHz QPOs (lower frequency ?_1 and upper frequency ?_2) both for Atoll and Z sources. For the data without shift-and-add, we find that Atoll and Z sources show different distributions of ?_1, ?_2 and ?_2/?_1, but the same distribution of ?? (difference of twin kHz QPOs), which indicates that twin kHz QPOs may share the common properties of LXMBs and have the same physical origins. The distribution of ?? is quite different from a constant value, so is ?_2/?_1 from a constant ratio. The weighted mean values and maxima of ?_1 and ?_2 in Atoll sources are slightly higher than those in Z sources. We also find that shift-and-add technique can reconstruct the distributions of ?_1 and ??. The K-S test results of ?_1 and ?? between Atoll and Z sources from data with shift-and-add are quite different from those without it, and we think that this may be caused by the selection biases of the sample. We also study the properties of the quality factor (Q) and the root-mean-squared (rms) amplitude of 4U 0614+09 with data from the two observational methods, but the errors are too big to make a robust conclusion. The NS spin frequency (?_s) distribution of 28 NS-LMXBs show a bigger mean value (˜ 408 Hz) than that (˜ 281 Hz) of the radio binary millisecond pulsars (MSPs), which may be due to the lack of the spin detections from Z sources (systematically lower than 281 Hz). Furthermore, on the relations between the kHz QPOs and NS spin frequency ?_s, we find the approximate correlations of the mean values of ?? with NS spin and its half, respectively.

  12. Quasi-periodic oscillations in accreting magnetic white dwarfs. I. Observational constraints in X-ray and optical

    NASA Astrophysics Data System (ADS)

    Bonnet-Bidaud, J. M.; Mouchet, M.; Busschaert, C.; Falize, E.; Michaut, C.

    2015-07-01

    Quasi-periodic oscillations (QPOs) are observed in the optical flux of some polars with typical periods of 1 to 3 s but none have been observed yet in X-rays where a significant part of the accreting energy is released. QPOs are expected and predicted from shock oscillations. Most of the polars have been observed by the XMM-Newton satellite. We made use of the homogeneous set of observations of the polars by XMM-Newton to search for the presence of QPOs in the (0.5-10 keV) energy range and to set significant upper limits for the brightest X-ray polars. We extracted high time-resolution X-ray light curves by taking advantage of the 0.07 s resolution of the EPIC-PN camera. Among the 65 polars observed with XMM-Newton from 1998 to 2012, a sample of 24 sources was selected on the basis of their counting rate in the PN instrument to secure significant limits. We searched for QPOs using Fast Fourier Transform (FFT) methods and defined limits of detection using statistical tools. Among the sample surveyed, none shows QPOs at a significant level. Upper limits to the fractional flux in QPOs range from 7% to 71%. These negative results are compared to the detailed theoretical predictions of numerical simulations based on a 2D hydrodynamical code presented in Paper II. Cooling instabilities in the accretion column are expected to produce shock quasi-oscillations with a maximum amplitude reaching ~40% in the bremsstrahlung (0.5-10 keV) X-ray emission and ~20% in the optical cyclotron emission. The absence of X-ray QPOs imposes an upper limit of ~(5-10) g cm-2 s-1 on the specific accretion rate but this condition is found inconsistent with the value required to account for the amplitudes and frequencies of the observed optical QPOs. This contradiction outlines probable shortcomings with the shock instability model. Figures 1-3 are available in electronic form at http://www.aanda.org

  13. Black hole spin inferred from 3:2 epicyclic resonance model of high-frequency quasi-periodic oscillations

    NASA Astrophysics Data System (ADS)

    Šrámková, E.; Török, G.; Kotrlová, A.; Bakala, P.; Abramowicz, M. A.; Stuchlík, Z.; Goluchová, K.; Klu?niak, W.

    2015-06-01

    Estimations of black hole spin in the three Galactic microquasars GRS 1915+105, GRO J1655-40, and XTE J1550-564 have been carried out based on spectral and timing X-ray measurements and various theoretical concepts. Among others, a non-linear resonance between axisymmetric epicyclic oscillation modes of an accretion disc around a Kerr black hole has been considered as a model for the observed high-frequency quasi-periodic oscillations (HF QPOs). Estimates of spin predicted by this model have been derived based on the geodesic approximation of the accreted fluid motion. Here we assume accretion flow described by the model of a pressure-supported torus and carry out related corrections to the mass-spin estimates. We find that for dimensionless black hole spin a ? cJ/GM2 ? 0.9, the resonant eigenfrequencies are very close to those calculated for the geodesic motion. Their values slightly grow with increasing torus thickness. These findings agree well with results of a previous study carried out in the pseudo-Newtonian approximation. The situation becomes different for a ? 0.9, in which case the resonant eigenfrequencies rapidly decrease as the torus thickness increases. We conclude that the assumed non-geodesic effects shift the lower limit of the spin, implied for the three microquasars by the epicyclic model and independently measured masses, from a ~ 0.7 to a ~ 0.6. Their consideration furthermore confirms compatibility of the model with the rapid spin of GRS 1915+105 and provides highly testable predictions of the QPO frequencies. Individual sources with a moderate spin (a ? 0.9) should exhibit a smaller spread of the measured 3:2 QPO frequencies than sources with a near-extreme spin (a ~ 1). This should be further examined using the large amount of high-resolution data expected to become available with the next generation of X-ray instruments, such as the proposed Large Observatory for X-ray Timing (LOFT).

  14. Non-thermal Gravitino Production in Tribrid Inflation

    E-print Network

    Antusch, Stefan

    2015-01-01

    We investigate non-thermal gravitino production after tribrid inflation in supergravity, which is a variant of supersymmetric hybrid inflation where three fields are involved in the inflationary model and where the inflaton field resides in the matter sector of the theory. In contrast to conventional supersymmetric hybrid inflation, where non-thermal gravitino production imposes severe constraints on the inflationary model, we find that the "non-thermal gravitino problem" is generically absent in models of tribrid inflation, mainly due to two effects: (i) With the inflaton in tribrid inflation (after inflation) being lighter than the waterfall field, the latter has a second decay channel with a much larger rate than for the decay into gravitinos. This reduces the branching ratio for the decay of the waterfall field into gravitinos. (ii) The inflaton generically decays later than the waterfall field, and does not produce gravitinos when it decays. This leads to a dilution of the gravitino population from the d...

  15. Effect of Non-Thermal Processing on Peanut Allergens.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peanut allergy is on the rise, and the reason is still unclear. Previously, roasting by thermal method has been shown to increase the allergenic potency of peanuts. In this study, we determined if non-thermal methods, such as, pulsed electric fields (PEF) and pulsed UV lights (PUV) affect peanut all...

  16. Electromagnetic field occupational exposure: non-thermal vs. thermal effects.

    PubMed

    Israel, M; Zaryabova, V; Ivanova, M

    2013-06-01

    There are a variety of definitions for "non-thermal effects" included in different international standards. They start by the simple description that they are "effects of electromagnetic energy on a body that are not heat-related effects", passing through the very general definition related to low-level effects: "biological effects ascribed to exposure to low-level electric, magnetic and electromagnetic fields, i.e. at or below the corresponding dosimetric reference levels in the frequency range covered in this standard (0 Hz-300 GHz)", and going to the concrete definition of "the stimulation of muscles, nerves, or sensory organs, vertigo or phosfenes". Here, we discuss what kind of effect does the non-thermal one has on human body and give data of measurements in different occupations with low-frequency sources of electromagnetic field such as electric power distribution systems, transformers, MRI systems and : video display units (VDUs), whereas thermal effects should not be expected. In some of these workplaces, values above the exposure limits could be found, nevertheless that they are in the term "non-thermal effects" on human body. Examples are workplaces in MRI, also in some power plants. Here, we will not comment on non-thermal effects as a result of RF or microwave exposure because there are not proven evidence about the existance of such effects and mechanisms for them are not clear. PMID:23675617

  17. Non-Thermal Fixed Point in a Holographic Superfluid

    E-print Network

    Carlo Ewerz; Thomas Gasenzer; Markus Karl; Andreas Samberg

    2015-05-11

    We study the far-from-equilibrium dynamics of a (2+1)-dimensional superfluid at finite temperature and chemical potential using its holographic description in terms of a gravitational system in 3+1 dimensions. Starting from various initial conditions corresponding to ensembles of vortex defects we numerically evolve the system to long times. At intermediate times the system exhibits Kolmogorov scaling the emergence of which depends on the choice of initial conditions. We further observe a universal late-time regime in which the occupation spectrum and different length scales of the superfluid exhibit scaling behaviour. We study these scaling laws in view of superfluid turbulence and interpret the universal late-time regime as a non-thermal fixed point of the dynamical evolution. In the holographic superfluid the non-thermal fixed point can be understood as a stationary point of the classical equations of motion of the dual gravitational description.

  18. Non-Thermal Emission from Massive Young Stellar Objects

    NASA Astrophysics Data System (ADS)

    Parkin, E. R.; Pittard, J. M.; Hoare, M. G.

    2010-05-01

    In the young stellar object (YSO) phase of their lives, massive stars drive bipolar molecular outflows. These outflows produce beautiful, often hourglass shaped, cavities. The central star possesses a powerful stellar wind ( v ˜ 2000 kms-1), and possibly a dense equatorial disk wind ( v ˜ 400 kms-1), which collide with the inner surface of the bipolar cavity and produces hot ( T ˜ 105 - 108 K) shocked plasma. A reverse shock is formed at the point where the ram pressure between the preshock flow balances the thermal pressure of the postshock flow and provides a site for the acceleration of non-thermal particles to relativistic energies. Hydrodynamical models of the wind interaction, coupled with calculations of the non-thermal energy spectrum, are used to explore the observable synchrotron and gamma-ray emission from these objects.

  19. Non-thermal fixed point in a holographic superfluid

    NASA Astrophysics Data System (ADS)

    Ewerz, Carlo; Gasenzer, Thomas; Karl, Markus; Samberg, Andreas

    2015-05-01

    We study the far-from-equilibrium dynamics of a (2 + 1)-dimensional super-fluid at finite temperature and chemical potential using its holographic description in terms of a gravitational system in 3 + 1 dimensions. Starting from various initial conditions corresponding to ensembles of vortex defects we numerically evolve the system to long times. At intermediate times the system exhibits Kolmogorov scaling the emergence of which depends on the choice of initial conditions. We further observe a universal late- time regime in which the occupation spectrum and different length scales of the superfluid exhibit scaling behaviour. We study these scaling laws in view of superfluid turbulence and interpret the universal late-time regime as a non-thermal fixed point of the dynamical evolution. In the holographic superfluid the non-thermal fixed point can be understood as a stationary point of the classical equations of motion of the dual gravitational description.

  20. Corona: Coordinated research on non-thermal processes in astrophysics

    NASA Technical Reports Server (NTRS)

    Mullan, Dermott J.

    1991-01-01

    Several problems in astrophysics are examined where departures from purely thermal behavior are expected to produce effects which are detectable by a variety of NASA satellites. The problems identified as worthy of study include coronal heating in stars, deposition of non-thermal particle energy in stars from external sources, and turbulence in atmospheres and winds of stars. The progress in solving these problems is summarized.

  1. Non-Thermal Electromagnetic Radiation Damage to Lens Epithelium

    Microsoft Academic Search

    Elvira Bormusov; Usha P. Andley; Naomi Sharon; Levi Schachter; Assaf Lahav; Ahuva Dovrat

    2008-01-01

    High frequency microwave electromagnetic radiation from mobile phones and other modern devices has the potential to damage eye tissues, but its effect on the lens epithelium is unknown at present. The objective of this study was to investigate the non-thermal effects of high frequency microwave electromagnetic radiation (1.1GHz, 2.22 mW) on the eye lens epithelium in situ. Bovine lenses were

  2. DESTRUCTION OF VOCs IN A NON-THERMAL PLASMA REACTOR

    Microsoft Academic Search

    C. Christodoulatos; K. Becker; P. J. Ricatto; G. P. Korfiatis; E. E. Kunhardt

    The work presented herein investigates the effectiveness and efficiency of a novel, non-thermal large-volume ambient pressure diffuse plasma for destruction of environmental air contaminants. The plasma characteristics, plasma chemistry, and contaminant destruction efficiency for selected contaminants including benzene, toluene, n-heptane, iso-octane, and methanol were investigated. Plasma spectroscopic studies employing gas mixtures of He with N2 of 1-20% yielded electron temperatures

  3. Syngas Production from Propane Using Atmospheric Non-thermal Plasma

    Microsoft Academic Search

    Fakhreddine Ouni; Ahmed Khacef; Jean Marie Cormier

    2009-01-01

    Propane steam reforming using a sliding discharge reactor was investigated under atmospheric pressure and low temperature\\u000a (420 K). Non-thermal plasma steam reforming proceeded efficiently and hydrogen was formed as a main product (H2 concentration up to 50%). By-products (C2-hydrocarbons, methane, carbon dioxide) were measured with concentrations lower than 6%. The mean electrical power injected\\u000a in the discharge is less than 2 kW.

  4. Non-thermal equilibrium parameters of weakly ionized plasmas

    Microsoft Academic Search

    A. A. Skorupski; S. Suckewer

    1974-01-01

    Generalized Boltzmann and Saha formulae for populations of atomic levels and degree of ionization for a two-temperature plasma in non-thermal equilibrium are given. Inelastic atom-atom type collisions are taken into account. Calculations based on these formulae are performed for optically thin or Lyman series optically thick hydrogen plasmas. They are in good agreement with results obtained by solving the non-linear

  5. Hydrothermal Synthesis Au-Bi2Te3 Nanocomposite Thermoelectric Film with a Hierarchical Sub-Micron Antireflection Quasi-Periodic Structure.

    PubMed

    Tian, Junlong; Zhang, Wang; Zhang, Yuan; Xue, Ruiyang; Wang, Yuhua; Zhang, Zhijian; Zhang, Di

    2015-01-01

    In this work, Au-Bi2Te3 nanocomposite thermoelectric film with a hierarchical sub-micron antireflection quasi-periodic structure was synthesized via a low-temperature chemical route using Troides helena (Linnaeus) forewing (T_FW) as the biomimetic template. This method combines chemosynthesis with biomimetic techniques, without the requirement of expensive equipment and energy intensive processes. The microstructure and the morphology of the Au-Bi2Te3 nanocomposite thermoelectric film was analyzed by X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), and transmission electron microscopy (TEM). Coupled the plasmon resonances of the Au nanoparticles with the hierarchical sub-micron antireflection quasi-periodic structure, the Au-Bi2Te3 nanocomposite thermoelectric film possesses an effective infrared absorption and infrared photothermal conversion performance. Based on the finite difference time domain method and the Joule effect, the heat generation and the heat source density distribution of the Au-Bi2Te3 nanocomposite thermoelectric film were studied. The heterogeneity of heat source density distribution of the Au-Bi2Te3 nanocomposite thermoelectric film opens up a novel promising technique for generating thermoelectric power under illumination. PMID:26047340

  6. Hydrothermal Synthesis Au-Bi2Te3 Nanocomposite Thermoelectric Film with a Hierarchical Sub-Micron Antireflection Quasi-Periodic Structure

    PubMed Central

    Tian, Junlong; Zhang, Wang; Zhang, Yuan; Xue, Ruiyang; Wang, Yuhua; Zhang, Zhijian; Zhang, Di

    2015-01-01

    In this work, Au-Bi2Te3 nanocomposite thermoelectric film with a hierarchical sub-micron antireflection quasi-periodic structure was synthesized via a low-temperature chemical route using Troides helena (Linnaeus) forewing (T_FW) as the biomimetic template. This method combines chemosynthesis with biomimetic techniques, without the requirement of expensive equipment and energy intensive processes. The microstructure and the morphology of the Au-Bi2Te3 nanocomposite thermoelectric film was analyzed by X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), and transmission electron microscopy (TEM). Coupled the plasmon resonances of the Au nanoparticles with the hierarchical sub-micron antireflection quasi-periodic structure, the Au-Bi2Te3 nanocomposite thermoelectric film possesses an effective infrared absorption and infrared photothermal conversion performance. Based on the finite difference time domain method and the Joule effect, the heat generation and the heat source density distribution of the Au-Bi2Te3 nanocomposite thermoelectric film were studied. The heterogeneity of heat source density distribution of the Au-Bi2Te3 nanocomposite thermoelectric film opens up a novel promising technique for generating thermoelectric power under illumination. PMID:26047340

  7. Talbot-carpets of periodic and quasi-periodic close-packed 2D mask structures calculated by a modified chirp-z-algorithm

    NASA Astrophysics Data System (ADS)

    Maass, Jacqueline; Sandfuchs, Oliver; Gatto, Alexandre; Thomae, Daniel; Brunner, Robert

    2012-06-01

    In this contribution we simulate theoretically the resulting 3D Talbot-carpets of different initial close-packed 2D mask structures. Especially, we investigate the transition from regular periodic to quasi-periodic tessellations. For the pure periodic mask structure a hexagonally tessellation was selected. The calculated field distribution adjacent to the mask still shows a lateral six-fold symmetry but also a rather complex characteristics in the propagation direction. In particular, the appearance and the repetition of self-imaging planes deviate significantly from the classical Talbot-effect. For the quasi-periodic tessellation a Penrose tapestry based on rhombus pairs was chosen. A pronounced lateral fivefold symmetry becomes visible in the field distribution. In the propagation direction dominant planes with increased intensity are observed clearly, but, instead of a simple periodicity, a complex behavior becomes obvious. The numerical algorithm used in our simulations is based on a modified angular spectrum method, in which Bluestein's fast Fourier (FFT) algorithm is applied. This approach allows to decouple the sampling points in the real space and in the spatial frequency domain so that both parameter can be chosen independently. The introduced fast and flexible algorithm requires a minimized number of numerical steps and a minimal computation time, but still offers high accuracy.

  8. IDENTIFICATION OF THE INFRARED NON-THERMAL EMISSION IN BLAZARS

    SciTech Connect

    Massaro, F.; Ajello, M. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); D'Abrusco, R.; Grindlay, J. E.; Smith, Howard A. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)

    2011-10-20

    Blazars constitute the most interesting and enigmatic class of extragalactic {gamma}-ray sources dominated by non-thermal emission. In this Letter, we show how the Wide Infrared Survey Explorer (WISE) infrared data make it possible to identify a distinct region of the [3.4]-[4.6]-[12] {mu}m color-color diagram where the sources dominated by the thermal radiation are separated from those dominated by non-thermal emission, in particular the blazar population. This infrared non-thermal region, which we indicate as the WISE blazar strip (WBS), will constitute a new powerful diagnostic tool when the full WISE survey data are released. The WBS can be used to extract new blazar candidates, to identify those of uncertain type and also to search for the counterparts of unidentified {gamma}-ray sources. We show one example of the value of the use of the WBS identifying the TeV source VER J0648+152, recently discovered by VERITAS.

  9. Can single O stars produce non-thermal radio emission? Or are they binaries?

    E-print Network

    Van Loo, Sven

    ). A fundamental question regarding non-thermal radio emission is its correlation with bina- rity. For WolfCan single O stars produce non-thermal radio emission? Or are they binaries? S. Van Loo 1, 2 1 Abstract: We present qualitative models for the non-thermal radio emission of single O stars, in terms

  10. Non-thermal Plasma for VOC Treatment in Flue Gases

    NASA Astrophysics Data System (ADS)

    Ikaunieks, Janis; Mezmale, Liga; Zandeckis, Aivars; Pubule, Jelena; Blumberga, Andra; Veidenbergs, Ivars

    2011-01-01

    The paper discusses non-thermal plasmas, their generation and characteristics, formation mechanisms of ozone and the treatment of volatile organic compounds (VOCs). In the experimental part, undecane (C11H24 as model VOCs) was treated with assistance of low temperature plasma at an atmospheric pressure which was generated in the so-called stack reactor. The gas composition was 13% of oxygen in nitrogen with impurities of carbon dioxide, carbon monoxide and undecane. The formation of by-products, as well as the removal efficiency, were investigated.

  11. The energy dependence of the three types of low-frequency quasi-periodic oscillations in the black hole candidate H1743-322

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Zhang, S.; Qu, J. L.; Gao, H. Q.; Zhao, H. H.; Huang, C. P.; Song, L. M.

    2013-07-01

    We investigate the properties of the centroid frequency of low-frequency quasi-periodic oscillation (LF QPOs, 0.1-30 Hz) during the 2003 outburst of H1743-322, by using the observational data of the Rossi X-ray Timing Explorer. We find that the frequency shows different energy dependences for each of the sub-classes of LF QPOs: the QPO frequency is proportional to photon energy for the type C QPOs while it is ambiguous for the type A and B QPOs. For type C QPOs, the slope of the frequency-energy relation versus frequency plot can be well described by a power law with frequency till ˜7.5 Hz. Beyond ˜7.5 Hz the slope goes down. The LF QPO amplitude decreases monotonically with the frequency for the type C but increases for the other two types. These properties provide a joint diagnostic for discriminating the different types of LF QPO.

  12. Late Holocene shoreline behavior in embayments of Lake Michigan: Influence of quasi-periodic lake-level variations and sediment supply

    SciTech Connect

    Thompson, T.A.; Baedke, S.J. (Indiana Univ., Bloomington, IN (United States). Indiana Geological Survey)

    1994-04-01

    Lake Michigan contains numerous former embayments into glacial deposits or bedrock. Many of the embayments contain dunes, spits, and captured lakes, but others contain arcuate strandplains of beach ridges. The strandplains are a geologic record of shoreline behavior and lake-level variation throughout the late Holocene. The larger strandplains show similar long-term patterns of beach-ridge development. The similar patterns are expected because variations in lake level are a primary control on shoreline behavior, and all embayments would have experienced relatively the same lake-level changes. Some variations in the long-term pattern of shoreline development do occur between strandplains. These dissimilarities are primarily a function of different rates of sediment supply to the shoreline of each embayment. Beach-ridge development within embayments can be represented on a rate of water level change versus rate of sediment supply diagram (Curray diagram) as three superimposed ovals on the positive rate of sediment supply side of the diagram. The three stacked ovals represent the three quasi-periodic lake-level variations defined by Thompson (1992) and show the position of the shoreline for a given time within the Curray diagram fields. For shorelines with a high rate of sediment supply, only the 30-year quasi-periodic variation would reach the aggradation line. For shorelines having significantly less sediment supply, rising lake level on the 150- and 600-year variations would force the 30-year oval across the aggradation line and well into the depositional and possibly the erosional transgression fields. Under these conditions erosion would occur that may remove, stack, or at least prevent one or more beach ridges from being developed.

  13. Non-thermal quantum channels as a thermodynamical resource

    E-print Network

    Miguel Navascués; Luis Pedro García-Pintos

    2015-06-15

    Quantum thermodynamics can be understood as a resource theory, whereby thermal states are free and the only allowed operations are unitary transformations commuting with the total Hamiltonian of the system. Previous literature on the subject has just focused on transformations between different state resources, overlooking the fact that quantum operations which do not commute with the total energy also constitute a potentially valuable resource. In this Letter, given a number of non-thermal quantum channels, we study the problem of how to integrate them in a thermal engine so as to distill a maximum amount of work. We find that, in the limit of asymptotically many uses of each channel, the distillable work is an additive function of the considered channels, computable for both finite dimensional quantum operations and bosonic channels. We apply our results to bound the amount of distillable work due to the natural non-thermal processes postulated in the Ghirardi-Rimini-Weber (GRW) collapse model. We find that, although GRW theory predicts the possibility to extract work from the vacuum at no cost, the power which a \\emph{collapse engine} could in principle generate is extremely low.

  14. Nitrogen oxides and methane treatment by non-thermal plasma

    NASA Astrophysics Data System (ADS)

    Alva, E.; Pacheco, M.; Colín, A.; Sánchez, V.; Pacheco, J.; Valdivia, R.; Soria, G.

    2015-03-01

    Non thermal plasma was used to treat nitrogen oxides (NOx) and methane (CH4), since they are important constituents of hydrocarbon combustion emissions processes and, both gases, play a key role in the formation of tropospheric ozone. These gases are involved in environmental problems like acid rain and some diseases such as bronchitis and pneumonia. In the case of methane is widely known its importance in the global climate change, and currently accounts for 30% of global warming. There is a growing concern for methane leaks, associated with a rapid expansion of unconventional oil and gas extraction techniques as well as a large-scale methane release from Arctic because of ice melting and the subsequent methane production of decaying organic matter. Therefore, methane mitigation is a key to avoid dangerous levels of global warming. The research, here reported, deals about the generation of non-thermal plasma with a double dielectric barrier (2DBD) at atmospheric pressure with alternating current (AC) for NOx and CH4 treatment. The degradation efficiencies and their respective power consumption for different reactor configurations (cylindrical and planar) are also reported. Qualitative and quantitative analysis of gases degradation are reported before and after treatment with cold plasma. Experimental and theoretical results are compared obtaining good removal efficiencies, superior to 90% and to 20% respectively for NOx and CH4.

  15. Application of non-thermal plasmas to pollution control

    SciTech Connect

    Penetrante, B.M.; Vogtlin, G.E.; Bardsley, J.N.; Vitello, P.A.; Wallman, P.H.

    1993-01-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (H[sub 2]S), (2) removal of trichloroethylene (TCE), and (3) removal of nitric oxides (NO[sub x]) Emphasis is placed on the energy cost for implementing the decomposition or removal of these pollutants. Some of the factors affecting the energy cost are discussed. We discuss in detail our work at LLNL on pulsed plasma processing for the treatment of NO[sub x] in diesel engine exhaust. Our results suggest that our plasma reactor can remove up to 70% of NO[sub x] with relatively high initial concentrations (up to 500 ppM) at a power consumption cost of 2.5% for an engine with an output of 14 kill and an exhaust gas flow rate of 1200 liters per minute.

  16. Application of non-thermal plasmas to pollution control

    SciTech Connect

    Penetrante, B.M.; Vogtlin, G.E.; Bardsley, J.N.; Vitello, P.A.; Wallman, P.H.

    1993-01-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (H{sub 2}S), (2) removal of trichloroethylene (TCE), and (3) removal of nitric oxides (NO{sub x}) Emphasis is placed on the energy cost for implementing the decomposition or removal of these pollutants. Some of the factors affecting the energy cost are discussed. We discuss in detail our work at LLNL on pulsed plasma processing for the treatment of NO{sub x} in diesel engine exhaust. Our results suggest that our plasma reactor can remove up to 70% of NO{sub x} with relatively high initial concentrations (up to 500 ppM) at a power consumption cost of 2.5% for an engine with an output of 14 kill and an exhaust gas flow rate of 1200 liters per minute.

  17. Mechanism of NO reduction with non-thermal plasma.

    PubMed

    Yu, Gang; Yu, Qi; Jiang, Yan-Long; Zeng, Ke-Si; Gu, Fan

    2005-01-01

    Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2/O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in Self-Consistent Field (SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction. PMID:16083121

  18. Non-thermal Processes in Black-Hole-Jet Magnetospheres

    E-print Network

    Rieger, Frank M

    2011-01-01

    The environs of supermassive black holes are among the universe's most extreme phenomena. Understanding the physical processes occurring in the vicinity of black holes may provide the key to answer a number of fundamental astrophysical questions including the detectability of strong gravity effects, the formation and propagation of relativistic jets, the origin of the highest energy gamma-rays and cosmic-rays, and the nature and evolution of the central engine in Active Galactic Nuclei (AGN). As a step towards this direction, this paper reviews some of the progress achieved in the field based on observations in the very high energy domain. It particularly focuses on non-thermal particle acceleration and emission processes that may occur in the rotating magnetospheres originating from accreting, supermassive black hole systems. Topics covered include direct electric field acceleration in the black hole's magnetosphere, ultra-high energy cosmic ray production, Blandford-Znajek mechanism, centrifugal acceleratio...

  19. Application of non-thermal plasma on gas cleansing

    NASA Astrophysics Data System (ADS)

    Pacheco, M.; Pacheco, J.; Moreno, H.; Santana, A.

    2008-10-01

    Non-thermal plasma technologies are an interesting complement or alternative, for some conventional systems used for gas pollution control (i.e. wet scrubbers and catalytic converters) because they are able to remove simultaneously several gas pollutants, with quite good efficiency at a relatively low-energy consumption. In this work, a dielectric barrier discharge was used to remove nitric oxides (NOx) and sulfur dioxide (SO2) from a mixture of air and water vapor. A chemical model was developed to obtain a toxic gas removal mechanism and to observe the behavior of the species in the plasma. The influence of water vapor addition on the toxic gases removal efficiency is also investigated. Several experimental parameters such as power, frequency, initial concentration of NOx and SO2 were tested and analyzed. Results of numerical simulation demonstrated good agreement with experimental data of the removal process achieving about 95% of efficiency removal of toxic gases studied.

  20. Numerical Simulation of Non-Thermal Food Preservation

    NASA Astrophysics Data System (ADS)

    Rauh, C.; Krauss, J.; Ertunc, Ö.; Delgado, a.

    2010-09-01

    Food preservation is an important process step in food technology regarding product safety and product quality. Novel preservation techniques are currently developed, that aim at improved sensory and nutritional value but comparable safety than in conventional thermal preservation techniques. These novel non-thermal food preservation techniques are based for example on high pressures up to one GPa or pulsed electric fields. in literature studies the high potential of high pressures (HP) and of pulsed electric fields (PEF) is shown due to their high retention of valuable food components as vitamins and flavour and selective inactivation of spoiling enzymes and microorganisms. for the design of preservation processes based on the non-thermal techniques it is crucial to predict the effect of high pressure and pulsed electric fields on the food components and on the spoiling enzymes and microorganisms locally and time-dependent in the treated product. Homogenous process conditions (especially of temperature fields in HP and PEF processing and of electric fields in PEF) are aimed at to avoid the need of over-processing and the connected quality loss and to minimize safety risks due to under-processing. the present contribution presents numerical simulations of thermofluiddynamical phenomena inside of high pressure autoclaves and pulsed electric field treatment chambers. in PEF processing additionally the electric fields are considered. Implementing kinetics of occurring (bio-) chemical reactions in the numerical simulations of the temperature, flow and electric fields enables the evaluation of the process homogeneity and efficiency connected to different process parameters of the preservation techniques. Suggestions to achieve safe and high quality products are concluded out of the numerical results.

  1. Revised Results for Non-thermal Recombination Flare Hard X-Ray Emission

    Microsoft Academic Search

    J. C. Brown; P. C. V. Mallik; N. R. Badnell

    2009-01-01

    Brown and Mallik (BM) recently showed that, for hot sources, recombination of non-thermal electrons (NTR) onto highly ionised heavy ions is not negligible compared to non-thermal bremsstrahlung (NTB) as a source of flare hard X-rays (HXRs) and so should be included in modelling non-thermal HXR flare emission. In view of major discrepancies between BM results for the THERMAL continua and

  2. NON-THERMAL PLASMA TECHNOLOGY FOR DEGRADATION OF ORGANIC COMPOUNDS IN WASTEWATER CONTROL: A CRITICAL REVIEW

    Microsoft Academic Search

    Hsu-Hui Cheng; Shiao-Shing Chen; Yu-Chi Wu; Din-Lit Ho

    Non-thermal plasma is an emerging technique in environmental pollution control technology, produced by the high-voltage discharge processes and therefore a large amount of high energy electrons and active species are generated. The degradation of difficult-degraded organic pollutions will be greatly enhanced by the active species generated from non-thermal plasma process. However, research on non-thermal plasma technology on organic wastewater cleaning

  3. On the Importance of Searching for Oscillations of the Jovian Inner Radiation Belt with a Quasi-Period of 40 Minutes

    E-print Network

    Lou, Y Q; Lou, Yu-Qing; Zheng, Chen

    2003-01-01

    Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-minute period(QP-40) from the south pole of Jupiter in February 1992. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt(IRB) within ~2-3 Jupiter's radius, where ralativistic electrons are known to be trapped via synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds. Modulated by such QP-40 IRB oscillations, relativistic electrons trapped in the IRB may escape from the magnetic circumpolar regions during a certain phase of each 40-min period to form circumpolar QP-40 electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic field at ~30-40 Jupiter radius give rise to QP-40 radio bursts with typical frequencie...

  4. ON MASS CONSTRAINTS IMPLIED BY THE RELATIVISTIC PRECESSION MODEL OF TWIN-PEAK QUASI-PERIODIC OSCILLATIONS IN CIRCINUS X-1

    SciTech Connect

    Toeroek, Gabriel; Bakala, Pavel; Sramkova, Eva; StuchlIk, Zdenek; Urbanec, Martin, E-mail: terek@volny.c, E-mail: pavel.bakala@fpf.slu.c, E-mail: sram_eva@centrum.c, E-mail: zdenek.stuchlik@fpf.slu.c, E-mail: martin.urbanec@fpf.slu.c [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava Bezrucovo nam. 13, CZ-746 01 Opava (Czech Republic)

    2010-05-01

    Boutloukos et al. discovered twin-peak quasi-periodic oscillations (QPOs) in 11 observations of the peculiar Z-source Circinus X-1. Among several other conjunctions the authors briefly discussed the related estimate of the compact object mass following from the geodesic relativistic precession model for kHz QPOs. Neglecting the neutron star rotation they reported the inferred mass M{sub 0} = 2.2 {+-} 0.3 M{sub sun}. We present a more detailed analysis of the estimate which involves the frame-dragging effects associated with rotating spacetimes. For a free mass we find acceptable fits of the model to data for (any) small dimensionless compact object angular momentum j = cJ/GM {sup 2}. Moreover, quality of the fit tends to increase very gently with rising j. Good fits are reached when M {approx} M{sub 0}[1 + 0.55(j + j {sup 2})]. It is therefore impossible to estimate the mass without independent knowledge of the angular momentum and vice versa. Considering j up to 0.3 the range of the feasible values of mass extends up to 3 M{sub sun}. We suggest that similar increase of estimated mass due to rotational effects can be relevant for several other sources.

  5. Quasi-Periodic Oscillations in Short Recurring Bursts of the magnetars SGR 1806-20 and SGR 1900+14 Observed With RXTE

    E-print Network

    Huppenkothen, D; Watts, A L; Gö?ü?, E

    2014-01-01

    Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806-20 and SGR 1900+14, observed with the Rossi X-ray Timing Explorer (RXTE). We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806-20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain the giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and s...

  6. On the Importance of Searching for Oscillations of the Jovian Inner Radiation Belt with a Quasi-Period of 40 Minutes

    E-print Network

    Yu-Qing Lou; Chen Zheng

    2003-07-14

    Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-minute period(QP-40) from the south pole of Jupiter in February 1992. Such polar QP-40 burst activities were found to correlate well with arrivals of high-speed solar winds at Jupiter. We advance the physical scenario that the inner radiation belt(IRB) within ~2-3 Jupiter's radius, where ralativistic electrons are known to be trapped via synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds. Modulated by such QP-40 IRB oscillations, relativistic electrons trapped in the IRB may escape from the magnetic circumpolar regions during a certain phase of each 40-min period to form circumpolar QP-40 electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic field at ~30-40 Jupiter radius give rise to QP-40 radio bursts with typical frequencies <0.2MHz. We predict that the synchrotron brightness of the IRB should vary on QP-40 timescales upon arrivals of high-speed solar winds with estimated magnitudes larger than 0.1Jy, detectable by ground-based radio telescopes. Using the real-time solar wind data from the spacecraft ACE, we show here that shch QP-40 pulsations of Jupiter's polar X-ray hot spot did in fact coincide with the arrival of high-speed solar wind at Jupiter.

  7. Time delay effect between long quasi-periodic oscillations of 37 GHz radio sources and the magnetic field of the nearest sunspots

    NASA Astrophysics Data System (ADS)

    Smirnova, V. V.; Riehokainen, A.; Solov'ev, A. A.; Kallunki, J.

    2015-06-01

    Measurements and the interpretation of the time delay effect between long quasi-periodic oscillations of sunspot magnetic fields and nearby millimeter radio sources observed at 37 GHz were the main goals of this work. Ground-based radio telescope operated by Metsähovi Radio Observatory, Aalto University, Finland was used to obtain time series variations of radio intensity at 37 GHz frequency, as well as, the Helioseismic and Magnetic Imager instrument on-board the Solar Dynamics Observatory spacecraft was used to obtain the magnetic field time series variations. Lags (time delays) in the interval of 15-35 minutes were obtained by cross-correlation analysis of time series and by direct geometrical measurements of distances between the radio sources and nearby sunspots. These distances were in the interval of 11-24 Mm. Corresponding time delays were defined as the relation of these distances to the sound speed. Time delays obtained by two different independent methods turned to be very close. This fact confirms the interpretation of the phenomenon under the study as a process of propagation of disturbances from the slowly oscillating sunspot to the radio source with the sound speed.

  8. Quasi-periodic patterns (QPP): large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity

    PubMed Central

    Thompson, Garth John; Pan, Wen-Ju; Magnuson, Matthew Evan; Jaeger, Dieter; Keilholz, Shella Dawn

    2013-01-01

    Functional connectivity measurements from resting state blood-oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) are proving a powerful tool to probe both normal brain function and neuropsychiatric disorders. However, the neural mechanisms that coordinate these large networks are poorly understood, particularly in the context of the growing interest in network dynamics. Recent work in anesthetized rats has shown that the spontaneous BOLD fluctuations are tightly linked to infraslow local field potentials (LFPs) that are seldom recorded but comparable in frequency to the slow BOLD fluctuations. These findings support the hypothesis that long-range coordination involves low frequency neural oscillations and establishes infraslow LFPs as an excellent candidate for probing the neural underpinnings of the BOLD spatiotemporal patterns observed in both rats and humans. To further examine the link between large-scale network dynamics and infraslow LFPs, simultaneous fMRI and microelectrode recording were performed in anesthetized rats. Using an optimized filter to isolate shared components of the signals, we found that time-lagged correlation between infraslow LFPs and BOLD is comparable in spatial extent and timing to a quasi-periodic pattern (QPP) found from BOLD alone, suggesting that fMRI-measured QPPs and the infraslow LFPs share a common mechanism. As fMRI allows spatial resolution and whole brain coverage not available with electroencephalography, QPPs can be used to better understand the role of infraslow oscillations in normal brain function and neurological or psychiatric disorders. PMID:24071524

  9. On the development of the Papaloizou-Pringle instability of the black hole-torus systems and quasi-periodic oscillations

    NASA Astrophysics Data System (ADS)

    Dönmez, O.

    2014-02-01

    We present the numerical study of dynamical instability of a pressure-supported relativistic torus, rotating around the black hole with a constant specific angular momentum on a fixed space-time background, in case of perturbation by a matter coming from the outer boundary. Two-dimensional hydrodynamical equations are solved at equatorial plane using the high resolution shock capturing method to study the effect of perturbation on the stable systems. We have found that the perturbed torus creates an instability which causes the gas falling into the black hole in a certain dynamical time. All the models indicate an oscillating torus with certain frequency around their instant equilibrium. The dynamic of the accreted torus varies with the size of initial stable torus, black hole spin and other variables, such as Mach number, sound speed, cusp location of the torus, etc. The mass accretion rate is slightly proportional to the torus-to-hole mass ratio in the black hole-torus system, but it strongly depends on the cusp location of the torus. The cusp located in the equipotential surfaces of the effective potential moves outwards into the torus. The dynamical change of the torus increases the mass accretion rate and triggers the Papaloizou-Pringle instability. It is also observed that the growth of the m = 1 mode of the Papaloizou-Pringle instability occurs for a wide range of fluid and hydrodynamical parameters and a black hole spin. We have also computed the quasi-periodic oscillations from the oscillating relativistic torus.

  10. A unified lense-thirring precession model for optical and X-ray quasi-periodic oscillations in black hole binaries

    SciTech Connect

    Veledina, Alexandra; Poutanen, Juri [Astronomy Division, Department of Physics, P.O. Box 3000, FI-90014, University of Oulu (Finland); Ingram, Adam, E-mail: alexandra.veledina@oulu.fi, E-mail: juri.poutanen@oulu.fi [Astronomical Institute "Anton Pannekoek," University of Amsterdam, Postbus 94249, 1098 GE Amsterdam (Netherlands)

    2013-12-01

    Recent observations of accreting black holes reveal the presence of quasi-periodic oscillations (QPO) in the optical power density spectra. The corresponding oscillation periods match those found in X-rays, implying a common origin. Among the numerous suggested X-ray QPO mechanisms, some may also work in the optical. However, their relevance to the broadband—optical through X-ray—spectral properties have not been investigated. For the first time, we discuss the QPO mechanism in the context of the self-consistent spectral model. We propose that the QPOs are produced by Lense-Thirring precession of the hot accretion flow, whose outer parts radiate in optical wavelengths. At the same time, its innermost parts are emitting X-rays, which explains the observed connection of QPO periods. We predict that the X-ray and optical QPOs should be either in phase or shifted by half a period, depending on the observer position. We investigate the QPO harmonic content and find that the variability amplitudes at the fundamental frequency are larger in the optical, while the X-rays are expected to have strong harmonics. We then discuss the QPO spectral dependence and compare the expectations to the existing data.

  11. Quasi-periodic Oscillations in Short Recurring Bursts of Magnetars SGR 1806-20 and SGR 1900+14 Observed with RXTE

    NASA Astrophysics Data System (ADS)

    Huppenkothen, D.; Heil, L. M.; Watts, A. L.; Gö?ü?, E.

    2014-11-01

    Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806-20 and SGR 1900+14, observed with Rossi X-ray Timing Explorer. We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806-20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and strong variability on short timescales. In this regime, standard Fourier methodology and more sophisticated Fourier analyses fail in equal parts by yielding an unacceptably large number of false-positive detections. This problem is not straightforward to solve in the Fourier domain. Instead, we show how simulations of light curves can offer a viable solution for QPO searches in these light curves.

  12. Numerical modeling of non-thermal plasma discharges

    SciTech Connect

    Rolader, G.E.; Hoffman, M.P. [Science Applications International Corp., Shalimar, FL (United States); Federle, S.P. [Air Force Wright Lab., Eglin AFB, FL (United States). Armament Directorate

    1995-12-31

    This paper documents a detailed numerical model developed to simulate the physical and chemical processes that occur in a Non-Thermal Plasma Discharge (NTPD). Ozone production with NTPDs is a mature technology, dating back more than 100 years. However, it has only been during the last 20 years that many researchers have investigated NTPDs for gaseous pollutant destruction. The model described in this paper is for a double dielectric NTPD, a common type, in which the working gas flows between two dielectrics, each covering an electrode. A high voltage, and corresponding high electric field, is applied to the electrodes, polarizing the dielectrics and causing the gas to breakdown. At atmospheric pressures this breakdown results in a multitude of small discharge channels, called microdischarges. The dielectrics limit the duration of each discharge, preventing the electrons and heavy particles from coming to thermal equilibrium, and the free electrons within the microdischarges reach temperatures on the order of 50,000 K, while the temperature of the heavy particles remains approximately constant. These energetic electrons collide with molecular species resulting in the formation of radicals and other highly reactive compounds, and after the discharge extinguishes, these reactive compounds collide with other species, potentially resulting in desired chemical reactions. The model presented in this paper is based on a control volume approach, and it simulates both the microdischarges and subsequent chemical kinetics. Sample calculations are presented and compared to experimental results to lend some validity to the model.

  13. The physics of non-thermal radiation in microquasars

    E-print Network

    V. Bosch-Ramon

    2008-10-27

    Microquasars are binary systems that harbor a normal star and a compact object (black-hole or neutron star), and show relativistic outflows (or jets). The matter that forms these jets is of likely stellar origin, previously expelled from the star and trapped in the potential well of the compact object. This matter is accreted by the compact object, forming a disk due to its angular momentum, and is eventually ejected in the form of a bipolar outflow (the jets), which generates radio emission and could also be a very high-energy emitter. To study and understand the radiation from microquasars, there is a set of elements that can play a major role and are to be taken into account: the photons and the expelled matter from the star in the case of high-mass systems; the accreted matter radiation; the jet; the magnetic field carried by the jet or filling the binary system; and the medium surrounding the microquasar at large scales (~pc). In this lecture, we consider these elements of the microquasar scenario and briefly describe the physical conditions and processes involved in the production of non-thermal radiation from radio to gamma-rays. The required energetics, particle acceleration and transport, several radiative mechanisms, and the impact of different photon absorption processes, are discussed.

  14. RXTE Observations M87: Investigating the Non-Thermal Continuum

    NASA Technical Reports Server (NTRS)

    Reynolds, Christopher S.

    2001-01-01

    This is the final report for NASA grant NAG5-7329, awarded for the RXTE Cycle 3 Guest Observer Program, "RXTE Observations of M87: Investigating the nonthermal continuum". This grant totaled $8000 and was spent over 3 years (4/1998-4/2001). It supported analysis of RXTE observations of the nearby giant elliptical galaxy M87 with the RXTE satellite. The main aim of these observations was to search for non-thermal emission from the core of M87 and the famous jet. This grant also partially funded supporting theoretical work. The observational campaign was performed in December 1997 and January 1998, and we were given the final data tape in April 1998. Sebastian Heinz (then a graduated student in our group) and I started to work on the data immediately. The results of our detailed analysis were submitted to the Astrophysical Journal in November 1998, and accepted for publication in March 1999. Tile paper was published in August, 1999. The journal reference is: A RXTE study of N187 and the core of the Virgo cluster, Reynolds C.S.,Heinx S., Fabian A.C., Begelman M.C., 1999, ApJ, 102, 1999. During this first year of the project, this grant supported Mr. Heinz's travel to the Paris Texas Symposium in December 1998, as well as providing funds for necessary maintenance of our computer system.

  15. Non-thermal discharge processing of gaseous pollutants

    SciTech Connect

    Vogtlin, G.; Penetrante, B.; Wallman, H.

    1993-08-27

    The electrical discharge techniques, called non-thermal, utilize high voltage breakdown of gases using short pulses of one to a few hundred nanoseconds. These short pulses between metal electrodes generate energetic electrons without appreciable thermal heating of the gas. The energetic electrons collide with gas molecules to form radicals. The radicals then react with pollutants to form harmless compounds. Our experimental device uses a wire in a pipe geometry. The wire is driven by a 40 kilovolt pulse 100 nanoseconds long. Gas is circulated in a loop through the pipe geometry in a closed system. This system permits the introduction of various gas combinations prior to testing. The recirculated gas can be heated to determine the effect on the electrical discharge, and chemical reactions. The efficiency of pollutant removal is the key to applications. We have been able to significantly improve the efficiency of NO removal by the addition of hydrocarbons. Nitric oxide has been removed with an energy cost of 15 ev per NO molecule. We believe the hydrocarbon additive serves by recycling the hydroxyl radicals during the oxidation and reduction of NO. The implementation of this process will depend largely on how much additives, electrical power consumption, and final NO{sub x} concentration are acceptable for a particular application.

  16. Application of non-thermal plasmas to pollution control. Revision 1

    Microsoft Academic Search

    B. M. Penetrante; G. E. Vogtlin; J. N. Bardsley; P. A. Vitello; P. H. Wallman

    1993-01-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (HS), (2) removal of trichloroethylene (TCE), and (3) removal of nitrogen oxides (NO). Emphasis is placed on the energy

  17. LOW-FREQUENCY (11 mHz) OSCILLATIONS IN H1743-322: A NEW CLASS OF BLACK HOLE QUASI-PERIODIC OSCILLATIONS?

    SciTech Connect

    Altamirano, D. [Astronomical Institute, 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098XH, Amsterdam (Netherlands); Strohmayer, T., E-mail: d.altamirano@uva.nl [Astrophysics Science Division, Mail Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-08-01

    We report the discovery of quasi-periodic oscillations (QPOs) at {approx}11 mHz in two RXTE and one Chandra observations of the black hole candidate H1743-322. The QPO is observed only at the beginning of the 2010 and 2011 outbursts at similar hard color and intensity, suggestive of an accretion state dependence for the QPO. Although its frequency appears to be correlated with X-ray intensity on timescales of a day, in successive outbursts eight months apart, we measure a QPO frequency that differs by less than Almost-Equal-To 2.2 mHz while the intensity had changed significantly. We show that this {approx}11 mHz QPO is different from the so-called Type C QPOs seen in black holes and that the mechanisms that produce the two flavors of variability are most probably independent. After comparing this QPO with other variability phenomena seen in accreting black holes and neutron stars, we conclude that it best resembles the so-called 1 Hz QPOs seen in dipping neutron star systems, although having a significantly lower (1-2 orders of magnitude) frequency. If confirmed, H1743-322 is the first black hole showing this type of variability. Given the unusual characteristics and the hard-state dependence of the {approx}11 mHz QPO, we also speculate whether these oscillations could instead be related to the radio jets observed in H1743-322. A systematic search for this type of low-frequency QPOs in similar systems is needed to test this speculation. In any case, it remains unexplained why these QPOs have only been seen in the last two outbursts of H1743-322.

  18. Quasi-periodic Fast-mode Wave Trains Within a Global EUV Wave and Sequential Transverse Oscillations Detected by SDO-AIA

    NASA Technical Reports Server (NTRS)

    Liu, Wei; Ofman, Leon; Nitta, Nariaki; Aschwanden, Markus J.; Schrijver, Carolus J.; Title, Alan M.; Tarbell, Theodore D.

    2012-01-01

    We present the first unambiguous detection of quasi-periodic wave trains within the broad pulse of a global EUV wave (so-called EIT wave) occurring on the limb. These wave trains, running ahead of the lateral coronal mass ejection (CME) front of 2-4 times slower, coherently travel to distances greater than approximately solar radius/2 along the solar surface, with initial velocities up to 1400 kilometers per second decelerating to approximately 650 kilometers per second. The rapid expansion of the CME initiated at an elevated height of 110 Mm produces a strong downward and lateral compression, which may play an important role in driving the primary EUV wave and shaping its front forwardly inclined toward the solar surface. The wave trains have a dominant 2 minute periodicity that matches the X-ray flare pulsations, suggesting a causal connection. The arrival of the leading EUV wave front at increasing distances produces an uninterrupted chain sequence of deflections and/or transverse (likely fast kink mode) oscillations of local structures, including a flux-rope coronal cavity and its embedded filament with delayed onsets consistent with the wave travel time at an elevated (by approximately 50%) velocity within it. This suggests that the EUV wave penetrates through a topological separatrix surface into the cavity, unexpected from CME-caused magnetic reconfiguration. These observations, when taken together, provide compelling evidence of the fast-mode MHD wave nature of the primary (outer) fast component of a global EUV wave, running ahead of the secondary (inner) slow component of CME-caused restructuring.

  19. EVIDENCE OF A WARM ABSORBER THAT VARIES WITH QUASI-PERIODIC OSCILLATION PHASE IN THE ACTIVE GALACTIC NUCLEUS RE J1034+396

    SciTech Connect

    Maitra, Dipankar; Miller, Jon M., E-mail: dmaitra@umich.ed, E-mail: jonmm@umich.ed [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2010-07-20

    A recent observation of the nearby (z = 0.042) narrow-line Seyfert 1 galaxy RE J1034+396 on 2007 May 31 showed strong quasi-periodic oscillations (QPOs) in the 0.3-10 keV X-ray flux. We present phase-resolved spectroscopy of this observation, using data obtained by the EPIC PN detector on board XMM-Newton. The 'low' phase spectrum, associated with the troughs in the light curve, shows (at >4{sigma} confidence level) an absorption edge at 0.86 {+-} 0.05 keV with an absorption depth of 0.3 {+-} 0.1. Ionized oxygen edges are hallmarks of X-ray warm absorbers in Seyfert active galactic nuclei; the observed edge is consistent with H-like O VIII and implies a column density of N{sub OVIII} {approx} 3 x 10{sup 18} cm{sup -2}. The edge is not seen in the 'high' phase spectrum associated with the crests in the light curve, suggesting the presence of a warm absorber in the immediate vicinity of the supermassive black hole that periodically obscures the continuum emission. If the QPO arises due to Keplerian orbital motion around the central black hole, the periodic appearance of the O VIII edge would imply a radius of {approx}9.4(M/[4x10{sup 6}M{sub sun}]){sup -2/3}(P/[1 hr]){sup 2/3} r{sub g} for the size of the warm absorber.

  20. QUASI-PERIODIC FAST-MODE WAVE TRAINS WITHIN A GLOBAL EUV WAVE AND SEQUENTIAL TRANSVERSE OSCILLATIONS DETECTED BY SDO/AIA

    SciTech Connect

    Liu Wei; Nitta, Nariaki V.; Aschwanden, Markus J.; Schrijver, Carolus J.; Title, Alan M.; Tarbell, Theodore D. [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Ofman, Leon, E-mail: weiliu@lmsal.com [Department of Physics, Catholic University of America, Washingtom, DC 20064 (United States)

    2012-07-01

    We present the first unambiguous detection of quasi-periodic wave trains within the broad pulse of a global EUV wave (so-called EIT wave) occurring on the limb. These wave trains, running ahead of the lateral coronal mass ejection (CME) front of 2-4 times slower, coherently travel to distances {approx}> R{sub Sun }/2 along the solar surface, with initial velocities up to 1400 km s{sup -1} decelerating to {approx}650 km s{sup -1}. The rapid expansion of the CME initiated at an elevated height of 110 Mm produces a strong downward and lateral compression, which may play an important role in driving the primary EUV wave and shaping its front forwardly inclined toward the solar surface. The wave trains have a dominant 2 minute periodicity that matches the X-ray flare pulsations, suggesting a causal connection. The arrival of the leading EUV wave front at increasing distances produces an uninterrupted chain sequence of deflections and/or transverse (likely fast kink mode) oscillations of local structures, including a flux-rope coronal cavity and its embedded filament with delayed onsets consistent with the wave travel time at an elevated (by {approx}50%) velocity within it. This suggests that the EUV wave penetrates through a topological separatrix surface into the cavity, unexpected from CME-caused magnetic reconfiguration. These observations, when taken together, provide compelling evidence of the fast-mode MHD wave nature of the primary (outer) fast component of a global EUV wave, running ahead of the secondary (inner) slow component of CME-caused restructuring.

  1. Evidence from Quasi-Periodic Oscillations for a Millisecond Pulsar in the Low Mass X-Ray Binary 4U 0614+091

    NASA Technical Reports Server (NTRS)

    Ford, E.; Kaaret, P.; Tavani, M.; Barret, D.; Bloser, P.; Grindlay, J.; Harmon, B. A.; Paciesas, W. S.; Zhang, S. N.

    1997-01-01

    We have detected quasi-periodic oscillations (QPOs) near 1 kHz from the low mass X-ray binary 4U 0614+091 in observations with RXTE. The observations span several months and sample the source over a large range of X-ray luminosity. In every interval QPOs are present above 400 Hz with fractional RMS amplitudes from 3 to 12% over the full PCA band. At high count rates, two high frequency QPOs are detected simultaneously. The difference of their frequency centroids is consistent with a constant value of 323 Hz in all observations. During one interval a third signal is detected at 328 +/- 2 Hz. This suggests the system has a stable 'clock' which is most likely the neutron star with spin period 3.1 msec. Thus, our observations of 4U 0614+091 and those of 4U 1728-34 provide the first evidence for millisecond pulsars within low-mass X-ray binary systems and reveal the 'missing-link' between millisecond radiopulsars and the late stages of binary evolution in low mass X-ray binaries. The constant difference of the high frequency QPOs sug,,ests a beat-frequency interpretation. In this model, the high frequency QPO is associated with the Keplerian frequency of the inner accretion disk and the lower frequency QPO is a 'beat' between the differential rotation frequency of the inner disk and the spinning neutron star. Assuming the high frequency QPO is a Keplerian orbital frequency for the accretion disk, we find a maximum mass of 1.9 solar mass and a maximum radius of 17 km for the neutron star.

  2. Non-Thermal Plasma System Development for CIDI Exhaust Aftertreatment

    SciTech Connect

    Balmer, M. Lou (Pacific Northwest National Laboratory (PNNL)); Tonkyn, Russell (Battelle Pacific Northwest Laboratories (BPNL)); Maupin, Gary; Yoon, Steven; Kolwaite, Ana (PNNL); Barlow, Stephen (BPNL); Domingo, Norberto; Storey, John M. (Oak Ridge National Laboratory); Hoard, John Wm. (Ford Research Laboratory); Howden, Ken (U.S. Dept. of Energy)

    2000-04-01

    There is a need for an efficient, durable technology to reduce NOx emissions from oxidative exhaust streams such as those produced by compression-ignition, direct injection (CIDI) diesel or lean-burn gasoline engines. A partnership formed between the DOE Office of Advanced Automotive Technology, Pacific Northwest National Laboratory, Oak Ridge National Laboratory and the USCAR Low Emission Technologies Research and Development Partnership is evaluating the effectiveness of a non-thermal plasma in conjunction with catalytic materials to mediate NOx and particulate emissions from diesel fueled light duty (CIDI) engines. Preliminary studies showed that plasma-catalyst systems could reduce up to 70% of NOx emissions at an equivalent cost of 3.5% of the input fuel in simulated diesel exhaust. These studies also showed that the type and concentration of hydrocarbon play a key role in both the plasma gas phase chemistry and the catalyst surface chemistry. More recently, plasma/catalyst systems have been evaluated for NOx reduction and particulate removal on a CIDI engine. Performance results for select plasma-catalyst systems for both simulated and actual CIDI exhaust will be presented. The effect of NOx and hydrocarbon concentration on plasma-catalyst performance will also be shown. SAE Paper SAE-2000-01-1601 {copyright} 2000 SAE International. This paper is published on this website with permission from SAE International. As a user of this website, you are permitted to view this paper on-line, download this pdf file and print one copy of this paper at no cost for your use only. The downloaded pdf file and printout of this SAE paper may not be copied, distributed or forwarded to others or for the use of others.

  3. Characterizing the non-thermal emission of Cas A

    E-print Network

    E. A. Helder; J. Vink

    2008-06-23

    We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize and quantify its non-thermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the inner shell. We tackle this problem by employing a Lucy-Richardson deconvolution technique and measuring spectral indices in the 4.2-6 keV band. We show that most of the continuum emission is coming from an inner ring that coincides with the location of the reverse shock. This inner ring includes filaments, whose X-ray emission has been found to be dominated by X-ray synchrotron emission. The X-ray emission from these filaments, both at the forward shock and from the inner ring, have relatively hard spectra with spectral index > -3.1. The regions emitting hard X-ray continuum contribute about 54% of the total X-ray emission in the 4.2-6 keV. This is lower than suggested by extrapolating the hard X-ray spectrum as measured by BeppoSAX-PDS and INTEGRAL. This can be reconciled by assuming a gradual steepening of the spectrum toward higher energies. We argue that the X-ray synchrotron emission is mainly coming from the Western part of the reverse shock. The reverse shock in the West is almost at rest in our observation frame, corresponding to a relatively high reverse shock velocity of ~6000 km/s in the frame of the freely expanding ejecta.

  4. Nonlinear ion-acoustic waves in an inhomogeneous plasma with non-thermal distribution of electrons

    NASA Astrophysics Data System (ADS)

    Singh, S. V.

    2015-06-01

    In the Earth's magnetosphere, the boundary layer regions are the sources for inhomogeneous plasmas and are natural laboratories to study wave phenomena. In these regions, particles distributions also differ from Maxwellian and are found to be non-thermal. Therefore, amplitude of the waves propagating through these regions can vary differently compared to the homogeneous plasmas. In this study, propagation of ion-acoustic waves (IAWs) in an inhomogeneous, warm electron-ion plasma is examined. The electrons are considered to be having non-thermal Cairn's type distribution and ions follow the fluid dynamical equations. Further, inhomogeneity is assumed in equilibrium density of the electrons and ions. The evolution of the nonlinear IAWs is governed by the Korteweg-de Vries (KdV) equation with variable coefficients. Analytical solution of the KdV equation shows that for a cold ion plasma and non-thermal electrons, the amplitude and the width of the nonlinear IAWs decreases and increases, respectively with the inclusion of the non-thermal distribution of electrons. It is interesting to note that nonlinear IAWs in this model can not propagate for whole range of non-thermal parameter, ?. The novel result of this study is that for nonlinear IAWs to propagate in the inhomogeneous two component plasma with ions and non-thermal electrons, the non-thermal parameter, ? <= 0.155. Results from our study may have impact on the propagation of the IAWs in the boundary layer regions of the Earth's magnetosphere where density inhomogeneities are appreciable.

  5. Discovery of a 450 Hz Quasi-Periodic Oscillation from the Microquasar GRO J1655-40 with the Rossi X-ray Timing Explorer

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We report the discovery with the Proportional Counter Array on board the Rossi X-Ray Timing Explorer of a 450 Hz quasi-periodic oscillation (QPO) in the hard X-ray flux from the Galactic microquasar GRO J1655-40. This is the highest frequency QPO modulation seen to date from a black hole. The QPO is detected only in the hard X-ray band above approx. 13 keV. It is both strong and narrow, with a typical rms (root mean square) amplitude of 4.5% in the 13-27 keV range and a width of approx. 40 Hz (FWHM). For two observations in which we detect the 450 Hz QPO, a previously known approx. 300 Hz QPO is also observed in the 2-13 keV band. We show that these two QPOs sometimes appear simultaneously, thus demonstrating the first detection of a pair of high-frequency QPOs in a black hole system. Prior to this, pairs of high-frequency QPOs have been detected only in neutron star systems. GRO J1655-40 is one of only a handful of black hole systems with a good dynamical mass constraint. For a nonrotating black hole with mass between 5.5 and 7.9 solar masses, the innermost stable circular orbit (ISCO) ranges from 45 to 70 km. For any mass in this range the radius at which the orbital frequency reaches 450 Hz is less than the ISCO radius, indicating that, if the modulation is caused by Kepler motion, the black hole must have appreciable spin. If the QPO frequency is set by the orbital frequency of matter at the ISCO, then for this mass range the dimensionless angular momentum lies in the range 0.15 < j < 0.5. Moreover, if the modulation is caused by oscillation modes in the disk or Lense-Thirring precession, then this would also require a rapidly rotating hole. We briefly discuss the implications of our findings for models of X-ray variability in black holes and neutron stars.

  6. Coupling Between Fluid Flow and Heat Transfer - A Mechanism for Quasi-Periodic Variations in CO2 Discharges from Deep Underground Sources

    NASA Astrophysics Data System (ADS)

    Pruess, K.

    2004-12-01

    Leakage of CO2 from underground sources is of interest in connection with volcanic hazards assessment, and with the integrity and safety of geologic disposal reservoirs for CO2 that have been proposed as a means for mitigating global warming from atmospheric emissions. Underground accumulations of CO2, whether naturally occurring or man-made, store vast amounts of compressional energy. At subsurface temperature and pressure conditions, CO2 is always buoyant relative to aqueous fluids, and its upward migration may conceivably give rise to a self-enhancing runaway release due to decompression and the much lower viscosity as compared to water. Natural occurrences of CO2 have been implicated in hydrothermal eruptions, and may be capable of causing "pneumatic" eruptions that are not powered by thermal energy. We have performed numerical simulations of CO2 release through fracture zones and faults in order to determine under what conditions, if any, a self-enhancing, eruptive release may be possible. Our simulations include coupling between multiphase fluid flow and associated heat transfer effects, and accurately represent the thermophysical properties of CO2 in sub-critical (liquid or gaseous) and supercritical conditions, as well as transitions between different phase compositions, and phase partitioning between CO2-rich and aqueous phases. The behavior of rising CO2 plumes is found to be strongly affected by heat transfer effects. As supercritical CO2 migrates upward it cools due to expansion. Much stronger cooling may arise from boiling of liquid CO2 that may occur after temperatures and pressures drop below critical values (Tcrit = 31.04 deg-C, Pcrit = 73.82 bar). Our simulations of CO2 migration up a fault zone produce quasi-periodic cycling of thermodynamic conditions and substantial variations of CO2 fluxes discharged at the land surface on a time scale of order 1 year. This behavior is explained in terms of an interplay between multiphase flow in the fault zone and conductive heat exchange with surrounding country rock of low permeability. CO2 upflow rates are reduced by heat transfer limitations, which give rise to substantial increase in fluid density as temperatures decline. A better understanding of natural hydrothermal and pneumatic eruptions is necessary in order that the effectiveness and safety of geologic disposal systems for CO2 may be evaluated. This work was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

  7. The sporadic non-thermal profile of auroral 557.7 nm [OI

    Microsoft Academic Search

    V. Ignatyev; S. Nikolashkin

    2002-01-01

    The rare case of a non-thermal profile of an emission 557.7 nm appearance in aurora during interferometric observations in January, 2000 on Maimaga observatory (63 N, 129.7 E, geogr.) is considered. On the basis of the analysis of the shape and half-width of a non-thermal profile of the line of auroral 557.7 nm [OI] is concluded, that its occurrence is

  8. Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

    Microsoft Academic Search

    Krishna P. Arjunan; Alisa Morss Clyne

    2011-01-01

    Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), recently emerged as an efficient tool in medical applications. Liquids and endothelial cells were treated with a non-thermal dielectric barrier discharge plasma. Plasma treatment of phosphate buffered saline (PBS) and serum-free medium increased ROS concentration in a

  9. Revised Results for Non-thermal Recombination Flare Hard X-Ray Emission

    Microsoft Academic Search

    J. C. Brown; P. C. V. Mallik; N. R. Badnell

    2009-01-01

    Brown and Mallik (BM) recently showed that, for hot sources, recombination of\\u000anon-thermal electrons (NTR) onto highly ionised heavy ions is not negligible\\u000acompared to non-thermal bremsstrahlung (NTB) as a source of flare hard X-rays\\u000a(HXRs) and so should be included in modelling non-thermal HXR flare emission.\\u000aIn view of major discrepancies between BM results for the THERMAL continua and

  10. Comparison of different types of non-thermal plasma treatment of mammalian cells

    Microsoft Academic Search

    S. Kalghatgi; C. Kelly; E. Cerchar; A. Fridman; J. Azizkhan-Clifford; G. Friedman

    2009-01-01

    Summary form only given. Non-thermal plasma is now being widely developed for various clinical applications, e.g. cancer treatment, blood coagulation and tissue sterilization. However, the effects of non-thermal plasma on mammalian cells are still unclear. In this paper we investigate the effects of the plasma on mammalian cells. One of the most critical of such effects could be DNA damage,

  11. EXPERIMENTAL ASSESSMENT OF NON-THERMAL PLASMA TECHNIQUES FOR REMOVAL OF PAPER INDUSTRY VOC EMISSIONS

    Microsoft Academic Search

    Mario G. Sobacchi; Alexei V. Saveliev; Alexander A Fridman; Alexander Gutsol; Lawrence A. Kennedy

    The experimental assessment of non-thermal plasma techniques for treating of volatile organic compounds (VOCs) emissions from the paper industry was performed. Two types of non-thermal discharges were tested: non-equilibrium gliding arc discharge and pulsed streamer corona discharge. For the compounds of interest in this study (methanol, acetone, dimethyl sulfide and ? -pinene), high removal efficiencies were obtained with power levels

  12. Analytical model for non-thermal pressure in galaxy clusters - II. Comparison with cosmological hydrodynamics simulation

    NASA Astrophysics Data System (ADS)

    Shi, Xun; Komatsu, Eiichiro; Nelson, Kaylea; Nagai, Daisuke

    2015-03-01

    Turbulent gas motion inside galaxy clusters provides a non-negligible non-thermal pressure support to the intracluster gas. If not corrected, it leads to a systematic bias in the estimation of cluster masses from X-ray and Sunyaev-Zel'dovich (SZ) observations assuming hydrostatic equilibrium, and affects interpretation of measurements of the SZ power spectrum and observations of cluster outskirts from ongoing and upcoming large cluster surveys. Recently, Shi & Komatsu developed an analytical model for predicting the radius, mass, and redshift dependence of the non-thermal pressure contributed by the kinetic random motions of intracluster gas sourced by the cluster mass growth. In this paper, we compare the predictions of this analytical model to a state-of-the-art cosmological hydrodynamics simulation. As different mass growth histories result in different non-thermal pressure, we perform the comparison on 65 simulated galaxy clusters on a cluster-by-cluster basis. We find an excellent agreement between the modelled and simulated non-thermal pressure profiles. Our results open up the possibility of using the analytical model to correct the systematic bias in the mass estimation of galaxy clusters. We also discuss tests of the physical picture underlying the evolution of intracluster non-thermal gas motions, as well as a way to further improve the analytical modelling, which may help achieve a unified understanding of non-thermal phenomena in galaxy clusters.

  13. Galaxy evolution: modelling the role of non-thermal pressure in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Birnboim, Yuval; Balberg, Shmuel; Teyssier, Romain

    2015-03-01

    Galaxy evolution depends strongly on the physics of the interstellar medium (ISM). Motivated by the need to incorporate the properties of the ISM in cosmological simulations, we construct a simple method to include the contribution of non-thermal components in the calculation of pressure of interstellar gas. In our method, we treat three non-thermal components - turbulence, magnetic fields and cosmic rays - and effectively parametrize their amplitude. We assume that the three components settle into a quasi-steady-state that is governed by the star formation rate, and calibrate their magnitude and density dependence by the observed radio-FIR correlation, relating synchrotron radiation to star formation rates of galaxies. We implement our model in single-cell numerical simulation of a parcel of gas with constant pressure boundary conditions and demonstrate its effect and potential. Then, the non-thermal pressure model is incorporated into RAMSES and hydrodynamic simulations of isolated galaxies with and without the non-thermal pressure model are presented and studied. Specifically, we demonstrate that the inclusion of realistic non-thermal pressure reduces the star formation rate by an order of magnitude and increases the gas depletion time by as much. We conclude that the non-thermal pressure can prolong the star formation epoch and achieve consistency with observations without invoking artificially strong stellar feedback.

  14. Arbitrary amplitude solitons in a non-ideal dusty plasma with non-thermal ions

    SciTech Connect

    Maharaj, S.K. [Hermanus Magnetic Observatory, P. O. Box 32, Hermanus, 7200 (South Africa); Pillay, S.R.; Bharuthram, R. [University of KwaZulu-Natal, Durban (South Africa)

    2005-10-31

    The Sagdeev potential method is used to investigate the non-linear propagation of the dust-acoustic wave in a weakly non-ideal dusty plasma comprising a negatively charged dust fluid, Boltzmann electrons and non-thermal ions which are characterised by a non-thermal parameter {alpha}. The non-ideal effects of volume reduction and attractive cohesive forces are introduced by adopting the van der Waal's equation of state for the dust fluid. Both supersonic and subsonic solitons are found to exist for a non-ideal dusty plasma and comparisons are made with the ideal case. The upper limit of the range of values of the non-thermal parameter for which soliton solutions are admissible, is examined as a function of the non-ideal parameters.

  15. The Swift Burst Alert Telescope Perspective on Non-thermal Emission in HIFLUGCS Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Wik, Daniel R.; Sarazin, Craig L.; Zhang, Yu-Ying; Baumgartner, Wayne H.; Mushotzky, Richard F.; Tueller, Jack; Okajima, Takashi; Clarke, Tracy E.

    2012-03-01

    The search for diffuse non-thermal, inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been underway for many years, with most detections being either of low significance or controversial. In this work, we investigate 14-195 keV spectra from the Swift Burst Alert Telescope (BAT) all-sky survey for evidence of non-thermal excess emission above the exponentially decreasing tail of thermal emission in the flux-limited HIFLUGCS sample. To account for the thermal contribution at BAT energies, XMM-Newton EPIC spectra are extracted from coincident spatial regions so that both thermal and non-thermal spectral components can be determined simultaneously. We find marginally significant IC components in six clusters, though after closer inspection and consideration of systematic errors we are unable to claim a clear detection in any of them. The spectra of all clusters are also summed to enhance a cumulative non-thermal signal not quite detectable in individual clusters. After constructing a model based on single-temperature fits to the XMM-Newton data alone, we see no significant excess emission above that predicted by the thermal model determined at soft energies. This result also holds for the summed spectra of various subgroups, except for the subsample of clusters with diffuse radio emission. For clusters hosting a diffuse radio halo, a relic, or a mini-halo, non-thermal emission is initially detected at the ~5? confidence level—driven by clusters with mini-halos—but modeling and systematic uncertainties ultimately degrade this significance. In individual clusters, the non-thermal pressure of relativistic electrons is limited to <~ 10% of the thermal electron pressure, with stricter limits for the more massive clusters, indicating that these electrons are likely not dynamically important in the central regions of clusters.

  16. Aspects of production and kinetic decoupling of non-thermal dark matter

    E-print Network

    Giorgio Arcadi; Piero Ullio

    2011-11-28

    We reconsider non-thermal production of WIMP dark matter in a systematic way and using a numerical code for accurate computations of dark matter relic densities. Candidates with large pair annihilation rates are favored, suggesting a connection with the anomalies in the lepton cosmic-ray flux detected by Pamela and Fermi. Focussing on supersymmetric models we will consider the impact of non-thermal production on the preferred mass scale for dark matter neutralinos. We have also developed a new formalism to solve the Boltzmann's equation for a system of coannihilating species without assuming kinetic equilibrium and applied it to the case of pure Winos.

  17. Aspects of production and kinetic decoupling of non-thermal dark matter

    E-print Network

    Arcadi, Giorgio

    2011-01-01

    We reconsider non-thermal production of WIMP dark matter in a systematic way and using a numerical code for accurate computations of dark matter relic densities. Candidates with large pair annihilation rates are favored, suggesting a connection with the anomalies in the lepton cosmic-ray flux detected by Pamela and Fermi. Focussing on supersymmetric models we will consider the impact of non-thermal production on the preferred mass scale for dark matter neutralinos. We have also developed a new formalism to solve the Boltzmann's equation for a system of coannihilating species without assuming kinetic equilibrium and applied it to the case of pure Winos.

  18. Mechanisms of interaction of non-thermal plasma with living cells

    NASA Astrophysics Data System (ADS)

    Kalghatgi, Sameer Ulhas

    Thermal plasmas and lasers have been widely used in medicine to cut, ablate and cauterize tissues through heating; in contrast, non-thermal plasma produces various highly active molecules and atoms without heat. As a result, its effects on living cells and tissues could be selective and tunable. This makes non-thermal plasma very attractive for medical applications. However, despite several interesting demonstrations of non-thermal plasma in blood coagulation and tissue sterilization, the biological and physical mechanisms of its interaction with living cells are still poorly understood impeding further development of non-thermal plasma as a clinical tool. Although several possible mechanisms of interaction have been suggested, no systematic experimental work has been performed to verify these hypotheses. Using cells in culture, it is shown in this work that non-thermal plasma created by dielectric barrier discharge (DBD) has dose-dependent effects ranging from increasing cell proliferation to inducing apoptosis which are consistent with the effects of oxidative stress. DNA damage is chosen as a marker to assess the effects of oxidative stress in a quantitative manner. It is demonstrated here that plasma induced DNA damage as well as other effects ranging from cell proliferation to apoptosis are indeed due to production of intracellular reactive oxygen species (ROS). We found that DNA damage is initiated primarily by plasma generated active neutral species which cannot be attributed to ozone alone. Moreover, it is found that extracellular media and its components play a critical role in the transfer of the non-thermal plasma initiated oxidative stress into cells. Specifically, it is found that the peroxidation efficiency of amino acids is the sole predictor of the ability of the medium to transfer the oxidative stress induced by non-thermal plasma. Phosphorylation of H2AX, a DNA damage marker, following plasma treatment is found to be ATR dependent and ATM independent, suggesting that non-thermal plasma may induce formation of bulky lesions unlike ionizing radiation (IR) or H2O2 which primarily produce DNA double strand breaks. Moreover, it is found that the pathway by which plasma generated oxidative stress is transferred across cellular membranes does not involve lipid peroxidation by-products, although lipid peroxidation does occur.

  19. A Stable 3:2 Twin Peak X-ray Quasi-periodic Oscillation from an Ultraluminous X-ray Source: Evidence for a 400 solar mass black hole

    NASA Astrophysics Data System (ADS)

    Pasham, Dheeraj Ranga Reddy; Strohmayer, Tod E.; Mushotzky, Richard

    2014-08-01

    X-ray high-frequency quasi-periodic oscillations (HFQPOs: 100-450 Hz) in a 3:2 frequency ratio--hypothesized to originate from close to the event horizon--have only been observed from stellar-mass black holes. Such general relativity-induced oscillations are expected to scale inversely with the black hole mass. Thus, the detection of a twin peak oscillation in an ultraluminous X-ray source in the range of a few Hz has been proposed as strong evidence for the existence of intermediate-mass black holes. We report the discovery of stable, twin-peak (3:2 frequency ratio) X-ray quasi-periodic oscillations (QPOs) from an ultraluminous X-ray source. The two QPOs at 3.32+-0.06 Hz and 5.07+-0.06 Hz have rms amplitudes of 3-5%. Scaling the frequencies to HFQPOs of stellar-mass black holes of known mass implies that the black hole is 428+-105 solar masses. Our result not only strongly argues that some ULXs are indeed intermediate-mass black holes but also suggests that the physical phenomenon causing HFQPOs in stellar-mass black holes scales to intermediate-mass black holes.

  20. Modeling and simulations of DC and RF atmospheric pressure non-thermal micro plasma discharges: Analysis and applications

    Microsoft Academic Search

    Tanvir Iqbal Farouk

    2009-01-01

    Atmospheric pressure non-thermal plasma discharges are attractive for a wide range of applications due to their operational flexibility. Among the different atmospheric pressure non-thermal plasma sources, atmospheric pressure non-thermal micro plasma discharge is a very recent development. However, the micron scale size of these discharges makes it difficult to measure basic plasma characteristics (species density, gas and electron temperature, electric

  1. Non-thermal laser-induced desorption of metal atoms with bimodal kinetic energy distribution

    NASA Astrophysics Data System (ADS)

    Götz, T.; Bergt, M.; Hoheisel, W.; Träger, F.; Stuke, M.

    1996-09-01

    Laser-induced desorption of metal atoms at low rate has been studied for pulsed excitation with wavelengths of ?=266, 355, 532 and 1064 nm. For this purpose sodium adsorbed on quartz served as a model system. The detached Na atoms were photo-ionized with the light of a second laser operating at ?=193 nm and their kinetic energy distribution was determined by time-of-flight measurements. For ?=1064 nm a distribution typical of thermal bond breaking is observed. If desorption, however, is stimulated with light of ?=266 or 532 nm, the kinetic energy distribution is non-thermal with a single maximum at E kin=0.16±0.02 eV. For ?=355 nm the non-thermal distribution is even bimodal with maxima appearing at E kin=0.16±0.02 and 0.33±0.02 eV. These values of the kinetic energies actually remain constant under variation of all experimental parameters. They appear to reflect the electronic and geometric properties of different binding sites from which the atoms are detached and thus constitute fingerprints of the metal surface. The non-thermal desorption mechanism is discussed in the framework of the Menzel-Gomer-Redhead scenario. The transition from non-thermal to thermal desorption at large fluences of the laser light could also be identified.

  2. Energetic Electron Propagation in the Decay Phase of Non-thermal Flare Emission

    NASA Astrophysics Data System (ADS)

    Huang, Jing; Yan, Yihua; Tsap, Yuri T.

    2014-06-01

    On the basis of the trap-plus-precipitation model, the peculiarities of non-thermal emission in the decay phase of solar flares have been considered. The calculation formulas for the escape rate of trapped electrons into the loss cone in terms of time profiles of hard X-ray (HXR) and microwave (MW) emission have been obtained. It has been found that the evolution of the spectral indices of non-thermal emission depend on the regimes of the pitch angle diffusion of trapped particles into the loss cone. The properties of non-thermal electrons related to the HXR and MW emission of the solar flare on 2004 November 3 are studied with Nobeyama Radioheliograph, Nobeyama Radio Polarimeters, RHESSI, and Geostationary Operational Environmental Satellite observations. The spectral indices of non-thermal electrons related to MW and HXR emission remained constant or decreased, while the MW escape rate as distinguished from that of the HXRs increased. This may be associated with different diffusion regimes of trapped electrons into the loss cone. New arguments in favor of an important role of the superstrong diffusion for high-energy electrons in flare coronal loops have been obtained.

  3. FIRST REPORT ON NON-THERMAL PLASMA REACTOR SCALING CRITERIA AND OPTIMIZATION MODELS

    EPA Science Inventory

    The purpose of SERDP project CP-1038 is to evaluate and develop non-thermal plasma (NTP) reactor technology for DoD air emissions control applications. The primary focus is on oxides of nitrogen (NOx) and a secondary focus on hazardous air pollutants (HAPs), especially volatile o...

  4. Unraveling the mysteries of the non-thermal universe using -ray observations of Active Galactic Nuclei

    E-print Network

    California at Santa Cruz, University of

    Unraveling the mysteries of the non-thermal universe using -ray observations of Active Galactic / min; Crab-like source at 0o Energy resolution: ~15% Low systematic errors: Flux ~20%, Photon index hole at the center (~106 to 109 x solar mass) At least 5% of all galaxies are active galaxies Active

  5. Non-thermal Plasma - Nanometer TiO2 Photocatalysis for Formaldehyde Decomposition 

    E-print Network

    Yuan, Q.; Feng, G.; Guang, X.

    2006-01-01

    In non-thermal plasma-nanometer TiO2 photocatalysis, the techniques of photocatalysis and plasma are combined, and do not need ultraviolet light. It can make use of some kinds of energy in the process of decomposing, while at the same time producing...

  6. EXPERIMENTAL AND CFD STUDIES OF NON-THERMAL PLASMAS FOR NOX CONTROL

    EPA Science Inventory

    Non-thermal plasmas (NTPs) represent a promising technology for the destruction of various toxic gases entrained in air streams. One challenging example of the need for hazardous gas control is the jet engine test cell (JETC) facility where very large amounts of NO(x)s are emitte...

  7. The properties of non-thermal X-ray filaments in young supernova remnants

    NASA Astrophysics Data System (ADS)

    Rettig, R.; Pohl, M.

    2012-09-01

    Context. Young supernova remnants (SNRs) exhibit narrow filaments of non-thermal X-ray emission whose widths can be limited either by electron energy losses or damping of the magnetic field. Aims: We want to investigate whether or not different models of these filaments can be observationally tested. Methods: Using observational parameters of four historical remnants, we calculated the filament profiles and compared the spectra of the filaments with those of the total non-thermal emission. For that purpose, we solved a one-dimensional stationary transport equation for the isotropic differential number density of the electrons. Results: We find that the difference between the spectra of filament and total non-thermal emission above 1 keV is more pronounced in the damping model than in the energy-loss model. Conclusions: A considerable damping of the magnetic field can result in an observable difference between the spectra of filament and total non-thermal emission, thus potentially permitting an observational discrimination between the energy-loss model and the damping model of the X-ray filaments.

  8. Experimental Analysis on NOx Reduction Process By Aerosol Assisted Non-Thermal Plasma

    Microsoft Academic Search

    K. Yamada; M. Itoh

    2005-01-01

    Summary form only given. Non-thermal plasma technique (NTPT) has been applied to several kinds of pollution gas disposal of large quantities. The major process of the disposal is the vapor reduction by condensation onto aerosol surface following the gas to particle conversion of pollution gas. Chang mentioned that the rate coefficient of surface reaction is much larger than that of

  9. Chemical filters by non-thermal atmospheric pressure plasmas for reactive fields

    Microsoft Academic Search

    Osamu Sakai; Tadasuke Morita; Yoshihiko Ueda; Noriaki Sano; Kunihide Tachibana

    2011-01-01

    Non-thermal plasmas in electrode configurations are designed in this study and investigated at atmospheric pressure for generation of reactive fields. A combination of insulated wire electrodes and bare metal wire electrodes makes it possible to obtain a filter-like assembly of microplasmas, even in ambient air or in aqueous solutions. Oxidation and reduction fields are obtained by controlling the gas supply

  10. Non-thermal plasma synthesis and passivation of luminescent silicon nanocrystals

    Microsoft Academic Search

    Lorenzo Mangolini

    2007-01-01

    A novel reactor for the controlled synthesis of small silicon nanocrystals has been developed. A non-thermal plasma is generated in a quartz tube through which a silane containing mixture is flown, resulting in the nucleation and growth of silicon nanoparticles. Given the short residence time in the reactor (<10 ms), very small crystallites are produced, and quantum confinement effects lead

  11. Treatment Carbon Dioxide Using Atmospheric Non-thermal Plasma Produced by Surface Discharge

    Microsoft Academic Search

    Nobuya Hayashi; Hiroshi Yoshida; Saburoh Satoh; Chobei Yamabe

    2004-01-01

    Decomposition and fixation of carbon dioxide (CO_2) were studied using a non-thermal plasma produced by the surface discharge. The mixture gas of carbon dioxide and hydrogen or water vapor was introduced to a discharge reactor in order to deoxidize carbon dioxide and produce organic compounds. The effective condition of the treatment was investigated by controlling several parameters such as a

  12. Direct methanol synthesis using non-thermal pulsed plasma generated by a solid state pulse generator

    Microsoft Academic Search

    Mamoru Okumoto; Kazuhiko Tsunoda; Shinji Katsura; Akira Mizuno

    1997-01-01

    Conversion of hydrocarbon fuels to methanol will promote their efficient utilization since methanol can easily be converted to hydrogen using low temperature heat energy, which would otherwise be disposed. Conventional process for methanol synthesis requires large amount of energy, therefore it can not be applied in the energy utilization system. The non-thermal plasma process can induce chemical reactions that do

  13. Investigation on elemental mercury oxidation mechanism by non-thermal plasma treatment

    Microsoft Academic Search

    Z. H. Wang; S. D. Jiang; Y. Q. Zhu; J. S. Zhou; J. H. Zhou; Z. S. Li; K. F. Cen

    2010-01-01

    Converting elemental mercury into divalent compound is one of the most important steps for mercury abatement from coal fired flue gas. The oxidation of elemental mercury was investigated in this paper using dielectric barrier discharge (DBD) non-thermal plasma (NTP) technology at room temperature. Effects of different flue gas components like oxygen, moisture, HCl, NO and SO2 were investigated. Results indicate

  14. Direct Nonoxidative Methane Conversion by Non-thermal Plasma: Experimental Study

    Microsoft Academic Search

    Yun Yang

    2003-01-01

    The direct non-oxidative conversion of methane to higher hydrocarbons in non-thermal plasma, namely dielectric barrier discharge and corona discharge, has been investigated experimentally at atmospheric pressure. In dielectric barrier discharge, the methane is mainly converted to ethane and propane with small amounts of unsaturated and higher hydrocarbons. While in corona discharge, methane was activated mainly to acetylene with small amount

  15. Excitation and ionization of atoms and ions in a non-thermal plasma. II. Ionization equilibrium

    Microsoft Academic Search

    S. Suckewer

    1970-01-01

    For Pt. I see ibid. 3, 3, 380 (1970). On the basis of the formulae presented in Part I, defining the populations of excited levels, formulae were derived which determine the degree of ionization of atoms and ions in a non-thermal plasma. These transform into the Saha formula for relatively high electron densities. In conjunction with the partition function derived

  16. Syngas Production from Propane using Atmospheric Non-Thermal Plasma F. Ouni, A. Khacef*

    E-print Network

    Paris-Sud XI, Université de

    has a potential for being an effective way for supplying hydrogen or synthesis gas Keywords: Non-thermal plasma, Sliding discharge, Propane, Hydrogen, Synthesis gas. 1. Introduction The increasing concern applications (1, 2) . Synthesis gas or syngas (mixture of hydrogen and carbon monoxide) are used as a major

  17. The effects of non-thermal plasmas on selected mammalian cells

    NASA Astrophysics Data System (ADS)

    Leduc, Mathieu

    Non-thermal plasma surface modifications have become indispensable processing steps in various industry and research sectors. Applications range from semiconductor processing to biotechnology and recently, plasma medicine. Non-thermal plasma sources have the advantage that a number of electron-driven chemical reactions can be produced while maintaining the gas (heavy species) temperature low, thus enabling the treatment of temperature-sensitive surfaces such as polymers, tissues and live cells. In the fields of biology and medicine, non-thermal plasmas have been primarily used for the deposition or modification of biocompatible polymers and for sterilization. Recently, non-thermal plasmas have been used to treat tissues and cells. A new field of research has emerged, Plasma Medicine, which studies the effects of non-thermal plasmas on cells and tissues for clinical applications. The Atmospheric Pressure Glow Discharge torch (APGD-t), a non-thermal plasma source, built in our laboratory was used to study the effects of non-thermal plasmas on mammalian cells. In its first application, we indirectly used the APGD-t to deposit a plasma-polymer on a glass surface and studied its effects on cultured cells. It was shown that the cells grew preferentially on the plasma-polymer, and their proliferation rate increased. The second application of the APGD-t was to further investigate previous observations of cell permeabilization obtained by plasma treatments and to apply non-thermal plasmas to cell transfection. It was demonstrated that the APGD-t is able to locally transfect adherent cells. We estimated the diameter of the pores created to be below 10 nm and that the pores remain open for less than 5 seconds. However, while investigating the mechanisms involved in cell transfection we observed that the use of higher gas flows in the negative controls (using the APGD-t but with the plasma turned off) also resulted in cell transfection. To further study this phenomena, we built a simple transfection device consisting of a straight glass capillary tube and a plastic support. Using three different gases and five different capillary diameters, we were able to relate the transfection efficiency to the dynamic pressure of the gas exiting the capillary tube. Finally, even though transfection of cells seem to depend more on the mechanical forces exerted by the gas flow than on the effects of the plasma, other applications of non-thermal plasma in the field of medicine are in development. However, published studies have focused on only the positive effects of non-thermal plasmas, neglecting the potentially induced adverse effects. Therefore, we studied if damage could be caused in cells following an indirect (APGD-t) or a direct (parallel electrodes DBD) plasma treatment. We found that a low power direct plasma treatment caused oxidative stress in HeLa cells. Both plasma sources were shown to produce DNA double-strand breaks but no lipid peroxidation. Also, the sequencing of plasma-treated naked plasmid DNA introduced in electrocompetent bacteria showed no evidence of mutations.

  18. Cluster mergers and non-thermal phenomena: expectations from a statistical magneto-turbulent model

    E-print Network

    R. Cassano; G. Brunetti

    2004-12-17

    The most important evidences for non-thermal phenomena in galaxy clusters comes from the spectacular synchrotron radio emission diffused over Mpc scale observed in a growing number of massive clusters. A promising possibility to explain giant radio halos is given by the presence of relativistic electrons reaccelerated by some kind of turbulence generated in the cluster volume during merger events. With the aim to investigate the connection between thermal and non-thermal properties of the ICM, in this paper we develope a statistical magneto-turbulent model which describes in a self-consistent way the evolution of the thermal ICM and that of the non-thermal emission from clusters. Making use of the extended Press & Schechter formalism, we follow cluster mergers and estimate the injection rate of the fluid turbulence generated during these energetic events. We then calculate the evolution of the spectrum of the relativistic electrons in the ICM during the cluster life by taking into account both the electron-acceleration due to the merger-driven turbulence and the relevant energy losses of the electrons. We end up with a synthetic population of galaxy clusters for which the evolution of the ICM and of the non-thermal spectrum emitted by the accelerated electrons is calculated. The generation of detectable non-thermal radio and hard X-ray emission in the simulated clusters is found to be possible during major merger events for reliable values of the model parameters. In addition the occurrence of radio halos as a function of the mass of the parent clusters is calculated and compared with observations. In this case it is found that the model expectations are in good agreement with observations.

  19. GEC Student Award for Excellence Finalist: Interaction of Non-Thermal Dielectric Barrier Discharge Plasma with DNA inside Cells

    Microsoft Academic Search

    Sameer Kalghatgi; Crystal Kelly; Gregory Fridman; Jane Clifford-Azizkhan; Alexander Fridman; Gary Friedman

    2008-01-01

    Direct non-thermal plasma is now being widely considered for various medical applications, viz; cancer treatment, coagulation, wound healing. However, the understanding of the interaction between non-thermal plasma and cells is lacking. Here we study the possibility that effects of the plasma treatment can penetrate though cellular membranes without destroying them. One of the most important of such effects to investigate

  20. Anisotropic Transport of Electrons in a Novel FET Channel with Chains of InGaAs Nano-Islands Embedded along Quasi-Periodic Multi-Atomic Steps on Vicinal (111)B GaAs

    SciTech Connect

    Akiyama, Y.; Kawazu, T. [National Institute for Materials Science, Tsukuba-shi, Ibaraki 305-0047 (Japan); IIS, University of Tokyo, Meguro-ku, Tokyo 153-8505 (Japan); Noda, T. [National Institute for Materials Science, Tsukuba-shi, Ibaraki 305-0047 (Japan); Sakaki, H. [National Institute for Materials Science, Tsukuba-shi, Ibaraki 305-0047 (Japan); IIS, University of Tokyo, Meguro-ku, Tokyo 153-8505 (Japan); Toyota Technological Institute, Tempaku-ku, Nagoya 468-8511 (Japan)

    2010-01-04

    We have studied electron transport in n-AlGaAs/GaAs heterojunction FET channels, in which chains of InGaAs nano-islands are embedded along quasi-periodic steps. By using two samples, conductance G{sub para}(V{sub g}) parallel to the steps and G{sub perp}(V{sub g}) perpendicular to them were measured at 80 K as functions of gate voltage V{sub g}. At sufficiently high V{sub g}, G{sub para} at 80 K is several times as high as G{sub perp}, which manifests the anisotropic two-dimensional transport of electrons. When V{sub g} is reduced to -0.7 V, G{sub perp} almost vanishes, while {sub Gpara} stays sizable unless V{sub g} is set below -0.8 V. These results indicate that 'inter-chain' barriers play stronger roles than 'intra-chain' barriers.

  1. Non-thermal Hard X-Ray Emission from Coma and Several Abell Clusters

    SciTech Connect

    Correa, C

    2004-02-05

    We report results of hard X-Ray observations of the clusters Coma, Abell 496, Abell754, Abell 1060, Abell 1367, Abell2256 and Abell3558 using RXTE data from the NASA HEASARC public archive. Specifically we searched for clusters with hard x-ray emission that can be fitted by a power law because this would indicate that the cluster is a source of non-thermal emission. We are assuming the emission mechanism proposed by Vahk Petrosian where the inter cluster space contains clouds of relativistic electrons that by themselves create a magnetic field and emit radio synchrotron radiation. These relativistic electrons Inverse-Compton scatter Microwave Background photons up to hard x-ray energies. The clusters that were found to be sources of non-thermal hard x-rays are Coma, Abell496, Abell754 and Abell 1060.

  2. Dark Matter Production Mechanisms with a Non-Thermal Cosmological History - A Classification

    E-print Network

    Kane, Gordon L; Nelson, Brent D; Zheng, Bob

    2015-01-01

    We perform a comprehensive study of models of dark matter (DM) in a Universe with a non-thermal cosmological history, i.e with a phase of pressure-less matter domination before the onset of big-bang nucleosynethesis (BBN). Such cosmological histories are generically predicted by UV completions that contain gravitationally coupled scalar fields (moduli). We classify the different production mechanisms for DM in this framework, generalizing previous works by considering a wide range of DM masses/couplings and allowing for DM to be in equilibrium with a "dark" sector. We identify four distinct parametric regimes for the production of relic DM, and derive accurate semi-analytic approximations for the DM relic abundance. Our results are particularly relevant for supersymmetric theories, in which the standard non-thermally produced DM candidates are disfavored by indirect detection constraints. We also comment on experimental signals in this framework, focusing on novel effects involving the power spectrum of DM de...

  3. Impact polarization as a diagnostic for non-thermal particles in solar flares

    NASA Astrophysics Data System (ADS)

    Vogt, E.; Sahal-Bréchot, S.; Hénoux, J.-C.

    2002-03-01

    Observations of linear polarization of lines (mainly H?) during solar flares have been reported. The orientation (predominantly radial) and magnitude of the H? polarization (about 5%) suggest an interpretation as impact polarization by low energy (<200 keV) non-thermal protons, which are not accessible by more direct diagnostic observations, such as hard X-rays (for non-thermal electrons) or gamma-ray lines (for high energy protons, above a few MeV) which will be observed by the HESSI spacecraft, soon to be launched by NASA. Impact polarization observations could thus provide useful complementary data for the study of accelerated particles in flares. However, observations in a single line such as H? can give at best an order of magnitude estimate of the accelerated protons number flux, so multiline polarimetric observations, as can be done by the franco-italian THEMIS telescope, are highly desirable.

  4. Comparison of non-thermal plasma techniques for abatement of volatile organic compounds and nitrogen oxides

    SciTech Connect

    Penetrante, B.M.; Hsiao, M.C.; Bardsley, J.N. [and others

    1996-01-11

    Non-thermal plasma processing is an emerging technology for the abatement of dilute concentrations of volatile organic compounds (VOCs), nitrogen oxides (NO{sub x}) and other hazardous air pollutants (HAPs) in atmospheric-pressure gas streams. Either electrical discharge or electron beam methods can produce these plasmas. Recent laboratory-scale experiments show that the electron beam method is remarkably more energy efficient than competing non-thermal plasma techniques based on pulsed corona and other types of electrical discharge plasma. Preliminary cost analysis based on these data also show that the electron beam method may be cost-competitive to thermal and catalytic methods that employ heat recovery or hybrid techniques.

  5. Non-Thermal Effects on CO NO Surface Catalytic Reaction on Square Surface: Monte Carlo Study

    Microsoft Academic Search

    M. Khalid; A. Qaisrani U; W. Ahmad

    2005-01-01

    A Monte Carlo simulation of the CO-NO heterogeneous catalytic reaction over a square surface has already been studied with a model based on the Langmuir-Hinshelwood (LH) mechanism. The results of this study are well known. Here we study the effects of transient non-thermal mobility of monomer (CO) based on precursor mechanism, diffusion of adsorbed nitrogen and oxygen atoms, on the

  6. On the use of a non-thermal plasma reactor for ethanol steam reforming

    Microsoft Academic Search

    O. Aubry; C. Met; A. Khacef; J. M. Cormier

    2005-01-01

    This work is dedicated to the steam reforming study of ethanol in a non-thermal plasma reactor at low temperature and at atmospheric pressure. The plasma reactor was powered by a high voltage 50Hz AC power supply with a 155mA sinusoidal current. The voltage delivered by this system was self-adjusted between 0.4 and 1kV according to the primary voltage of the

  7. Magnetic energy storage and the thermal versus non-thermal hard X-ray hypotheses

    Microsoft Academic Search

    D. S. Spicer

    1982-01-01

    It is shown by elementary electromagnetic theory that flare mechanisms requiring pre-flare energy storage (inductive energy storage) are incapable of accelerating sufficient electrons to satisfy the 'non-thermal' hard X-ray hypothesis. It is demonstrated that these flare mechanisms can accelerate per unit time no more electrons than the number of electrons that carries the net current associated with the free magnetic

  8. Magnetic energy storage and the thermal versus non-thermal hard X-ray hypotheses

    Microsoft Academic Search

    D Spicer

    1982-01-01

    It is shown by elementary electromagnetic theory that flare mechanisms requiring pre-flare energy storage (inductive energy storage) are incapable of accelerating sufficient electrons to satisfy the non-thermal hard X-ray hypothesis. It is demonstrated that these flare mechanisms can accelerate per unit time no more electrons than the number of electrons that carries the net current associated with the free magnetic

  9. The Non-Thermal Effect of Millimeter Wave Radiation on the Puffing of Giant Chromosomes

    Microsoft Academic Search

    F. Kremer; C. Koschnitzke; L. Santo; P. Quick; A. Poglitsch

    1983-01-01

    A non-thermal influence of millimeter wave radiation (swept in frequency from 64.1 GHz to 69.1 GHz, sweeptime 6 s, and with stabilized frequencies of 67.200 ± 0.001 GHz and 68.200 ± 0.001 GHz, power density < 5 mW\\/cm2) on the puffing of giant chromosomes of the midge Acricotopus lucidus (Diptera, Chironomidae) was found. The effect is manifested as a reduction

  10. Advances in Ultraviolet Light Technology for Non-thermal Processing of Liquid Foods

    Microsoft Academic Search

    Tatiana Koutchma

    2009-01-01

    A negative, public reaction is growing over the addition of chemical preservatives to liquid foods and beverages to extend\\u000a their shelf life and to protect against foodborne pathogens. As a physical method, ultraviolet light (UV) irradiation has\\u000a a positive consumer image and is of interest to the food industry as a low cost non-thermal method of preservation. Recent\\u000a advances in

  11. Why Is Non-thermal Line Broadening of Lower Transition Region Lines Independent of Spatial Resolution?

    NASA Astrophysics Data System (ADS)

    De Pontieu, B.; Mcintosh, S. W.; Martínez-Sykora, J.; Peter, H.; Pereira, T. M. D.

    2014-12-01

    Spectral observations of the solar transition region (TR) and corona typically show broadening of the spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant (10-30 km/s), correlated with the intensity, and has been attributed to waves, macro and micro turbulence, nanoflares, etc... Here we study spectra of the low TR Si IV 1403 Angstrom line obtained at high spatial and spectral resolution with the Interface Region Imaging Spectrograph (IRIS). We find that the large improvement in spatial resolution (0.33 arcsec) of IRIS compared to previous spectrographs (2 arcsec) does not resolve the non-thermal line broadening which remains at pre-IRIS levels of 20 km/s. This surprising invariance to spatial resolution indicates that the physical processes behind the non-thermal line broadening either occur along the line-of-sight (LOS) and/or on spatial scales (perpendicular to the LOS) smaller than 250 km. Both effects appear to play a role. Comparison with IRIS chromospheric observations shows that, in regions where the LOS is more parallel to the field, magneto-acoustic shocks driven from below impact the low TR leading to strong non-thermal line broadening from line-of-sight integration across the shock at the time of impact. This scenario is confirmed by advanced MHD simulations. In regions where the LOS is perpendicular to the field, the prevalence of small-scale twist is likely to play a significant role in explaining the invariance and the correlation with intensity.

  12. Fluctuation-dissipation theorems for systems in non-thermal equilibrium and applications

    Microsoft Academic Search

    G. S. Agarwal

    1972-01-01

    The linear response theory of systems obeying Fokker-Planck equations is discussed under the assumption that the principle of detailed balance is satisfied. This theory is used to obtain fluctuation-dissipation theorems for systems in a non-thermal equilibrium state corresponding to the steady state solution of the Fokker-Planck equation. Some of the aspects of the threshold region of a single mode laser

  13. Dust-acoustic solitary waves in dusty plasmas with non-thermal ions

    SciTech Connect

    Asgari, H.; Muniandy, S. V.; Wong, C. S. [Plasma Technology Research Center, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2013-02-15

    Most studies on dusty plasmas have assumed that electrons and ions follow Maxwellian distributions. However, in the presence of energetic ions, the distribution of ions tends to be non-Maxwellian. It is shown here that the existence of non-thermal ions would increase the phase velocity of a dust-acoustic wave. It is also found that the change in the phase velocity profoundly affects the characteristics of a dust-acoustic solitary wave.

  14. Surface modification and characterizations of basalt fibers with non-thermal plasma

    Microsoft Academic Search

    G. J. Wang; Y. W. Liu; Y. J. Guo; Z. X. Zhang; M. X. Xu; Z. X. Yang

    2007-01-01

    Atmospheric-pressure non-thermal plasmas have been increasingly promoted for polymer surface modification. In this paper, atmospheric-pressure plasmas of oxygen, argon, hydrogen and mixture gases of nitrogen and hydrogen were used to surface modification of basalt fibers in order to illuminate their chemical durability, surface active groups and roughness etc. The plasma-induced surface changes on morphologies and active groups were characterized by

  15. Intracellular DNA damage induced by non-thermal, intense narrowband electric fields

    Microsoft Academic Search

    Naoyuki Nomura; Masahiko Yano; Sunao Katsuki; Hidenori Akiyama; Keisuke Abe; Shin-Ichi Abe

    2009-01-01

    Intracellular DNA damages caused by intense burst sinusoidal electric fields (IBSEFs) were investigated by means of an alkaline comet assay method. Non-thermal, 200 mus-long IBSEF with various frequency values (300 kHz-100 MHz) and strengths (up to 200 kV\\/m) was applied to Chinese hamster ovary (CHO) cells in a suspending medium between 1 mm gap parallel electrodes. The comet assay suggests

  16. SynGas Production from Organic Waste Using Non-Thermal-Pulsed Discharge

    Microsoft Academic Search

    Young N. Chun; Si W. Kim; Hyoung O. Song; Jae O. Chae

    2005-01-01

    The purpose of this study was to develop a technology that can convert biogas to synthesis gas (SynGas), a low-emission substituted energy, using a non-thermal-pulsed plasma method. To investigate the characteristics of Syn-Gas production from simulated biogas, the reforming characteristics in relation to variations in pulse frequency, biogas component ratio (C3H8\\/CO2), vapor flow ratio (H2O\\/total flow rate [TFR]), biogas velocity,

  17. Steam plasma reforming of biogas by non-thermal pulsed discharge

    Microsoft Academic Search

    Young Nam Chun; Si Wouk Kim; Hyoung Oon Song

    2004-01-01

    The purpose of this study was to develop technology that can convert biogas to synthesis gas (SynGas), a low emission substituted\\u000a energy, using a non-thermal pulsed plasma method. To investigate the characteristics of the SynGas production from simulated\\u000a biogas, the reforming characteristics were studied about the variations of pulse frequency, biogas component ratio (C3H8\\/CO2), vapor flow ratio (H2O\\/TFR), biogas velocity

  18. Gas-to-liquids process using multi-phase flow, non-thermal plasma microreactor

    Microsoft Academic Search

    An?l A??ral; Tomohiro Nozaki; Masahiko Nakase; Shuhei Yuzawa; Ken Okazaki

    2011-01-01

    A multi-phase flow non-thermal plasma microreactor based on dielectric barrier discharge has been developed for partial oxidation of methane to liquid oxygenates at atmospheric pressure. A pulsed water injection method has been used to remove condensable liquid components from the active discharge region. The effect of the pulsed water injection on methane conversion, yield of oxygenates and hydrogen peroxide (H2O2)

  19. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

    Microsoft Academic Search

    Xiao Long Hao; Ming Hua Zhou; Le Cheng Lei

    2007-01-01

    TiO2 photocatalyst (P-25) (50mgL?1) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO2 were obviously increased. Pulsed high-voltage discharge

  20. Effects of gap and elevated pressure on ethanol reforming in a non-thermal plasma reactor

    Microsoft Academic Search

    Trung Q. Hoang; Xinli Zhu; Lance L. Lobban; Richard G. Mallinson

    2011-01-01

    Production of hydrogen for fuel cell vehicles, mobile power generators and for hydrogen-enhanced combustion from ethanol is demonstrated using energy-efficient non-thermal plasma reforming. A tubular reactor with a multipoint electrode system operated in pulsed mode was used. Complete conversion can be achieved with high selectivity (based on ethanol) of H2 and CO of 111% and 78%, respectively, at atmospheric pressure.

  1. Application of non-thermal atmospheric pressure ac plasmas to the carbon dioxide reforming of methane

    Microsoft Academic Search

    Stephanie L. Brock; Tomoko Shimojo; Steven L. Suib; Yuji Hayashi; Hiroshige Matsumoto

    2002-01-01

    Methane conversions of 11.9%, yields of hydrogen as high as 23.3% and energy yields of 1.0 mol H2\\/kWh have been achieved from CO2 reforming of CH4 in non-thermal, atmospheric pressure plasma reactors with Pt coated electrodes. Two reactors have been studied. A novel fan type reactor consisting of a movable rotor and immobile stator produced the highest yields in contrast

  2. The Swift BAT Perspective on Non-Thermal Emission in HIFLUGCS Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Wik, Daniel R.

    2011-01-01

    The search for diffuse non-thermal, inverse Compton (IC) emission from galaxy clusters at hard X-ray energies has been underway for many years, with most detections being either of low significance or controversial. Until recently, comprehensive surveys of hard X-ray emission from clusters were not possible; instead, individually proposed-for. long observations would be collated from the archive. With the advent of the Swift BAT all sky survey, any c1u,;ter's emission above 14 keV can be probed with nearly uniform sensitivity. which is comparable to that of RXTE, Beppo-SAX, and Suzaku with the 58-month version of the survey. In this work. we search for non-thermal excess emission above the exponentially decreasing, high energy thermal emission in the flux-limited HIFLUGCS sample. The BAT emission from many of the detected clusters is marginally extended; we are able to extract the total flux for these clusters using fiducial models for their spatial extent. To account for thermal emission at BAT energies, XMM-Newton EPIC spectra are extracted from coincident spatial regions so that both the thermal and non-thermal spectral components can be determined simultaneou,;ly in joint fits. We find marginally significant IC components in 6 clusters, though after closer inspection and consideration of systematic errors we are unable to claim a clear detection in any of them. The spectra of all clusters are also summed to enhance a cumulative non-thermal signal not quite detectable in individual clusters. After constructing a model based on single temperature

  3. Hollow silicon carbide nanoparticles from a non-thermal plasma process

    NASA Astrophysics Data System (ADS)

    Coleman, Devin; Lopez, Thomas; Yasar-Inceoglu, Ozgul; Mangolini, Lorenzo

    2015-05-01

    We demonstrate the synthesis of hollow silicon carbide nanoparticles via a two-step process involving the non-thermal plasma synthesis of silicon nanoparticles, followed by their in-flight carbonization, also initiated by a non-thermal plasma. Simple geometric considerations associated with the expansion of the silicon lattice upon carbonization, in combination of the spherical geometry of the system, explain the formation of hollow nanostructures. This is in contrast with previous reports that justify the formation of hollow particles by means of out-diffusion of the core element, i.e., by the Kirkendall nanoscale effect. A theoretical analysis of the diffusion kinetics indicates that interaction with the ionized gas induces significant nanoparticle heating, allowing for the fast transport of carbon into the silicon particle and for the subsequent nucleation of the beta-silicon carbide phase. This work confirms the potential of non-thermal plasma processes for the synthesis of nanostructures composed of high-melting point materials, and suggests that such processes can be tuned to achieve morphological control.

  4. NON-THERMAL EMISSIONS FROM COOL CORES HEATED BY COSMIC RAYS IN GALAXY CLUSTERS

    SciTech Connect

    Fujita, Yutaka [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan); Ohira, Yutaka, E-mail: fujita@vega.ess.sci.osaka-u.ac.jp [Theory Centre, Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan)

    2012-02-10

    We study non-thermal emissions from cool cores in galaxy clusters. We adopted a recent model in which cosmic rays (CRs) prevail in the cores and stably heat them through CR streaming. The non-thermal emissions come from the interaction between CR protons and intracluster medium (ICM). Comparison between the theoretical predictions and radio observations shows that the overall CR spectra must be steep, and most of the CRs in the cores are low-energy CRs. Assuming that the CRs are injected through active galactic nucleus activities, we study the nature of the shocks that are responsible for the CR acceleration. The steep CR spectra are likely to reflect the fact that the shocks travel in hot ICM with fairly small Mach numbers. We also study the dependence on the CR streaming velocity. The results indicate that synchrotron emissions from secondary electrons should be observed as radio mini-halos in the cores. In particular, low-frequency observations (e.g., LOFAR) are promising. However, the steepness of the spectra makes it difficult to detect non-thermal X-ray and gamma-ray emissions from the cores. The low-energy CRs may be heating optical filaments observed in the cores.

  5. Thermal and non-thermal seed populations and their contribution to coronal shock acceleration

    NASA Astrophysics Data System (ADS)

    Battarbee, Markus; Vainio, Rami; Laitinen, Timo

    Charged particle acceleration in coronal and interplanetary CME-driven shocks is currently considered the primary source of large solar energetic particle (SEP) intensities. In large SEP events, the particles accelerated at the shock generate Alfvénic turbulence in the ambient medium, which facilitates particle trapping and repeated shock crossings, thus bootstrapping the acceleration process. In order to study this process, we have developed a Monte Carlo simulation method, where particles are traced in prescribed large-scale electromagnetic fields utilizing the guiding center approximation. In our simulations, particles are scattered in the turbulence according to quasilinear theory, with the scattering amplitude directly proportional to the intensity of Alfvén waves at gyro-resonant wavenumbers. The Alfvén waves are traced simultaneously with the particles, so that the wave field is propagated outwards from the Sun using WKB propagation supplemented with a phenomenological wavenumber diffusion term and a growth rate computed from the net flux of the accelerated particles. In this work, we study how the thermal and the non-thermal portions of the acceleration seed population participate in the acceleration process. We model the seed particle population by using a kappa distribution, in order to mimic a thermal bulk plasma supplemented by a non-thermal high-energy tail. We will study the contribution of the thermal and non-thermal populations to the wave generation, and their participation in the accelerated particle populations, in different phases of the evolution of the SEP event. With this model, we can estimate the requirements for the source population to produce observed solar events.

  6. Non-thermal Plasma Induces Apoptosis in Melanoma Cells via Production of Intracellular Reactive Oxygen Species

    PubMed Central

    Sensenig, Rachel; Kalghatgi, Sameer; Cerchar, Ekaterina; Fridman, Gregory; Shereshevsky, Alexey; Torabi, Behzad; Arjunan, Krishna Priya; Podolsky, Erica; Fridman, Alexander; Friedman, Gary; Azizkhan-Clifford, Jane; Brooks, Ari D.

    2012-01-01

    Non-thermal atmospheric pressure dielectric barrier discharge (DBD) plasma may provide a novel approach to treat malignancies via induction of apoptosis. The purpose of this study was to evaluate the potential of DBD plasma to induce apoptosis in melanoma cells. Melanoma cells were exposed to plasma at doses that did not induce necrosis, and cell viability and apoptotic activity were evaluated by Trypan blue exclusion test, Annexin-V/PI staining, caspase-3 cleavage, and TUNEL® analysis. Trypan blue staining revealed that non-thermal plasma treatment significantly decreased the viability of cells in a dose-dependent manner 3 and 24 h after plasma treatment. Annexin-V/PI staining revealed a significant increase in apoptosis in plasma-treated cells at 24, 48, and 72 h post-treatment (p<0.001). Caspase-3 cleavage was observed 48 h post-plasma treatment at a dose of 15 J/cm2. TUNEL® analysis of plasma-treated cells demonstrated an increase in apoptosis at 48 and 72 h post-treatment (p<0.001) at a dose of 15 J/cm2. Pre-treatment with N-acetyl-L-cysteine (NAC), an intracellular reactive oxygen species (ROS) scavenger, significantly decreased apoptosis in plasma-treated cells at 5 and 15 J/cm2. Plasma treatment induces apoptosis in melanoma cells through a pathway that appears to be dependent on production of intracellular ROS. DBD plasma production of intracellular ROS leads to dose-dependent DNA damage in melanoma cells, detected by ?-H2AX, which was completely abrogated by pre-treating cells with ROS scavenger, NAC. Plasma-induced DNA damage in turn may lead to the observed plasma-induced apoptosis. Since plasma is non-thermal, it may be used to selectively treat malignancies. PMID:21046465

  7. UBIQUITOUS NON-THERMALS IN ASTROPHYSICAL PLASMAS: RESTATING THE DIFFICULTY OF MAINTAINING MAXWELLIANS

    SciTech Connect

    Scudder, J. D. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 54420 (United States); Karimabadi, H., E-mail: jack-scudder@uiowa.edu [SciberQuest, Del Mar, CA 92014 (United States)

    2013-06-10

    This paper outlines the rather narrow conditions on a radiatively decoupled plasma where a Maxwell-Boltzmann (MB) distribution can be assumed with confidence. The complementary non-thermal distribution with non-perturbative kurtosis is argued to have a much broader purview than has previously been accepted. These conditions are expressed in terms of the electron Knudsen number, K{sub e} , the ratio of the electron mean free path to the scale length of electron pressure. Rather generally, f(v < v{sub 2}(K{sub e} )) will be Gaussian, so that MB atomic or wave particle effects controlled by speeds v < v{sub 2} {identical_to} w(15/8K{sub e} ){sup 1/4} will remain defensible, where w is the most probable speed. The sufficient condition for Spitzer-Braginskii plasma fluid closure at the energy equation requires globally K{sub e} (s) {<=} 0.01; this global condition pertains to the maximum value of K{sub e} along the arc length s of the magnetic field (to its extremities) provided that contiguous plasma remains uncoupled from the radiation field. The non-thermal regime K{sub e} > 0.01 is common in all main-sequence stellar atmospheres above approximately 0.05 stellar radii from the surface. The entire solar corona and wind are included in this regime where non-thermal distributions with kurtosis are shown to be ubiquitous, heat flux is not well modeled by Spitzer-Braginskii closure, and fluid modeling is qualitative at best.

  8. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    PubMed Central

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W.; Jeong, Chang-Mo

    2013-01-01

    PURPOSE Autoclaves and UV sterilizers have been commonly used to prevent cross-infections between dental patients and dental instruments or materials contaminated by saliva and blood. To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated. MATERIALS AND METHODS After inoculating E. coli and B. subtilis the diamond burs and polyvinyl siloxane materials were sterilized by exposing them to the plasma for different lengths of time (30, 60, 90, 120, 180 and, 240 seconds). The diamond burs and polyvinyl siloxane materials were immersed in PBS solutions, cultured on agar plates and quantified by counting the colony forming units. The data were analyzed using one-way ANOVA and significance was assessed by the LSD post hoc test (?=0.05). RESULTS The device was effective in killing E. coli contained in the plasma device compared with the UV sterilizer. The atmospheric pressure non-thermal air plasma device contributed greatly to the sterilization of diamond burs and polyvinyl siloxane materials inoculated with E. coli and B. subtilis. Diamond burs and polyvinyl siloxane materials inoculated with E. coli was effective after 60 and 90 seconds. The diamond burs and polyvinyl siloxane materials inoculated with B. subtilis was effective after 120 and 180 seconds. CONCLUSION The atmospheric pressure non-thermal air plasma device was effective in killing both E. coli and B. subtilis, and was more effective in killing E. coli than the UV sterilizer. PMID:23508991

  9. Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

    PubMed Central

    Arjunan, Krishna Priya; Friedman, Gary; Fridman, Alexander; Clyne, Alisa Morss

    2012-01-01

    Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm–2 had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm–2 plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization. PMID:21653568

  10. Field-enhanced electrodes for additive-injection non-thermal plasma (NTP) processor

    DOEpatents

    Rosocha, Louis A. (Los Alamos, NM); Ferreri, Vincent (Westminster, CO); Kim, Yongho (Los Alamos, NM)

    2009-04-21

    The present invention comprises a field enhanced electrode package for use in a non-thermal plasma processor. The field enhanced electrode package includes a high voltage electrode and a field-enhancing electrode with a dielectric material layer disposed in-between the high voltage electrode and the field-enhancing electrode. The field-enhancing electrode features at least one raised section that includes at least one injection hole that allows plasma discharge streamers to occur primarily within an injected additive gas.

  11. Non-thermal X-rays from the Ophiuchus galaxy cluster and dark matter annihilation

    E-print Network

    Stefano Profumo

    2008-05-14

    We investigate a scenario where the recently discovered non-thermal hard X-ray emission from the Ophiuchus cluster originates from inverse Compton scattering of energetic electrons and positrons produced in weakly interacting dark matter pair annihilations. We show that this scenario can account for both the X-ray and the radio emission, provided the average magnetic field is of the order of 0.1 microGauss. We demonstrate that GLAST will conclusively test the dark matter annihilation hypothesis. Depending on the particle dark matter model, GLAST might even detect the monochromatic line produced by dark matter pair annihilation into two photons.

  12. Non-thermal plasma destruction of allyl alcohol in waste gas: kinetics and modelling

    NASA Astrophysics Data System (ADS)

    DeVisscher, A.; Dewulf, J.; Van Durme, J.; Leys, C.; Morent, R.; Van Langenhove, H.

    2008-02-01

    Non-thermal plasma treatment is a promising technique for the destruction of volatile organic compounds in waste gas. A relatively unexplored technique is the atmospheric negative dc multi-pin-to-plate glow discharge. This paper reports experimental results of allyl alcohol degradation and ozone production in this type of plasma. A new model was developed to describe these processes quantitatively. The model contains a detailed chemical degradation scheme, and describes the physics of the plasma by assuming that the fraction of electrons that takes part in chemical reactions is an exponential function of the reduced field. The model captured the experimental kinetic data to less than 2 ppm standard deviation.

  13. ICRF Wave Propagation and Absorption in Plasmas with Non-thermal Populations

    SciTech Connect

    R.J. Dumont; C.K. Phillips; D.N. Smithe

    2002-06-18

    Some results obtained with the one dimensional, all orders, full wave code METS, which has been successfully employed in the past to describe a number of experiments, are reported. By using massively parallel computers, this code has been extended to handle non-thermal populations. Various physical situations, in which non-Maxwellian species are expected to be encountered, are studied, such as simultaneous neutral beam injection and high harmonic fast wave electron heating or ion cyclotron resonance heating in the presence of fusion products.

  14. RELATION BETWEEN THE CORONAL MASS EJECTION ACCELERATION AND THE NON-THERMAL FLARE CHARACTERISTICS

    SciTech Connect

    Berkebile-Stoiser, S.; Veronig, A. M.; Bein, B. M.; Temmer, M., E-mail: asv@igam.uni-graz.at [Institute of Physics, University of Graz, A-8010 Graz (Austria)

    2012-07-01

    We investigate the relationship between the main acceleration phase of coronal mass ejections (CMEs) and the particle acceleration in the associated flares as evidenced in Reuven Ramaty High Energy Solar Spectroscopic Imager non-thermal X-rays for a set of 37 impulsive flare-CME events. Both the CME peak velocity and peak acceleration yield distinct correlations with various parameters characterizing the flare-accelerated electron spectra. The highest correlation coefficient is obtained for the relation of the CME peak velocity and the total energy in accelerated electrons (c = 0.85), supporting the idea that the acceleration of the CME and the particle acceleration in the associated flare draw their energy from a common source, probably magnetic reconnection in the current sheet behind the erupting structure. In general, the CME peak velocity shows somewhat higher correlations with the non-thermal flare parameters than the CME peak acceleration, except for the spectral index of the accelerated electron spectrum, which yields a higher correlation with the CME peak acceleration (c Almost-Equal-To -0.6), indicating that the hardness of the flare-accelerated electron spectrum is tightly coupled to the impulsive acceleration process of the rising CME structure. We also obtained high correlations between the CME initiation height h{sub 0} and the non-thermal flare parameters, with the highest correlation of h{sub 0} to the spectral index {delta} of flare-accelerated electrons (c Almost-Equal-To 0.8). This means that CMEs erupting at low coronal heights, i.e., in regions of stronger magnetic fields, are accompanied by flares that are more efficient at accelerating electrons to high energies. In the majority of events ({approx}80%), the non-thermal flare emission starts after the CME acceleration, on average delayed by Almost-Equal-To 6 minutes, in line with the standard flare model where the rising flux rope stretches the field lines underneath until magnetic reconnection sets in. We find that the current sheet length at the onset of magnetic reconnection is 21 {+-} 7 Mm. The flare hard X-ray peaks are well synchronized with the peak of the CME acceleration profile, and in 75% of the cases they occur within {+-}5 minutes. Our findings provide strong evidence for the tight coupling between the CME dynamics and the particle acceleration in the associated flare in impulsive events, with the total energy in accelerated electrons being closely correlated with the peak velocity (and thus the kinetic energy) of the CME, whereas the number of electrons accelerated to high energies is decisively related to the CME peak acceleration and the height of the pre-eruptive structure.

  15. Removal of Elemental Mercury from a Gas Stream Facilitated by a Non-Thermal Plasma Device

    SciTech Connect

    Charles Mones

    2006-12-01

    Mercury generated from anthropogenic sources presents a difficult environmental problem. In comparison to other toxic metals, mercury has a low vaporization temperature. Mercury and mercury compounds are highly toxic, and organic forms such as methyl mercury can be bio-accumulated. Exposure pathways include inhalation and transport to surface waters. Mercury poisoning can result in both acute and chronic effects. Most commonly, chronic exposure to mercury vapor affects the central nervous system and brain, resulting in neurological damage. The CRE technology employs a series of non-thermal, plasma-jet devices to provide a method for elemental mercury removal from a gas phase by targeting relevant chemical reactions. The technology couples the known chemistry of converting elemental mercury to ionic compounds by mercury-chlorine-oxygen reactions with the generation of highly reactive species in a non-thermal, atmospheric, plasma device. The generation of highly reactive metastable species in a non-thermal plasma device is well known. The introduction of plasma using a jet-injection device provides a means to contact highly reactive species with elemental mercury in a manner to overcome the kinetic and mass-transfer limitations encountered by previous researchers. To demonstrate this technology, WRI has constructed a plasma test facility that includes plasma reactors capable of using up to four plasma jets, flow control instrumentation, an integrated control panel to operate the facility, a mercury generation system that employs a temperature controlled oven and permeation tube, combustible and mercury gas analyzers, and a ductless fume hood designed to capture fugitive mercury emissions. Continental Research and Engineering (CR&E) and Western Research Institute (WRI) successfully demonstrated that non-thermal plasma containing oxygen and chlorine-oxygen reagents could completely convert elemental mercury to an ionic form. These results demonstrate potential the application of this technology for removing elemental mercury from flue gas streams generated by utility boilers. On an absolute basis, the quantity of reagent required to accomplish the oxidation was small. For example, complete oxidation of mercury was accomplished using a 1% volume fraction of oxygen in a nitrogen stream. Overall, the tests with mercury validated the most useful aspect of the CR&E technology: Providing a method for elemental mercury removal from a gas phase by employing a specific plasma reagent to either increase reaction kinetics or promote reactions that would not have occurred under normal circumstances.

  16. Evaluation of quasi periodicity in cardiac rhythm

    Microsoft Academic Search

    Ravindra Sheth; Christopher Druzgalski

    2009-01-01

    Summary form only given. Variability of cardiac activity reflected in electrocardiograms has been of considerable interest and the subject of different studies. In particular, the presented project included development of a scheme for presentation of cardiac activity and a comparative evaluation of heart rate variability. The graphical representation of cardiac rhythm variability is demonstrated in a form of circular displays,

  17. Non-thermal plasma instabilities induced by deformation of the electron energy distribution function

    NASA Astrophysics Data System (ADS)

    Dyatko, N. A.; Kochetov, I. V.; Napartovich, A. P.

    2014-08-01

    Non-thermal plasma is a key component in gas lasers, microelectronics, medical applications, waste gas cleaners, ozone generators, plasma igniters, flame holders, flow control in high-speed aerodynamics and others. A specific feature of non-thermal plasma is its high sensitivity to variations in governing parameters (gas composition, pressure, pulse duration, E/N parameter). This sensitivity is due to complex deformations of the electron energy distribution function (EEDF) shape induced by variations in electric field strength, electron and ion number densities and gas excitation degree. Particular attention in this article is paid to mechanisms of instabilities based on non-linearity of plasma properties for specific conditions: gas composition, steady-state and decaying plasma produced by the electron beam, or by an electric current pulse. The following effects are analyzed: the negative differential electron conductivity; the absolute negative electron mobility; the stepwise changes of plasma properties induced by the EEDF bi-stability; thermo-current instability and the constriction of the glow discharge column in rare gases. Some of these effects were observed experimentally and some of them were theoretically predicted and still wait for experimental confirmation.

  18. Laser ablation of metals: the transition from non-thermal processes to thermal evaporation

    NASA Astrophysics Data System (ADS)

    Götz, T.; Bergt, M.; Hoheisel, W.; Träger, F.; Stuke, M.

    1996-04-01

    The mechanisms of laser-stimulated ablation of metal surfaces have been investigated for different regimes of incident photon fluence. For this purpose, small Na particles served as a model system. They were held under ultrahigh vacuum conditions and exposed to laser radiation with wavelengths ranging from the ultraviolet to the near infrared spectral range. The ablation products were photoionized by light of a second laser. Their mass as well as their kinetic energy distributions were determined by time-of-flight measurements. The results show that initially, at low laser fluence, ablation occurs along one or even two non-thermal reaction pathways. At this stage, predominantly atoms come off. The non-thermal mechanism can be understood within the framework of the Menzel-Gomer-Redhead scenario. As the fluence grows thermal decomposition gradually takes over and an increasing amount of dimers is found. Under certain experimental conditions the rate of dimers detached from the surface per laser pulse can by far surmount the rate of atoms. Finally, for even larger fluences, evidence for detachment of large particulates is found.

  19. Effects of non-thermal atmospheric plasma on human periodontal ligament mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    Mileti?, M.; Mojsilovi?, S.; Oki? ?or?evi?, I.; Maleti?, D.; Pua?, N.; Lazovi?, S.; Malovi?, G.; Milenkovi?, P.; Petrovi?, Z. Lj; Bugarski, D.

    2013-08-01

    Here we investigate the influences of non-thermal atmospheric plasma on human mesenchymal stem cells isolated from periodontal ligament (hPDL-MSCs). A specially redesigned plasma needle was used as the source of low-temperature plasma and its effects on different hPDL-MSC functions were investigated. Cell cultures were obtained from extracted normal impacted third molars and characterized for their phenotype and multi-potential differentiation. The hPDL-MSCs possessed all the typical MSC properties, including clonogenic ability, high proliferation rate, specific phenotype and multilineage differentiation. The data regarding the interaction of plasma with hPDL-MSCs demonstrated that plasma treatment inhibited the migration of hPDL-MSCs and induced some detachment, while not affecting their viability. Additionally, plasma significantly attenuated hPDL-MSCs' proliferation, but promoted their osteogenic differentiation. The results of this study indicated that a non-thermal plasma offers specific activity with non-destructive properties that can be advantageous for future dental applications.

  20. Degradation of pharmaceutical compounds in water by non-thermal plasma treatment.

    PubMed

    Magureanu, Monica; Mandache, Nicolae Bogdan; Parvulescu, Vasile I

    2015-09-15

    Pharmaceutical compounds became an important class of water pollutants due to their increasing consumption over the last years, as well as due to their persistence in the environment. Since conventional waste water treatment plants are unable to remove certain non-biodegradable pharmaceuticals, advanced oxidation processes was extensively studied for this purpose. Among them, non-thermal plasma was also recently investigated and promising results were obtained. This work reviews the recent research on the oxidative degradation of pharmaceuticals using non-thermal plasma in contact with liquid. As target compounds, several drugs belonging to different therapeutic groups were selected: antibiotics, anticonvulsants, anxiolytics, lipid regulators, vasodilatators, contrast media, antihypertensives and analgesics. It was found that these compounds were removed from water relatively fast, partly degraded, and partly even mineralized. In order to ensure the effluent is environmentally safe it is important to identify the degradation intermediates and to follow their evolution during treatment, which requires complex chemical analysis of the solutions. Based on this analysis, degradation pathways of the investigated pharmaceuticals under plasma conditions were suggested. After sufficient plasma treatment the final organic by-products present in the solutions were mainly small molecules in an advanced oxidation state. PMID:26057260

  1. The sporadic non-thermal profile of auroral 557.7 nm [OI

    NASA Astrophysics Data System (ADS)

    Ignatyev, V.; Nikolashkin, S.

    The rare case of a non-thermal profile of an emission 557.7 nm appearance in aurora during interferometric observations in January, 2000 on Maimaga observatory (63 N, 129.7 E, geogr.) is considered. On the basis of the analysis of the shape and half-width of a non-thermal profile of the line of auroral 557.7 nm [OI] is concluded, that its occurrence is caused by the transient sporadic intensification of the process of the dissociative recombination of the molecular ion of oxygen in restricted area of the ionospheric F layer. The calculation showed that in the moment of registration of dissociative profile on heights 200-220 kms the surplus concentration of oxygen ions of n(O2 +)~3104 cm-3 was produced as result of electron precipitation with energy of 0.02-0.4 keV . It is suggested that emission excitation process going with maximal probability in the recombination channel with the thermal energy radiation of ? d =0.83 eV.

  2. Time-variable Non-thermal Emission in the Planetary Nebula IRAS 15103–5754

    NASA Astrophysics Data System (ADS)

    Suárez, Olga; Gómez, José F.; Bendjoya, Philippe; Miranda, Luis F.; Guerrero, Martín A.; Uscanga, Lucero; Green, James A.; Rizzo, J. Ricardo; Ramos-Larios, Gerardo

    2015-06-01

    The beginning of photoionization marks the transition between the post-AGB and planetary nebula (PN) phases of stars with masses ? 8 M ? . This critical phase is difficult to observe, as it lasts only a few decades. The combination of jets and magnetic fields, the key agents of PN shaping, could give rise to synchrotron emission, but this has never been observed before in any PNe, since free–free emission from the ionized gas is expected to dominate its radio spectrum. In this paper we report radio continuum observations taken with the ATCA between 1 and 46 GHz of the young PN IRAS 15103–5754. Our observations in 2010–2011 show non-thermal emission compatible with synchrotron emission from electrons accelerated at a shock with spectral index ? ? -0.54. However, in 2012, the spectral index ? ? -0.28 is no longer compatible with synchrotron emission in these types of processes. Several hypotheses are discussed to explain this change. The more plausible ones are related to the presence of the newly photoionized region in this young PN: either energy loss of electrons due to Coulomb collisions with the plasma, or selective suppression of synchrotron radiation due to the Razin effect. We postulate that the observed flattening of non-thermal radio spectra could be a hallmark identifying the beginning of the PN phase.

  3. Evaluation of non-thermal effects by microwave irradiation in hydrolysis of waste-activated sludge.

    PubMed

    Byun, I G; Lee, J H; Lee, J M; Lim, J S; Park, T J

    2014-01-01

    The activation energy (Ea) for waste-activated sludge (WAS) hydrolysis was compared between microwave irradiation (MW) and conventional heating (CH) methods to evaluate the non-thermal effect of MW. The microwave-assisted hydrolysis of WAS was assumed to follow the first-order kinetics on the basis of volatile suspended solids (VSS) conversion to soluble chemical oxygen demand (SCOD) for different initial VSS concentrations. By comparing the VSS decrement and the SCOD increment between MW and CH at different absolute temperatures of 323, 348 and 373 K, the average ratio of VSS conversion to SCOD was determined to range from 1.42 to 1.64 g SCOD/g VSS. These results corresponded to the theoretical value of 1.69 g SCOD/g VSS based on the assumption that the molecular formula of sludge was C10H19O3N. Consequently, the Ea of the MW-assisted WAS hydrolysis was much lower than that of CH for the same temperature conditions. The non-thermal effect of MW in the hydrolysis of WAS could be identified with the lower Ea than that of CH. PMID:25116507

  4. Non-thermal CMSSM with a 125 GeV Higgs

    E-print Network

    Luis Aparicio; Michele Cicoli; Bhaskar Dutta; Sven Krippendorf; Anshuman Maharana; Francesco Muia; Fernando Quevedo

    2015-02-19

    We study the phenomenology of the CMSSM/mSUGRA with non-thermal neutralino dark matter. Besides the standard parameters of the CMSSM we include the reheating temperature as an extra parameter. Imposing radiative electroweak symmetry breaking with a Higgs mass around 125 GeV and no dark matter overproduction, we contrast the scenario with different experimental bounds from colliders (LEP, LHC), cosmic microwave background (Planck), direct (LUX, XENON100, CDMS, IceCube) and indirect (Fermi) dark matter searches. The allowed parameter space is characterised by a Higgsino-like LSP with a mass around 300 GeV. The observed dark matter abundance can be saturated for reheating temperatures around 2 GeV while larger temperatures require extra non-neutralino dark matter candidates and extend the allowed parameter space. Sfermion and gluino masses are in the few TeV region. These scenarios can be achieved in string models of sequestered supersymmetry breaking which avoid cosmological moduli problems and are compatible with gauge coupling unification. Astrophysics and particle physics experiments will fully investigate this non-thermal scenario in the near future.

  5. Application of non-thermal plasmas to pollution control. Revision 1

    SciTech Connect

    Penetrante, B.M.; Vogtlin, G.E.; Bardsley, J.N.; Vitello, P.A.; Wallman, P.H.

    1993-06-01

    Non-thermal plasma techniques can be used to destroy many types of hazardous molecules. They are particularly efficient when the toxic materials are present in very small concentrations. This paper discusses three particular applications of non-thermal plasmas: (1) decomposition of hydrogen sulfide (H{sub 2}S), (2) removal of trichloroethylene (TCE), and (3) removal of nitrogen oxides (NO{sub x}). Emphasis is placed on the energy cost for implementing the decomposition or removal of these pollutants. Some of the factors affecting the energy cost are discussed. The authors discuss in detail their work at LLNL on pulsed plasma processing for the treatment of NO{sub x} in diesel engine exhaust. The results suggest that their plasma reactor can remove up to 70% of NO with relatively high initial concentrations (up to 500 ppM) at a power consumption cost of 2.5% for an engine with an output of 14 kW and an exhaust gas flow rate of 1,200 liters per minute.

  6. Non-thermal production of Wino dark matter via the decay of long-lived particles

    NASA Astrophysics Data System (ADS)

    Moroi, Takeo; Nagai, Minoru; Takimoto, Masahiro

    2013-07-01

    We consider supersymmetric models in which the neutral Wino is the lightest superparticle (LSP), and study the possibility that non-thermally produced Wino plays the role of dark matter. The thermal relic density of Wino is smaller than the present mass density of dark matter if {m_{{widetilde{W}}}} ? 2.9 TeV; however, even with smaller Wino mass, the Wino can be the dominant component of dark matter if it is non-thermally produced by the decay of a long-lived particle. In order to study such a possibility in detail, we perform a precise calculation of the present mass density of Wino produced by the decay of a long- lived particle, taking account of the following effects: (i) coannihilation among charged and neutral Winos, and (ii) Sommerfeld effect on the pair annihilation cross section of Winos. We consider several well-motivated cases where the long-lived particle corresponds to cosmological moduli fields, gravitino, or axino, and discuss the implication of the Wino LSP for these cases.

  7. Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission

    E-print Network

    Eric Agol

    2000-06-06

    The recent detection of polarized radiation from Sgr A* requires a non-thermal electron distribution for the emitting plasma. The Faraday rotation measure must be small, placing strong limits on the density and magnetic field strength. We show that these constraints rule out advection-dominated accretion flow models. We construct a simple two-component model which can reproduce both the radio to mm spectrum and the polarization. This model predicts that the polarization should rise to nearly 100% at shorter wavelengths. The first component, possibly a black-hole powered jet, is compact, low density, and self-absorbed near 1 mm with ordered magnetic field, relativistic Alfven speed, and a non-thermal electron distribution. The second component is poorly constrained, but may be a convection-dominated accretion flow with dM/dt~10^-9 M_Sun/yr, in which feedback from accretion onto the black hole suppresses the accretion rate at large radii. The black hole shadow should be detectable with sub-mm VLBI.

  8. Thermal and Non-Thermal Radiation from Pulsars: Hints of Physics

    NASA Astrophysics Data System (ADS)

    Dai, S.; Xu, R.

    2012-12-01

    Thermal and non-thermal radiation from pulsars carries significant information from surface and would have profound implications on the state of dense matter in compact stars. For the non-thermal radio emission, subpulse drifting phenomena suggest the existence of Ruderman-Sutherland-like gap-sparking and strong binding of particles on pulsar polar caps. While conventional neutron star models can hardly provide such a high binding energy, the strong self-bound surface of quark-cluster stars can naturally solve this problem. As for the thermal one, the featureless X-ray spectra of pulsars may indicate a bare surface without atmosphere, and the ultrarelativistic fireball of ?-ray bursts and supernovae would also require strong self-bound surfaces. Recent achievements in measuring pulsar mass and mass-radius relation further indicate a stiff equation of state and a self-bound surface. Therefore, we conjecture that matters inside pulsar-like compact stars could be in a quark-cluster phase. The surface of quark-cluster stars is chromatically confined and could initially be bare. Such a surface can not only explain above features, but may also promote a successful core-collapse supernova, and the hydro-cyclotron oscillation of the electron sea above the surface could be responsible for those absorption features detected in the X-ray spectrum.

  9. The Multi-Instrument (EVE-RHESSI) DEM for Solar Flares, and Implications for Non-thermal Emission

    NASA Astrophysics Data System (ADS)

    McTiernan, J. M.; Caspi, A.; Warren, H. P.

    2013-12-01

    Observations of hard X-ray bremmstrahlung from solar flares directly probe the non-thermal electron population. For low energies, however, the spectra are typically dominated by thermal emission and the low energy extent of the non-thermal spectrum can be only loosely quantified. To address this issue, we combine observations from the EUV Variability Experiment (EVE) on-board the Solar Dynamics Observatory (SDO) and X-ray data from the Reuven Ramaty High Energy Spectroscopic Imager (RHESSI). For a sample of solar flares, we model the emission using a Differential Emission Measure (DEM) for the thermal emission seen with both instruments and a power law fit for the non-thermal emission observed by RHESSI. Spectra for both instruments are fit simultaneously in a self-consistent manner. This improvement over the traditional isothermal approximation for thermal flare emission is intended to resolve the ambiguity in the range where the thermal and non-thermal components may have similar photon fluxes. This "crossover" range can extend up to 30 keV for medium to large solar flares. It is expected that a low energy cutoff of the non-thermal electron spectrum is in this energy range, but is obscured by thermal emission. For each flare in the sample we establish limits for the low energy cutoff of the non-thermal spectrum. These limits, in turn, can be used to establish limits on the energy of non-thermal electrons accelerated during the flare. This research is supported by NASA contract NAS5-98033 and NASA Heliophysics Guest Investigator Grant NNX12AH48G.

  10. kHz QUASI-PERIODIC OSCILLATIONS FROM THE 2000 AND 2010 X-RAY TRANSIENTS LOCATED IN THE GLOBULAR CLUSTER TERZAN 5: EXO1745-248 AND IGR J17480-2446

    SciTech Connect

    Barret, Didier, E-mail: didier.barret@irap.omp.eu [Institut de Recherche en Astrophysique et Planetologie and Universite de Toulouse (UPS), 9 Avenue du Colonel Roche, BP 44346, 31028, Toulouse Cedex 4 (France)

    2012-07-01

    EXO1745-248 is a transient neutron star low-mass X-ray binary located in the globular cluster Terzan 5. It was in outburst in 2000 and displayed during one Rossi X-ray Timing Explorer observation a highly coherent quasi-periodic oscillation (QPO) at frequencies between 670 and 715 Hz. Applying a maximum likelihood method to fit the X-ray power density spectrum, we show that the QPO can be detected on segments as short as T = 48 s. We find that its width is consistent with being constant, while previous analysis based on longer segment duration (200 s) found it variable. If the QPO frequency variations in EXO1745-248 follow a random walk (i.e., the contribution of the drift to the measured width increases like {radical}T), we derive an intrinsic width of {approx}2.3 Hz. This corresponds to an intrinsic quality factor of Q {approx} 297 {+-} 50 at 691 Hz. We also show that Q is consistent with being constant between 2.5 and 25 keV. IGR J17480-2446 is another X-ray transient located in Terzan 5. It is a very interesting object showing accretion-powered pulsations and burst oscillations at 11 Hz. We report on the properties of its kHz QPOs detected between October 18 and October 23, soon after the source had moved from the so-called Atoll state to the Z state. Its QPOs are typical of persistent Z sources; in the sense that they have low Q factors ({approx}30) and low rms amplitudes ({approx}5%). The highest frequency (at 870 Hz), if orbital, sets a lower limit on the inner disk radius of {approx}18.5 km and an upper limit to the dipole moment of the magnetic field {mu} {<=} 5 Multiplication-Sign 10{sup 26} G cm{sup 3}.

  11. kHz Quasi-periodic Oscillations from the 2000 and 2010 X-Ray Transients Located in the Globular Cluster Terzan 5: EXO1745-248 and IGR J17480-2446

    NASA Astrophysics Data System (ADS)

    Barret, Didier

    2012-07-01

    EXO1745-248 is a transient neutron star low-mass X-ray binary located in the globular cluster Terzan 5. It was in outburst in 2000 and displayed during one Rossi X-ray Timing Explorer observation a highly coherent quasi-periodic oscillation (QPO) at frequencies between 670 and 715 Hz. Applying a maximum likelihood method to fit the X-ray power density spectrum, we show that the QPO can be detected on segments as short as T = 48 s. We find that its width is consistent with being constant, while previous analysis based on longer segment duration (200 s) found it variable. If the QPO frequency variations in EXO1745-248 follow a random walk (i.e., the contribution of the drift to the measured width increases like \\sqrt{T}), we derive an intrinsic width of ~2.3 Hz. This corresponds to an intrinsic quality factor of Q ~ 297 ± 50 at 691 Hz. We also show that Q is consistent with being constant between 2.5 and 25 keV. IGR J17480-2446 is another X-ray transient located in Terzan 5. It is a very interesting object showing accretion-powered pulsations and burst oscillations at 11 Hz. We report on the properties of its kHz QPOs detected between October 18 and October 23, soon after the source had moved from the so-called Atoll state to the Z state. Its QPOs are typical of persistent Z sources; in the sense that they have low Q factors (~30) and low rms amplitudes (~5%). The highest frequency (at 870 Hz), if orbital, sets a lower limit on the inner disk radius of ~18.5 km and an upper limit to the dipole moment of the magnetic field ? <= 5 × 1026 G cm3.

  12. Thermal and Non-thermal Physiochemical Processes in Nanoscale Films of Amorphous Solid Water

    SciTech Connect

    Smith, R. Scott; Petrik, Nikolay G.; Kimmel, Gregory A.; Kay, Bruce D.

    2012-01-17

    Amorphous solid water (ASW) is a metastable form of water created by vapor deposition onto a cold substrate (typically less than 130 K). Since this unusual form of water only exists on earth in laboratories with highly specialized equipment, it is fair to ask why there is any interest in studying this esoteric material. Much of the scientific interest involves using ASW as a model system to explore the physical and reactive properties of liquid water and aqueous solutions. Other researchers are interested in ASW because it is believed to be the predominate form of water in the extreme cold temperatures found in many astrophysical and planetary environments. In addition, ASW is a convenient model system for studying the stability of metastable systems (glasses) and the properties of highly porous materials. A fundamental understanding of such properties has applications in a diverse range of disciplines including cryobiology, food science, pharmaceuticals, astrophysics and nuclear waste storage among others.There exist several excellent reviews on the properties of ASW and supercooled liquid water and a new comprehensive review is beyond the scope of this Account. Instead, we focus on our research over the past 15 years using molecular beams and surface science techniques to probe the thermal and non thermal properties of nanoscale films of ASW. We use molecular beams to precisely control the deposition conditions (flux, incident, energy, incident angle) to create compositionally-tailored, nanoscale films of ASW at low temperatures. To study the transport properties (viscosity, diffusivity), the amorphous films can be heated above their glass transition temperatures, Tg, at which time they transform into deeply supercooled liquids prior to crystallization. The advantage of this approach is that at temperatures near Tg the viscosity is approximately 15 orders of magnitude larger than a normal liquid, and therefore the crystallization kinetics are dramatically slowed, increasing the time available for experiments. For example, near Tg, on a typical laboratory time scale (e.g. {approx}1000 s), a water molecule moves less than a molecular distance. For this reason, nanoscale films help to probe the behavior and reactions of supercooled liquid at these low temperatures. ASW films can be used for investigating the non-thermal reactions relevant to radiolysis. In this account we will present a survey of our research on the thermal and non thermal properties of ASW using this approach.

  13. Disinfection of Staphylococcus Aureus by pulsed non-thermal atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

    2011-10-01

    The aim of this paper was to study the effect of low-temperature atmospheric plasma jet on non-pathogenic bacteria's colonies. In this regard, Germicidal effect of time and distance of ICP He and He/N2 plasma jet on Staphylococcus Aureus were reported. The gas discharges were generated by a 40 KHz high voltage power supply which led to the inductively coupled plasma. The results showed that He/N2 enhance the sterilization time in comparison of He plasma. To the best of our knowledge this is the first study which has compared the effect of sterilization of ICP Helium and Helium-Nitrogen plasma in listed conditions. Also, the distance dependence showed that the germicidal effect was not linear the distance of electrode and sample. The protein leakage test and SEM of bacteria morphology confirmed the sterilization effect of non-thermal atmospheric pressure plasma jet.

  14. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats?

    PubMed Central

    Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

    2012-01-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

  15. Non-thermal processes in non-standard accelerators: protostellar jets and runaway stars

    NASA Astrophysics Data System (ADS)

    Araudo, Anabella T.; del Valle, M. Victoria

    2014-11-01

    In addition to efficient particle accelerators in the Galaxy, such as supernova remnants and pulsar wind nebulae, other sources can accelerate particles up to very high energies. We present the case of protostellar jets and runaway stars, where strong shocks act upon electrons and protons through a diffusive process. The detection of synchrotron radio emission from these sources indicates that at least electrons are accelerated in these systems. If protons are accelerated as well, both population of relativistic particles can produce high-energy radiation through a variety of processes. We show results from models of the non-thermal emission, from radio to gamma rays, in these kind of sources. High-energy photons from both protostellar jets and massive runaways might be detectable with the current facilities in the GeV domain, or by the forthcoming Cherenkov arrays. A clear detection would prove that young stars are also cosmic ray accelerators.

  16. Atmospheric-Pressure Non-thermal Plasma-JET effects on PS and PE surfaces

    NASA Astrophysics Data System (ADS)

    Arrieta, J.; Asenjo, J.; Vargas, I.; Solis, Y.

    2015-03-01

    The Atmospheric-Pressure Non-Thermal Plasma (APNTP) has become a topic of a great interest for a wide spectrum of applications in different industry branches, including the surface of treatment processes. In this work we evaluate the effect of an argon APNTP exposure to determine changes suffered by a polystyrene (PS) and polyethylene (PE) polymer surface through RAMAN spectroscopy and SEM. It was determined that the hydrophilic change in energetic terms, i.e. surface activation in the PS and PE polymers is addition of oxygen by surface activation when the samples with jet plasma are exposed with the inert argon gas. It was possible to characterize the hydrophilic shift based on the change in intensity of the spectra.

  17. Time-variable non-thermal emission in the planetary nebula IRAS 15103-5754

    E-print Network

    Suarez, Olga; Bendjoya, Philippe; Miranda, Luis F; Guerrero, Martin A; Uscanga, Lucero; Green, James A; Rizzo, J Ricardo; Ramos-Larios, Gerardo

    2015-01-01

    The beginning of photoionization marks the transition between the post-Asymptotic Giant Branch (post-AGB) and planetary nebula (PN) phases of stars with masses radio spectrum. In this paper we report radio continuum observations taken with the Australia Telescope Compact Array between 1 and 46 GHz of the young PN IRAS 15103-5754. Our observations in 2010-2011 show non-thermal emission compatible with synchrotron emission from electrons accelerated at a shock with spectral index $\\alpha \\simeq -0.54$. However, in 2012, the spectral index $\\alpha \\simeq -0.28$ is no longer compatible with synchrotron emission in these types of processes. Several hypothesis are discussed to explain th...

  18. Dust-acoustic shock formation in dusty plasmas with non-thermal ions

    NASA Astrophysics Data System (ADS)

    Asgari, H.; Muniandy, S. V.; Wong, C. S.

    2013-01-01

    In this study, the nonlinear Burgers equation in the presence of the dust charge fluctuation is derived and the shock-like solution is determined. It is well known that in order to have a monotonic or oscillatory shock wave, a source of dissipation is needed. By using the experimental data reported in the laboratory observation of self-excited dust-acoustic shock waves [Heinrich et al., Phys. Rev. Lett. 103, 115002 (2009)], it is shown that dust charge fluctuation can be considered as a candidate for the source of dissipation needed for the dust-acoustic shock formation. By examining the effects of non-thermal ions on dust-acoustic shock's characteristics, a possible theoretical explanation for the discrepancies observed between theory and experiment is proposed.

  19. Dust-acoustic shock formation in dusty plasmas with non-thermal ions

    SciTech Connect

    Asgari, H.; Muniandy, S. V.; Wong, C. S. [Plasma Technology Research Center, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2013-01-15

    In this study, the nonlinear Burgers equation in the presence of the dust charge fluctuation is derived and the shock-like solution is determined. It is well known that in order to have a monotonic or oscillatory shock wave, a source of dissipation is needed. By using the experimental data reported in the laboratory observation of self-excited dust-acoustic shock waves [Heinrich et al., Phys. Rev. Lett. 103, 115002 (2009)], it is shown that dust charge fluctuation can be considered as a candidate for the source of dissipation needed for the dust-acoustic shock formation. By examining the effects of non-thermal ions on dust-acoustic shock's characteristics, a possible theoretical explanation for the discrepancies observed between theory and experiment is proposed.

  20. Surface modification of Raw and Frit glazes by non-thermal helium plasma jet

    NASA Astrophysics Data System (ADS)

    Ghasemi, M.; Sohbatzadeh, F.; Mirzanejhad, S.

    2015-06-01

    In this study, non-thermal atmospheric pressure plasma jet (APPJ) was utilized to improve the adhesion of Raw and Frit glazes. These glazes are widely used in industry to make chinaware, decorative dishes and tiles applied at wall and floor. As they should be painted before use, increasing their adhesive properties leads to a better paint durability. Electrical and optical characteristics of the plasma jet are investigated to optimize for efficient treatment. Contact angle measurement and surface energy calculation demonstrate a drastic increase after the plasma treatment indicating wettability and paintability enhancement. Moreover, atomic force microscopy and X-ray photoelectron spectroscopy analyses were performed on the specimens to explore the influence of helium plasma jet on the physical and chemical properties of the glazes, microscopically. AFM analysis reveals surface etching resulted from the bombardment of the solid surfaces by the APPJ using helium fed gas. The process aims to enhance adhesive properties of glaze surfaces.

  1. Estimations of local thermal impact on living organisms irradiated by non-thermal microwaves

    E-print Network

    Shatalov, Vladimir

    2013-01-01

    Pennes' differential equation for bioheat transfer and the heat transfer equation are solved for the temperature distribution in a living tissue with spherical inclusions, irradiated by microwave power. It is shown that relative temperature excess in a small inclusion in the tissue in some cases is inversely proportional to its radius and does not depend on the applied power. In pulsing RF fields the effect is amplified proportionally to the ratio of the pulse period to the pulse duration. The local temperature rise significantly outpaces the averaged one and therefore the Watt to Weight SAR limits may be insufficient to estimate the safety of RF radiation and the conventional division of the biological effects of electromagnetic fields on the thermal and non-thermal needs to be revised.

  2. Control of the Proliferation of Mammalian Cells by the Non-Thermal Atmospheric Pressure Plasmas

    NASA Astrophysics Data System (ADS)

    Lee, Hae June; Ha, Chang Seung; Ma, Yonghao; Lee, Jungyeol; Song, Kiwon

    2012-10-01

    Recent development of the atmospheric pressure plasmas (APPs) reported dramatic achievement on the applications to sterilization, wound healing, blood coagulation, and so on. These effects are coming from the abundant electrons, various ions, radicals, and neutral atoms which cause specific interactions with cells. However, the application of APPs to human cells has been mainly focused on cell death, but not so much on cell proliferation. In this study, the effects of a non-thermal dielectric barrier discharge (DBD) were investigated for three different human cell lines. It was observed that the exposure of APP to human adipose-derived stem cells (ASC) and the primary lung fibroblast IMR-90 cells induced increased cell proliferation in a specific condition. On the other hand, the same exposure of APP to HeLa cells dramatically decreased their viability. These observations suggest that different types of human cells differentially respond to the exposure of APP.

  3. Non-thermal enhancement of electron-positron pair creation in burning thermonuclear laboratory plasmas

    NASA Astrophysics Data System (ADS)

    Hill, E. G.; Rose, S. J.

    2014-12-01

    We estimate the number of electron-positron pairs which will be produced during the burning of a Deuterium-Tritium (DT) plasma in conditions that are anticipated will be achieved at the National Ignition Facility. In particular we consider, for the first time, the effect of including the gamma photons produced in a low probability channel of the DT reaction. It is found that non-thermal effects driven by the fusion products are the dominant method of pair production, and lead to a number density of positrons within the capsule in excess of 3 × 1017 cm-3. The positrons are predominately produced by the Bethe-Heitler process and destroyed by two photon annihilation.

  4. Non-thermal influences on the control of skin blood flow have minimal effects on heat transfer during exercise.

    PubMed Central

    Nadel, E. R.

    1986-01-01

    During exercise, circulatory reflexes ensure that the cardiac output is sufficiently elevated to meet the oxygen delivery requirements of the contracting skeletal muscles and the heat delivery requirements of the body to the skin. The latter requirements are met by increasing skin blood flow. These increases are largely driven by elevations in the body temperatures, although non-thermal effects on the control of skin blood flow occur in certain conditions. These effects are largely the consequence of high and/or low baroreflex stimulation. Even in the face of such non-thermal effects, which occur during exercise in the heat, the body's requirements for heat transfer from core to skin are largely met by the increased skin blood flow. Thus, non-thermal effects on the control of skin blood flow are relatively unimportant in the body's overall regulatory response to exercise. PMID:3751137

  5. Non-thermal plasma techniques for abatement of volatile organic compounds and nitrogen oxides

    SciTech Connect

    Penetrante, B.M.; Hsiao, M.C.; Bardsley, J.N.; Merritt, B.T.; Vogtlin, G.E.; Wallman, P.H. [Lawrence Livermore National Lab., CA (United States); Kuthi, A.; Burkhart, C.P.; Bayless, J.R. [First Point Scientific, Inc., Agoura Hills, CA (United States)

    1995-12-04

    Non-thermal plasma processing is an emerging technology for the abatement of volatile organic compounds (VOCs) and nitrogen oxides (NO{sub x}) in atmospheric-pressure air streams. Either electrical discharge or electron beam methods can produce these plasmas. Each of these methods can be implemented in many ways. There are many types of electrical discharge reactors, the variants depending on the electrode configuration and electrical power supply (pulsed, AC or DC). Two of the more extensively investigated types of discharge reactors are based on the pulsed corona and dielectric-barrier discharge. Recently, compact low-energy (<200 keV) electron accelerators have been developed to meet the requirements of industrial applications such as crosslinking of polymer materials, curing of solvent-free coatings, and drying of printing inks. Special materials have also been developed to make the window thin and rugged. Some of these compact electron beam sources are already commercially available and could be utilized for many pollution control applications. In this paper we will present a comparative assessment of various nonthermal plasma reactors. The thrust of our work has been two-fold: (1) to understand the scalability of various non-thermal plasma reactors by focusing on the energy efficiency of the electron and chemical kinetics, and (2) to identify the byproducts to ensure that the effluent gases from the processor are either benign or much easier and less expensive to dispose of compared to the original pollutants. We will present experimental results using a compact electron beam reactor and various types of electrical discharge reactors. We have used these reactors to study the removal of NO{sub x} and a wide variety of VOCS. We have studied the effects of background gas composition and gas temperature on the decomposition chemistry.

  6. Non-Thermal Signatures in Low State Spectra of Black Hole X-Ray Transients

    NASA Astrophysics Data System (ADS)

    Esin, A. A.; Tomsick, J. A.

    2001-05-01

    Many transient and persistent Black Hole X-ray Binaries (BHXBs) show characteristic state transitions between low/hard and high/soft spectral states. A typical low/hard state X-ray spectrum, as seen for example in Cyg X-1 and GRO J0422+32, is a power-law with a photon index of order 1.4-1.6 and an exponential cutoff with a characteristic e-folding energy ~ 100 keV. These spectra are generally interpreted as emission from hot thermal plasma modeled either as an accretion disk corona, or as a hot accretion flow inside a truncated thin disk. We show that low state spectra of three transient BHXBs, XTE J1118+480, XTE J1550-564, and 4U1630-47, do not show the characteristic hard X-ray turnover. The absence of the turnover is difficult to understand in the context of the thermal Comptonization models, and argues for the presence of non-thermal emission in these systems. We propose that a typical hard power-law spectrum can be produced both in the (thermal) accretion flow or in the (non-thermal) jet (as suggested by Fender et al. 2000). The strength of the jet emission relative to that from the accretion flow (and therefore whether we observe the thermal cutoff in the spectrum or not) can depend on several parameters, e.g. inclination of the jet with respect to the binary and the observer, mass accretion rate, accretion flow configuration. This work was supported by Chandra Postdoctoral Fellowship grant #PF8-10002 awarded by the Chandra X-Ray Center, which is operated by the SAO for NASA under contract NAS8-39073, and by a CASS Postdoctoral Fellowship.

  7. Local Group dSph radio survey with ATCA - II. Non-thermal diffuse emission

    NASA Astrophysics Data System (ADS)

    Regis, Marco; Richter, Laura; Colafrancesco, Sergio; Profumo, Stefano; de Blok, W. J. G.; Massardi, Marcella

    2015-04-01

    Our closest neighbours, the Local Group dwarf spheroidal (dSph) galaxies, are extremely quiescent and dim objects, where thermal and non-thermal diffuse emissions lack, so far, of detection. In order to possibly study the dSph interstellar medium, deep observations are required. They could reveal non-thermal emissions associated with the very low level of star formation, or to particle dark matter annihilating or decaying in the dSph halo. In this work, we employ radio observations of six dSphs, conducted with the Australia Telescope Compact Array in the frequency band 1.1-3.1 GHz, to test the presence of a diffuse component over typical scales of few arcmin and at an rms sensitivity below 0.05 mJy beam-1. We observed the dSph fields with both a compact array and long baselines. Short spacings led to a synthesized beam of about 1 arcmin and were used for the extended emission search. The high-resolution data mapped background sources, which in turn were subtracted in the short-baseline maps, to reduce their confusion limit. We found no significant detection of a diffuse radio continuum component. After a detailed discussion on the modelling of the cosmic ray (CR) electron distribution and on the dSph magnetic properties, we present bounds on several physical quantities related to the dSphs, such that the total radio flux, the angular shape of the radio emissivity, the equipartition magnetic field, and the injection and equilibrium distributions of CR electrons. Finally, we discuss the connection to far-infrared and X-ray observations.

  8. Non-thermal desorption from interstellar dust grains via exothermic surface reactions

    E-print Network

    R. T. Garrod; V. Wakelam; E. Herbst

    2007-03-08

    Aims: The gas-phase abundance of methanol in dark quiescent cores in the interstellar medium cannot be explained by gas-phase chemistry. In fact, the only possible synthesis of this species appears to be production on the surfaces of dust grains followed by desorption into the gas. Yet, evaporation is inefficient for heavy molecules such as methanol at the typical temperature of 10 K. It is necessary then to consider non-thermal mechanisms for desorption. But, if such mechanisms are considered for the production of methanol, they must be considered for all surface species. Methods: Our gas-grain network of reactions has been altered by the inclusion of a non-thermal desorption mechanism in which the exothermicity of surface addition reactions is utilized to break the bond between the product species and the surface. Our estimated rate for this process derives from a simple version of classical unimolecular rate theory with a variable parameter only loosely contrained by theoretical work. Results: Our results show that the chemistry of dark clouds is altered slightly at times up to 10^6 yr, mainly by the enhancement in the gas-phase abundances of hydrogen-rich species such as methanol that are formed on grain surfaces. At later times, however, there is a rather strong change. Instead of the continuing accretion of most gas-phase species onto dust particles, a steady-state is reached for both gas-phase and grain-surface species, with significant abundances for the former. Nevertheless, most of the carbon is contained in an undetermined assortment of heavy surface hydrocarbons. Conclusions: The desorption mechanism discussed here will be better constrained by observational data on pre-stellar cores, where a significant accretion of species such as CO has already occurred.

  9. Killing of adherent oral microbes by a non-thermal atmospheric plasma jet.

    PubMed

    Rupf, Stefan; Lehmann, Antje; Hannig, Matthias; Schäfer, Barbara; Schubert, Andreas; Feldmann, Uwe; Schindler, Axel

    2010-02-01

    Atmospheric plasma jets are being intensively studied with respect to potential applications in medicine. The aim of this in vitro study was to test a microwave-powered non-thermal atmospheric plasma jet for its antimicrobial efficacy against adherent oral micro-organisms. Agar plates and dentin slices were inoculated with 6 log(10) c.f.u. cm(-2) of Lactobacillus casei, Streptococcus mutans and Candida albicans, with Escherichia coli as a control. Areas of 1 cm(2) on the agar plates or the complete dentin slices were irradiated with a helium plasma jet for 0.3, 0.6 or 0.9 s mm(-2), respectively. The agar plates were incubated at 37 degrees C, and dentin slices were vortexed in liquid media and suspensions were placed on agar plates. The killing efficacy of the plasma jet was assessed by counting the number of c.f.u. on the irradiated areas of the agar plates, as well as by determination of the number of c.f.u. recovered from dentin slices. A microbe-killing effect was found on the irradiated parts of the agar plates for L. casei, S. mutans, C. albicans and E. coli. The plasma-jet treatment reduced the c.f.u. by 3-4 log(10) intervals on the dentin slices in comparison to recovery rates from untreated controls. The microbe-killing effect was correlated with increasing irradiation times. Thus, non-thermal atmospheric plasma jets could be used for the disinfection of dental surfaces. PMID:19910483

  10. Large amplitude dust-acoustic double layers in non-thermal plasmas with positive and negative dust

    SciTech Connect

    Maharaj, S. K. [South African National Space Agency Space Science, P O Box 32, Hermanus 7200 (South Africa); Bharuthram, R. [University of the Western Cape, Modderdam Road, Bellville 7530 (South Africa); Singh, S. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Pillay, S. R. [University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa)

    2011-11-29

    The existence of large amplitude double layers in a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons is investigated using the Sagdeev pseudopotential technique. Both positive potential and negative potential double layers are found to be supported by the model. The variation of the maximum amplitudes of the double layers and corresponding Mach numbers are examined as a function of various plasma parameters. In particular, we investigate to what extent ion non-thermal effects are required for positive potential double layers to occur.

  11. Production of stable, non-thermal atmospheric pressure rf capacitive plasmas using gases other than helium or neon

    DOEpatents

    Park, Jaeyoung; Henins, Ivars

    2005-06-21

    The present invention enables the production of stable, steady state, non-thermal atmospheric pressure rf capacitive .alpha.-mode plasmas using gases other than helium and neon. In particular, the current invention generates and maintains stable, steady-state, non-thermal atmospheric pressure rf .alpha.-mode plasmas using pure argon or argon with reactive gas mixtures, pure oxygen or air. By replacing rare and expensive helium with more readily available gases, this invention makes it more economical to use atmospheric pressure rf .alpha.-mode plasmas for various materials processing applications.

  12. Characterization of Al 2 O 3 Supported Nickel Catalysts Derived from RF Non-thermal Plasma Technology

    Microsoft Academic Search

    Ben Jang; Michael Helleson; Chunkai Shi; Adam Rondinone; Viviane Schwartz; Chengdu Liang; Steve Overbury

    2008-01-01

    Catalysts derived from non-thermal plasma techniques have previously shown unusual and highly advantageous catalytic properties\\u000a including room temperature reduction, unusual metal particle structure and metal-support interactions, and enhanced selectivity\\u000a and stability. This study focuses on the characterization of Al2O3 supported Ni catalysts derived from the RF non-thermal plasma technique with in-situ XRD, TPR-MS and STEM and on relating\\u000a the results

  13. Non-thermal atmospheric pressure plasma source techniques on 3,7- bis (dimethylamino)-phenothiazin-5-ium chloride

    NASA Astrophysics Data System (ADS)

    Kotowich, Steven

    Studies of a non-thermal atmospheric pressure plasma source on an organic heterocycle were conducted to determine reaction parameters and rearrangement conditions. The target compound 3,7-bis(dimethylamino)-phenothiazin-5-ium chloride, commonly referred to as methylene blue, was determine to polymerize after exposure to a non-thermal atmospheric pressure plasma source. The presence of charge retention and a free electron radical were detected inherent to the polymer. Evaluation of the structure and mechanism of the polymer were also presented for evidence and clarification. Additional description of the plasma source environment was correlated to the manipulation of the target compound.

  14. Non-Thermal Hard X-Ray Emission in Galaxy Clusters Observed with the BeppoSAX PDS

    NASA Technical Reports Server (NTRS)

    Nevalainen, Jukka H.; Oosterbroeck, T.; Bonamente, Max; Six, N. Frank (Technical Monitor)

    2002-01-01

    We studied the X-ray emission in a sample of clusters using the BeppoSAX PDS instrument in the 20 -- 80 keV energy band. We estimated the non-thermal cluster emission (HXR) by modeling the thermal contribution from the cluster gas and the non-thermal contamination from the AGN in the field, and propagating the corresponding uncertainties. We also evaluated and propagated the systematic uncertainties due to the background fluctuations. The resulting non-thermal component is detected at a sigma level in approx. 50 % of the non-significantly AGN-contaminated clusters, i.e. in clusters A2142, A2256, A3376, Coma, Ophiuchus and Virgo. Furthermore, Virgo is detected at a 4 sigma level. All the clusters detected at a 2 sigma level exhibit some degree of merger signatures, i.e. deviations from the azimuthally symmetric brightness and temperature distributions, while the relaxed clusters are detected at a lower confidence. The data are consistent with a scenario whereby relaxed clusters have no non-thermal hard X-ray component, whereas merger clusters do, with a 20 -- 80 keV luminosity of approx. 10(exp 42-44)((h(sub 50))(exp -2))(erg/s). Consistent with merger boosting of cluster temperatures, the non-thermal luminosity increases by 2-3 orders of magnitude between the average cluster temperatures 2 and 10 keV, as L(sub NTE) is proportional to T(sup j) with j = 2.4+/-0.3. These results corroborate the assumption which is the essential element in most non-thermal hard X-ray emission models. The co-added spectrum of all non-significantly AGN-contaminated clusters indicates a power-law spectrum for the non-thermal component with a photon index of 1.5+/-0.25 at 1 sigma confidence level. Unless there is a high energy cut-off in the electron velocity distribution, the total spectrum implies that Inverse Compton scatter of Cosmic Microwave Background photons from electron population dominates over the non-thermal bremsstrahlung in producing hard X-rays in clusters on the merger shock acceleration of electrons in clusters.

  15. Non-thermal and transient thermal effects of burst 100 MHz sinusoidal electric fields on apoptotic activity in HeLa cells

    Microsoft Academic Search

    Sunao Katsuki; Kazunori Mitsutake; Masahiko Yano; Hidenori Akiyama; Hirofumi Kai; Tsuyoshi Shuto

    2010-01-01

    This paper describes non-thermal and transient thermal effects of burst 100 MHz, 100 kV\\/m sinusoidal electric fields on the apoptotic activity in cultured HeLa cells. Two kinds of pulsing sequences, 50 0.2 ms-long pulses with 2 s intervals and a single 10 ms-long pulse, were used for the non-thermal and the superposition of transient thermal shock on the non-thermal loading,

  16. MAXIMUM LIKELIHOOD FITTING OF X-RAY POWER DENSITY SPECTRA: APPLICATION TO HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS FROM THE NEUTRON STAR X-RAY BINARY 4U1608-522

    SciTech Connect

    Barret, Didier [Institut de Recherche en Astrophysique et Planetologie and Universite de Toulouse (UPS), 31028, Toulouse Cedex 4 (France); Vaughan, Simon, E-mail: didier.barret@irap.omp.eu [X-Ray and Observational Astronomy Group, University of Leicester, Leicester, LE1 7RH (United Kingdom)

    2012-02-20

    High-frequency quasi-periodic oscillations (QPOs) from weakly magnetized neutron stars display rapid frequency variability (second timescales) and high coherence with quality factors up to at least 200 at frequencies about 800-850 Hz. Their parameters have been estimated so far from standard min({chi}{sup 2}) fitting techniques, after combining a large number of power density spectra (PDS), to have the powers normally distributed (the so-called Gaussian regime). Before combining PDS, different methods to minimize the effects of the frequency drift to the estimates of the QPO parameters have been proposed, but none of them relied on fitting the individual PDS. Accounting for the statistical properties of PDS, we apply a maximum likelihood method to derive the QPO parameters in the non-Gaussian regime. The method presented is general, easy to implement, and can be applied to fitting individual PDS, several PDS simultaneously, or their average, and is obviously not specific to the analysis of kHz QPO data. It applies to the analysis of any PDS optimized in frequency resolution and for low-frequency variability or PDS containing features whose parameters vary on short timescales, as is the case for kHz QPOs. It is equivalent to the standard {chi}{sup 2} minimization fitting when the number of PDS fitted is large. The accuracy, reliability, and superiority of the method is demonstrated with simulations of synthetic PDS, containing Lorentzian QPOs of known parameters. Accounting for the broadening of the QPO profile, due to the leakage of power inherent to windowed Fourier transforms, the maximum likelihood estimates of the QPO parameters are asymptotically unbiased and have negligible bias when the QPO is reasonably well detected. By contrast, we show that the standard min({chi}{sup 2}) fitting method gives biased parameters with larger uncertainties. The maximum likelihood fitting method is applied to a subset of archival Rossi X-ray Timing Explorer data of the neutron star X-ray binary 4U1608-522, for which we show that the lower kHz QPO parameters can be measured on timescales as short as 8 s. To demonstrate the potential use of the results of the maximum likelihood method, we show that in the observation analyzed the time evolution of the frequency is consistent with a random walk. We then show that the broadening of the QPO due to the frequency drift scales as {radical}T, as expected from a random walk (T is the integration time of the PDS). This enables us to estimate the intrinsic quality factor of the QPO to be {approx}260, whereas previous analysis indicated a maximum value around 200.

  17. INTERIM GUIDELINES FOR THE DISPOSAL/DESTRUCTION OF PCBS AND PCB ITEMS BY NON-THERMAL METHODS

    EPA Science Inventory

    The report is an interim resource and guideline document to help EPA regional offices implement the polychlorinated biphenyl (PCB) regulations (40 CFR 761) for using non-thermal methods of destroying/disposing of PCBs. The report describes and evaluates various alternative chemic...

  18. Constraint of Non-thermal X-ray Emission from the On-going Merger Cluster Abell 3376 with Suzaku

    E-print Network

    Naomi Kawano; Yasushi Fukazawa; Sho Nishino; Kazuhiro Nakazawa; Takao Kitaguchi; Kazuo Makishima; Tadayuki Takahashi; Motohide Kokubun; Naomi Ota; Takaya Ohashi; Naoki Isobe; J. Patrick Henry; Ann Hornschemeier

    2008-05-23

    Clusters of galaxies are among the best candidates for particle acceleration sources in the universe, a signature of which is non-thermal hard X-ray emission from the accelerated relativistic particles. We present early results on Suzaku observations of non-thermal emission from Abell 3376, which is a nearby on-going merger cluster. Suzaku observed the cluster twice, focusing on the cluster center containing the diffuse radio emission to the east, and cluster peripheral region to the west. For both observations, we detect no excess hard X-ray emission above the thermal cluster emission. An upper limit on the non-thermal X-ray flux of $2.1\\times10^{-11}$ erg cm$^{-2}$ s$^{-1}$ (15--50 keV) at the 3$\\sigma$ level from a $34\\times34$ arcmin$^2$ region, derived with the Hard X-ray Detector (HXD), is similar to that obtained with the BeppoSAX/PDS. Using the X-ray Imaging Spectrometer (XIS) data, the upper limit on the non-thermal emission from the West Relic is independently constrained to be $microwave background (CMB) photons, the intracluster magnetic field $B$ is limited to be $>0.03\\mu$G (HXD) and $>0.10\\mu$G (XIS).

  19. Phenotypic and genetic differentiation among yellow monkeyflower populations from thermal and non-thermal soils in Yellowstone National Park.

    PubMed

    Lekberg, Ylva; Roskilly, Beth; Hendrick, Margaret F; Zabinski, Catherine A; Barr, Camille M; Fishman, Lila

    2012-09-01

    In flowering plants, soil heterogeneity can generate divergent natural selection over fine spatial scales, and thus promote local adaptation in the absence of geographic barriers to gene flow. Here, we investigate phenotypic and genetic differentiation in one of the few flowering plants that thrives in both geothermal and non-thermal soils in Yellowstone National Park (YNP). Yellow monkeyflowers (Mimulus guttatus) growing at two geothermal ("thermal") sites in YNP were distinct in growth form and phenology from paired populations growing nearby (<500 m distant) in non-thermal soils. In simulated thermal and non-thermal environments, thermal plants remained significantly divergent from non-thermal plants in vegetative, floral, mating system, and phenological traits. Plants from both thermal populations flowered closer to the ground, allocated relatively more to sexual reproduction, were more likely to initiate flowering under short daylengths, and made smaller flowers that could efficiently self-fertilize without pollinators. These shared differences are consistent with local adaptation to life in the ephemeral window for growth and reproduction created by winter and spring snowmelt on hot soils. In contrast, habitat type (thermal vs. non-thermal) explained little of the genetic variation at neutral markers. Instead, we found that one thermal population (Agrostis Headquarters; AHQ-T) was strongly differentiated from all other populations (all F (ST) > 0.34), which were only weakly differentiated from each other (all F (ST) < 0.07). Phenotypic differentiation of thermal M. guttatus, but little population genetic evidence of long-term ecotypic divergence, encourages further investigations of the potential for fine-scale adaptation and reproductive isolation across the geothermal gradient in Yellowstone. PMID:22437908

  20. Non-thermal emission from standing relativistic shocks: an application to red giant winds interacting with AGN jets

    NASA Astrophysics Data System (ADS)

    Bosch-Ramon, V.

    2015-03-01

    Context. Galactic and extragalactic relativistic jets are surrounded by rich environments that are full of moving objects, such as stars and dense medium inhomogeneities. These objects can enter into the jets and generate shocks and non-thermal emission. Aims: We characterize the emitting properties of the downstream region of a standing shock formed due to the interaction of a relativistic jet with an obstacle. We focus on the case of red giants interacting with an extragalactic jet. Methods: We perform relativistic axisymmetric hydrodynamical simulations of a relativistic jet meeting an obstacle of very large inertia. The results are interpreted in the framework of a red giant whose dense and slow wind interacts with the jet of an active galactic nucleus. Assuming that particles are accelerated in the standing shock generated in the jet as it impacts the red giant wind, we compute the non-thermal particle distribution, the Doppler boosting enhancement, and the non-thermal luminosity in gamma rays. Results: The available non-thermal energy from jet-obstacle interactions is potentially enhanced by a factor of ~100 when accounting for the whole surface of the shock induced by the obstacle, instead of just the obstacle section. The observer gamma-ray luminosity, including the effective obstacle size, the flow velocity and Doppler boosting effects, can be ~300 (?j/10)2 times higher than when the emitting flow is assumed at rest and only the obstacle section is considered, where ?j is the jet Lorentz factor. For a whole population of red giants inside the jet of an active galactic nucleus, the predicted persistent gamma-ray luminosities may be potentially detectable for a jet pointing approximately to the observer. Conclusions: Obstacles interacting with relativistic outflows, for instance clouds and populations of stars for extragalactic jets, or stellar wind inhomogeneities in microquasar jets and in winds of pulsars in binaries, should be taken into account when investigating the origin of the non-thermal emission from these sources.

  1. [Hydrogen sulfide removal by the combination of non-thermal plasma and biological process].

    PubMed

    Li, Hua-Qin; He, Jue-Cong; Chen, Zhou-Yang; Li, Bao-Ren; Huang, Qian-Ru; Zhang, Zai-Li; Wei, Zai-Shan

    2014-04-01

    A bench scale system integrating a non-thermal plasma (NTP) unit with a biotricking filtration (BTF) unit for the treatment of gases containing hydrogen sulfide (H2S) was investigated. The additional use of the biotrickling filter to NTP reactor not only leads to the enhancement of hydrogen sulfide removal efficiency up from 83.4% to 90.1%, but also eliminates gas-phase intermediate products from NTP degradation of H2S to produce sulfate and H2O. The dynamic changes of microbial community in BTF influenced by ozone from NTP were assessed by PCR-DGGE. Results show that the microbial community was affected by ozone. After the integration, a part of microorganisms disappeared, and meanwhile some new microorganisms appeared. The microbial community structure in BTF changed from eight bands to nine bands; three bands which have the functions of desulfurization disappeared and four bands which have the functions of desulfurization appeared; five bands which have the functions of desulfurization and sulfate reduction were unchanged. The bacterial groups in the BTF unit of NTP-BTF system include Uncultured Thiobacillus sp., Acidithiobacillus thiooxidans strain dfI, Uncultured Thiobacillus sp., Uncultured Acidiphilium sp., Uncultured Xanthomonadaceae bacterium clone SBLE6C12, Uncultured 8-Proteobacterium and Paracraurococcus sp. 1PNM-27. PMID:24946573

  2. Conversion of carbon disulfide in air by non-thermal plasma.

    PubMed

    Yan, Xiao; Sun, Yifei; Zhu, Tianle; Fan, Xing

    2013-10-15

    Carbon disulfide (CS2), a typical odorous organic sulfur compound, has adverse effects on human health and is a potential threat to the environment. In the present study, CS2 conversion in air by non-thermal plasma (NTP) was systematically investigated using a link tooth wheel-cylinder plasma reactor energized by a DC power supply. The results show that corona discharge is effective in removing CS2. The CS2 conversion increases with the increase of specific input energy (SIE). Both short-living (e.g. O, OH radicals) and long-living species contribute to the CS2 conversion, but the short-living species play a more important role. Both gaseous and solid products are formed during the conversion of CS2. Gaseous products mainly include CO, CO2, OCS, SO2, SO3 and H2SO4. The yields of CO and CO2 increase, the yields of OCS and SO2 follow bell curves while the sum yield of SO3 and H2SO4 remains constant as SIE increases. The solid products, consisting of CO3(2-), SO4(2-) and possible polymeric sulfur, deposit on the inner wall and electrodes of the plasma reactor. PMID:24041772

  3. Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare

    E-print Network

    T. Minoshima; T. Yokoyama; N. Mitani

    2007-10-02

    We study the non-thermal emissions in a solar flare occurring on 2003 May 29 by using RHESSI hard X-ray (HXR) and Nobeyama microwave observations. This flare shows several typical behaviors of the HXR and microwave emissions: time delay of microwave peaks relative to HXR peaks, loop-top microwave and footpoint HXR sources, and a harder electron energy distribution inferred from the microwave spectrum than from the HXR spectrum. In addition, we found that the time profile of the spectral index of the higher-energy ($\\gsim 100$ keV) HXRs is similar to that of the microwaves, and is delayed from that of the lower-energy ($\\lsim 100$ keV) HXRs. We interpret these observations in terms of an electron transport model called {\\TPP}. We numerically solved the spatially-homogeneous {\\FP} equation to determine electron evolution in energy and pitch-angle space. By comparing the behaviors of the HXR and microwave emissions predicted by the model with the observations, we discuss the pitch-angle distribution of the electrons injected into the flare site. We found that the observed spectral variations can qualitatively be explained if the injected electrons have a pitch-angle distribution concentrated perpendicular to the magnetic field lines rather than isotropic distribution.

  4. Non-thermal radiation from molecular clouds illuminated by cosmic rays from nearby supernova remnants

    E-print Network

    Stefano Gabici; Sabrina Casanova; Felix A. Aharonian

    2008-09-30

    Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if cosmic rays can leave the accelerator and diffusively reach the cloud. We consider the situation in which a molecular cloud is located in the proximity of a supernova remnant which is accelerating cosmic rays and gradually releasing them into the interstellar medium. We calculate the multiwavelength spectrum from radio to gamma rays which emerges from the cloud as the result of cosmic ray interactions. The total energy output is dominated by the gamma ray emission, which can exceed the emission from other bands by an order of magnitude or more. This suggests that some of the unidentified TeV sources detected so far, with no obvious or very weak counterpart in other wavelengths, might be associated with clouds illuminated by cosmic rays coming from a nearby source.

  5. Direct chemical oxidation: a non-thermal technology for the destruction of organic wastes

    SciTech Connect

    Balazs, G.B.; Cooper, J. F.; Lewis, P. R.; Adamson, M. G.

    1998-02-01

    Direct Chemical Oxidation (DCO) is a non-thermal, ambient pressure, aqueous-based technology for the oxidative destruction of the organic components of hazardous or mixed waste streams. The process has been developed for applications in waste treatment and chemical demilitarization and decontamination at LLNL since 1992, and is applicable to the destruction of virtually all solid or liquid organics, including: chlorosolvents, oils and greases, detergents, organic-contaminated soils or sludges, explosives, chemical and biological warfare agents, and PCB's. [1-15] The process normally operates at 80-100 C, a heating requirement which increases the difficulty of surface decontamination of large objects or, for example, treatment of a wide area contaminated soil site. The driver for DCO work in FY98 was thus to investigate the use of catalysts to demonstrate the effectiveness of the technology for organics destruction at temperatures closer to ambient. In addition, DCO is at a sufficiently mature stage of development that technology transfer to a commercial entity was a logical next step, and was thus included in FY98 tasks.

  6. Non-thermal CMSSM with a 125 GeV Higgs

    E-print Network

    Aparicio, Luis; Dutta, Bhaskar; Krippendorf, Sven; Maharana, Anshuman; Muia, Francesco; Quevedo, Fernando

    2015-01-01

    We study the phenomenology of the CMSSM/mSUGRA with non-thermal neutralino dark matter. Besides the standard parameters of the CMSSM we include the reheating temperature as an extra parameter. Imposing radiative electroweak symmetry breaking with a Higgs mass around 125 GeV and no dark matter overproduction, we contrast the scenario with different experimental bounds from colliders (LEP, LHC), cosmic microwave background (Planck), direct (LUX, XENON100, CDMS, IceCube) and indirect (Fermi) dark matter searches. The allowed parameter space is characterised by a Higgsino-like LSP with a mass around 300 GeV. The observed dark matter abundance can be saturated for reheating temperatures around 2 GeV while larger temperatures require extra non-neutralino dark matter candidates and extend the allowed parameter space. Sfermion and gluino masses are in the few TeV region. These scenarios can be achieved in string models of sequestered supersymmetry breaking which avoid cosmological moduli problems and are compatible w...

  7. EVIDENCE OF NON-THERMAL X-RAY EMISSION FROM HH 80

    SciTech Connect

    López-Santiago, J. [Instituto de Matemática Interdisciplinar, S. D. Astronomía y Geodesia, Facultad de Ciencias Matemáticas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)] [Instituto de Matemática Interdisciplinar, S. D. Astronomía y Geodesia, Facultad de Ciencias Matemáticas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Peri, C. S.; Benaglia, P. [Instituto Argentino de Radioastronomía (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina)] [Instituto Argentino de Radioastronomía (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina); Bonito, R. [Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)] [Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Miceli, M. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)] [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Albacete-Colombo, J. F. [Universidad Nacional del COMAHUE, Monseñor Esandi y Ayacucho, 8500 Viedma, Río Negro (Argentina)] [Universidad Nacional del COMAHUE, Monseñor Esandi y Ayacucho, 8500 Viedma, Río Negro (Argentina); De Castro, E. [Dpto. de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain)] [Dpto. de Astrofísica y CC. de la Atmósfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2013-10-20

    Protostellar jets appear at all stages of star formation when the accretion process is still at work. Jets travel at velocities of hundreds of km s{sup –1}, creating strong shocks when interacting with the interstellar medium. Several cases of jets have been detected in X-rays, typically showing soft emission. For the first time, we report evidence of hard X-ray emission possibly related to non-thermal processes not explained by previous models of the post-shock emission predicted in the jet/ambient interaction scenario. HH 80 is located at the south head of the jet associated with the massive protostar IRAS 18162-2048. It shows soft and hard X-ray emission in regions that are spatially separated, with the soft X-ray emission region situated behind the region of hard X-ray emission. We propose a scenario for HH 80 where soft X-ray emission is associated with thermal processes from the interaction of the jet with denser ambient matter and hard X-ray emission is produced by synchrotron radiation at the front shock.

  8. Bactericidal efficacy of atmospheric pressure non-thermal plasma (APNTP) against the ESKAPE pathogens.

    PubMed

    Flynn, Padrig B; Higginbotham, Sarah; Alshraiedeh, Nid'a H; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2015-07-01

    The emergence of multidrug-resistant pathogens within the clinical environment is presenting a mounting problem in hospitals worldwide. The 'ESKAPE' pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) have been highlighted as a group of causative organisms in a majority of nosocomial infections, presenting a serious health risk due to widespread antimicrobial resistance. The stagnating pipeline of new antibiotics requires alternative approaches to the control and treatment of nosocomial infections. Atmospheric pressure non-thermal plasma (APNTP) is attracting growing interest as an alternative infection control approach within the clinical setting. This study presents a comprehensive bactericidal assessment of an in-house-designed APNTP jet both against biofilms and planktonic bacteria of the ESKAPE pathogens. Standard plate counts and the XTT metabolic assay were used to evaluate the antibacterial effect of APNTP, with both methods demonstrating comparable eradication times. APNTP exhibited rapid antimicrobial activity against all of the ESKAPE pathogens in the planktonic mode of growth and provided efficient and complete eradication of ESKAPE pathogens in the biofilm mode of growth within 360s, with the exception of A. baumannii where a >4log reduction in biofilm viability was observed. This demonstrates its effectiveness as a bactericidal treatment against these pathogens and further highlights its potential application in the clinical environment for the control of highly antimicrobial-resistant pathogens. PMID:25963338

  9. Antitumor action of non thermal plasma sources, DBD and Plasma Gun, alone or in combined protocols

    NASA Astrophysics Data System (ADS)

    Robert, Eric; Brullé, Laura; Vandamme, Marc; Riès, Delphine; Le Pape, Alain; Pouvesle, Jean-Michel

    2012-10-01

    The presentation deals with the assessment on two non thermal plasma sources developed and optimized for oncology applications. The first plasma source is a floating-electrode dielectric barrier discharge powered at a few hundreds of Hz which deliver air-plasma directly on the surface of cell culture medium in dishes or on the skin or organs of mice bearing cancer tumors. The second plasma source, so called Plasma Gun, is a plasma jet source triggered in noble gas, transferred in high aspect ratio and flexible capillaries, on targeting cells or tumors after plasma transfer in air through the ``plasma plume'' generated at the capillary outlet. In vitro evidence for massive cancer cell destruction and in vivo tumor activity and growth rate reductions have been measured with both plasma sources. DNA damages, cell cycle arrests and apoptosis induction were also demonstrated following the application of any of the two plasma source both in vitro and in vivo. The comparison of plasma treatment with state of the art chemotherapeutic alternatives has been performed and last but not least the benefit of combined protocols involving plasma and chemotherapeutic treatments has been evidenced for mice bearing orthotopic pancreas cancer and is under evaluation for the colon tumors.

  10. Single-step non-thermal plasma synthesis of 3C-SiC nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaukulkar, Rohan P.; de Peuter, Koen; Ghodes, Jacob A.; Pylypenko, Svitlana; Cloud, Jacqueline E.; Yang, Yongan; Stradins, Paul; Agarwal, Sumit

    2015-01-01

    We present a scalable, single-step, non-thermal plasma synthesis technique for the growth of sub-5 nm, hydrogenated amorphous carbon (a-C:H) coated 3C-SiC nanoparticles (NPs). In a tubular flow reactor, we first nucleate and grow c-Si NPs upstream in a SiH4/Ar plasma. These c-Si NPs are then transported by gas flow to a downstream C2H2/Ar plasma, and carburized in-flight by carbon-containing radicals and ions to 3C-SiC NPs. X-ray diffraction and transmission electron microscopy indicate an NP size of ˜4 nm. X-ray photoelectron spectroscopy analysis confirms that the c-Si NPs are completely carburized to 3C-SiC. Fourier transform infrared spectroscopy shows that the surface of the 3C-SiC NPs is coated with a-C:H with some alkenyl termination, which can facilitate further solution-based surface functionalization for biomedical applications.

  11. Pyrite-enhanced methylene blue degradation in non-thermal plasma water treatment reactor.

    PubMed

    Benetoli, Luís Otávio de Brito; Cadorin, Bruno Mena; Baldissarelli, Vanessa Zanon; Geremias, Reginaldo; de Souza, Ivan Gonçalvez; Debacher, Nito Angelo

    2012-10-30

    In this study, methylene blue (MB) removal from an aqueous phase by electrical discharge non-thermal plasma (NTP) over water was investigated using three different feed gases: N(2), Ar, and O(2). The results showed that the dye removal rate was not strongly dependent on the feed gas when the electrical current was kept the same for all gases. The hydrogen peroxide generation in the water varied according to the feed gas (N(2)

  12. In vivo non-thermal irreversible electroporation impact on rat liver galvanic apparent internal resistance

    NASA Astrophysics Data System (ADS)

    Golberg, A.; Laufer, S.; Rabinowitch, H. D.; Rubinsky, B.

    2011-02-01

    Non-thermal irreversible electroporation (NTIRE) is a biophysical phenomenon which involves application of electric field pulses to cells or tissues, causing certain rearrangements in the membrane structure leading to cell death. The treated tissue ac impedance changes induced by electroporation were shown to be the indicators for NTIRE efficiency. In a previous study we characterized in vitro tissue galvanic apparent internal resistance (GAIR) changes due to NTIRE. Here we describe an in vivo study in which we monitored the GAIR changes of a rat liver treated by NTIRE. Electrical pulses were delivered through the same Zn/Cu electrodes by which GAIR was measured. GAIR was measured before and for 3 h after the treatment at 15 min intervals. The results were compared to the established ac bioimpedance measurement method. A decrease of 33% was measured immediately after the NTIRE treatment and a 40% decrease was measured after 3 h in GAIR values; in the same time 40% and 47% decrease respectively were measured by ac bioimpedance analyses. The temperature increase due to the NTIRE was only 0.5 °C. The results open the way for an inexpensive, self-powered in vivo real-time NTIRE effectiveness measurement.

  13. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water.

    PubMed

    Hao, Xiao Long; Zhou, Ming Hua; Lei, Le Cheng

    2007-03-22

    TiO(2) photocatalyst (P-25) (50mgL(-1)) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO(2) were obviously increased. Pulsed high-voltage discharge process with TiO(2) had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10x10(-6) to 1.50x10(-6)Ms(-1), the ozone formation rate from 1.99x10(-8) to 2.35x10(-8)Ms(-1), respectively. In addition, this process had no influence on the photocatalytic properties of TiO(2). The introduction of TiO(2) photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants. PMID:16987594

  14. Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Jung, Heesoo; Park, Jaeyoung; Yoo, Eun Sang; Han, Gill-Sang; Jung, Hyun Suk; Ko, Min Jae; Park, Sanghoo; Choe, Wonho

    2013-08-01

    A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti3+ ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing.A key challenge to the industrial application of nanotechnology is the development of fabrication processes for functional devices based on nanomaterials which can be scaled up for mass production. In this report, we disclose the results of non-thermal radio-frequency (rf) atmospheric pressure plasma (APP) based deposition of TiO2 nanoparticles on a flexible substrate for the fabrication of dye-sensitized solar cells (DSSCs). Operating at 190 °C without a vacuum enclosure, the APP method can avoid thermal damage and vacuum compatibility restrictions and utilize roll-to-roll processing over a large area. The various analyses of the TiO2 films demonstrate that superior film properties can be obtained by the non-thermal APP method when compared with the thermal sintering process operating at 450 °C. The crystallinity of the anatase TiO2 nanoparticles is significantly improved without thermal agglomeration, while the surface defects such as Ti3+ ions are eliminated, thus providing efficient charge collecting properties for solar cells. Finally, we successfully fabricated a flexible DSSC with an energy conversion efficiency of 4.2% using a transparent plastic substrate. This work demonstrates the potential of non-thermal APP technology in the area of device-level, nano-enabled material manufacturing. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01889j

  15. Temperature diagnostics of a non-thermal plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Schäfer, Jan

    2013-09-01

    The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 ?m which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 ?m which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The work was supported in part by the Deutsche Forschungsgemeinschaft within SFB-TR 24.

  16. Non-thermal high-energy emission from colliding winds of massive stars

    E-print Network

    A. Reimer; M. Pohl; O. Reimer

    2005-10-25

    Colliding winds of massive star binary systems are considered as potential sites of non-thermal high-energy photon production. This is motivated merely by the detection of synchrotron radio emission from the expected colliding wind location. Here we investigate the properties of high-energy photon production in colliding winds of long-period WR+OB-systems. We found that in the dominating leptonic radiation process anisotropy and Klein-Nishina effects may yield spectral and variability signatures in the gamma-ray domain at or above the sensitivity of current or upcoming gamma-ray telescopes. Analytical formulae for the steady-state particle spectra are derived assuming diffusive particle acceleration out of a pool of thermal wind particles, and taking into account adiabatic and all relevant radiative losses. For the first time we include their advection/convection in the wind collision zone, and distinguish two regions within this extended region: the acceleration region where spatial diffusion is superior to convective/advective motion, and the convection region defined by the convection time shorter than the diffusion time scale. The calculation of the Inverse Compton radiation uses the full Klein-Nishina cross section, and takes into account the anisotropic nature of the scattering process. This leads to orbital flux variations by up to several orders of magnitude which may, however, be blurred by the geometry of the system. The calculations are applied to the typical WR+OB-systems WR 140 and WR 147 to yield predictions of their expected spectral and temporal characteristica and to evaluate chances to detect high-energy emission with the current and upcoming gamma-ray experiments. (abridged)

  17. PAMELA Satellite Data as a Signal of Non-Thermal Wino LSP Dark Matter

    E-print Network

    Gordon Kane; Ran Lu; Scott Watson

    2009-06-27

    Satellite data is accumulating that suggests and constrains dark matter physics. We argue there is a very well motivated theoretical preexisting framework consistent with dark matter annihilation being observed by the PAMELA satellite detector. The dark matter is (mainly) the neutral W boson superpartner, the wino with mass below 200 GeV. Using the program GALPROP we study the annihilation products and backgrounds together. Antimatter and gammas from annihilating winos contribute below this energy. We explain why PAMELA data does not imply no antiproton signal was observed by PAMELA or earlier experiments, and explain why the antiproton analysis was misunderstood by earlier papers. Wino annihilation does not describe the Fermi e+ + e- data (except partially below ~ 100 GeV). At higher energies we expect astrophysical mechanisms, and we simply parameterize them so the combination can describe all the data. We emphasize several predictions for satellite data to test the wino interpretation, particularly the turndown of the positron and antiproton spectra above 100 GeV. Most other interpretations require a large rise in the positron rates above 100 GeV. We focus on studying this well-motivated and long predicted wino interpretation, rather than comparisons with other interpretations. We emphasize that interpretations also depend very strongly on assumptions about the cosmological history of the universe, and on propagation of antiprotons and positrons in the galaxy. The winos PAMELA is observing arose from some non-thermal sources such as moduli decay rather than a universe that cooled in thermal equilibrium after the big bang. Then it is appropriate to normalize the wino density to the local relic density, and no "boost factors" are needed to obtain the reported PAMELA rates.

  18. Exploring the connection between the stellar wind and the non-thermal emission in LS 5039

    E-print Network

    V. Bosch-Ramon; C. Motch; M. Ribo; R. Lopes de Oliveira; E. Janot-Pacheco; I. Negueruela; J. M. Paredes; A. Martocchia

    2007-07-18

    LS 5039 has been observed with several X-ray instruments so far. The source presents X-ray variability at orbital timescales in flux and photon index. The system harbors an O-type main sequence star with moderate mass loss. At present, the link between the X-rays and the stellar wind is unclear. New XMM-Newton observations have been performed around periastron and apastron passages in September 2005, when the stellar wind activity was apparently higher. April 2005 Chandra observations on LS 5039 are also revisited. Moreover, a compilation of Halpha EW data obtained since 1992, from which the stellar mass loss evolution can be approximately inferred, is carried out. XMM-Newton observations show higher and harder emission around apastron than around periastron. No signatures of thermal emission or a reflection iron line indicating the presence of an accretion disk are found in the spectrum, and the hydrogen column density (NH) is compatible with being the same in both observations and consistent with the interstellar value. 2005 Chandra observations show a hard X-ray spectrum, and possibly high fluxes. The Halpha EW shows yearly variations of a ~ 10%, and does not seem to be correlated with X-ray fluxes obtained at similar phases, unlike it would be expected in the wind accretion scenario. 2005 XMM-Newton and Chandra observations are consistent with 2003 RXTE/PCA results. The constancy of the NH seems to imply that either the X-ray emitter is located at >~ 1012 cm from the compact object, or the real N_H is 3-27 times smaller than the one predicted by a spherical symmetric wind model. We suggest that the multiwavelength non-thermal emission of LS 5039 is related to the radio jets and unlikely produced inside the binary system.

  19. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters

    Microsoft Academic Search

    Evan Million; Steve Allen

    2009-01-01

    We report the discovery of spatially-extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 < Gamma < 2.0. A control sample of regular, dynamically relaxed clusters, without radio halos

  20. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio halo clusters

    Microsoft Academic Search

    E. T. Million; S. W. Allen

    2009-01-01

    We report the discovery of spatially extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio haloes. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 < Gamma < 2.0. A control sample of regular, dynamically relaxed clusters, without radio

  1. Nano-droplet ejection and nucleation of materials submitted to non-thermal plasma filaments

    Microsoft Academic Search

    J.-P. Borra; N. Jidenko; C. Dutouquet; O. Aguerre; J. Hou; A. Weber

    2011-01-01

    Methods to induce non-thermal atmospheric pressure plasma filaments are presented with related properties for micro, streamer and prevented spark discharges, respectively, induced in planar Dielectric Barrier Discharges with one electrode covered by dielectric material (mono-DBD) or point-to-plane Corona. Two mechanisms of nano-particles formation are depicted from aerosol size distributions and TEM analysis. 0.1-10 mJ prevented spark discharges produce 10-100 nm

  2. Dust ion-acoustic solitary and shock waves in a dusty plasma with non-thermal electrons

    Microsoft Academic Search

    H. Alinejad

    2010-01-01

    A theoretical investigation of the one dimensional dynamics of nonlinear electrostatic dust ion-acoustic (DIA) waves in an\\u000a unmagnetized dusty plasma consisting of ion fluid, non-thermal electrons and fluctuating immobile dust particles has been\\u000a made by the reductive perturbation technique. The basic features of DIA solitary and shock waves are studied by deriving the\\u000a Korteweg-de Vries (KdV) and KdV Burger equations,

  3. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Microsoft Academic Search

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-01-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (HâS) in a non-thermal plasma and recover hydrogen (Hâ) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys),

  4. Excitation and ionization of atoms and ions in a non-thermal plasma. I. Populations of excited levels

    Microsoft Academic Search

    S. Suckewer

    1970-01-01

    The author presents formulae for the populations of levels of excited atoms and ions of a plasma in non-thermal equilibrium over a wide range of electron densities. The validity of the method presented is established by comparison of the calculated population of excited levels of hydrogen-like ions with the results of McWhirter and Hearn (1963). For illustration, the population of

  5. Studies on a non-thermal pulsed corona plasma between two parallel-plate electrodes in water

    Microsoft Academic Search

    M M Sein; Z Bin Nasir; U Telgheder; T C Schmidt

    2012-01-01

    A non-thermal plasma generated between two parallel-plate electrodes submerged in water was studied in this work. The surface of one of the stainless-steel electrodes (the cathode) was coated with a ceramic layer of Al2O3. This reactor cell was connected to a water cycle and the discharge was carried out in a closed loop and therefore an equilibrium was established during

  6. NOVEL COMPOSITE HYDROGEN-PERMEABLE MEMBRANES FOR NON-THERMAL PLASMA REACTORS FOR THE DECOMPOSITION OF HYDROGEN SULFIDE

    Microsoft Academic Search

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Ji-Jun Zhang; Guibing Zhao; Robyn J. Alcanzare; Linna Wang; Ovid A. Plumb

    2004-01-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (HâS) in a non-thermal plasma and recover hydrogen (Hâ) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys),

  7. Silicon nanocrystal production through non-thermal plasma synthesis: a comparative study between silicon tetrachloride and silane precursors

    Microsoft Academic Search

    Ozgul Yasar-Inceoglu; Thomas Lopez; Ebrahim Farshihagro; Lorenzo Mangolini

    2012-01-01

    Silicon nanocrystals with sizes between 5 and 10 nm have been produced in a non-thermal plasma reactor using silicon tetrachloride as precursor. We demonstrate that high-quality material can be produced with this method and that production rates as high as 140 mg h?1 can be obtained, with a maximum precursor utilization rate of roughly 50%. Compared to the case in

  8. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    Microsoft Academic Search

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibing Zhao; Sanil John

    2006-01-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (HâS) in a non-thermal plasma and recover hydrogen (Hâ) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys),

  9. Combined effects of laser and non-thermal electron beams on hydrodynamics and shock formation in the Shock Ignition scheme

    NASA Astrophysics Data System (ADS)

    Nicolai, Ph.; Feugeas, J. L.; Touati, M.; Breil, J.; Dubroca, B.; Nguyen-Buy, T.; Ribeyre, X.; Tikhonchuk, V.; Gus'kov, S.

    2014-10-01

    An issue to be addressed in Inertial Confinement Fusion (ICF) is the detailed description of the kinetic transport of relativistic or non-thermal electrons generated by laser within the time and space scales of the imploded target hydrodynamics. We have developed at CELIA the model M1, a fast and reduced kinetic model for relativistic electron transport. The latter has been implemented into the 2D radiation hydrodynamic code CHIC. In the framework of the Shock Ignition (SI) scheme, it has been shown in simplified conditions that the energy transferred by the non-thermal electrons from the corona to the compressed shell of an ICF target could be an important mechanism for the creation of ablation pressure. Nevertheless, in realistic configurations, taking the density profile and the electron energy spectrum into account, the target has to be carefully designed to avoid deleterious effects on compression efficiency. In addition, the electron energy deposition may modify the laser-driven shock formation and its propagation through the target. The non-thermal electron effects on the shock propagation will be analyzed in a realistic configuration.

  10. Dust ion-acoustic solitary and shock waves in a dusty plasma with non-thermal electrons

    NASA Astrophysics Data System (ADS)

    Alinejad, H.

    2010-05-01

    A theoretical investigation of the one dimensional dynamics of nonlinear electrostatic dust ion-acoustic (DIA) waves in an unmagnetized dusty plasma consisting of ion fluid, non-thermal electrons and fluctuating immobile dust particles has been made by the reductive perturbation technique. The basic features of DIA solitary and shock waves are studied by deriving the Korteweg-de Vries (KdV) and KdV Burger equations, respectively. It is shown that the special patterns of nonlinear electrostatic waves are significantly modified by the presence of the non-thermal electron component. In particular, the rarefactive solitary and shock structures are found with smaller amplitude in comparison to the isothermal case. The transition from DIA solitary to shock waves is also studied which is related to the contributions of the dispersive and dissipative terms. It is found that the dust charge fluctuation is a source of dissipation, and is responsible for the formation of the dust ion-acoustic shock waves. Furthermore, the dissipative effect becomes important and may prevail over that of dispersion as the population of non-thermal electrons present decreases. The present investigation may be of relevance to electrostatic solitary structures observed in many space dusty plasma, such as Saturn’s E-ring.

  11. Evaluation of a non-thermal plasma needle to eliminate ex vivo biofilms in root canals of extracted human teeth

    PubMed Central

    Schaudinn, C; Jaramillo, D; Freire, M O; Sedghizadeh, P P; Nguyen, A; Webster, P; Costerton, J W; Jiang, C

    2013-01-01

    Aim To evaluate the efficacy of a non-thermal plasma (NTP) at atmospheric pressure on ex vivo biofilm in root canals of extracted teeth. Methodology Intra-canal contents from three teeth with root canal infections were collected, pooled, and grown in thirty-five microCT-mapped root canals of extracted and instrumented human teeth. One group of teeth was treated with NTP, another with 6% NaOCl, and one set was left untreated. The intra-canal contents from twenty-seven teeth (nine teeth in each group) were plated on agar and colony forming units were determined. Parametric test of one-way Analysis of Variance (ANOVA) was used to analyze statistical significance. The remaining teeth were cut open, stained with LIVE/DEAD® and examined with confocal laser scanning microscopy. Results The untreated root canals were covered with biofilm of varying thickness. The treatment with the non-thermal plasma decreased the number of viable bacteria in these biofilms by one order of magnitude, while the NaOCl control achieved a reduction of more than four magnitudes. Both the NTP and the NaOCl treatment results were significantly different from the negative control (P< 0.05). Conclusion The non-thermal plasma displayed antimicrobial activity against endodontic biofilms in root canals, but was not as effective as the use of 6 % NaOCl. PMID:23480318

  12. Biological Effects Induced by Non-thermal Ultrasound and Implications for Cancer Therapy: A Review of the Current Literature.

    PubMed

    Tang, Justin; Guha, Chandan; Tomé, Wolfgang A

    2015-04-01

    Recent advancements in imaging and targeting have expanded the utility of ultrasound therapy with increasing attention being paid to the application of ultrasound in cancer therapy. We present in this article a review of the biological effects of non-thermal ultrasound that could find application in cancer treatment in the near and long term. A careful examination of the ultrasound parameters that elicited these observed effects is needed so that one may refine and apply these results for clinical application. Reported biological effects from non-thermal ultrasound have been categorized into mechanical and chemical means of action. Cavitation and acoustic radiation force are the main contributors to sonomechanical effects of ultrasound while reactive oxygen species contribute to its sonochemical effects. These two categories are responsible for observations such as induction of apoptosis in cancer cells, disturbance of the cytoskeleton, enhancement of gene transfection and chemotherapeutic potency, and modulation of cellular proliferation and protein synthesis. In this review we have considered the biological effects of non-thermal ultrasound, the range of parameters at which these biological effects are observed, and the applicability of the observed biological effects to cancer therapy. PMID:24502548

  13. Decontamination of Bacillus subtilis Spores in a Sealed Package Using a Non-thermal Plasma System

    NASA Astrophysics Data System (ADS)

    Keener, Kevin M.; Jensen, J. L.; Valdramidis, V. P.; Byrne, E.; Connolly, J.; Mosnier, J. P.; Cullen, P. J.

    The safety of packaged food and medical devices is a major concern to consumers and government officials. Recent inventions (PK-1 and PK-2) based on the principles of non-thermal, atmospheric plasma has shown significant reduction in bacterial contamination inside a sealed package. The objective of this study was to evaluate the PK-1 and PK-2 systems in the reduction of Bacillus subtilis spores using packages containing air or modified atmosphere (MA) gas (65% O2/30% CO2/5% N2). The experimental design consisted of the following parameters: (1) two voltage conditions: 13.5 kV with 1.0 cm electrode gap (PK-1) and 80 kV with 4.5 cm electrode gap (PK-2), (2) two treatment conditions: inside and outside the field of ionization, (3) PK-1 and PK-2 optimized treatment times: 300 and 120 s, respectively, and (4) two package gas types: air and modified atmosphere (MA) gas (65% O2/30% CO2/5% N2). Measurements included: (1) bacterial reductions of Bacillus subtilis var. niger (B. atrophaeus), (2) ozone, nitrous oxides (NOx), and carbon monoxide concentrations, and (3) relative humidity. Bacillus subtilis (1.7 × 106/strip) were loaded into sterile uncovered petri dishes and treated with ionization generated in packages using air or MA gas blend. Samples were treated for 300 s (PK-1) or 120 s (PK-2) and stored at room ­temperature for 24 h. Results documented relative humidity (RH) ranged from 20% to 30%. After 300 s of PK-1 treatment (13.5 kV/44 W/1.0 cm gap), ozone concentrations were 6,000 ppm (air) and 7,500 ppm (MA). After 120 s of PK-2 treatment (80 kV/150 W/4.5 cm), ozone concentrations were 7,500 ppm (air) and 12,000 ppm (MA). Ozone and NOx concentrations were non-detect (ND) after 24 h. PK-1 carbon monoxide levels were <20 ppm (air) and <100 ppm (MA) after 24 h. The PK-2 carbon monoxide levels were <20 ppm (air) and <400 ppm (MA) after 24 h. Treatments showed reductions in spores of greater than 6 log10 after 24 h. Reductions were maintained without additional re-growth at 72 h. These results indicate that the PK-1 and PK-2 systems have the capacity to reduce Bacillus subtilis spores in an in-package ionization process.

  14. Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma

    PubMed Central

    Schäfer, J.; Foest, R.; Reuter, S.; Kewitz, T.; Šperka, J.; Weltmann, K.-D.

    2012-01-01

    The heat convection generated by micro filaments of a self-organized non-thermal atmospheric pressure plasma jet in Ar is characterized by employing laser schlieren deflectometry (LSD). It is demonstrated as a proof of principle, that the spatial and temporal changes of the refractive index n in the optical beam path related to the neutral gas temperature of the plasma jet can be monitored and evaluated simultaneously. The refraction of a laser beam in a high gradient field of n(r) with cylindrical symmetry is given for a general real refraction index profile. However, the usually applied Abel approach represents an ill-posed problem and in particular for this plasma configuration. A simple analytical model is proposed in order to minimize the statistical error. Based on that, the temperature profile, specifically the absolute temperature in the filament core, the FWHM, and the frequencies of the collective filament dynamics are obtained for non-stationary conditions. For a gas temperature of 700 K inside the filament, the presented model predicts maximum deflection angles of the laser beam of 0.3 mrad which is in accordance to the experimental results obtained with LSD. Furthermore, the experimentally obtained FWHM of the temperature profile produced by the filament at the end of capillary is (1.5 ± 0.2) mm, which is about 10 times wider than the visual radius of the filament. The obtained maximum temperature in the effluent is (450 ± 30) K and is in consistence with results of other techniques. The study demonstrates that LSD represents a useful low-cost method for monitoring the spatiotemporal behaviour of microdischarges and allows to uncover their dynamic characteristics, e.g., the temperature profile even for challenging diagnostic conditions such as moving thin discharge filaments. The method is not restricted to the miniaturized and self-organized plasma studied here. Instead, it can be readily applied to other configurations that produce measurable gradients of refractive index by local gas heating and opens new diagnostics prospects particularly for microplasmas. PMID:23126765

  15. Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma

    SciTech Connect

    Schaefer, J.; Foest, R.; Reuter, S.; Weltmann, K.-D. [INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Kewitz, T. [Institute of Experimental and Applied Physics, University Kiel, 24098 Kiel (Germany); Sperka, J. [Department of Physical Electronics, Masaryk University, 61137 Brno (Czech Republic)

    2012-10-15

    The heat convection generated by micro filaments of a self-organized non-thermal atmospheric pressure plasma jet in Ar is characterized by employing laser schlieren deflectometry (LSD). It is demonstrated as a proof of principle, that the spatial and temporal changes of the refractive index n in the optical beam path related to the neutral gas temperature of the plasma jet can be monitored and evaluated simultaneously. The refraction of a laser beam in a high gradient field of n(r) with cylindrical symmetry is given for a general real refraction index profile. However, the usually applied Abel approach represents an ill-posed problem and in particular for this plasma configuration. A simple analytical model is proposed in order to minimize the statistical error. Based on that, the temperature profile, specifically the absolute temperature in the filament core, the FWHM, and the frequencies of the collective filament dynamics are obtained for non-stationary conditions. For a gas temperature of 700 K inside the filament, the presented model predicts maximum deflection angles of the laser beam of 0.3 mrad which is in accordance to the experimental results obtained with LSD. Furthermore, the experimentally obtained FWHM of the temperature profile produced by the filament at the end of capillary is (1.5 {+-} 0.2) mm, which is about 10 times wider than the visual radius of the filament. The obtained maximum temperature in the effluent is (450 {+-} 30) K and is in consistence with results of other techniques. The study demonstrates that LSD represents a useful low-cost method for monitoring the spatiotemporal behaviour of microdischarges and allows to uncover their dynamic characteristics, e.g., the temperature profile even for challenging diagnostic conditions such as moving thin discharge filaments. The method is not restricted to the miniaturized and self-organized plasma studied here. Instead, it can be readily applied to other configurations that produce measurable gradients of refractive index by local gas heating and opens new diagnostics prospects particularly for microplasmas.

  16. Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Schäfer, J.; Foest, R.; Reuter, S.; Kewitz, T.; Šperka, J.; Weltmann, K.-D.

    2012-10-01

    The heat convection generated by micro filaments of a self-organized non-thermal atmospheric pressure plasma jet in Ar is characterized by employing laser schlieren deflectometry (LSD). It is demonstrated as a proof of principle, that the spatial and temporal changes of the refractive index n in the optical beam path related to the neutral gas temperature of the plasma jet can be monitored and evaluated simultaneously. The refraction of a laser beam in a high gradient field of n(r) with cylindrical symmetry is given for a general real refraction index profile. However, the usually applied Abel approach represents an ill-posed problem and in particular for this plasma configuration. A simple analytical model is proposed in order to minimize the statistical error. Based on that, the temperature profile, specifically the absolute temperature in the filament core, the FWHM, and the frequencies of the collective filament dynamics are obtained for non-stationary conditions. For a gas temperature of 700 K inside the filament, the presented model predicts maximum deflection angles of the laser beam of 0.3 mrad which is in accordance to the experimental results obtained with LSD. Furthermore, the experimentally obtained FWHM of the temperature profile produced by the filament at the end of capillary is (1.5 ± 0.2) mm, which is about 10 times wider than the visual radius of the filament. The obtained maximum temperature in the effluent is (450 ± 30) K and is in consistence with results of other techniques. The study demonstrates that LSD represents a useful low-cost method for monitoring the spatiotemporal behaviour of microdischarges and allows to uncover their dynamic characteristics, e.g., the temperature profile even for challenging diagnostic conditions such as moving thin discharge filaments. The method is not restricted to the miniaturized and self-organized plasma studied here. Instead, it can be readily applied to other configurations that produce measurable gradients of refractive index by local gas heating and opens new diagnostics prospects particularly for microplasmas.

  17. NON-THERMAL RESPONSE OF THE CORONA TO THE MAGNETIC FLUX DISPERSAL IN THE PHOTOSPHERE OF A DECAYING ACTIVE REGION

    SciTech Connect

    Harra, L. K. [UCL-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT (United Kingdom); Abramenko, V. I. [Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314 (United States)

    2012-11-10

    We analyzed Solar Dynamics Observatory line-of-sight magnetograms for a decaying NOAA active region (AR) 11451 along with co-temporal Extreme-Ultraviolet Imaging Spectrometer (EIS) data from the Hinode spacecraft. The photosphere was studied via time variations of the turbulent magnetic diffusivity coefficient, {eta}(t), and the magnetic power spectrum index, {alpha}, through analysis of magnetogram data from the Helioseismic and Magnetic Imager (HMI). These measure the intensity of the random motions of magnetic elements and the state of turbulence of the magnetic field, respectively. The time changes of the non-thermal energy release in the corona was explored via histogram analysis of the non-thermal velocity, v {sub nt}, in order to highlight the largest values at each time, which may indicate an increase in energy release in the corona. We used the 10% upper range of the histogram of v {sub nt} (which we called V {sup upp} {sub nt}) of the coronal spectral line of Fe XII 195 A. A 2 day time interval was analyzed from HMI data, along with the EIS data for the same field of view. Our main findings are the following. (1) The magnetic turbulent diffusion coefficient, {eta}(t), precedes the upper range of the v {sub nt} with the time lag of approximately 2 hr and the cross-correlation coefficient of 0.76. (2) The power-law index, {alpha}, of the magnetic power spectrum precedes V {sup upp} {sub nt} with a time lag of approximately 3 hr and the cross-correlation coefficient of 0.5. The data show that the magnetic flux dispersal in the photosphere is relevant to non-thermal energy release dynamics in the above corona. The results are consistent with the nanoflare mechanism of the coronal heating, due to the time lags being consistent with the process of heating and cooling the loops heated by nanoflares.

  18. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters

    Microsoft Academic Search

    Evan Million; S. W. Allen

    2008-01-01

    We report the discovery of spatially-extended, non-thermal-like emission\\u000acomponents in Chandra X-ray spectra for five of a sample of seven massive,\\u000amerging galaxy clusters with powerful radio halos. The emission components can\\u000abe fitted by power-law models with mean photon indices in the range 1.5 < Gamma\\u000a< 2.0. A control sample of regular, dynamically relaxed clusters, without radio\\u000ahalos

  19. Non-thermal processes on ice and liquid micro-jet surfaces

    NASA Astrophysics Data System (ADS)

    Olanrewaju, Babajide O.

    The primary focus of this research is to investigate non-thermal processes occurring on ice surfaces and the photo-ejection of ions from liquid surfaces. Processes at the air-water/ice interface are known to play a very important role in the release of reactive halogen species with atmospheric aerosols serving as catalysts. The ability to make different types of ice with various morphologies, hence, different adsorption and surface properties in vacuum, provide a useful way to probe the catalytic effect of ice in atmospheric reactions. Also, the use of the liquid jet technique provides the rare opportunity to probe liquid samples at the interface; hitherto impossible to investigate with traditional surface science techniques. In Chapter 2, the effect of ice morphology on the release of reactive halogen species from photodissociation of adsorbed organic halides on ice will be presented. Quantum state resolved measurements of neutral atomic iodine from the photon irradiation of submonolayer coverages of methyl iodide adsorbed on low temperature water ice were conducted. Temperature programmed desorption (TPD) studies of methyl iodide adsorbed on ice were performed to provide information on the effect of ice morphology on the adsorption of submonolayer methyl iodide. The interaction and autoionization of HCl on low-temperature (80{140 K) water ice surfaces has been studied using low-energy (5-250 eV) electron-stimulated desorption (ESD) and temperature programmed desorption (TPD). A detailed ESD study of the interactions of low concentrations of HCl with low-temperature porous amorphous solid water (PASW), amorphous solid water (ASW) and crystalline ice (CI) surfaces will be presented in Chapter 3. The ESD cation yields from HCl adsorbed on ice, as well as the coverage dependence, kinetic energy distributions and TPD measurements were all monitored. Probing liquid surface using traditional surface science technique is usually difficult because of the problem of keeping the liquid surface clean and the distortion of information by the interference of equilibrium dense vapor above the liquid. By using the liquid jet technique the ejection of ions from surface of micron sized liquid can be adequately probed with a linear time-of-flight mass spectrometer. The photoionization of pure water and aqueous solutions of NaOH, NaCl and HCl is presented in Chapter 4. The aim of this investigation was to provide a fundamental understanding of the structure of water/vacuum interfaces. In Chapter 5, the ejection of ions from salt solutions containing divalent cations is also presented. The goal of the experiment was to figure out the solvation structure and reaction dynamics of divalent metal ions, M2+ on the surface of aqueous solution. A lot of work has been done in the gas phase either by a pickup-type cluster source or by collision induced dissociation of ejected ions from electrospray. For the first time the direct monitoring of ions ejected from liquid into gas phase is explored. Possible ejection mechanisms for the ejection of cations are discussed extensively in both Chapters 4 and 5. The results presented in this thesis is a combination of experiments performed at the Georgia Institute of Technology and the Pacific Northwest National Laboratory (PNNL) which includes experiments on ice and micro-jet respectively. The results in Chapters 2 and 3 have been submitted to the Journal of Chemical Physics and the Journal of Physical Chemistry respectively. It is important to note that the data presented in Chapter 3 was originally taken by Dr Janine Herring-Captain as part of her thesis work. It is also presented in this thesis due to effort in analyzing the data and preparation of the submitted manuscript. Chapter 4 and 5 represents papers which will also be submitted for publication in the open scientific literature. All the work leading to the results presented in these two chapters were done during my visit to PNNL and I would like to acknowledge that the instrumentation and data acquisition were done in collaboration with Nikolai Pet

  20. Three-dimensional Simulations of the Non-thermal Broadband Emission from Young Supernova Remnants Including Efficient Particle Acceleration

    NASA Astrophysics Data System (ADS)

    Ferrand, Gilles; Decourchelle, Anne; Safi-Harb, Samar

    2014-07-01

    Supernova remnants are believed to be major contributors to Galactic cosmic rays. In this paper, we explore how the non-thermal emission from young remnants can be used to probe the production of energetic particles at the shock (both protons and electrons). Our model couples hydrodynamic simulations of a supernova remnant with a kinetic treatment of particle acceleration. We include two important back-reaction loops upstream of the shock: energetic particles can (1) modify the flow structure and (2) amplify the magnetic field. As the latter process is not fully understood, we use different limit cases that encompass a wide range of possibilities. We follow the history of the shock dynamics and of the particle transport downstream of the shock, which allows us to compute the non-thermal emission from the remnant at any given age. We do this in three dimensions, in order to generate projected maps that can be compared with observations. We observe that completely different recipes for the magnetic field can lead to similar modifications of the shock structure, although to very different configurations of the field and particles. We show how this affects the emission patterns in different energy bands, from radio to X-rays and ?-rays. High magnetic fields (>100 ?G) directly impact the synchrotron emission from electrons, by restricting their emission to thin rims, and indirectly impact the inverse Compton emission from electrons and also the pion decay emission from protons, mostly by shifting their cut-off energies to respectively lower and higher energies.

  1. The non-thermal superbubble in IC 10: the generation of cosmic ray electrons caught in the act

    NASA Astrophysics Data System (ADS)

    Heesen, Volker; Brinks, Elias; Krause, Martin G. H.; Harwood, Jeremy J.; Rau, Urvashi; Rupen, Michael P.; Hunter, Deidre A.; Chy?y, Krzysztof T.; Kitchener, Ged

    2015-02-01

    Superbubbles are crucial for stellar feedback, with supposedly high (of the order of 10 per cent) thermalization rates. We combined multiband radio continuum observations from the Very Large Array (VLA) with Effelsberg data to study the non-thermal superbubble (NSB) in IC 10, a starburst dwarf irregular galaxy in the Local Group. Thermal emission was subtracted using a combination of Balmer H? and VLA 32 GHz continuum maps. The bubble's non-thermal spectrum between 1.5 and 8.8 GHz displays curvature and can be well fitted with a standard model of an ageing cosmic ray electron population. With a derived equipartition magnetic field strength of 44 ± 8 ?G, and measuring the radiation energy density from Spitzer MIPS maps as 5 ± 1 × 10-11 erg cm-3, we determine, based on the spectral curvature, a spectral age of the bubble of 1.0 ± 0.3 Myr. Analysis of the LITTLE THINGS H I data cube shows an expanding H I hole with 100 pc diameter and a dynamical age 3.8 ± 0.3 Myr, centred to within 16 pc on IC 10 X-1, a massive stellar mass black hole (M > 23 M?). The results are consistent with the expected evolution for a superbubble with a few massive stars, where a very energetic event like a Type Ic supernova/hypernova has taken place about 1 Myr ago. We discuss alternatives to this interpretation.

  2. Non-Thermal Plasma Treatment Diminishes Fungal Viability and Up-Regulates Resistance Genes in a Plant Host

    PubMed Central

    Panngom, Kamonporn; Lee, Sang Hark; Park, Dae Hoon; Sim, Geon Bo; Kim, Yong Hee; Uhm, Han Sup; Park, Gyungsoon; Choi, Eun Ha

    2014-01-01

    Reactive oxygen and nitrogen species can have either harmful or beneficial effects on biological systems depending on the dose administered and the species of organism exposed, suggesting that application of reactive species can possibly produce contradictory effects in disease control, pathogen inactivation and activation of host resistance. A novel technology known as atmospheric-pressure non-thermal plasma represents a means of generating various reactive species that adversely affect pathogens (inactivation) while simultaneously up-regulating host defense genes. The anti-microbial efficacy of this technology was tested on the plant fungal pathogen Fusarium oxysporum f.sp. lycopersici and its susceptible host plant species Solanum lycopercicum. Germination of fungal spores suspended in saline was decreased over time after exposed to argon (Ar) plasma for 10 min. Although the majority of treated spores exhibited necrotic death, apoptosis was also observed along with the up-regulation of apoptosis related genes. Increases in the levels of peroxynitrite and nitrite in saline following plasma treatment may have been responsible for the observed spore death. In addition, increased transcription of pathogenesis related (PR) genes was observed in the roots of the susceptible tomato cultivar (S. lycopercicum) after exposure to the same Ar plasma dose used in fungal inactivation. These data suggest that atmospheric-pressure non-thermal plasma can be efficiently used to control plant fungal diseases by inactivating fungal pathogens and up-regulating mechanisms of host resistance. PMID:24911947

  3. The non-thermal superbubble in IC 10: the generation of cosmic ray electrons caught in the act

    E-print Network

    Heesen, Volker; Krause, Martin G H; Harwood, Jeremy J; Rau, Urvashi; Rupen, Michael P; Hunter, Deidre A; Chyzy, Krzysztof T; Kitchener, Ged

    2014-01-01

    Superbubbles are crucial for stellar feedback, with supposedly high (of the order of 10 per cent) thermalization rates. We combined multiband radio continuum observations from the Very Large Array (VLA) with Effelsberg data to study the non-thermal superbubble (NSB) in IC 10, a starburst dwarf irregular galaxy in the Local Group. Thermal emission was subtracted using a combination of Balmer H$\\alpha$ and VLA 32 GHz continuum maps. The bubble's non-thermal spectrum between 1.5 and 8.8 GHz displays curvature and can be well fitted with a standard model of an ageing cosmic ray electron population. With a derived equipartition magnetic field strength of $44\\pm 8~\\rm\\mu G$, and measuring the radiation energy density from Spitzer MIPS maps as $5\\pm 1\\times 10^{-11}~\\rm erg\\, cm^{-3}$, we determine, based on the spectral curvature, a spectral age of the bubble of $1.0\\pm 0.3~\\rm Myr$. Analysis of the LITTLE THINGS HI data cube shows an expanding HI hole with 100 pc diameter and a dynamical age of $3.8\\pm 0.3~\\rm Myr...

  4. Three-dimensional simulations of the non-thermal broadband emission from young supernova remnants including efficient particle acceleration

    SciTech Connect

    Ferrand, Gilles; Safi-Harb, Samar [Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Decourchelle, Anne, E-mail: gferrand@physics.umanitoba.ca, E-mail: samar@physics.umanitoba.ca, E-mail: anne.decourchelle@cea.fr [Laboratoire AIM (CEA/Irfu, CNRS/INSU, Université Paris VII), CEA Saclay, bât. 709, F-91191 Gif sur Yvette (France)

    2014-07-01

    Supernova remnants are believed to be major contributors to Galactic cosmic rays. In this paper, we explore how the non-thermal emission from young remnants can be used to probe the production of energetic particles at the shock (both protons and electrons). Our model couples hydrodynamic simulations of a supernova remnant with a kinetic treatment of particle acceleration. We include two important back-reaction loops upstream of the shock: energetic particles can (1) modify the flow structure and (2) amplify the magnetic field. As the latter process is not fully understood, we use different limit cases that encompass a wide range of possibilities. We follow the history of the shock dynamics and of the particle transport downstream of the shock, which allows us to compute the non-thermal emission from the remnant at any given age. We do this in three dimensions, in order to generate projected maps that can be compared with observations. We observe that completely different recipes for the magnetic field can lead to similar modifications of the shock structure, although to very different configurations of the field and particles. We show how this affects the emission patterns in different energy bands, from radio to X-rays and ?-rays. High magnetic fields (>100 ?G) directly impact the synchrotron emission from electrons, by restricting their emission to thin rims, and indirectly impact the inverse Compton emission from electrons and also the pion decay emission from protons, mostly by shifting their cut-off energies to respectively lower and higher energies.

  5. Human Milk Composition and Preservation: Evaluation of High-Pressure Processing as a Non-Thermal Pasteurisation Technology.

    PubMed

    Sousa, Sílvia G; Delgadillo, Ivonne; Saraiva, Jorge A

    2014-10-14

    Human milk is seen not only as a food, but as a functional and dynamic biologic system. It provides nutrients, bioactive components and immune factors, promoting adequate and healthy growth of newborn infants. When mothers cannot supply their children, donated breast milk is the nutrition recommended by the World Health Organization (WHO), as it is a better alternative than infant formula. However, because of the manner in which donor milk is handled in human milk banks (HMB) many of the properties ascribed to mother's own milk are diminished or destroyed. The major process responsible for these losses is Holder pasteurisation. High-pressure processing (HPP) is a novel non-thermal pasteurisation technology that is being increasingly applied in food industries worldwide, primarily as an alternative to thermal treatment. This is due to its capacity to inactivate microorganisms while preserving both nutritional and bioactive components of foods. This review describes human milk composition and preservation, and critically discusses HMB importance and practices, highlighting HPP as a potential non-thermal pasteurisation technology for human milk preservation. HPP technology is described and the few currently existing studies of its effects in human milk are presented. PMID:25313944

  6. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio halo clusters

    NASA Astrophysics Data System (ADS)

    Million, E. T.; Allen, S. W.

    2009-11-01

    We report the discovery of spatially extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio haloes. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 < ? < 2.0. A control sample of regular, dynamically relaxed clusters, without radio haloes but with comparable mean thermal temperatures and luminosities, shows no compelling evidence for similar components. Detailed X-ray spectral mapping reveals the complex thermodynamic states of the radio halo clusters. Our deepest observations, of the Bullet Cluster 1E0657-56, demonstrate a spatial correlation between the strongest power-law X-ray emission, highest thermal pressure and brightest 1.34 GHz radio halo emission in this cluster. We confirm the presence of a shock front in the 1E0657-56 and report the discovery of a new, large-scale shock front in Abell 2219. We explore possible origins for the power-law X-ray components. These include inverse-Compton scattering of cosmic microwave background photons by relativistic electrons in the clusters; bremsstrahlung from suprathermal electrons energized by Coulomb collisions with an energetic, non-thermal proton population; and synchrotron emission associated with ultrarelativistic electrons. Interestingly, we show that the power-law signatures may also be due to complex temperature and/or metallicity structure in clusters particularly in the presence of metallicity gradients. In this case, an important distinguishing characteristic between the radio halo clusters and control sample of predominantly cool-core clusters is the relatively low central X-ray surface brightness of the former. Our results have implications for previous discussions of soft excess X-ray emission from clusters and highlight the importance of further deep X-ray and radio mapping, coupled with new hard X-ray, ?-ray and TeV observations, for improving our understanding of the non-thermal particle populations in these systems.

  7. Emergence of non-thermal statistics in isolated quantum spin clusters after a series of non-adiabatic perturbations

    E-print Network

    Ji, Kai

    2011-01-01

    We show numerically that, if a finite isolated cluster of interacting spins 1/2 with the initial thermal occupations of energy eigenstates is subjected to a series of small non-adiabatic perturbations by external magnetic field, then the resulting occupations are no longer describable by the exponential thermal statistics. The emerging non-thermal occupations are significantly higher than the thermal ones on both the low and the high ends of the energy spectra. This behavior semi-quantitatively agrees with the statistics predicted for the so-called "quantum micro-canonical" (QMC) ensemble, which includes all possible quantum superpositions with a given energy expectation value. Our findings also indicate that the eigenstates of the perturbation operators are generically localized in the energy basis of the unperturbed Hamiltonian. This kind of localization possibly protects the thermal behavior in the macroscopic limit. Finally, we propose that one can obtain the experimental evidence of the QMC-like statisti...

  8. Non-thermal Dark Matter Production from the Electroweak Phase Transition: Multi-TeV WIMPs and "Baby-Zillas"

    E-print Network

    Adam Falkowski; Jose Miguel No

    2012-11-23

    Particle production at the end of a first-order electroweak phase transition may be rather generic in theories beyond the standard model. Dark matter may then be abundantly produced by this mechanism if it has a sizable coupling to the Higgs field. For an electroweak phase transition occuring at a temperature T_EW ~ 50-100 GeV, non-thermally generated dark matter with mass M_X > TeV will survive thermalization after the phase transition, and could then potentially account for the observed dark matter relic density in scenarios where a thermal dark matter component is either too small or absent. Dark matter in these scenarios could then either be multi-TeV WIMPs whose relic abundace is mostly generated at the electroweak phase transition, or "Baby-Zillas" with mass M_GUT >> M_X >> v_EW that never reach thermal equilibrium in the early universe.

  9. Non-thermal dark matter production from the electroweak phase transition: multi-TeV WIMPs and "baby-zillas"

    NASA Astrophysics Data System (ADS)

    Falkowski, Adam; No, Jose M.

    2013-02-01

    Particle production at the end of a first-order electroweak phase transition may be rather generic in theories beyond the standard model. Dark matter may then be abundantly produced by this mechanism if it has a sizable coupling to the Higgs field. For an electroweak phase transition occuring at a temperature T EW 50-100 GeV, non- thermally generated dark matter with mass M X > TeV will survive thermalization after the phase transition, and could then potentially account for the observed dark matter relic density in scenarios where a thermal dark matter component is either too small or absent. Dark matter in these scenarios could then either be multi-TeV WIMPs whose relic abundace is mostly generated at the electroweak phase transition, or " Baby-Zillas" with mass M GUT ? M X ? {v_{EW}} that never reach thermal equilibrium in the early universe.

  10. Non-thermal effects on femtosecond laser ablation of polymers extracted from the oscillation of time-resolved reflectivity

    NASA Astrophysics Data System (ADS)

    Kumada, Takayuki; Akagi, Hiroshi; Itakura, Ryuji; Otobe, Tomohito; Nishikino, Masaharu; Yokoyama, Atsushi

    2015-06-01

    The dynamics of femtosecond laser ablation of transparent polymers were examined using time-resolved reflectivity. When these polymers were irradiated by a pump pulse with fluence above the ablation threshold of 0.8-2.0 J/cm2, we observed the oscillation of the reflectivity caused by the interference between the reflected probe pulses from the sample surface and the thin layer due to the non-thermal photomechanical effects of spallation. As the fluence of the pump pulse increased, the separation velocity of the thin layer increased from 6 km/s to the asymptotic value of 11 km/s. It is suggested that the velocities are determined by shock-wave velocities of the photo-excited layer.

  11. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters

    NASA Astrophysics Data System (ADS)

    Million, Evan; Allen, Steve

    2009-09-01

    We report the discovery of spatially-extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 < ? < 2.0. A control sample of regular, dynamically relaxed clusters, without radio halos but with comparable mean thermal temperatures and luminosities, shows no compelling evidence for similar components. Detailed X-ray spectral mapping reveals the complex thermodynamic states of the radio halo clusters. Our deepest observations, of the Bullet Cluster 1E0657-56, demonstrate a spatial correlation between the strongest power-law X-ray emission, highest thermal pressure, and brightest 1.34GHz radio halo emission in this cluster. We confirm the presence of a shock front in the 1E0657-56 and report the discovery of a clear, large-scale shock front in Abell 2219. We explore possible origins for the power-law X-ray components. One explanation of particular interest is that the power-law signatures may be due to complex temperature and/or metallicity structure in clusters particularly in the presence of metallicity gradients. In this case, an important distinguishing characteristic between the radio halo clusters and control sample of predominantly cool-core clusters is the relatively low central X-ray surface brightness of the former. Our results highlight the importance of further deep X-ray and radio mapping, coupled with new hard X-ray, ?-ray and TeV observations, for improving our understanding of the non-thermal particle populations in these systems.

  12. Non-thermal Radiation from Collisions of Compact Objects with Intermediate-scale Jets in Active Galaxies

    NASA Astrophysics Data System (ADS)

    Bednarek, W.; Banasi?ski, P.

    2015-07-01

    Massive black holes in active galaxies are immersed in huge concentrations of late-type stars in the galactic bulges and also early-type massive stars in the nuclear stellar clusters, which are additionally surrounded by quasi-spherical halos on a scale of several kpc that contain from a few hundred up to several thousand globular clusters (GCs). It is expected that significant numbers of red giant stars, massive stars, and also GCs can move through the jet expelled from the central engine of the active galaxy. We consider collisions of stars from the galactic bulge, nuclear cluster, and GCs with the jet plasma. As a result of such collisions, multiple shocks are expected to appear in the jet around these compact objects. Therefore, the plasma in the kpc-scale jet can be significantly disturbed. We show that particles can be accelerated on these shocks up to multi-TeV energies. TeV leptons emit synchrotron radiation, extending up to X-ray energies, and also comptonize radiation produced in a stellar cluster and also the microwave background radiation to TeV ?-ray energies. We show that such non-thermal radiation is likely to be detectable from the intermediate-scale jets of nearby active galaxies for a reasonable number of stars and GCs immersed within the jet. As an example, we calculate the expected non-thermal emission in X-ray and gamma-ray energies from the nearby radio galaxy Cen A, from which steady gamma-ray emission with a complex spectrum has recently been reported by Fermi and the HESS Observatories.

  13. Silicon drift detector based X-ray spectroscopy diagnostic system for the study of non-thermal electrons at Aditya tokamak

    SciTech Connect

    Purohit, S., E-mail: pshishir@ipr.res.in; Joisa, Y. S.; Raval, J. V.; Ghosh, J.; Tanna, R.; Shukla, B. K.; Bhatt, S. B. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

    2014-11-15

    Silicon drift detector based X-ray spectrometer diagnostic was developed to study the non-thermal electron for Aditya tokamak plasma. The diagnostic was mounted on a radial mid plane port at the Aditya. The objective of diagnostic includes the estimation of the non-thermal electron temperature for the ohmically heated plasma. Bi-Maxwellian plasma model was adopted for the temperature estimation. Along with that the study of high Z impurity line radiation from the ECR pre-ionization experiments was also aimed. The performance and first experimental results from the new X-ray spectrometer system are presented.

  14. Enhancement of the helium resonance lines in the solar atmosphere by suprathermal electron excitation I: non-thermal transport of helium ions

    E-print Network

    G. R. Smith; C. Jordan

    2002-08-16

    Models of the solar transition region made from lines other than those of helium cannot account for the strength of the helium lines. However, the collisional excitation rates of the helium resonance lines are unusually sensitive to the energy of the exciting electrons. Non-thermal motions in the transition region could drive slowly-ionizing helium ions rapidly through the steep temperature gradient, exposing them to excitation by electrons characteristic of higher temperatures than those describing their ionization state. We present the results of calculations which use a more physical representation of the lifetimes of the ground states of He I and He II than was adopted in earlier work on this process. New emission measure distributions are used to calculate the temperature variation with height. The results show that non-thermal motions can lead to enhancements of the He I and He II resonance line intensities by factors that are comparable with those required. Excitation by non-Maxwellian electron distributions would reduce the effects of non-thermal transport. The effects of non-thermal motions are more consistent with the observed spatial distribution of helium emission than are those of excitation by non-Maxwellian electron distributions alone. In particular, they account better for the observed line intensity ratio I(537.0 A)/I(584.3 A), and its variation with location.

  15. Novel AC and DC Non-Thermal Plasma Sources for Cold Surface Treatment of Polymer Films and Fabrics at Atmospheric Pressure

    Microsoft Academic Search

    Yuri Akishev; Michail Grushin; Anatoly Napartovich; Nikolay Trushkin

    2002-01-01

    Novel types of non-thermal plasma sources at atmospheric pressure based on multi-pin DC (direct current) diffusive glow discharge and AC (alternative current) streamer barrier corona have been elaborated and tested successfully for cold surface treatment of polymer films [polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET),] and polyester fabric. Results on physical properties ofdischarges mentioned and output energy characteristics of new

  16. Why is Non-Thermal Line Broadening of Spectral Lines in the Lower Transition Region of the Sun Independent of Spatial Resolution?

    NASA Astrophysics Data System (ADS)

    De Pontieu, B.; McIntosh, S.; Martinez-Sykora, J.; Peter, H.; Pereira, T. M. D.

    2015-01-01

    Spectral observations of the solar transition region (TR) and corona show broadening of spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant (5-30 km s-1) and correlated with intensity. Here we study spectra of the TR Si iv 1403 Å line obtained at high resolution with the Interface Region Imaging Spectrograph (IRIS). We find that the large improvement in spatial resolution (0.?33) of IRIS compared to previous spectrographs (2?) does not resolve the non-thermal line broadening which, in most regions, remains at pre-IRIS levels of about 20 km s-1. This invariance to spatial resolution indicates that the processes behind the broadening occur along the line-of-sight (LOS) and/or on spatial scales (perpendicular to the LOS) smaller than 250 km. Both effects appear to play a role. Comparison with IRIS chromospheric observations shows that, in regions where the LOS is more parallel to the field, magneto-acoustic shocks driven from below impact the TR and can lead to significant non-thermal line broadening. This scenario is supported by MHD simulations. While these do not show enough non-thermal line broadening, they do reproduce the long-known puzzling correlation between non-thermal line broadening and intensity. This correlation is caused by the shocks, but only if non-equilibrium ionization is taken into account. In regions where the LOS is more perpendicular to the field, the prevalence of small-scale twist is likely to play a significant role in explaining the invariance and correlation with intensity.

  17. Use of non-thermal plasma and UV-light for removal of odour from sludge treatment.

    PubMed

    Andersen, K B; Feilberg, A; Beukes, J A

    2012-01-01

    Non-thermal plasma (NTP) systems can be used for abatement of odour nuisances. Odour reductions are achieved by radical-initiated oxidation and dust collection in the plasma reactor. For some emissions a sequence of NTP followed by UV-light can improve the odour reduction further. This study was conducted to evaluate the efficiency of NTP technology combined with UV-light towards odour emissions from sludge treatment. Air from a pilot sludge dryer was treated with a pilot NTP and a UV unit. The effect of using an acid scrubber upstream the NTP system was also tested. Thermal desorption gas chromatography and mass spectrometry (TD-GC/MS) was used to analyse samples taken from the inlet and the outlet of the NTP system. The TD-GC/MS used was also equipped with a sniffing port that made it possible to record odour-active compounds eluting from the column. Relative amounts of odour-active compounds in the inlet and the outlet flow from the NTP system were compared. Bag samples from inlet and outlet were also separately analysed by an external lab and by two operators using a one-man olfactometer, a modified NasalRanger(TM). These results indicated a significant odour removal efficiency of 70-90% depending on the settings and combinations of abatement equipment. PMID:22907448

  18. Chandra measurements of non-thermal X-ray emission from massive, merging, radio-halo clusters

    E-print Network

    Million, E T

    2008-01-01

    We report the discovery of spatially-extended, non-thermal or hot, quasi-thermal emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos: Abell 665, 2163, 2255, 2319, and 1E0657-56. The emission components can be fitted by power-law models with mean photon indices in the range 1.4 20 keV. A control sample of regular, dynamically relaxed clusters without radio halos but with comparable thermal temperatures and luminosities shows no evidence for similar components in their Chandra spectra. Detailed X-ray spectral mapping reveals the complex thermodynamic states of the radio halo clusters. We report the discovery of a clear, large-scale shock front in Abell 2219. Our deepest observations, of the Bullet Cluster 1E0657-56, demonstrate a spatial correlation between the strongest power law X-ray emission, highest thermal pressure, and brightest 1.34GHz radio halo emission in this cluster. The integrated flux and mean spectral index of the...

  19. Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters

    E-print Network

    E. T. Million; S. W. Allen

    2009-07-16

    We report the discovery of spatially-extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 Abell 2219. We explore possible origins for the power-law X-ray components. These include inverse Compton scattering of cosmic microwave background photons by relativistic electrons in the clusters; bremsstrahlung from supra-thermal electrons energized by Coulomb collisions with an energetic, nonthermal proton population; and synchrotron emission associated with ultra-relativistic electrons. Interestingly, we show that the power-law signatures may also be due to complex temperature and/or metallicity structure in clusters particularly in the presence of metallicity gradients. In this case, an important distinguishing characteristic between the radio halo clusters and control sample of predominantly cool-core clusters is the relatively low central X-ray surface brightness of the former.

  20. Non-minimal Higgs inflation and non-thermal leptogenesis in a supersymmetric Pati-Salam model

    NASA Astrophysics Data System (ADS)

    Pallis, C.; Toumbas, N.

    2011-12-01

    We consider a supersymmetric (SUSY) Grand Unified Theory (GUT) based on the gauge group GPS = SU(4)C × SU(2)L × SU(2)R, which incorporates non-minimal chaotic inflation, driven by a quartic potential associated with the Higgs fields involved in the spontaneous breaking of GPS. The inflationary model relies on renormalizable superpotential terms and does not lead to overproduction of magnetic monopoles. It is largely independent of the one-loop radiative corrections and can become consistent with the current observational data on the inflationary observables, with the symmetry breaking scale of GPS assuming its SUSY value. Within our model, the strong CP and the ? problems of the minimal SUSY standard model can be resolved via a Peccei-Quinn symmetry. Moreover baryogenesis occurs via non-thermal leptogenesis realized by the out-of-equilibrium decay of the right-handed neutrinos, which are produced by the inflaton's decay. We consider two versions of such a scenario, assuming that the inflaton decays to the lightest or to the next-to-lightest right-handed neutrino. Both scenaria can become compatible with the constraints arising from the baryon asymmetry of the universe, the gravitino limit on the reheating temperature and the upper bound on the light neutrino masses, provided that the gravitino is somehow heavy. In the second scenario, extra restrictions from the SU(4)C GUT symmetry on the heaviest Dirac neutrino mass and the data on the atmospheric neutrino oscillations can be also met.

  1. Effects of Background Fluid on the Efficiency of Inactivating Yeast with Non-Thermal Atmospheric Pressure Plasma

    PubMed Central

    Ryu, Young-Hyo; Kim, Yong-Hee; Lee, Jin-Young; Shim, Gun-Bo; Uhm, Han-Sup; Park, Gyungsoon; Choi, Eun Ha

    2013-01-01

    Non-thermal plasma at atmospheric pressure has been actively applied to sterilization. However, its efficiency for inactivating microorganisms often varies depending on microbial species and environments surrounding the microorganisms. We investigated the influence of environmental factors (surrounding media) on the efficiency of microbial inactivation by plasma using an eukaryotic model microbe, Saccharomyces cerevisiae, to elucidate the mechanisms for differential efficiency of sterilization by plasma. Yeast cells treated with plasma in water showed the most severe damage in viability and cell morphology as well as damage to membrane lipids, and genomic DNA. Cells in saline were less damaged compared to those in water, and those in YPD (Yeast extract, Peptone, Dextrose) were least impaired. HOG1 mitogen activated protein kinase was activated in cells exposed to plasma in water and saline. Inactivation of yeast cells in water and saline was due to the acidification of the solutions by plasma, but higher survival of yeast cells treated in saline may have resulted from the additional effect related to salt strength. Levels of hydroxyl radical (OH.) produced by plasma were the highest in water and the lowest in YPD. This may have resulted in differential inactivation of yeast cells in water, saline, and YPD by plasma. Taken together, our data suggest that the surrounding media (environment) can crucially affect the outcomes of yeast cell plasma treatment because plasma modulates vital properties of media, and the toxic nature of plasma can also be altered by the surrounding media. PMID:23799081

  2. Modeling of non-equilibrium and non-thermal plasma discharge in air: Three temperature modeling approach

    NASA Astrophysics Data System (ADS)

    Mahamud, Rajib; Farouk, Tanvir

    2014-10-01

    The rapid progress in atmospheric pressure non-thermal plasma discharge has made air to be a preferable choice for feed gas. Despite the ease of operation of such discharges in air, the preference of air provides added complexity to modeling and simulations in terms of kinetics and different temperature modes. The diatomic nature of both N2 and O2 contributes to this complexity. In this work we report simulation results from a one-dimensional multi-physics model. A dc driven air plasma discharge operating at atmospheric and higher pressure is simulated. The model considers 50 species and 200 elementary reactions. The reaction scheme considers electron introduced and heavy particle reactions for N2 and O2 as well as interactions between nitrogen and oxygen. In addition to the species conservation equations, poisson's equation three different temperature's are resolved - electron, vibrational and translational. A special focus has been the coupling between the different temperatures to accurately resolve the energy cascade. The predictions from the model are found to be in good qualitative agreement against experimental measurements available in the literature. Work was supported by DARPA under Army Research Office (ARO) Grant No. W911NF1210007.

  3. The behavior of beams of relativistic non-thermal electrons under the influence of collisions and synchrotron losses

    NASA Technical Reports Server (NTRS)

    Mctiernan, James M.; Petrosian, Vahe

    1989-01-01

    For many astrophysical situations, such as in solar flares or cosmic gamma-ray bursts, continuum gamma rays with energies up to hundreds of MeV were observed, and can be interpreted to be due to bremsstrahlung radiation by relativistic electrons. The region of acceleration for these particles is not necessarily the same as the region in which the radiation is produced, and the effects of the transport of the electrons must be included in the general problem. Hence it is necessary to solve the kinetic equation for relativistic electrons, including all the interactions and loss mechanisms relevant at such energies. The resulting kinetic equation for non-thermal electrons, including the effects of Coulomb collisions and losses due to synchrotron emission, was solved analytically in some simple limiting cases, and numerically for the general cases including constant and varying background plasma density and magnetic field. New approximate analytic solutions are presented for collision dominated cases, for small pitch angles and all energies, synchrotron dominated cases, both steady-state and time dependent, for all pitch angles and energies, and for cases when both synchrotron and collisional energy losses are important, but for relativistic electrons. These analytic solutions are compared to the full numerical results in the proper limits. These results will be useful for calculation of spectra and angular distribution of the radiation (x rays, gamma-rays, and microwaves) emitted via synchrotron or bremsstrahlung processes by the electrons. These properties and their relevance to observations will be observed in subsequent papers.

  4. Acetaldehyde removal using an atmospheric non-thermal plasma combined with a packed bed: role of the adsorption process.

    PubMed

    Klett, C; Duten, X; Tieng, S; Touchard, S; Jestin, P; Hassouni, K; Vega-González, A

    2014-08-30

    This work is an attempt in order to help towards understanding the influence of the adsorption process on the removal of a VOC (acetaldehyde, CH3CHO) using cyclic non thermal plasma (NTP) combined with a packed-bed of a catalyst support, ?-Al2O3. In the first part, the results obtained by placing the saturated alumina pellets inside the plasma discharge zone are discussed, in terms of acetaldehyde removal, CO and CO2 production. In the second part, adsorption of CH3CHO, CO, CO2 and O3 was carried out, from single and multicomponent mixtures of the different compounds. The results showed that (i) the adsorption capacities followed the order CH3CHO?? CO2>CO; (ii) O3 was decomposed on the alumina surface; (iii) CO oxidation occurred on the surface when O3 was present. In the third part, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to follow the alumina surface during acetaldehyde adsorption. DRIFTS measurements demonstrated that besides the bands of molecularly adsorbed acetaldehyde, several absorptions appeared on the spectra showing the intermediate surface transformation of acetaldehyde already at 300K. Finally, the relationship between the adsorption results and the NTP combined with a packed-bed process is discussed. PMID:25072139

  5. Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

    PubMed

    Han, Geum-Jun; Kim, Jae-Hoon; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Seo, Deog-Gyu; Son, Ho-Hyun; Cho, Byeong-Hoon

    2014-12-01

    This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability. PMID:25311730

  6. Development of hydrophilic dental wax without surfactant using a non-thermal air atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2014-06-01

    Dental wax (DW), a low-melting and high-molecular-weight organic mixture, is widely used in dentistry for forming moulds of teeth. Hydrophilicity is an important property for DW, as a wet dental investment is used to surround the wax before wax burnout is performed. However, recent attempts to improve the hydrophilicity of DW using a surfactant have resulted in the reduced mechanical properties of the dental investment, leading to the failure of the dental restoration. This study applied a non-thermal air atmospheric pressure plasma jet (AAPPJ) for DW surface treatment and investigated its effect on both DW hydrophilicity and the dental investment's mechanical properties. The results showed that the application of the AAPPJ significantly improved the hydrophilicity of the DW, and that the results were similar to that of cleaner-treated DW using commercially available products with surfactant. A surface chemical analysis indicated that the improvement of hydrophilicity was related to an increase in the number of oxygen-related bonds on the DW surface following the removal of carbon hydrate in both AAPPJ and cleaner-treated DW. However, cleaner treatment compromised the mechanical property of the dental investment when the dental investment was in contact with the treated DW, while the AAPPJ treatment did not. Therefore, the use of AAPPJ to treat DW is a promising method for accurate dental restoration, as it induces an improvement in hydrophilicity without harming the dental investment.

  7. Inactivation of Candida Biofilms by Non-Thermal Plasma and Its Enhancement for Fungistatic Effect of Antifungal Drugs

    PubMed Central

    Sun, Peng; Wu, Haiyan; Zhu, Weidong; Liu, Wei; Zhang, Jue; Fang, Jing; Li, Ruoyu

    2012-01-01

    We investigated the antifungal effect of non-thermal plasma, as well as its combination with common antifungal drugs, against Candida biofilms. A direct current atmospheric pressure He/O2 (2%) plasma microjet (PMJ) was used to treat Candida biofilms in a 96-well plate. Inactivation efficacies of the biofilms were evaluated by XTT assay and counting colony forming units (CFUs). Morphological properties of the biofilms were evaluated by Scanning Electron Microscope (SEM). The sessile minimal inhibitory concentrations (SMICs) of fluconazole, amphotericin B, and caspofungin for the biofilms were also tested. Electron Spin Resonance (ESR) spectroscopy was used to detect the reactive oxygen species (ROS) generated directly and indirectly by PMJ. The Candida biofilms were completely inactivated after 1 min PMJ treatment, where severely deformed fungal elements were observed in SEM images. The SMICs of the tested antifungal drugs for the plasma-treated biofilms were decreased by 2–6 folds of dilution, compared to those of the untreated controls. ROS such as hydroxyl radical (•OH), superoxide anion radical (•O2-) and singlet molecular oxygen (1O2) were detected by ESR. We hence conclude that He/O2 (2%) plasma alone, as well as in combination with common antifungal drugs, is able to inactivate Candida biofilms rapidly. The generation of ROS is believed to be one of the underlying mechanisms for the fungicidal activity of plasma. PMID:22808213

  8. Effects of Surface Treatments on Nylon 6,6 via Non-thermal Atmospheric Plasma for Thermoplastic Adhesives

    NASA Astrophysics Data System (ADS)

    Wu, Chi-Chin; Bujanda, Andres; Demaree, John; Robinette, Jason; Weerasooriya, Amanda; Flanagan, David; ARL Plasma Group, CCEP, WMRD Team

    2015-03-01

    This work aims to modify the properties of Nylon 6,6 surfaces for attaining improved interfacial adhesion to thermoplastic composites utilizing atmospheric non-thermal plasma treatments followed by silane treatments using 3-aminopropyltriethoxysilane (APS) in some cases. An L-shaped dielectric barrier discharge configuration was employed to expose nylon substrates to oxygen-containing gas plasmas such as He/O2 and He/H2O, respectively, at room temperature. The chemically-modified surface of the substrate after plasma exposure was immediately examined by static water contact angle wettability measurements and X-ray photoelectron spectroscopy. It was found that the surface hydrophilicity was substantially enhanced and the amount of surface oxygen was significantly increased after a three-minute plasma exposure due to the increased surface energy and additional O-H bonds. The enhancements on interfacial adhesion were evaluated with lap shear tests using three types of adhesives: EPON 825/D230, EPON 825/D2000 and sikaflex252, respectively. The results of tensile tests on the adhesive joints showed an almost ~ 300% increase in interfacial adhesive strength for EPON 825/D230 bonds after plasma treatments. Finite element modeling of adhesive joints for bond strength is underway to compare with experimental results and study the quantitative relations between the mechanical properties within the bond and at interfaces.

  9. A combined process of non-thermal plasma with sludge stabilization for the simultaneous reduction of odor and organic waste.

    PubMed

    Shin, S; Hwang, H-J; Song, J

    2011-01-01

    Odor emissions and sludge disposals have become most challenging issues in many sludge treatment plants, and separate chemical oxidation processes have been commonly employed for these problems. It is, therefore, necessary to develop a combined process that simultaneously reduces the odor emissions and the amount of waste sludge. In this study, a non-thermal plasma reactor using a dielectric barrier discharge type was employed to treat a gas stream contaminated with 10 ppm(v) of H(2)S, and then the ozone-laden gas stream was supplied to a sludge stabilizer to reduce the organic constituents. The specific energy input to the plasma was varied to investigate the performance of the combined process. When the specific energy inputs were 200, 260, and 360 J/L, the rates of ozone generation from the plasma reactor were 0.036, 0.070, 0.144 g-O(3)/h, respectively. At these experimental conditions, the removal efficiencies of H(2)S were 60, 75, and >99%, and total chemical oxygen demand (TCOD) reduction efficiencies of 33, 61 and 67% were observed. In addition, a soluble organic fraction of the sludge increased at ratios of 1.9, 8.9, and 10.7%, respectively. Consequently, the combined process effectively and simultaneously reduced the odor compounds as well as the organic constituents and particles in the waste sludge. PMID:22170832

  10. Performance evaluation of non-thermal plasma injection for elemental mercury oxidation in a simulated flue gas.

    PubMed

    An, Jiutao; Shang, Kefeng; Lu, Na; Jiang, Yuze; Wang, Tiecheng; Li, Jie; Wu, Yan

    2014-03-15

    The use of non-thermal plasma (NTP) injection approach to oxidize elemental mercury (Hg(0)) in simulated flue gas at 110°C was studied, where a surface discharge plasma reactor (SDPR) inserted in the simulated flue duct was used to generate and inject active species into the flue gas. Approximately 81% of the Hg(0) was oxidized and 20.5?gkJ(-1) of energy yield was obtained at a rate of 3.9JL(-1). A maximal Hg(0) oxidation efficiency was found with a change in the NTP injection air flow rate. A high Hg(0) oxidation efficiency was observed in the mixed flue gas that included O2, H2O, SO2, NO and HCl. Chemical and physical processes (e.g., ozone, N2 metastable states and UV-light) were found to contribute to Hg(0) oxidation, with ozone playing a dominant role. The deposited mercury species on the internal surface of the flue duct was analyzed using X-ray photoelectron spectroscopy (XPS) and electronic probe microanalysis (EPMA), and the deposit was identified as HgO. The mercury species is thought to primarily exist in the form of HgO(s) by adhering to the suspended aerosols in the gas-phase. PMID:24513449

  11. Non-thermal plasma-assisted NOx reduction over Na-Y zeolites: The promotional effect of acid sites

    SciTech Connect

    Kwak, Ja Hun; Peden, Charles HF; Szanyi, Janos

    2006-06-01

    The effect of acid sites on the catalytic activities of a series of H+-modified Na-Y zeolites was investigated in the non-thermal plasma assisted NOx reduction reaction using a simulated diesel engine exhaust gas mixture. The acid sites were formed by NH4+ ion exchange and subsequent heat treatment of a NaY zeolite. The catalytic activities of these H+-modified NaY zeolites significantly increased with the number of acid sites. This NOx conversion increase was correlated with the decrease in the amount of unreacted NO2. The increase in the number of acid sites did not change the NO level, it stayed constant. Temperature programmed desorption following NO2 adsorption showed the appearance of a high temperature desorption peak at 453 K in addition to the main desorption feature of 343 K observed for the base Na-Y. The results of both the IR and TPD experiments revealed the formation of crotonaldehyde, resulting from condensation reaction of adsorbed acetaldehyde. Strong adsorptions of both NOx and hydrocarbon species are proposed to be responsible for the higher catalytic activity of H+-modified Na-Y zeolites in comparison to the base NaY material

  12. An investigation of the treatment of particulate matter from gasoline engine exhaust using non-thermal plasma.

    PubMed

    Ye, Dan; Gao, Dengshan; Yu, Gang; Shen, Xianglin; Gu, Fan

    2005-12-01

    A plasma reactor with catalysts was used to treat exhaust gas from a gasoline engine in order to decrease particulate matter (PM) emissions. The effect of non-thermal plasma (NTP) of the dielectric discharges on the removal of PM from the exhaust gas was investigated experimentally. The removal efficiency of PM was based on the concentration difference in PM for particle diameters ranging from 0.3 to 5.0 microm as measured by a particle counter. Several factors affecting PM conversion, including the density of plasma energy, reaction temperature, flow rate of exhaust gas, were investigated in the experiment. The results indicate that PM removal efficiency ranged approximately from 25 to 57% and increased with increasing energy input in the reactor, reaction temperature and residence time of the exhaust gas in the reactor. Enhanced removal of the PM was achieved by filling the discharge gap of the reactor with Cu-ZSM-5 catalyst pellets. In addition, the removal of unburned hydrocarbons was studied. Finally, available approaches for PM conversion were analyzed involving the interactions between discharge and catalytic reactions. PMID:16129557

  13. Quasi periodic motions from Hipparchus to Kolmogorov Giovanni Gallavotti

    E-print Network

    Roma "La Sapienza", Università di

    and quanti- tative meaning that was summarized in all its surprising rigor and power in the Almagest with angular velocities 1, . . . , n that is, implicitly, in use in the Almagest, but following contem- porary

  14. Quasi periodic motions from Hipparchus to Kolmogorov. Giovanni Gallavotti

    E-print Network

    that was summarized in all its surprising rigor and power in the Almagest of Ptolemy (¸100­175 d.C.). 5--7 We thus that is, implicitly, in use in the Almagest, but following the ter­ minology of contemporary mathematics

  15. Quasi periodic motions from Hipparchus to Kolmogorov. Giovanni Gallavotti

    E-print Network

    Roma "La Sapienza", Università di

    that was summarized in all its surprising rigor and power in the Almagest of Ptolemy (#24;100-175 d.C.). 5{7 We thus that is, implicitly, in use in the Almagest, but following the ter- minology of contemporary mathematics

  16. Random walk in quasi-periodic random environment

    E-print Network

    Paris-Sud XI, Université de

    of finite range random walk on Z in random environment. The set of possible jumps is assumed to be a fixed Abstract We consider a one-dimensional random walk with finite range in a random medium de- scribed classifications : 60F17, 60J10, 60K37, 37A45, 37C55, 37E10. Key words and phrases : finite range random walk

  17. Optical properties of Cantor-like quasi-periodic superlattices

    Microsoft Academic Search

    Wei G. Feng; Nian-Hua Liu; Xiang Wu

    1993-01-01

    The optical properties of a cantor-like metal-insulator superlattice for both p-polarized and s- polarized wave are studied by employing the transfer matrix formalism. Based on the hydrodynamic theory and taking account of retardation effect, we have calculated the dispersion relations of the electromagnetic modes of the superlattices. The results show that the dispersion relations of the modes have rich multi-fractal

  18. Visual Quasi-Periodicity A.W.M. Smeulders

    E-print Network

    Smeulders, Arnold

    . Periodicity in a sequence can be caused by regularity in the motion of the object. Alternatively, it can be caused by the regularity in appearance of the object over time. Or, it can be caused by the motion to good detection results. We present a novel approach to periodic motion analysis that is inspired

  19. Quasi-periodic jet launching in HD 163296

    NASA Astrophysics Data System (ADS)

    Ellerbroek, Lucas; Podio, Linda; Dougados, Catherine; Cabrit, Sylvie; Kaper, Lex; Sana, Hugues; De Koter, Alex; Sitko, Michael; Klaassen, Pamela; Grindlay, Jonathan; Waters, Rens; Bacciotti, Francesca; Nisini, Brunella

    2013-07-01

    From the structure of the jet from the Herbig Ae star HD 163296 we infer that it is the result of nearly periodic (15 yr) ejection events. Iron is not depleted in the high-velocity jet, indi- cating its dust content is low. However, the photometric behavior of the central source does indicate that a significant amount of dust is episodically lifted from the disk sur- face, probably on larger radial distances and lower velocities than the atomic jet.

  20. Quasi-periodic variation in the solar neutrino flux revisited

    Microsoft Academic Search

    I. Liritzis

    1995-01-01

    Neutrino capture rate data from the Homestake chlorine experiment (1970–1990) has been spectrally analysed. The data were smoothed by a 4-month equally-spaced sequence and by a cubic spline polynomial approximation. Fourier (FFT), maximum entropy spectrum analysis (MESA), and power spectrum analysis (PSA) employing the Blackman-Tukey window were used. The significant periodicities obtained are: 1 ± 0.1, 1.4 ± 0.2, 2.4

  1. Cellular attachment and differentiation on titania nanotubes exposed to air- or nitrogen-based non-thermal atmospheric pressure plasma.

    PubMed

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity. Furthermore, it was demonstrated that this treatment leads to improved osseointegration in vitro. PMID:25420027

  2. Cellular Attachment and Differentiation on Titania Nanotubes Exposed to Air- or Nitrogen-Based Non-Thermal Atmospheric Pressure Plasma

    PubMed Central

    Seo, Hye Yeon; Kwon, Jae-Sung; Choi, Yu-Ri; Kim, Kwang-Mahn; Choi, Eun Ha; Kim, Kyoung-Nam

    2014-01-01

    The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ), elicited from one of two different gas sources (nitrogen and air), to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in cellular activity. Furthermore, it was demonstrated that this treatment leads to improved osseointegration in vitro. PMID:25420027

  3. Effect of additive gases on synthesis of organic compounds from carbon dioxide using non-thermal plasma produced by atmospheric surface discharges

    Microsoft Academic Search

    Nobuya Hayashi; Tsutomu Yamakawa; Seiji Baba

    2006-01-01

    Reduction and recycling of carbon dioxide (CO2) were performed using a non-thermal plasma produced by a surface discharge at atmospheric pressure. Useful hydrocarbons (CHs) such as dimethyl ether and methane were produced at the discharge voltage of 11kV, when hydrogen (H2) gas was mixed with CO2 and the mixture ratio was 50%. The conversion of CO2 to the CHs mixing

  4. Non-thermal RF plasma effects on surface properties of Pd\\/TiO 2 catalysts for selective hydrogenation of acetylene

    Microsoft Academic Search

    Yanan Li; Ben W. L. Jang

    2011-01-01

    Non-thermal RF plasma modification has been applied to Pd\\/TiO2 catalysts for selective hydrogenation of acetylene in the presence of ethylene. High ethylene selectivity and high acetylene conversion were obtained over the plasma-treated catalysts. To understand the plasma effect, the catalysts were characterized by differential scanning calorimetry in hydrogen (H2-DSC), pulse H2 chemisorption, X-ray photoelectron spectroscopy (XPS), Diffuse Reflectance Infrared Fourier

  5. Comparison of specific methane yield of perennial ryegrass prepared by thermal drying versus non-thermal drying in small-scale batch digestion tests.

    PubMed

    Nolan, P; McEniry, J; Doyle, E M; O'Kiely, P

    2014-10-01

    Dried milled biomass samples are frequently utilised in small-scale batch digestion tests. However, herbage chemical composition can be altered by thermal drying, and this may affect specific methane (CH4) yields. Thus, the specific CH4 yield of herbage pre- and post-ensiling, prepared by two preparation methods were compared. Perennial ryegrass samples were either non-thermally dried (i.e. subject to cryogenic conditions, -196 °C) or thermally dried (40 °C), prior to milling. Specific CH4 yield was subsequently determined in a small-scale batch digestion test. Herbage pre-ensiling yielded 204 and 243 L CH4 kg(-1)VS(added) and herbage post-ensiling yielded 212 and 188 L CH4 kg(-1)VS(added) with non-thermal dried and thermal dried sample preparation methods, respectively. Due to opposing effects of thermal drying on CH4 yields of herbage either pre- or post-ensiling, it is not recommended to use thermal drying. Instead, it is recommended that non-thermal dried herbage samples are used in small-scale batch digestion tests. PMID:25084047

  6. NOVEL COMPOSITE HYDROGEN-PERMEABLE MEMBRANES FOR NON-THERMAL PLASMA REACTORS FOR THE DECOMPOSITION OF HYDROGEN SULFIDE

    SciTech Connect

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Ji-Jun Zhang; Guibing Zhao; Robyn J. Alcanzare; Linna Wang; Ovid A. Plumb

    2004-07-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Experiments involving methane conversion reactions were conducted with a preliminary pulsed corona discharge reactor design in order to test and improve the reactor and membrane designs using a non-toxic reactant. This report details the direct methane conversion experiments to produce hydrogen, acetylene, and higher hydrocarbons utilizing a co-axial cylinder (CAC) corona discharge reactor, pulsed with a thyratron switch. The reactor was designed to accommodate relatively high flow rates (655 x 10{sup -6} m{sup 3}/s) representing a pilot scale easily converted to commercial scale. Parameters expected to influence methane conversion including pulse frequency, charge voltage, capacitance, residence time, and electrode material were investigated. Conversion, selectivity and energy consumption were measured or estimated. C{sub 2} and C{sub 3} hydrocarbon products were analyzed with a residual gas analyzer (RGA). In order to obtain quantitative results, the complex sample spectra were de-convoluted via a linear least squares method. Methane conversion as high as 51% was achieved. The products are typically 50%-60% acetylene, 20% propane, 10% ethane and ethylene, and 5% propylene. First Law thermodynamic energy efficiencies for the system (electrical and reactor) were estimated to range from 38% to 6%, with the highest efficiencies occurring at short residence time and low power input (low specific energy) where conversion is the lowest (less than 5%). The highest methane conversion of 51% occurred at a residence time of 18.8 s with a flow rate of 39.4 x 10{sup -6} m{sup 3}/s (5 ft{sup 3}/h) and a specific energy of 13,000 J/l using niobium and platinum coated stainless steel tubes as cathodes. Under these conditions, the First Law efficiency for the system was 8%. Under similar reaction conditions, methane conversions were {approx}50% higher with niobium and platinum coated stainless steel cathodes than with a stainless steel cathode.

  7. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    SciTech Connect

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibing Zhao; Sanil John

    2006-09-30

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. Several pulsed corona discharge (PCD) reactors have been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. Visual observation shows that the corona is not uniform throughout the reactor. The corona is stronger near the top of the reactor in argon, while nitrogen and mixtures of argon or nitrogen with H{sub 2}S produce stronger coronas near the bottom of the reactor. Both of these effects appear to be explainable base on the different electron collision interactions with monatomic versus polyatomic gases. A series of experiments varying reactor operating parameters, including discharge capacitance, pulse frequency, and discharge voltage were performed while maintaining constant power input to the reactor. At constant reactor power input, low capacitance, high pulse frequency, and high voltage operation appear to provide the highest conversion and the highest energy efficiency for H{sub 2}S decomposition. Reaction rates and energy efficiency per H{sub 2}S molecule increase with increasing flow rate, although overall H{sub 2}S conversion decreases at constant power input. Voltage and current waveform analysis is ongoing to determine the fundamental operating characteristics of the reactors. A metal infiltrated porous ceramic membrane was prepared using vanadium as the metal and an alumina tube. Experiments with this type of membrane are continuing, but the results thus far have been consistent with those obtained in previous project years: plasma driven permeation or superpermeability has not been observed. A new test cell specially designed to test the membranes has been constructed to provide basic science data on superpermeability.

  8. Three-dimensional magnetohydrodynamic studies of the non-thermal X-ray morphologies of SN 1006

    NASA Astrophysics Data System (ADS)

    Yu, Huan; Fang, Jun; Zhang, Peng Fei; Zhang, Li

    2015-07-01

    Context. The observations of the synchrotron emission from the supernova remnant (SNR) SN 1006 indicate a bilateral morphology, which is mainly characterized by two opposite bright limbs with knots and filaments along the boundary of the remnant. The morphology is not strictly circular with disturbances and bumps at the rim of the remnant. For instance, one big bump is located on the northeastern (NE) limb and several relatively small ones on the southwestern (SW) limb on the detected morphologies from the observations in the radio and X-rays. Aims: The generation of the asymmetric morphology of non-thermal X-rays for SN 1006 is investigated through three-dimensional (3D) magnetohydrodynamic simulations. Moreover, the density distribution of the ambient material can be investigated by comparing the resulting synchrotron morphology with the detected images of the hard X-ray emission. Methods: First, the remnant was simulated as a supernova explosion evolved in a turbulent plasma with a relatively small amplitude for the turbulence. In the model, several spherical cavities with lower densities compared with the background plasma were employed to reproduce the detected bumps at the bright limbs. Second, the effect of the modification on the morphology of the remnant due to efficient cosmic ray acceleration was investigated by adopting a lower adiabatic index. Results: If we assume that the injection efficiency of electrons into the diffusive shock acceleration process at the shock follows the quasi-parallel scenario, the hard X-ray morphology of SN 1006 with bumps in the bright NE and SW regions can be generally reproduced by employing cavities in the background medium in the non-modification scenario. Furthermore, in the modification case with a lower adiabatic index of 1.2 for the remnant evolved in a uniform medium, bubbles can be produced with relatively small extensions on the SNR boundary that result from the hydrodynamical instabilities that in turn overtake the forward shock. Conclusions: The SNR propagating in the turbulent medium with a relatively small amplitude can reproduce the knotty and filamentary morphology of the remnant better than what evolved in the uniform environment; moreover, the big bump on the NE limb can be explained as the result of a lower-density region, which has a radius of about 2.5 pc and a density of about 0.4 times of the general ambient medium, swept by the shock front, and the other smaller ones on the SW limb can either be reproduced with smaller regions with lower densities swept by the shock or be explained as the protrusions in the scenario of the efficient cosmic ray acceleration when the instability fingers effectively overtake the forward shock.

  9. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    SciTech Connect

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-10-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. A pulsed corona discharge (PCD) reactor has been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. A nonthermal plasma cannot be produced in pure H{sub 2}S with our reactor geometry, even at discharge voltages of up to 30 kV, because of the high dielectric strength of pure H{sub 2}S ({approx}2.9 times higher than air). Therefore, H{sub 2}S was diluted in another gas with lower breakdown voltage (or dielectric strength). Breakdown voltages of H{sub 2}S in four balance gases (Ar, He, N{sub 2} and H{sub 2}) have been measured at different H{sub 2}S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H{sub 2}S and the balance gas. H{sub 2}S conversion and the reaction energy efficiency depend on the balance gas and H{sub 2}S inlet concentrations. With increasing H{sub 2}S concentrations, H{sub 2}S conversion initially increases, reaches a maximum, and then decreases. H{sub 2}S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gases, such as N{sub 2} and H{sub 2}. These observations can be explained by the proposed reaction mechanism of H{sub 2}S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H{sub 2}S into hydrogen and sulfur.

  10. ASCA and RXTE observations of non-thermal X-ray emission from galactic supernova remnants: G156.2+5.7

    NASA Astrophysics Data System (ADS)

    Pannuti, T. G.; Allen, G. E.

    We are conducting a survey of Galactic shell-type supernova remnants (SNRs) known or suspected to possess non-thermal components to their X-ray emission using new and archived observations made with such X-ray satellites as ROSAT, ASCA, RXTE, Chandra and XMM-Newton. This research is intended to probe the phenomenon of cosmic-ray acceleration by Galactic SNRs and estimate the maximum energy of cosmic-ray electrons accelerated by these sources. To illustrate this work, we examine the X-ray spectrum of the northwestern rim of an SNR suspected to have a non-thermal component to its X-ray emission, G156.2+5.7 (RX J04591+5147), over the energy range ?0.7-12.0 keV using observations made by the ASCA GIS and the RXTE PCA. We compare fits made to the non-thermal component using two models, a simple power law and SRCUT. Both models give acceptable fits: the photon index derived from the fit made with the power law model ( ?=2.0 +0.2-0.5) is comparable to values obtained for the bright rims of other SNRs with hard X-ray spectra. Using the SRCUT model, we derive a value of 2.42 +0.24-0.23×10 17 Hz for the cutoff frequency ?cutoff: based on this value and assuming a mean magnetic field strength of 14 ?G, we estimate the cutoff energy Ecutoff of cosmic-ray electrons accelerated by G156.2+5.7 to be ?32 TeV. This energy value is well short of the "knee" feature of the cosmic-ray spectrum.

  11. Final Report: Fiscal Year 1997 demonstration of omnivorous non-thermal mixed waste treatment: Direct chemical oxidation of organic solids and liquids using peroxydisulfate

    SciTech Connect

    Cooper, J.F.

    1998-01-01

    Direct Chemical Oxidation (DCO) is a non-thermal, ambient pressure, aqueous-based technology for the oxidative destruction of the organic components of hazardous or mixed waste streams. The process has been developed for applications in waste treatment, chemical demilitarization and decontamination at LLNL since 1992. The process uses solutions of the peroxydisulfate ion (typically sodium or ammonium salts) to completely mineralize the organics to carbon dioxide and water. The expended oxidant may be electrolytically regenerated to minimize secondary waste. The paper briefly describes: free radical and secondary oxidant formation; electrochemical regeneration; offgas stream; and throughput.

  12. Observations of the Non-Thermal X-ray Emission from the Galactic Supernova Remnant G347.3-0.5

    NASA Technical Reports Server (NTRS)

    Pannuti, Thomas G.; Allen, Glenn E.

    2002-01-01

    G347.3-0.5 (ALEX J1713.7-3946) is a member of the new class of shell-type Galactic supernova remnants (SNRs) that feature non-thermal components to their X-ray emission. We have analyzed the X-ray spectrum of this SNR over a broad energy range (0.5 to 30 key) using archived data from observations made with two satellites, the R6ntgensatellit (ROSA I) and the Advanced Satellite for Cosmology and Astrophysics (ASCA), along with data from our own observations made with the Rossi X-ray Timing Explorer (RXTE) Using a combination of the models EQUIL and SRCUT to fit thermal and non-thermal emission, respectively, from this SNR, we find evidence for a modest thermal component to G347.30.5's diffuse emission with a corresponding energy of kT approx. = 1.4 key. We also obtain an estimate of 70 Texas for the maximum energy of the cosmic-ray electrons that, have been accelerated by this SNR.

  13. A Chandra view of non-thermal emission in the northwestern region of supernova remnant RCW 86: Particle acceleration and magnetic fields

    SciTech Connect

    Castro, Daniel; Lopez, Laura A.; Figueroa-Feliciano, Enectali [MIT-Kavli Center for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Slane, Patrick O.; Yamaguchi, Hiroya [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ramirez-Ruiz, Enrico [Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95060 (United States)

    2013-12-10

    The shocks of supernova remnants are believed to accelerate particles to cosmic ray (CR) energies. The amplification of the magnetic field due to CRs propagating in the shock region is expected to have an impact on both the emission from the accelerated particle population as well as the acceleration process itself. Using a 95 ks observation with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory, we map and characterize the synchrotron emitting material in the northwest region of RCW 86. We model spectra from several different regions, both filamentary and diffuse, where emission appears to be dominated by synchrotron radiation. The fine spatial resolution of Chandra allows us to obtain accurate emission profiles across three different non-thermal rims in this region. The narrow width (l ? 10''-30'') of these filaments constrains the minimum magnetic field strength at the post-shock region to approximately 80 ?G.

  14. Effect of Simulated Diesel Exhaust Gas Composition and Temperature on NOx Reduction of Alumina and Zeolite Catalysts in Combination with Non-Thermal Plasma

    SciTech Connect

    Panov, Alexander G.; Balmer, Mari Lou; Yoon, Ilsop S.; Ebeling, Ana C.; Tonkyn, Russell G.; Barlow, Stephan E.

    2001-01-01

    NOx reduction under simulated lean burn conditions was studied using a non-thermal plasma in combination with zeolite and alumina catalysts. The influence of temperature and plasma treatment on the catalytic performance was investigated. Zeolite catalyst B showed high activity in the 150-300 degree Celcius temperature region. Alumina Catalyst D was most active at temperatures higher than 250 degrees Celcius. In addition, the alumina catalyst was effective in oxidation of aldehydes formed during plasma treatment of the reaction mixture. When the reaction was carried out over a catalyst bed consisting of separate layers of the zeolite and alumina catalyst, the catalyst temperature range for significant NOx reduction was expanded to 150-500 degrees Celcius.

  15. A new XMM-Newton observation of Pictor A radio lobes confirms the non-thermal origin of the X-ray emission

    E-print Network

    G. Migliori; P. Grandi; G. G. C. Palumbo; G. Brunetti; G. Malaguti; M. Guainazzi

    2005-11-03

    X-ray emission from the eastern radio lobe of the FRII Radio Galaxy Pictor A was serendipitously discovered by a short observation of XMM-Newton in 2001. The X-ray spectrum, accumulated on a region covering about half of the entire radio lobe, was well described by both a thermal model and a power law, making non-univocal the physical interpretation. A new XMM-Newton observation performed in 2005 has allowed the detection of the X-ray emission from both radio lobes and unambiguously revealed its non-thermal origin. The X-ray emission is due to Inverse Compton (IC) of the cosmic microwave background photons by relativistic electrons in the lobe. We confirm the discrepancy between the magnetic field, as deduced from the comparison of the IC X-ray and radio fluxes, and the equipartition value.

  16. Simulated morphologies of non-thermal emission from the supernova remnant RX J0852.0-4622 in a turbulent medium

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Yu, Huan; Zhang, Li

    2014-12-01

    The morphologies of the X-rays from synchrotron radiation and the ?-rays produced via either inverse Compton scattering or proton-proton interaction for the supernova remnant RX J0852.0-4622 are investigated using a three-dimensional magnetohydrodynamic simulation. The simulation is initiated with the supernova ejecta imbedded in the turbulent environment, and the distributions of the density and the magnetic field within the shock wave can be obtained. Assuming that the number of the protons accelerated by the forward shock is proportional to the local density since more protons can be injected into the diffusive shock acceleration process with a higher density, the morphology of the emission produced via the inelastic collisions between the accelerated protons with the ambient matter is achieved. Furthermore, the X-ray map of the synchrotron radiation and the ?-ray image of the inverse Compton scattering can be obtained with the assumption that the relativistic electrons have a similar spatial distribution as the protons. The results show that the shock front is distorted by the turbulent medium, and the morphologies of the non-thermal emission from RX J0852.0-4622, which shows a broken shell with bright rims at the shock in the observed images both in the X-ray band and in the TeV ?-ray band, can be generally reproduced using the model. It can be concluded that the observed broken morphologies of the non-thermal emission with bright regions along the shock are the result of the remnant evolving in a turbulent plasma.

  17. Impulsive Energy Release and Non-thermal Emission in a Confined M4.0 Flare Triggered by Rapidly Evolving Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Kushwaha, Upendra; Joshi, Bhuwan; Cho, Kyung-Suk; Veronig, Astrid; Tiwari, Sanjiv Kumar; Mathew, S. K.

    2014-08-01

    We present observations of a confined M4.0 flare from NOAA 11302 on 2011 September 26. Observations at high temporal, spatial, and spectral resolution from the Solar Dynamics Observatory, Reuven Ramaty High Energy Solar Spectroscopic Imager, and Nobeyama Radioheliograph observations enabled us to explore the possible triggering and energy release processes of this flare despite its very impulsive behavior and compact morphology. The flare light curves exhibit an abrupt rise of non-thermal emission with co-temporal hard X-ray (HXR) and microwave (MW) bursts that peaked instantly without any precursor emission. This stage was associated with HXR emission up to 200 keV that followed a power law with photon spectral index (?) ~ 3. Another non-thermal peak, observed 32 s later, was more pronounced in the MW flux than the HXR profiles. Dual peaked structures in the MW and HXR light curves suggest a two-step magnetic reconnection process. Extreme ultraviolet (EUV) images exhibit a sequential evolution of the inner and outer core regions of magnetic loop systems while the overlying loop configuration remained unaltered. Combined observations in HXR, (E)UV, and H? provide support for flare models involving the interaction of coronal loops. The magnetograms obtained by the Helioseismic and Magnetic Imager reveal emergence of magnetic flux that began ~five hr before the flare. However, the more crucial changes in the photospheric magnetic flux occurred about one minute prior to the flare onset with opposite polarity magnetic transients appearing at the early flare location within the inner core region. The spectral, temporal, and spatial properties of magnetic transients suggest that the sudden changes in the small-scale magnetic field have likely triggered the flare by destabilizing the highly sheared pre-flare magnetic configuration.

  18. Ultraviolet light and ultrasound as non-thermal treatments for the inactivation of microorganisms in fresh ready-to-eat foods.

    PubMed

    Birmpa, Angeliki; Sfika, Vasiliki; Vantarakis, Apostolos

    2013-10-01

    The effects of two non thermal disinfection processes, Ultraviolet light (UV 254 nm) and Ultrasound (US) on the inactivation of bacteria and color in two freshly cut produces (lettuce and strawberry) were investigated. The main scope of this work was to study the efficacy of UV and US on the decontamination of inoculated lettuce and strawberries with a cocktail of four bacteria, Escherichia coli, Listeria innocua, Salmonella Enteritidis and Staphylococcus aureus. Treatment of lettuce with UV reduced significantly the population of E. coli, L. innocua, S. Enteritidis and S. aureus by 1.75, 1.27, 1.39 and 1.21 log CFU/g, respectively. Furthermore, more than a 2-log CFU/g reduction of E. coli and S. Enteritidis was achieved with US. In strawberries, UV treatment reduced bacteria only by 1-1.4 log CFU/g. The maximum reductions of microorganisms, observed in strawberries after treatment with US, were 3.04, 2.41, 5.52 and 6.12 log CFU/g for E. coli, S. aureus, S. Enteritidis and L. innocua, respectively. Treatment with UV and US, for time periods (up to 45 min) did not significantly (p>0.05) change the color of lettuce or strawberry. Treatment with UV and US reduced the numbers of selected inoculated bacteria on lettuce and strawberries, which could be good alternatives to other traditional and commonly used technologies such as chlorine and hydrogen peroxide solutions for fresh produce industry. These results suggest that UV and US might be promising, non-thermal and environmental friendly disinfection technologies for freshly cut produce. PMID:23827815

  19. Reactions of oxides of nitrogen (NO{sub x}) leading to the formation of nitric acid (HNO{sub 3}) in non-thermal plasmas (NTPs). White paper for the Strategic Environmental Research and Development Program (SERDP) (Compliance Project CP-1038: Development of non-thermal plasma reactor technology for control of atmospheric emissions)

    SciTech Connect

    Rosocha, L.A. [Los Alamos National Lab., NM (United States); Miziolek, A.W.; Nusca, M.J. [Army Research Lab., Watertown, MA (United States); Chang, J.S. [McMaster Univ., Hamilton, Ontario (Canada); Herron, J.T. [National Inst. for Standards and Technology (United States)

    1998-08-17

    SERDP Compliance Project CP-1038 (Development of Non-Thermal Plasma Reactor Technology for Control of Atmospheric Emissions) has been commissioned to evaluate and develop non-thermal plasma (NTP) reactor technology, a form of low-temperature plasma chemical processing, for Department of Defense (DoD) applications. The primary emphasis is on the control of emissions of oxides of nitrogen (NO{sub x}), with a secondary emphasis on hazardous air pollutant (HAP) emission control (primarily volatile organic compounds--VOCs). In this white paper, as a SERDP-requested deliverable, the authors will verify the NO{sub x} removal reactions in NTPs, especially those converging on nitric acid (HNO{sub 3}) as a primary reaction product. The benefit of making HNO{sub 3} as a primary terminal de-NO{sub x} product is that it can be easily neutralized by relatively simple caustic (base) scrubbers--although the economics of scrubber systems needs to be compared with the conversion to particles that can be filtered or precipitated. Jet engines also emit a significant amount of SO{sub x} in their exhaust; NTPs also remove SO{sub x} and actually do it more effectively in combination with NO{sub x}. This will not be dealt with in this particular white paper.

  20. Non-Thermal Decontamination of a Model Dry Particle Food System Dhaval K. Joshi1, Gregory J. Fleischman2, Susanne Keller2 , Kalyani Narayanan1 , Nathan M. Anderson2

    E-print Network

    Heller, Barbara

    Non-Thermal Decontamination of a Model Dry Particle Food System Dhaval K. Joshi1, Gregory J 60501 Abstract The goal of study was to develop a method of inoculating a model dry particle food system 1. Develop a method for inoculation of a model dry particle food system. 2. Utilize a model dry

  1. Probing the extent of the non-thermal emission from the Vela X region at TeV energies with H.E.S.S.

    NASA Astrophysics Data System (ADS)

    Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Couturier, C.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O.' C.; Dubois, F.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Grondin, M.-H.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzy?ski, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Klochkov, D.; Klu?niak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Menzler, U.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nguyen, N.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, ?.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Wouters, D.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2012-12-01

    Context. Vela X is a region of extended radio emission in the western part of the Vela constellation: one of the nearest pulsar wind nebulae, and associated with the energetic Vela pulsar (PSR B0833-45). Extended very-high-energy (VHE) ?-ray emission (HESS J0835-455) was discovered using the H.E.S.S. experiment in 2004. The VHE ?-ray emission was found to be coincident with a region of X-ray emission discovered with ROSAT above 1.5 keV (the so-called Vela X cocoon): a filamentary structure extending southwest from the pulsar to the centre of Vela X. Aims: A deeper observation of the entire Vela X nebula region, also including larger offsets from the cocoon, has been performed with H.E.S.S. This re-observation was carried out in order to probe the extent of the non-thermal emission from the Vela X region at TeV energies and to investigate its spectral properties. Methods: To increase the sensitivity to the faint ?-ray emission from the very extended Vela X region, a multivariate analysis method combining three complementary reconstruction techniques of Cherenkov-shower images is applied for the selection of ?-ray events. The analysis is performed with the On/Off background method, which estimates the background from separate observations pointing away from Vela X; towards regions free of ?-ray sources but with comparable observation conditions. Results: The ?-ray surface brightness over the large Vela X region reveals that the detection of non-thermal VHE ?-ray emission from the PWN HESS J0835-455 is statistically significant over a region of radius 1.2° around the position ? = 08h35m00s, ? = -45°36'00'' (J2000). The Vela X region exhibits almost uniform ?-ray spectra over its full extent: the differential energy spectrum can be described by a power-law function with a hard spectral index ? = 1.32 ± 0.06stat ± 0.12sys and an exponential cutoff at an energy of (14.0 ± 1.6stat ± 2.6sys) TeV. Compared to the previous H.E.S.S. observations of Vela X the new analysis confirms the general spatial overlap of the bulk of the VHE ?-ray emission with the X-ray cocoon, while its extent and morphology appear more consistent with the (more extended) radio emission, contradicting the simple correspondence between VHE ?-ray and X-ray emissions. Morphological and spectral results challenge the interpretation of the origin of ?-ray emission in the GeV and TeV ranges in the framework of current models.

  2. Diffuse X-rays in the Galactic center region -- The zoo of iron line clumps, non-thermal filaments and hot plasmas --

    E-print Network

    Aya Bamba; Hiroshi Murakami; Atsushi Senda; Shin-ichiro Takagi; Jun Yokogawa; Katsuji Koyama

    2002-02-01

    This paper reports the diffuse X-ray features around the Galactic center observed with Chandra. We confirm the ASCA and Ginga discoveries of the large-scale thin-thermal plasma with strong lines in the Galactic center region. In addition, many small clumps of emission lines from neutral (6.4 keV line) to He-like (6.7 keV line) irons are discovered. The 6.4 keV line clumps would be reflection nebulae, while those of the 6.7 keV line are likely SNRs. We also find emission lines of intermediate energy between 6.5-6.7 keV, which are attributable to young SNRs in non equilibrium ionization. Non-thermal filaments or belts with X-ray spectra of no emission line are found, suggesting the Fermi acceleration site in a rapidly expanding shell. All these suggest that multiple-supernovae or extremely large explosion had occurred around the Galactic center region in the recent past.

  3. Remediation of dichloromethane (CH2Cl2) using non-thermal, atmospheric pressure plasma generated in a packed-bed reactor.

    PubMed

    Abd Allah, Zaenab; Whitehead, J Christopher; Martin, Philip

    2014-01-01

    This work describes the application of a non-thermal plasma generated in a dielectric barrier packed-bed plasma reactor for the remediation of dichloromethane (CH2Cl2, DCM). The overall aim of this investigation is to identify the role of key process parameters and chemical mechanisms on the removal efficiency of DCM in plasma. The influence of process parameters, such as oxygen concentration, concentration of initial volatile organic compounds (VOCs), energy density, plasma residence time, and background gas, on the removal efficiency of 500 ppm DCM was investigated. Results showed a maximum removal efficiency with the addition of 2-4% oxygen into a nitrogen plasma. It is thought that oxygen concentrations in excess of 4% decreased the decomposition of chlorinated VOCs as a result of ozone and nitrogen oxide formation. Increasing the residence time and the energy density resulted in increasing the removal efficiency of chlorinated VOCs in plasma. A chemical kinetic model has been developed on the basis of the proposed reaction scheme, and the calculation of end product concentrations are in general good agreement with the observed values. With the understanding of the effect of the key parameters, it has been possible to optimize the remediation process. PMID:24274359

  4. First hard x-ray detection of the non-thermal emission around the arches cluster: Morphology and spectral studies with NuSTAR

    SciTech Connect

    Krivonos, Roman A.; Tomsick, John A.; Barriere, Nicolas M.; Bodaghee, Arash; Boggs, Steven E.; Craig, William W. [Space Science Lab, University of California, Berkeley, CA 94720 (United States); Bauer, Franz E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Catlica de Chile, Casilla 306, Santiago 22 (Chile); Baganoff, Frederick K. [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Christensen, Finn E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Grefenstette, Brian W.; Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Hailey, Charles J.; Mori, Kaya; Nynka, Melania [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hong, JaeSub [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W., E-mail: krivonos@ssl.berkeley.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-02-01

    The Arches cluster is a young, densely packed massive star cluster in our Galaxy that shows a high level of star formation activity. The nature of the extended non-thermal X-ray emission around the cluster remains unclear. The observed bright Fe K? line emission at 6.4 keV from material that is neutral or in a low ionization state can be produced either by X-ray photoionization or by cosmic-ray particle bombardment or both. In this paper, we report on the first detection of the extended emission around the Arches cluster above 10 keV with the NuSTAR mission, and present results on its morphology and spectrum. The spatial distribution of the hard X-ray emission is found to be consistent with the broad region around the cluster where the 6.4 keV line is observed. The interpretation of the hard X-ray emission within the context of the X-ray reflection model puts a strong constraint on the luminosity of the possible illuminating hard X-ray source. The properties of the observed emission are also in broad agreement with the low-energy cosmic-ray proton excitation scenarioþ.

  5. Effects of a non thermal plasma treatment alone or in combination with gemcitabine in a MIA PaCa2-luc orthotopic pancreatic carcinoma model.

    PubMed

    Brullé, Laura; Vandamme, Marc; Riès, Delphine; Martel, Eric; Robert, Eric; Lerondel, Stéphanie; Trichet, Valérie; Richard, Serge; Pouvesle, Jean-Michel; Le Pape, Alain

    2012-01-01

    Pancreatic tumors are the gastrointestinal cancer with the worst prognosis in humans and with a survival rate of 5% at 5 years. Nowadays, no chemotherapy has demonstrated efficacy in terms of survival for this cancer. Previous study focused on the development of a new therapy by non thermal plasma showed significant effects on tumor growth for colorectal carcinoma and glioblastoma. To allow targeted treatment, a fibered plasma (Plasma Gun) was developed and its evaluation was performed on an orthotopic mouse model of human pancreatic carcinoma using a MIA PaCa2-luc bioluminescent cell line. The aim of this study was to characterize this pancreatic carcinoma model and to determine the effects of Plasma Gun alone or in combination with gemcitabine. During a 36 days period, quantitative BLI could be used to follow the tumor progression and we demonstrated that plasma gun induced an inhibition of MIA PaCa2-luc cells proliferation in vitro and in vivo and that this effect could be improved by association with gemcitabine possibly thanks to its radiosensitizing properties. PMID:23300736

  6. AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR

    SciTech Connect

    Lopez-Santiago, J.; Pereira, V.; De Castro, E. [Dpto. de Astrofisica y CC. de la Atmosfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Miceli, M.; Bonito, R. [Dipartimento di Fisica, Universita di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Del Valle, M. V.; Romero, G. E. [Instituto Argentino de Radioastronomia (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina); Albacete-Colombo, J. F. [Centro Universitario Regional Zona Atlantica (CURZA), Universidad Nacional del COMAHUE, Monsenor Esandi y Ayacucho, 8500 Viedma, Rio Negro (Argentina); Damiani, F. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)

    2012-09-20

    Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace due to the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30'' northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.

  7. Measuring the non-thermal pressure in early type galaxy atmospheres: A comparison of X-ray and optical potential profiles in M87 and NGC1399

    E-print Network

    E. Churazov; W. Forman; A. Vikhlinin; S. Tremaine; O. Gerhard; C. Jones

    2008-05-29

    We compare the gravitational potential profiles of the elliptical galaxies NGC 4486 (M87) and NGC 1399 (the central galaxy in the Fornax cluster) derived from X-ray and optical data. This comparison suggests that the combined contribution of cosmic rays, magnetic fields and micro-turbulence to the pressure is ~10% of the gas thermal pressure in the cores of NGC 1399 and M87, although the uncertainties in our model assumptions (e.g., spherical symmetry) are sufficiently large that the contribution could be consistent with zero. In the absence of any other form of non-thermal pressure support, these upper bounds translate into upper limits on the magnetic field of ~10-20 muG at a distance of 1'-2' from the centers of NGC1399 and M87. We show that these results are consistent with the current paradigm of cool cluster cores, based on the assumption that AGN activity regulates the thermal state of the gas by injecting energy into the intra-cluster medium. The limit of ~10-20% on the energy density in the form of relativistic protons applies not only to the current state of the gas, but essentially to the entire history of the intra-cluster medium, provided that cosmic ray protons evolve adiabatically and that their spatial diffusion is suppressed.

  8. Induced apoptosis in melanocytes cancer cell and oxidation in biomolecules through deuterium oxide generated from atmospheric pressure non-thermal plasma jet.

    PubMed

    Kumar, Naresh; Attri, Pankaj; Yadav, Dharmendra Kumar; Choi, Jinsung; Choi, Eun Ha; Uhm, Han Sup

    2014-01-01

    Recently, atmospheric-pressure non-thermal plasma-jets (APPJ) are being for the cancer treatment. However, APPJ still has drawbacks such as efficiency and rise in temperature after treatment. So, in this work, a synergetic agent D2O vapour is attached to APPJ which not only increase the efficiency of plasma source against cancer treatment, but also controlled the temperature during the treatment. OD generated by the combination of D2O + N2 plasma helped in enhancing the efficiency of APPJ. We observed OD induced apoptosis on melanocytes G361 cancer cells through DNA damage signalling cascade. Additionally, we observed that plasma induces ROS, which activated MAPK p38 and inhibits p42/p44 MAPK, leading to cancer cell death. We have also studied DNA oxidation by extracting DNA from treated cancer cell and then analysed the effects of OD/OH/D2O2/H2O2 on protein modification and oxidation. Additionally, we attempted molecular docking approaches to check the action of D2O2 on the apoptosis related genes. Further, we confirmed the formation of OD/OH simultaneously in the solution using optical emission spectroscopy. Moreover, the simultaneous generation of D2O2/H2O2 was detected by the use of confocal Raman spectroscopy and density measurements. PMID:25534001

  9. Effects of the electrical excitation signal parameters on the geometry of an argon-based non-thermal atmospheric pressure plasma jet.

    PubMed

    Benabbas, Mohamed Tahar; Sahli, Salah; Benhamouda, Abdallah; Rebiai, Saida

    2014-12-01

    A non-thermal atmospheric pressure argon plasma jet for medical applications has been generated using a high-voltage pulse generator and a homemade dielectric barrier discharge (DBD) reactor with a cylindrical configuration. A plasma jet of about 6 cm of length has been created in argon gas at atmospheric pressure with an applied peak to peak voltage and a frequency of 10 kV and 50 kHz, respectively. The length and the shape of the created plasma jet were found to be strongly dependent on the electrode setup and the applied voltage and the signal frequency values. The length of the plasma jet increases when the applied voltage and/or its frequency increase, while the diameter at its end is significantly reduced when the applied signal frequency increases. For an applied voltage of 10 kV, the plasma jet diameter decreases from near 5 mm for a frequency of 10 kHz to less than 1 mm at a frequency of 50 kHz. This obtained size of the plasma jet diameter is very useful when the medical treatment must be processed in a reduced space. PACS 2008: 52.50.Dg; 52.70.-m; 52.80.-s. PMID:26088991

  10. Induced apoptosis in melanocytes cancer cell and oxidation in biomolecules through deuterium oxide generated from atmospheric pressure non-thermal plasma jet

    PubMed Central

    Kumar, Naresh; Attri, Pankaj; Yadav, Dharmendra Kumar; Choi, Jinsung; Choi, Eun Ha; Uhm, Han Sup

    2014-01-01

    Recently, atmospheric-pressure non-thermal plasma-jets (APPJ) are being for the cancer treatment. However, APPJ still has drawbacks such as efficiency and rise in temperature after treatment. So, in this work, a synergetic agent D2O vapour is attached to APPJ which not only increase the efficiency of plasma source against cancer treatment, but also controlled the temperature during the treatment. OD generated by the combination of D2O + N2 plasma helped in enhancing the efficiency of APPJ. We observed OD induced apoptosis on melanocytes G361 cancer cells through DNA damage signalling cascade. Additionally, we observed that plasma induces ROS, which activated MAPK p38 and inhibits p42/p44 MAPK, leading to cancer cell death. We have also studied DNA oxidation by extracting DNA from treated cancer cell and then analysed the effects of OD/OH/D2O2/H2O2 on protein modification and oxidation. Additionally, we attempted molecular docking approaches to check the action of D2O2 on the apoptosis related genes. Further, we confirmed the formation of OD/OH simultaneously in the solution using optical emission spectroscopy. Moreover, the simultaneous generation of D2O2/H2O2 was detected by the use of confocal Raman spectroscopy and density measurements. PMID:25534001

  11. Development of ultra-hydrophilic and non-cytotoxic dental vinyl polysiloxane impression materials using a non-thermal atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kwon, Jae-Sung; Kim, Yong Hee; Choi, Eun Ha; Kim, Kyoung-Nam

    2013-05-01

    Dental vinyl polysiloxane (VPS) impression materials are widely used for the replication of intraoral tissue where hydrophilicity is important as the oral tissues are surrounded by wet saliva. Recent attempts to improve the wettability of VPS using a ‘surfactant’, however, have resulted in a high level of cytotoxicity. Hence, in this study, application of a non-thermal atmospheric-pressure plasma jet (NTAPPJ) on VPS and its effects in terms of both hydrophilicity and cytotoxicity were investigated. The results showed that the application of the plasma jet resulted in significant improvement of hydrophilicity of VPS that had no surfactant, whereby the results were similar to commercially available products with the surfactant. The surface chemical analysis results indicated that this was due to the oxidation and decreased amount of hydrocarbon on the surface following NTAPPJ exposure. Meanwhile, an NTAPPJ-treated sample was shown to be non-cytotoxic. Therefore, the use of dental VPS impression materials without any surfactant, in conjunction with an NTAPPJ treatment, is a promising method for ultra-hydrophilic but yet non-cytotoxic materials.

  12. Discovery of Non Thermal X-Rays from the Northwest Shell of the New SNR RX J1713.7-3946 The Second SN1006 ?

    E-print Network

    Koyama, K; Matsuzaki, K; Nishiuchi, M; Sugizaki, M; Torii, K; Yamauchi, S; Aschenbach, B; Koyama, Katsuji; Kinugasa, Kenzo; Matsuzaki, Keiichi; Nishiuchi, Mamiko; Sugizaki, Mutusmi; Torii, Ken'ichi; Yamauchi, Shigeo; Aschenbach, Bernd

    1997-01-01

    We report ASCA results of a featureless X-ray spectrum from RX J1713.7-3946, a new shell-like SNR discovered with the ROSAT all sky survey. The northwest part of RX J1713.7-3946 was in the field of the ASCA Galactic Plane Survey Project and was found to exhibit a shell-like structure. The spectrum, however shows neither line emission nor any signature of a thermal origin. Instead, a power-law model with a photon index of 2.4-2.5 gives reasonable fit to the spectrum, suggesting a non-thermal origin. Together with the similarity to SN1006, we propose that RX J1713.7-3946 is the second example, after SN1006, of a synchrotron X-ray radiation from a shell of SNRs. Since the synchrotron X-rays suggest existence of extremely high energy charged particles in the SNR shell, our discovery should have strong impact on the origin of the cosmic X-rays.

  13. First Hard X-Ray Detection of the Non-Thermal Emission Around the Arches Cluster: Morphology and Spectral Studies With NuSTAR

    NASA Technical Reports Server (NTRS)

    Krivonos, Roman A.; Tomsick, John A.; Bauer, Franz E.; Baganoff, Frederick K.; Barriere, Nicolas M.; Bodaghee, Arash; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Grefenstette, Brian W.; Hailey, Charles J.; Harrison, Fiona A.; Hong, JaeSub; Madsen, Kristin K.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Zhang, William W.

    2014-01-01

    The Arches cluster is a young, densely packed massive star cluster in our Galaxy that shows a high level of star formation activity. The nature of the extended non-thermal X-ray emission around the cluster remains unclear. The observed bright Fe K(alpha) line emission at 6.4 keV from material that is neutral or in a low ionization state can be produced either by X-ray photoionization or by cosmic-ray particle bombardment or both. In this paper, we report on the first detection of the extended emission around the Arches cluster above 10 keV with the NuSTAR mission, and present results on its morphology and spectrum. The spatial distribution of the hard X-ray emission is found to be consistent with the broad region around the cluster where the 6.4 keV line is observed. The interpretation of the hard X-ray emission within the context of the X-ray reflection model puts a strong constraint on the luminosity of the possible illuminating hard X-ray source. The properties of the observed emission are also in broad agreement with the low-energy cosmic-ray proton excitation scenario. Key words: cosmic rays - Galaxy: center - ISM: general - X-rays: individual (Arches cluster)

  14. Discovery of Non Thermal X-Rays from the Northwest Shell of the New SNR RX J1713.7-3946: The Second SN1006 ?

    E-print Network

    Katsuji Koyama; Kenzo Kinugasa; Keiichi Matsuzaki; Mamiko Nishiuchi; Mutusmi Sugizaki; Ken'ichi Torii; Shigeo Yamauchi; Bernd Aschenbach

    1997-04-19

    We report ASCA results of a featureless X-ray spectrum from RX J1713.7-3946, a new shell-like SNR discovered with the ROSAT all sky survey. The northwest part of RX J1713.7-3946 was in the field of the ASCA Galactic Plane Survey Project and was found to exhibit a shell-like structure. The spectrum, however shows neither line emission nor any signature of a thermal origin. Instead, a power-law model with a photon index of 2.4-2.5 gives reasonable fit to the spectrum, suggesting a non-thermal origin. Together with the similarity to SN1006, we propose that RX J1713.7-3946 is the second example, after SN1006, of a synchrotron X-ray radiation from a shell of SNRs. Since the synchrotron X-rays suggest existence of extremely high energy charged particles in the SNR shell, our discovery should have strong impact on the origin of the cosmic X-rays.

  15. Induced apoptosis in melanocytes cancer cell and oxidation in biomolecules through deuterium oxide generated from atmospheric pressure non-thermal plasma jet

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Attri, Pankaj; Yadav, Dharmendra Kumar; Choi, Jinsung; Choi, Eun Ha; Uhm, Han Sup

    2014-12-01

    Recently, atmospheric-pressure non-thermal plasma-jets (APPJ) are being for the cancer treatment. However, APPJ still has drawbacks such as efficiency and rise in temperature after treatment. So, in this work, a synergetic agent D2O vapour is attached to APPJ which not only increase the efficiency of plasma source against cancer treatment, but also controlled the temperature during the treatment. OD generated by the combination of D2O + N2 plasma helped in enhancing the efficiency of APPJ. We observed OD induced apoptosis on melanocytes G361 cancer cells through DNA damage signalling cascade. Additionally, we observed that plasma induces ROS, which activated MAPK p38 and inhibits p42/p44 MAPK, leading to cancer cell death. We have also studied DNA oxidation by extracting DNA from treated cancer cell and then analysed the effects of OD/OH/D2O2/H2O2 on protein modification and oxidation. Additionally, we attempted molecular docking approaches to check the action of D2O2 on the apoptosis related genes. Further, we confirmed the formation of OD/OH simultaneously in the solution using optical emission spectroscopy. Moreover, the simultaneous generation of D2O2/H2O2 was detected by the use of confocal Raman spectroscopy and density measurements.

  16. Non-thermal X-ray Emission from the Northwestern Rim of the Galactic Supernova Remnant G266.2-1.2 (RX J0852.0-4622)

    NASA Astrophysics Data System (ADS)

    Pannuti, Thomas G.; Allen, Glenn E.; Filipovi?, Miroslav D.; De Horta, Ain; Stupar, Milorad; Agrawal, Rashika

    2010-10-01

    We present a detailed spatially resolved spectroscopic analysis of two observations (with a total integration time of 73280 s) made of the X-ray-luminous northwestern rim complex of the Galactic supernova remnant (SNR) G266.2-1.2 (RX J0852.0-4622) with the Chandra X-ray Observatory. G266.2-1.2 is a member of a class of Galactic SNRs which feature X-ray spectra dominated by non-thermal emission: in the cases of these SNRs, the emission is believed to have a synchrotron origin and studies of the X-ray spectra of these SNRs can lend insight into how SNRs accelerate cosmic-ray particles. The Chandra observations have clearly revealed fine structure in this rim complex (including a remarkably well-defined leading shock) and the spectra of these features are dominated by non-thermal emission. We have measured the length scales of the upstream structures at eight positions along the rim and derive lengths of 0.02-0.08 pc (assuming a distance of 750 pc to G266.2-1.2). We have also extracted spectra from seven regions in the rim complex (as sampled by the ACIS-S2, -S3, and -S4 chips) and fit these spectra with such models as a simple power law as well as the synchrotron models SRCUT and SRESC. We have constrained our fits to the latter two models using estimates for the flux densities of these filaments at 1 GHz as determined from radio observations of this rim complex made with the Australia Telescope Compact Array. Statistically acceptable fits to all seven regions are derived using each model: differences in the fit parameters (such as photon index and cutoff frequency) are seen in different regions, which may indicate variations in shock conditions and the maximum energies of the cosmic-ray electrons accelerated at each region. Finally, we estimate the maximum energy of cosmic-ray electrons accelerated along this rim complex to be approximately 40 TeV (corresponding to one of the regions of the leading shock structure assuming a magnetic field strength of 10 ?G). We include a summary of estimated maximum energies for both Galactic SNRs as well as SNRs located in the Large Magellanic Cloud. Like these other SNRs, it does not appear that G266.2-1.2 is currently accelerating electrons to the knee energy (~3000 TeV) of the cosmic-ray spectrum. This result is not surprising, as there is some evidence that loss mechanisms which are not important for the accelerated cosmic-ray nucleons at energies just below the knee might cut off electron acceleration.

  17. Suzaku Observations of Thermal and Non-Thermal X-Ray Emission from the Middle-Aged Supernova Remnant G156.2+5.7

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Petre, Robert; Hwang, Una; Yamaguchi, Hiroya; Mori, Koji; Tsunemi, Hiroshi

    2008-01-01

    We present results from X-ray analysis of a Galactic middle-aged supernova remnant (SNR) G156.2+5.7 which is bright and largely extended in X-ray wavelengths, showing a clear circular shape (radius approx.50'). Using the Suzaku satellite, we observed this SNR in three pointings; partially covering the northwestern (NW) rim, the eastern (E) rim, and the central portion of this SNR. In the NW rim and the central portion, we confirm that the X-ray spectra consist of soft and hard-tail emission, while in the E rim we find no significant hard-tail emission. The soft emission is well fitted by either a one-component or two-component non-equilibrium ionization (NEI) model. In the NW and E rims, a one-component (the swept-up interstellar medium) NEI model well represents the soft emission. On the other hand, in the central portion, a two-component (the interstellar medium and the metal-rich ejecta) NEI model fits the soft emission better than the one-component NEI model from a statistical point of view. The relative abundances in the ejecta component suggest that G156.2+5.7 is a remnant from a core-collapse SN explosion whose progenitor mass is less than 15 Solar Mass. The origin of the hard-tail emission detected in the NW rim and the central portion of the SNR is highly likely non-thermal synchrotron emission from relativistic electrons. In the NW rim, the relativistic electrons seems to be accelerated by a forward shock with a slow velocity of APPROX.500 km/sec.

  18. The Role of Higher-Order Modes on the Electromagnetic Whistler-Cyclotron Wave Fluctuations of Thermal and Non-Thermal Plasmas

    NASA Technical Reports Server (NTRS)

    Vinas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto; Araneda, Jamie A.

    2014-01-01

    Two fundamental challenging problems of laboratory and astrophysical plasmas are the understanding of the relaxation of a collisionless plasmas with nearly isotropic velocity distribution functions and the resultant state of nearly equipartition energy density with electromagnetic plasma turbulence. Here, we present the results of a study which shows the role that higher-order-modes play in limiting the electromagnetic whistler-like fluctuations in a thermal and non-thermal plasma. Our main results show that for a thermal plasma the magnetic fluctuations are confined by regions that are bounded by the least-damped higher order modes. We further show that the zone where the whistler-cyclotron normal modes merges the electromagnetic fluctuations shifts to longer wavelengths as the beta(sub e) increases. This merging zone has been interpreted as the beginning of the region where the whistler-cyclotron waves losses their identity and become heavily damped while merging with the fluctuations. Our results further indicate that in the case of nonthermal plasmas, the higher-order modes do not confine the fluctuations due to the effective higher-temperature effects and the excess of suprathermal plasma particles. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic bi-Maxwellian and Tsallis-kappa-like magnetized electron-proton plasma. Our results indicate that the spontaneously emitted electromagnetic fluctuations are in fact enhanced over these quasi modes suggesting that such modes play an important role in the emission and absorption of electromagnetic fluctuations in thermal or quasi-thermal plasmas.

  19. Generation Of Atmospheric Pressure Non-Thermal Plasma By Diffusive And Constricted Discharges In Rest And Flowing Gases (Air And Nitrogen)

    NASA Astrophysics Data System (ADS)

    Akishev, Y.; Grushin, M.; Karalnik, V.; Kochetov, I.; Napartovich A.; Trushkin N.

    2010-07-01

    Weekly ionized non-thermal plasma (NTP) is of great interest for many applications because of its strong non-equilibrium state wherein an average electron energy Te exceeds markedly gas temperature Tg, i.e. electrons in the NTP are strongly overheated compared to neutral gas. Energetic electrons due to frequent collisions with the neutrals excite and dissociate effectively atoms and molecules of the plasma-forming gas that results in a creation of physically-, and bio-chemically active gaseous medium in a practically cold background gas. At present there are many kinds of plasma sources working at low and atmospheric pressure and using MW, RF, low frequency, pulsed and DC power supplies for NTP generation. The NTP at atmospheric pressure is of considerable interest for practice. A reason is that sustaining the NTP at atmospheric pressure at first allows us to avoid the use of expensive vacuum equipment and second gives opportunity to use the NTP for treatment of the exhausted gases and polluted liquids. The second opportunity cannot be realized at all with use of the NTP at low pressure. Main subject of this talk is low current atmospheric pressure gas discharges powering with DC power supplies. Plasma forming gases are air and nitrogen which are much cheaper compared to rare gases like He or Ar. Besides, great interest to molecular nitrogen as plasma forming gas is caused first of all its unique capability to accumulate huge energy in vibration, electron (metastables) and dissociated (atomic) states providing high chemical reactivity of the activated nitrogen. All active particles mentioned above have a long lifetime, and they can be therefore transported for a long distance away from place of their generation. Different current modes (diffusive and constricted) of these discharges are discussed. Experimental and numerical results on generation of chemically active species in the diffusive and constricted mode are presented. Some data on the usage of the atmospheric pressure NTP for gas cleanup, surface treatment and sterilization are given.

  20. CO2 reforming of CH4 over CeO2-doped Ni/Al2O3 nanocatalyst treated by non-thermal plasma.

    PubMed

    Rahemi, Nader; Haghighi, Mohammad; Babaluo, Ali Akbar; Jafari, Mahdi Fallah; Estifaee, Pooya

    2013-07-01

    Ni/Al2O3 and Ni/Al2O3-CeO2 nanocatalysts have been prepared with impregnation method, treated with non-thermal plasma, characterized and tested for dry reforming of methane. For catalyst characterization, the following techniques have been used: XRD, FESEM, TEM, EDX dot mapping, BET, FTIR, TG-DTG, and XPS techniques. According to XRD and XPS, Ni in all catalysts exists as NiO and NiAl2O4 that existence of NiAl2O4 reveals strong interaction between active phase and support. Catalyst particles had smaller average particle size in plasma treated Ni/Al2O3-CeO2 nanocatalyst with less agglomeration. Homogenous dispersion of active phase, narrower particle size distribution, and uniform morphology has been observed in ceria containing plasma treated catalyst. The plasma treated Ni/Al2O3-CeO2 nanocatalyst showed bigger NiAl2O4/NiO ratio in XPS analysis that is indicative of stronger interaction between Ni and Al2O3 in the presence of CeO2. The dry reforming of methane was carried out at 550-850 degrees C using a mixture of CH4:CO2 (0.5:2). Improved morphology of the plasma treated Ni/Al2O3-CeO2 nanocatalyst, resulted from both CeO2 and plasma treatment, caused higher ability of catalyst in H2 and CO production. Product yield decreased at higher GHSVs, due to the fact that mass transport limitations will be more severe at low residence time, but this reduction would be less noticeable in the plasma treated Ni/Al2O3-CeO2 nanocatalyst. In addition, the plasma treated Ni/Al2O3-CeO2 nanocatalyst can keep the reactivity without deactivation for either CH4 or CO2 conversion better than other investigated catalysts. PMID:23901509

  1. The beneficial use of non-thermal plasma in synthesis of Ni/Al2O3-MgO nanocatalyst used in hydrogen production from reforming of CH4/CO2 greenhouse gases

    NASA Astrophysics Data System (ADS)

    Estifaee, Pooya; Haghighi, Mohammad; Babaluo, Ali Akbar; Rahemi, Nader; Jafari, Mahdi Fallah

    2014-07-01

    In our continuing effort to investigate the effect of non-thermal plasma on CH4/CO2 reforming catalysts, Ni/Al2O3-MgO nanocatalyst is investigated. The impregnated and plasma treated nanocatalysts are characterized using XRD, FESEM, TEM, EDX Dot-Mapping, BET, TG-DTG, XPS and FTIR techniques. XRD patterns show high dispersion and strong interaction of active phase. FESEM images display smaller particle size and a narrow particle size distribution for plasma treated sample. According to the BET analysis, the calculated surface area of plasma treated sample is 11% higher. TEM images show particles of active phase are fairly small and well-dispersed as a result of plasma treatment. XPS and EDX analysis reveal better dispersion of active phase as a result of plasma treatment. In addition to better structural and physicochemical properties, the Ni/Al2O3-MgO nanocatalyst which treated by non-thermal plasma has higher activity and significant anti-coke properties in the CH4/CO2 reforming reaction at 550-850 °C temperature range using a mixture of CH4:CO2 = 0.5-2.

  2. Association of depletions, enhancements and quasi-periodic variations in TEC with amplitude scintillations

    Microsoft Academic Search

    P. V. S. Rama Rao; B. V. Ramana Rao; D. S. V. V. D. Prasad

    1990-01-01

    Several TEC depletions associated with amplitude scintillations are reported from the Waltair observing station located between the equator and the anomaly-crest region. The characteristics of the TEC depletions are discussed, and statistics are given regarding the amplitude and duration of the depletions and their diurnal, seasonal, and solar-cycle dependences. Faraday rotation and scintillation data are derived from 136-MHz radio-beacon signals,

  3. Quasi-periodic (~mHz) dayside auroral brightennings associated with high-speed solar wind

    NASA Astrophysics Data System (ADS)

    Liou, K.

    2013-12-01

    It has been reported that dayside auroral pulsations of a few mHz frequency can occur when variations of solar wind dynamic pressure at the same frequency appear. Magnetospheric compression/decompression is attributed to the auroral pulsations. Here we report another type of dayside auroral pulsations not associated with solar wind dynamic pressure changes by using global auroral images acquired from the Ultraviolet Imager (UVI) on board the Polar satellite. From one periodic (~2 - 8 mHz) auroral event that occurred on February 8, 2000, it is found that the auroral enhancements covered most of the day (~05 - 16 MLT) sector and did not show a latitudinal dependence. Based on in situ particle data from DMSP SSJ/4, the brightennings were associated mainly with enhanced particle precipitations from the central plasma sheet (i.e., diffuse aurora). There was no geomagnetic pulsation on the ground and in the dawn sector of the magnetosheath as indicated by the Geotail measurements. While the auroral pulsations occurred during high solar wind speed (> 600 km/s), they commenced when the interplanetary magnetic field turned northward, suggesting the Kelvin-Helmholtz instability being a source of the pulsations. We will present detail analysis results and discuss other possible mechanisms in the context of current theories.

  4. Quasi-periodic non-stationary solutions of 3D Euler equations for incompressible flow

    E-print Network

    Ershkov, Sergey V

    2015-01-01

    A novel derivation of non-stationary solutions of 3D Euler equations for incompressible inviscid flow is considered here. Such a solution is the product of 2 separated parts: - one consisting of the spatial component and the other being related to the time dependent part. Spatial part of a solution could be determined if we substitute such a solution to the equations of motion (equation of momentum) with the requirement of scale-similarity in regard to the proper component of spatial velocity. So, the time-dependent part of equations of momentum should depend on the time-parameter only. The main result, which should be outlined, is that the governing (time-dependent) ODE-system consist of 2 Riccati-type equations in regard to each other, which has no solution in general case. But we obtain conditions when each component of time-dependent part is proved to be determined by the proper elliptical integral in regard to the time-parameter t, which is a generalization of the class of inverse periodic functions.

  5. Quasi-Periodic Transitions in Axially Forced Taylor-Couette Flow

    Microsoft Academic Search

    Manish Sinha; Alexander J. Smits

    2000-01-01

    We study a variation of the classical Taylor-Couette problem: with the outer cylinder stationary, the inner cylinder rotates at constant angular velocity while executing harmonic oscillations in the axial direction. Using kalliroscope suspension, we present experimental visualization and quantitative measurements of a Naimark-Sacker bifurcation within this flow. At a fixed axial Reynolds number and beyond the instability curve in (Re_Omega-omega)

  6. A low-dimensional model system for quasi-periodic plasma perturbations

    SciTech Connect

    Constantinescu, D. [Department of Applied Mathematics, University of Craiova, Association Euratom-MECI (Romania); Dumbrajs, O. [Institute of Solid State Physics, University of Latvia, Association Euratom-UL (Latvia); Igochine, V.; Lackner, K.; Meyer-Spasche, R.; Zohm, H. [Max-Planck Institut fuer Plasmaphysik, Association Euratom-IPP (Germany)

    2011-06-15

    Larger scale plasma instabilities not leading to an immediate termination of a discharge often result in periodic nonlinear perturbations of the plasma. A minimal possible model is formulated for description of the system with drive and relaxation processes which have different time scales. The model is based on two equations: the first being responsible for the relaxation dynamics and the second for the drive. The model can be generalized to describe the pellet injection.

  7. Intensity-Modulated Radiotherapy Optimization in a Quasi-Periodically Deforming Patient Model

    SciTech Connect

    Soehn, Matthias, E-mail: Matthias.Soehn@med.uni-tuebingen.d [Section for Biomedical Physics, University Hospital for Radiation Oncology, Tuebingen (Germany); Weinmann, Martin [Department of Radiotherapy, University Hospital for Radiation Oncology, Tuebingen (Germany); Alber, Markus [Section for Biomedical Physics, University Hospital for Radiation Oncology, Tuebingen (Germany)

    2009-11-01

    Purpose: To present the implementation of a probability-based, four-dimensional (4D) intensity-modulated radiotherapy (IMRT) planning approach that explicitly optimizes the accumulated dose to moving tissue, estimated using the patient's probability density function (pdf) of respiratory motion. This is termed 'optimization in tissue's-eye-view'. Methods and Materials: The method incorporates 4D Monte Carlo dose calculation in multiple geometries of a respiratory-correlated CT dataset. The instance doses are weighted according to the breathing pdf and accumulated in a common reference geometry, which involves dose warping based on deformable registration. The algorithm produces deliverable multileaf collimator segments and was tested on a sample lung cancer patient dataset with large target excursion. Accumulated doses of the moving target and organs at risk of this plan were compared with those of corresponding margin-based static IMRT plans for free-breathing and gated treatment, as well as target tracking. Results: Target tracking provided best target coverage. Both the presented 4D IMRT approach for free-breathing treatment and gated treatment gave similar results for target coverage and lung dose, with significantly better target coverage than the margin-based static IMRT plan for free-breathing treatment. Conclusions: The presented 4D planning concept offers an alternative to gating by providing the optimal dose for free-breathing IMRT treatment. Although the focus of this study was 4D lung planning, the approach can be generally applied for IMRT optimization in randomly deforming patient models.

  8. Limit(quasi)periodic point sets as quasicrystals with p-adic internal spaces

    Microsoft Academic Search

    Michael Baake; Robert V. Moody; Martin Schlottmann

    1998-01-01

    Model sets (or cut and project sets) provide a familiar and commonly used method of constructing and studying nonperiodic point sets. Here we extend this method to situations where the internal spaces are no longer Euclidean, but instead spaces with p-adic topologies or even with mixed Euclidean\\/p-adic topologies. We show that a number of well known tilings precisely fit this

  9. Construction of 2D quasi-periodic Rauzy tiling by similarity transformation

    SciTech Connect

    Zhuravlev, V. G.; Maleev, A. V., E-mail: andr_mal@mail.ru [Vladimir State Humanitarian University (Russian Federation)

    2009-05-15

    A new approach to constructing self-similar fractal tilings is proposed based on the construction of semigroups generated by a finite set of similarity transformations. The Rauzy tiling-a 2D analog of 1D Fibonacci tiling generated by the golden mean-is used as an example to illustrate this approach. It is shown that the Rauzy torus development and the elementary fractal boundary of Rauzy tiling can be constructed in the form of a set of centers of similarity semigroups generated by two and three similarity transformations, respectively. A centrosymmetric tiling, locally dual to the Rauzy tiling, is constructed for the first time and its parameterization is developed.

  10. Studying X-Ray Binaries with High Energy Frequency Quasi-Periodic Oscillations

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald J. (Technical Monitor); Kaaret, P.

    2003-01-01

    The goal of this investigation is to further our understanding of the dynamics of accreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fields. The main focus of this work has been a multi-year program of simultaneous millisecond x-ray timing and spectral observations carried out with the Rossi X-Ray Timing Explorer (RXTE) to perform the x-ray timing and one of the satellites Asca, BeppoSAX, or Chandra to perform x-ray spectral measurements. With the advent of Chandra, we have extended our work to include imaging of X-ray jets from binaries and the study of extragalactic X-ray binaries. Significant progress was made over the past year.

  11. Quasi-periodic bedding in the sedimentary rock record of mars

    USGS Publications Warehouse

    Lewis, K.W.; Aharonson, O.; Grotzinger, J.P.; Kirk, R.L.; McEwen, A.S.; Suer, T.-A.

    2008-01-01

    Widespread sedimentary rocks on Mars preserve evidence of surface conditions different from the modern cold and dry environment, although it is unknown how long conditions favorable to deposition persisted. We used 1-meter stereo topographic maps to demonstrate the presence of rhythmic bedding at several outcrops in the Arabia Terra region. Repeating beds are ???10 meters thick, and one site contains hundreds of meters of strata bundled into larger units at a ???10:1 thickness ratio. This repetition likely points to cyclicity in environmental conditions, possibly as a result of astronomical forcing. If deposition were forced by orbital variation, the rocks may have been deposited over tens of millions of years.

  12. Studying X-Ray Binaries with High Frequency Quasi-Periodic Oscillations

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald (Technical Monitor); Kaaret, Philip

    2004-01-01

    The goal of this investigation is to further our understanding of the dynamics of accreting neutron stars and black holes in the hope of using these systems as probes of the physics of strong gravitational fields. The main focus of this work has been a multi-year program of millisecond X-ray timing and spectral observations of accreting compact objects. include imaging of X-ray jets from binaries and the study of extragalactic X-ray binaries. past year. Nine papers were accepted and/or published, as listed below. Seven of these are new since our previous annual report. With the advent of Chandra, we have extended our work to Significant progress was made over the The presentation of several talks and posters at astronomical meetings were supported by this grant. The PI was the lead organizer of "X-Ray Timing 2003: Rossi and Beyond", a major conference held in Cambridge, MA, in November, 2003. A t the conference we reviewed the accomplishments of the Rossi X-Ray Timing Explorer and developed the scientific motivation for a future X-ray timing mission. This conference was well attended and generated a significant amount of interest.

  13. An investigation of fixed separation in quasi-periodic and aperiodic, unsteady, two-dimensional flows

    E-print Network

    Helu, Moneer Mohammad

    2007-01-01

    This study asses the kinematic theory of fixed separation in unsteady, two-dimensional flows that has been proposed by Haller (2004). Experimental investigations were conducted that utilized the rotor-oscillator flow to ...

  14. The quasi-periodic nature of wall slip for molten plastics in large amplitude oscillatory shear 

    E-print Network

    Adrian, David Warren

    1992-01-01

    as needed in the test. Also, the theorem shows that phase space analysis only O X ? 2 x(t) Figure 12. Attractor reconstruction of Ueda's attractor shown in Figure 10. 32 requires one observable variable. This reduces the number of sensors needed..., the ellipse deforms according to whether the uncertainty increases or decreases with time. The Lyapunov exponent of the 1th axis is related to the length of the principal axis p;(t): P(0) p, (ti) pj ( t] ) t=o Figure l3. Ellipse in phase plane showing...

  15. Quasi-periodic magnetotail flow reversals during prolonged intervals with southward IMF

    Microsoft Academic Search

    R. Walker; M. Ashour-Abdalla; M. El-Alaoui

    2006-01-01

    We have used a global magnetohydrodynamic simulation to investigate magnetospheric convection during a prolonged interval with southward interplanetary magnetic field on February 13 and 14 2001 We used ACE solar wind observations to drive the MHD simulation Early in the simulated interval a near-Earth neutral line located between 20RE and 40RE drove flows earthward and then around the near-Earth obstacle

  16. Simultaneous observations of Jovian quasi-periodic radio emissions by the Galileo and Cassini spacecraft

    E-print Network

    Gurnett, Donald A.

    frequency component of the bursts, producing the characteristic ``type III like'' spectral shape. INDEX by Kurth et al. [1989] using the Voyager plasma wave wideband instrument [Scarf and Gurnett, 1977

  17. Low-, middle-, and high-frequency quasi-periodical oscillations in light curves of classical fuors

    NASA Astrophysics Data System (ADS)

    Ibragimov, M. A.

    UBVR-photoelectric monitoring of three classical fuors obtained at Mt. Maidanak Observatory in the 1978, 1981-1994 seasons is discussed. The monitoring data include 541, 1369, and 1323 individual observations for FU Ori, V1057 Cyg, and V1515 Cyg, respectively. Digital analysis of this prolonged homogeneous series allows us to establish that there are three kinds of quasiperiodical variation in light curves of classical fuors: low-frequency oscillations of large-scale light curve with periods of about a few units of 103 days; middle-frequency oscillations of large-scale light curve with periods of about a few units of l02 days; and high-frequency oscillations of small-scale light curve with periods of about a and few units of 101 days.

  18. Non-thermal effects of power-line magnetic fields (50 Hz) on gene expression levels of pluripotent embryonic stem cells-the role of tumour suppressor p53.

    PubMed

    Czyz, Jaroslaw; Nikolova, Teodora; Schuderer, Jürgen; Kuster, Niels; Wobus, Anna M

    2004-01-10

    The diffusion of extremely low-frequency (50 Hz) electromagnetic fields (ELF-EMF) in the human environment raises the question of the induction of biological effects of EMF on mammalian cells. We used the model of mouse pluripotent embryonic stem (ES) cells, which have the capacity to develop in vitro into cells of all lineages, to analyse non-thermal effects of ELF-EMF. Wild type (wt) and p53-deficient ES cells were exposed under controlled conditions to ELF-EMF signals simulating power-line (50 Hz) magnetic field (PL-MF) exposure. Different flux densities of 0.1 mT, 1.0 mT or 2.3 mT and intermittency schemes with various ON/OFF cycles were applied for 6 h or 48 h during the first stages of cell differentiation. Transcript levels of regulatory genes, such as egr-1, p21, c-jun, c-myc, hsp70 and bcl-2, were analysed by semi-quantitative RT-PCR immediately after exposure or after a recovery time of 18 h. Intermittent PL-MF exposure to 5 min ON/30 min OFF cycles at a flux density of 2.3 mT for 6 h resulted in a significant up-regulation of c-jun, p21 and egr-1 mRNA levels in p53-deficient, but not in wild-type cells. No significant effects were observed in both cell systems by PL-MF at lower flux densities, longer exposure time or after 18 h recovery time. Our data indicate that 5 min ON/30 min OFF intermittent PL-MF exposure is capable of evoking non-thermal responses in ES cells, dependent on the cellular p53 function. The nature of the biological responses triggered by PL-MF is discussed. PMID:14706519

  19. Towards a Better Understanding of the GRB Phenomenon: a New Model for GRB Prompt Emission and its effects on the New Non-Thermal L$_\\mathrm{i}^\\mathrm{NT}$-E$_\\mathrm{peak,i}^\\mathrm{rest,NT}$ relation

    E-print Network

    Guiriec, S; Daigne, F; Zhang, B; Hascoet, R; Nemmen, R; Thompson, D; Bhat, N; Gehrels, N; Gonzalez, M; Kaneko, Y; McEnery, J; Mochkovitch, R; Racusin, J; Ryde, F; Sacahui, J; Unsal, A

    2015-01-01

    We reanalyze the prompt emission of two of the brightest Fermi GRBs (080916C and 090926A) with a new model composed of 3 components: (i) a thermal-like component--approximated with a black body (BB)--interpreted as the jet photosphere emission of a magnetized relativistic outflow, (ii) a non-thermal component--approximated with a Band function--interpreted as synchrotron radiation in an optically thin region above the photosphere either from internal shocks or magnetic field dissipation, and (iii) an extra power law (PL) extending from low to high energies likely of inverse Compton origin, even though it remains challenging. Through fine-time spectroscopy down to the 100 ms time scale, we follow the smooth evolution of the various components. From this analysis the Band function is globally the most intense component, although the additional PL can overpower the others in sharp time structures. The Band function and the BB component are the most intense at early times and globally fade across the burst durati...

  20. THE NON-THERMAL INTRACLUSTER MEDIUM

    SciTech Connect

    Lieu, Richard; Bonamente, Massimiliano [Department of Physics, University of Alabama, Huntsville, AL 35899 (United States); Quenby, John [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

    2010-10-01

    WMAP's detection of the Sunyaev-Zel'dovich effect at a much reduced level among several large samples of rich clusters is interpreted in terms of conventional physics. It has been suggested that the central soft X-ray and EUV excess found in some clusters cannot be of thermal origin, due to problems with rapid gas cooling and the persistent non-detection of the O VII line, but may arise from inverse Compton scattering between intracluster relativistic electrons and the cosmic microwave background (CMB). In fact, recent XMM-Newton observations of the soft X-rays from Coma and Abell 3112 are equally well fitted by a power law or a thermal virialized gas. Therefore, the missing Sunyaev-Zel'dovich flux could partly be due to an overestimate of the central density of virialized electrons which scatter the CMB. Synchrotron radiation in an intracluster magnetic field of strength of a few {mu}G is responsible for significant additional electron energy loss. Equipartition between relativistic particle and magnetic field energy densities is a realistic possibility. GHz radiation data from a Coma cluster halo yields information on the high-energy steepening of the cluster relativistic electron spectrum. Cluster microwave emission in the WMAP passbands by higher energy cosmic-ray electrons and gamma-ray emission from an accompanying cosmic-ray proton flux are also considered. The energetic electrons could originate from active galactic nucleus jet injection, then distributed cluster wide by Alfven wave sweeping, with accompanying in situ Fermi acceleration.

  1. Thermal and non-thermal laser dissection.

    PubMed

    Steiner, R

    1994-01-01

    Conventional cw-(continuous wave) laser systems such as the CO2- and Nd:YAG-laser are well established in medical therapy for tumour resection, tissue cutting, vaporisation and coagulation. The argon-ion laser is also a "classic" laser type with applications in ophthalmology, dermatology and for micro-surgery. New lasers in the IR-range of the optical spectrum appear on the market as pulsed lasers for tissue ablation searching for their specific fields of application. There is some confusion about laser applications at the moment until the new techniques and methods have proven to be really superior to other techniques. But knowing more about the laser tissue interactions one can estimate the potential of a new laser source. This article gives a short overview over the actual laser systems and the reaction processes with soft and hard tissue. PMID:8000889

  2. Kinetics of Non-Thermal Atmospheric Pressure

    E-print Network

    Kaganovich, Igor

    statistical properties of avalanches. Random displacement due to diffusion Initial particle position Possible Discharges #12;3 Formation of Microdischarges in DBD Cathode directed streamer Electron Avalanche Avalanche-10 eVAvalanche => Streamer => Microdischarge #12;4 Avalanche to Streamer Transition (2D) System of PDEs

  3. Economic assessment of proposed electric-discharge non-thermal plasma field-pilot demonstration units for NO{sub x} removal in jet-engine exhaust: White paper for SERDP Project CP-1038

    SciTech Connect

    Rosocha, L.A. [Los Alamos National Lab., NM (United States); Chang, J.S.; Urashima, Kuniko; Kim, S.J. [McMaster Univ. (Canada); Miziolek, A.W. [Army Research Lab. (United States)

    1999-01-05

    This project is currently evaluating non-thermal plasma (NTP) technologies for treating jet-engine exhaust arising from DoD test facilities. In the past, some economic analyses for NTP de-NO{sub x} have shown that it is not economical, compared to other techniques. The main reasons for this conclusion was that the previous analyses examined stand-alone, or less mature electrical-discharge reactors, or electron-beam based systems that incorporated both chemical additives and quite expensive electron accelerators. Also, in contrast to more recent developments, both the discharge and electron-beam techniques of the past did not extensively incorporate methods to increase the yields of active NO{sub x}-decomposing species. In an earlier White paper and a Project Report, the authors have analyzed the costs of more mature NTP systems incorporating chemical additives and new-concept NTP technologies for jet-engine emissions control and have shown lower exhaust-gas treatment costs for NTP systems compared to baseline standard de-NO{sub x} technologies like Selective Catalytic Reduction (SCR) combined with a wet scrubber or SCR combined with an electrostatic precipitator (ESP). In this paper, the authors will examine their most-promising candidate NTP reactor systems for a field-pilot demonstration on jet-engine exhaust and discuss the economic analyses for these hybrid units, which show that the economics of the proposed candidate systems are more favorable than earlier NTP reactor economic-assessment conclusions for NO{sub x} removal.

  4. ON THE CLUSTER PHYSICS OF SUNYAEV-ZEL'DOVICH AND X-RAY SURVEYS. I. THE INFLUENCE OF FEEDBACK, NON-THERMAL PRESSURE, AND CLUSTER SHAPES ON Y-M SCALING RELATIONS

    SciTech Connect

    Battaglia, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St George, Toronto, ON M5S 3H4 (Canada); Bond, J. R.; Pfrommer, C.; Sievers, J. L. [Canadian Institute for Theoretical Astrophysics, 60 St George, Toronto, ON M5S 3H8 (Canada)

    2012-10-20

    The utility of large Sunyaev-Zel'dovich (SZ) surveys for determining cosmological parameters from cluster abundances is limited by the theoretical uncertainties in the integrated SZ-flux-to-mass relation, Y-M. We explore how non-thermal pressure and the anisotropic shape of the gas distribution of the intracluster medium (ICM) impacts Y-M scaling using a suite of smoothed particle hydrodynamic simulations of the cosmic web. We contrast results for models with different treatments of entropy injection and transport, varying radiative cooling, star formation and accompanying supernova feedback, cosmic rays, and energetic feedback from active galactic nuclei (AGNs). We find that the gas kinetic-to-thermal pressure ratio, P {sub kin}/P {sub th}, from internal bulk motions depends on the cluster mass, and increases in the outer-cluster due to enhanced substructure, as does the asphericity of the ICM gas. With only a {approx}5%-10% correction to projected (observable) ellipticities, we can infer the three-dimensional ellipticities. Our simulated Y-M slope roughly follows the self-similar prediction, except for a steepening due to a deficit of gas in lower mass clusters at low redshift in our AGN feedback simulations. AGN feedback enhances the overall Y-M scatter, from {approx}11% to {approx}13% (z = 0) and to {approx}15% (z = 1), a reflection of the accretion history variations due to cluster merging. If we split the cluster system into lower, middle, and upper bands of both P {sub kin}/P {sub th} and long-to-short axis ratio, we find a {approx}10% effect on Y-M. Identifying observable second parameters related to internal bulk flows and anisotropy for cluster selection to minimize Y-M scatter in a 'fundamental plane' would allow tighter cosmological parameter constraints.

  5. On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. I. The Influence of Feedback, Non-thermal Pressure, and Cluster Shapes on Y-M Scaling Relations

    NASA Astrophysics Data System (ADS)

    Battaglia, N.; Bond, J. R.; Pfrommer, C.; Sievers, J. L.

    2012-10-01

    The utility of large Sunyaev-Zel'dovich (SZ) surveys for determining cosmological parameters from cluster abundances is limited by the theoretical uncertainties in the integrated SZ-flux-to-mass relation, Y-M. We explore how non-thermal pressure and the anisotropic shape of the gas distribution of the intracluster medium (ICM) impacts Y-M scaling using a suite of smoothed particle hydrodynamic simulations of the cosmic web. We contrast results for models with different treatments of entropy injection and transport, varying radiative cooling, star formation and accompanying supernova feedback, cosmic rays, and energetic feedback from active galactic nuclei (AGNs). We find that the gas kinetic-to-thermal pressure ratio, P kin/P th, from internal bulk motions depends on the cluster mass, and increases in the outer-cluster due to enhanced substructure, as does the asphericity of the ICM gas. With only a ~5%-10% correction to projected (observable) ellipticities, we can infer the three-dimensional ellipticities. Our simulated Y-M slope roughly follows the self-similar prediction, except for a steepening due to a deficit of gas in lower mass clusters at low redshift in our AGN feedback simulations. AGN feedback enhances the overall Y-M scatter, from ~11% to ~13% (z = 0) and to ~15% (z = 1), a reflection of the accretion history variations due to cluster merging. If we split the cluster system into lower, middle, and upper bands of both P kin/P th and long-to-short axis ratio, we find a ~10% effect on Y-M. Identifying observable second parameters related to internal bulk flows and anisotropy for cluster selection to minimize Y-M scatter in a "fundamental plane" would allow tighter cosmological parameter constraints.

  6. Metal-rich multi-phase gas in M87: AGN-driven metal transport, magnetic-field supported multi-temperature gas, and constraints on non-thermal emission observed with XMM-Newton

    E-print Network

    A. Simionescu; N. Werner; A. Finoguenov; H. Boehringer; M. Brueggen

    2008-02-07

    We use deep (~120 ks) XMM-Newton data of the M87 halo to analyze its spatially resolved temperature structure and chemical composition. We focus particularly on the regions of enhanced X-ray brightness associated with the inner radio lobes, which are known not to be described very well by single-temperature spectral models. Compared to a simple two-temperature fit, we obtain a better and more physical description of the spectra using a model that involves a continuous range of temperatures in each spatial bin. The range of temperatures of the multiphase gas spans ~0.6-3.2 keV. Such a multiphase structure is only possible if thermal conduction is suppressed by magnetic fields. In the multi-temperature regions, we find a correlation between the amount of gas cooler than the surrounding X-ray plasma and the metallicity, and conclude that the cool gas is more metal-rich than the ambient halo. We estimate the average Fe abundance of the cool gas to ~2.2 solar. Our results thus point toward the key role of the active galactic nucleus (AGN) in transporting heavy elements into the intracluster medium. The abundance ratios of O/Si/S/Fe in and outside the X-ray arms are similar, indicating that the dominant fraction of metals in the gas halo was uplifted by AGN outbursts relatively recently compared to the age of M87. Our estimate for the mass of the cool gas is 5e8 M_sun, which probably stems from a mixture of ICM, stellar mass loss, and Type Ia supernova products. ~30-110 Myr are required to produce the observed metals in the cool gas. Finally, we put upper limits on possible non-thermal X-ray emission from M87 and, combining it with the 90 cm radio maps, we put lower limits of around ~0.5-1.0 muG on the magnetic field strength.

  7. Low-cost, deterministic quasi-periodic photonic structures for light trapping in thin film silicon solar cells

    E-print Network

    Sheng, Xing

    Light trapping has been an important issue for thin film silicon solar cells because of the low absorption coefficient in the near infrared range. In this paper, we present a photonic structure which combines anodic aluminum ...

  8. Quasi-Periodic Schroedinger Operators in One Dimension, Absolutely Continuous Spectra, Bloch Waves and Integrable Hamiltonian Systems

    Microsoft Academic Search

    Luigi Chierchia

    1986-01-01

    In the first chapter, the eigenvalue problem for a periodic Schrodinger operator, Lf = (-d('2)\\/dx('2) + v)f = Ef, is viewed as a two-dimensional Hamiltonian system which is integrable in the sense of Arnold and Liouville. With the aid of the Floquet-Bloch theory, it is shown that such a system is conjugate to two harmonic oscillators with frequencies (alpha) and

  9. Exploiting visual quasi-periodicity for real-time chewing event detection using active appearance models and support vector machines

    Microsoft Academic Search

    Steven Cadavid; Mohamed Abdel-Mottaleb; Abdelsalam Helal

    Steady increases in healthcare costs and obesity have inspired recent studies into cost-effective, assistive systems capable\\u000a of monitoring dietary habits. Few researchers, though, have investigated the use of video as a means of monitoring dietary\\u000a activities. Video possesses several inherent qualities, such as passive acquisition, that merits its analysis as an input\\u000a modality for such an application. To this end,

  10. Beach-ridge development in Lake Michigan: Shoreline behavior in response to quasi-periodic lake-level events

    USGS Publications Warehouse

    Thompson, T.A.; Baedke, S.J.

    1996-01-01

    Strandplains of arcuate beach ridges are common in coastal embayments in parts of the Great Lakes. Similarities in beach-ridge development and geomorphology are recognizable in many of the embayments in the Lake Michigan basin despite differences in size and shape, available sediment type and supply, predepositional slope and topography, and hydrographic regime between the embayments. These similarities are primarily a product of three scales of quasiperiodic lake-level variation ranging in time from 30 to 600 years and in water level change from 0.5 to 3.7 m. The interaction of these three lake-level variations can be represented on a Curray (1964) diagram (rate of water level change versus rate of sediment supply). The position of any shoreline on the diagram and the type of behavior the shoreline is experiencing is a product of the interaction of the three variations. Two large Strandplains of late Holocene beach ridges occur at opposite ends of Lake Michigan (Toleston Beach and Thompson embayment). The two areas exhibit similar patterns of beach-ridge development for the past 2600 calendar years. That is, both areas form beach ridges about every 30 years. Groups of 4 to 6 beach ridges reflect a longer-term lake-level variation of about 150 years. Only during the largest variation of about 600 years in duration do the two areas differ. The rise to the 1700 cal yr B.P. high caused the erosion of beach ridges back to 2800 cal yrs B.P. in northern Lake Michigan. In southern Lake Michigan, no erosion occurred during this lake level high. Differences in shoreline development between the two areas are related to the rate of sediment supply to the shorelines. As the sediment sink for the southern half of Lake Michigan, the southern strandplain received a greater sediment flux than the northern strandplain during the latter part of the late Holocene and produced a continuous record of beach-ridge development. ?? 1995 Elsevier Science B.V. All rights reserved.

  11. Quasi-periodic oscillations and chaos in ion-gas-discharge actively mode-locked ion lasers

    Microsoft Academic Search

    L. A. Mel'Nikov; Iu. P. Sinichkin; G. N. Tatarkov

    1991-01-01

    The characteristics of the destruction of active mode locking (AML) in an argon-ion laser were investigated theoretically and experimentally. Experimental results showed that the destruction of the AML regime coincides with the appearance of satellite pulses causing regular and chaotic instabilities in the pulse train. A theoretical model is developed for studying the main factors responsible for both the stable

  12. Tight neurovascular coupling in a rat model of quasi-periodic interictal spiking using multispectral optical imaging

    NASA Astrophysics Data System (ADS)

    Pouliot, Philippe; Truong, Van Tri; Zhang, Cong; Dubeau, Simon; Lesage, Frédéric

    2012-10-01

    The hemodynamic responses to 4-aminopyridine (4-AP) induced focal epileptic spikes and electrical stimulations are compared in a rat model. Nonlinearities are quantified with biophysical models. Supranormal oxygen consumption from epileptic spikes is inferred. In one recording, interictal spikes followed an almost periodic pattern. Such rhythmic spiking is a well-documented phenomenon in electrophysiological studies, but the hemodynamics correlates have been less studied. Spikes occurred every 12.5 +/- 1.0 s. Peaks in total hemoglobin (HbT), a proxy for regional cerebral blood volume, followed spikes by 2.6 +/- 0.3 s. Troughs in HbT preceded spikes by 1.68 +/- 1.2 s. The narrowness of this distribution is surprising. From it, one may derive a significant but paradoxical fall in HbT several seconds before the spikes, but which this decrease in HbT is better interpreted as being due to the interictal spike that occurred before.

  13. A class of periodic and quasi-periodic trajectories of particles settling under gravity in a viscous fluid

    E-print Network

    Maria L. Ekiel-Jezewska

    2014-08-25

    We investigate regular configurations of a small number of particles settling under gravity in a viscous fluid. The particles do not touch each other and can move relative to each other. The dynamics is analyzed in the point-particle approximation. A family of regular configurations is found with periodic oscillations of all the settling particles. The oscillations are shown to be robust under some out-of-phase rearrangements of the particles. In the presence of an additional particle above such a regular configuration, the particle periodic trajectories are horizontally repelled from the symmetry axis, and flattened vertically. The results are used to propose a mechanism how a spherical cloud, made of a large number of particles distributed at random, evolves and destabilizes.

  14. Comprehensive Analysis of RXTE Data from Cyg X-1: Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations

    E-print Network

    Nickolai Shaposhnikov; Lev Titarchuk

    2006-02-04

    We present timing and spectral analysis of ~ 2.2 Ms of RXTE archival data from Cyg X-1. Using a generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between the 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index-QPO frequency correlation shows a saturation of the photon index Gamma ~ 2.1 at high values of the low frequency \

  15. Quasi-periodic oscillations in accreting magnetic white dwarfs II. The asset of numerical modelling for interpreting observations

    E-print Network

    Busschaert, C; Michaut, C; Bonnet-Bidaud, J -M; Mouchet, M

    2015-01-01

    Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. High-energy radiation coming from those objects is emitted from the accretion column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. The radiation hydrodynamics code Hades was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. The oscillation frequencies and amplitudes in the X-ray and optic...

  16. Acoustic waveform of continuous bubbling in a non-Newtonian fluid: From laboratory bubbles to quasi-periodic volcanic phenomena

    NASA Astrophysics Data System (ADS)

    Vidal, V.; Ichihara, M.; Ripepe, M.; Kurita, K.

    2009-12-01

    Due to decompression when magma flows up the volcanic conduit, bubbles nucleate, coalesce, rise and explode at the surface of the conduit. On the field, one possible tool to investigate this dynamics is to analyze the acoustic signal produced by the explosion of such bubbles. In order to investigate this phenomenon at the laboratory scale, taking into account the complex lava rheology, we setup the following experiment. A constant air flow-rate is injected at the bottom of a plexiglas cell, filled by a non-Newtonian fluid. Bubbles form, rise, coalesce, and burst at the fluid free surface. A 4-microphones array records the acoustic signal produced by the successive bubble burstings. The bubble rising and explosion dynamics are monitored by both a normal and high-speed video camera. We focus on the acoustic signal associated with the continuous bubble bursting at the fluid surface. Due to the fluid rheological properties, the bubble shape is elongated, and, when bursting at the free surface, acts as a resonator. For a given fluid concentration, at constant flow rate, repetitive bubble bursting occurs at the surface. We report a modulation pattern of the acoustic waveform through time. High-speed images recording shows that the film rupture time directly affects the waveform. Moreover, we point out the existence of a precursor acoustic signal, recorded on the microphone array, previous to each bursting. The time-delay between this precursor and the bursting signal is well correlated with the bursting signal frequency content. Their joint modulation through time is driven by the fluid rheology, which strongly depends on the presence of small, satellite bubbles trapped in the fluid due to the yield stress. Finally, the spectrograms point out a frequency gliding of the harmonics towards higher values, a feature observed on some volcanoes, but still unexplained at present day.

  17. Comparative Kinetic Study and Microwaves Non-Thermal Effects on the Formation of Poly(amic acid) 4,4?-(Hexafluoroisopropylidene)diphthalic Anhydride (6FDA) and 4,4?-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction Activated by Microwave, Ultrasound and Conventional Heating

    PubMed Central

    Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

    2011-01-01

    Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system. PMID:22072913

  18. Neptune's non-thermal radio emissions - Phenomenology and source locations

    NASA Technical Reports Server (NTRS)

    Rabl, Gerald K. F.; Ladreiter, H.-P.; Rucker, Helmut O.; Kaiser, Michael L.

    1992-01-01

    During the inbound and the outbound leg of Voyager 2's encounter with Neptune, the Planetary Radio Astronomy (PRA) experiment aboard the spacecraft detected short radio bursts at frequencies within the range of about 500-1300 kHz, and broad-banded smoothly varying emission patterns within the frequency range from about 40-800 kHz. Both emissions can be described in terms of a period of 16.1 hours determining Neptune's rotation period. Furthermore, just near closest approach, a narrow-banded smoothly varying radio component was observed occurring between 600 and 800 kHz. After giving a brief overview about some general characteristics of Neptune's nonthermal radio emission, the source locations of Neptune's emission components are determined, using an offset tilted dipole model for Neptune's magnetic field. Assuming that the emission originates near the electron gyrofrequency a geometrical beaming model is developed in order to fit the observed emission episodes.

  19. Microwave interferometry for high pressure non-thermal pulsed plasma

    Microsoft Academic Search

    Xinpei Lu; M. Laroussi

    2008-01-01

    Summary form only given. Atmospheric pressure non-equilibrium plasmas are now used in many applications including those where low-pressure plasmas have traditionally been used. However, measurements of key plasma parameters in the highly collisional regime exhibited at atmospheric pressure offer challenges, which usually have to satisfy requirements that are different than those found at low pressures. In this paper, a millimeter

  20. Atmospheric Pressure Non-Thermal Air Plasma Jet

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam; Al-Mashraqi, Ahmed; Benghanem, Mohamed; Al Shariff, Samir

    2013-09-01

    Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. This work was supported by the National Science, Technology and Innovation Plan(NSTIP) through the Science and Technology Unit (STU) at Taibah University, Al Madinah Al Munawwarah, KSA, with the grant number 08-BIO24-5.