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1

Distant quasi-periodic orbits around Mercury  

NASA Astrophysics Data System (ADS)

In this paper, distant quasi-periodic orbits around Mercury are studied for future Mercury missions. All of these orbits have relatively large sizes, with their altitudes near or above the Mercury sphere of influence. The research is carried out in the framework of the elliptic restricted three-body problem (ER3BP) to account for the planet's non-negligible orbital eccentricity. Retrograde and prograde quasi-periodic trajectories in the planar ER3BP are generalized from periodic orbits in the CR3BP by the homotopy algorithm, and the shape evolution of such quasi-periodic trajectories around Mercury is investigated. Numerical simulations are performed to evaluate the stability of these distant orbits in the long term. These two classes of orbits present different characteristics: retrograde orbits can maintain shape stability with a large size, although the trajectories in some regions may oscillate with larger amplitudes; for prograde orbits, the range of existence is much smaller, and their trajectories easily move away from the vicinity of Mercury when the orbits become larger. Distant orbits can be used to explore the space environment in the vicinity of Mercury, and some orbits can be taken as transfer orbits for low-cost Mercury return missions or other programs for their high maneuverability.

Ma, Xue; Li, Junfeng

2013-01-01

2

Quasi-periodicities in Chinese precipitation time series  

NASA Astrophysics Data System (ADS)

Although climate change deeply affects China, climatic time series are expected to show quasi-periodic behavior. This hypothesis has been tested by means of Autocorrelation Spectral Analysis (ASA) to detect quasi-periodicities in precipitation time series of 132 climate stations spread over China for the period from 1951 to 2002. A Continuous Wavelet Transform (CWT) has also been applied in order to examine if these quasi-periods are stable in time. Finally, it has been tested whether precipitation series recorded at neighboring stations show similar spectral behavior and can thus be grouped. All in all, our hypothesis regarding quasi-periodicities has been verified. Most of the time series show significant quasi-periods. A 2-3 year quasi-periodicity is predominant in many different regions of China. The result of ASA is that precipitation series from neighboring stations often show similar quasi-periods and therefore a grouping seems to be justified. However, the outcome of CWT provides more detailed information. In north-eastern China several series show similar quasi-periods which are statistically significant at different times; here, a grouping would be incorrect. In addition, the results of CWT show a less uniform pattern of quasi-periods in the southern inland regions. Whereas ASA shows a relatively uniform pattern of 2-3 year quasi-periods, CWT detects 2-3, 4-5 and 6-7 year quasi-periods. Nevertheless, although the quasi-periods are detected as being unstable, time series from neighboring stations sometimes show analogous significant quasi-periods within the same time frame and can thus be grouped. This can be seen in the northern part of central China, near the border to North Korea and along the coast of the South China Sea.

Hartmann, H.; Becker, S.; King, L.

2008-05-01

3

Embedding of Analytic Quasi-Periodic Cocycles into Analytic Quasi-Periodic Linear Systems and its Applications  

NASA Astrophysics Data System (ADS)

In this paper, we prove that any analytic quasi-periodic cocycle close to constant is the Poincaré map of an analytic quasi-periodic linear system close to constant, which bridges both methods and results in quasi-periodic linear systems and cocycles. We also show that the almost reducibility of an analytic quasi-periodic linear system is equivalent to the almost reducibility of its corresponding Poincaré cocycle. By the local embedding theorem and the equivalence, we transfer the recent local almost reducibility results of quasi-periodic linear systems (Hou and You, in Invent Math 190:209-260, 2012) to quasi-periodic cocycles, and the global reducibility results of quasi-periodic cocycles (Avila, in Almost reducibility and absolute continuity, 2010; Avila et al., in Geom Funct Anal 21:1001-1019, 2011) to quasi-periodic linear systems. Finally, we give a positive answer to a question of Avila et al. (Geom Funct Anal 21:1001-1019, 2011) and use it to study point spectrum of long-range quasi-periodic operator with Liouvillean frequency. The embedding also holds for some nonlinear systems.

You, Jiangong; Zhou, Qi

2013-11-01

4

Characteristics of quasi-periodic scintillations observed at low latitude  

NASA Astrophysics Data System (ADS)

Quasi-periodic scintillations are characterized as primary deep fadeout in field strength, associated with regular ringing patterns before and after it. In this paper, observations of quasi-periodic scintillations using geostationary satellite (FLEETSAT) transmissions operating at frequency 250 MHz at low-latitude ground station, Varanasi (geomagnetic latitude 14°55'N, longitude 153°59'E), are reported. The results indicate that the quasi-periodic scintillations are most likely produced by plasma blobs/bubbles present in the E and F regions of the ionosphere which are helpful in identifying the generation mechanism of the associated irregularities. The various characteristic features of the different types of quasi-periodic scintillations observed at low latitude are discussed for the first time in detail based on a highly comprehensive analysis of longer data sets using autocorrelation, power spectrum, and scintillation index analysis. The computed horizontal scale size of the quasi-periodic scintillations producing irregularity varies from 100 to 1300 m which shows that the irregularities are of intermediate-scale sizes. The spectral index obtained from the slopes of power spectrum varies from -2 to -8. All of these observed results are important for identifying the generation mechanism of ionospheric irregularities associated with quasi-periodic scintillations. The observed fading patterns, especially the modulation of the diffraction patterns (fading envelopes), can be explained by considering an obstacle called radio lens in the ionosphere elongated in one direction. For the first time, we have successfully simulated the amplitude versus time plots of almost all types of quasi-periodic scintillation patches and found that our modeled and observed characteristics of quasi-periodic scintillation patches compare well with each other.

Patel, Kalpana; Singh, Ashutosh K.; Singh, A. K.; Singh, R. P.

2009-12-01

5

Periodic and Quasi-Periodic Structures for Antenna Applications  

Microsoft Academic Search

Printed periodic and quasi-periodic structures can be employed to control reflection and transmission properties of incident waves as a function of structure geometry. As this can be done mostly independently for both polarizations, different kinds of polarizers (reflection and transmission polarizer from linear to circular polarization or twist polarizers) can be realized. A local variation of element geometry allow the

Dietmar Pilz; Wolfgang Menzel

1999-01-01

6

Quasi-periodic quantum dot arrays produced by electrochemical synthesis  

SciTech Connect

We discuss a ``gentle`` electrochemical technique for fabricating quasi-periodic quantum dot arrays. The technique exploits a self-organizing phenomenon to produce quasi-periodic arrangement of dots and provides excellent control over dot size and interdot spacing. Unlike conventional nanolithography, it does not cause radiation damage to the structures during exposure to pattern delineating beams (e-beam, ion-beam or x-ray). Moreover, it does not require harsh processing steps like reactive ion etching, offers a minimum feature size of {approximately}40 {angstrom}, allows the fabrication of structures on nonplanar surfaces (e.g. spherical or cylindrical substrates), is amenable to mass production (millions of wafers can be processed simultaneously) and is potentially orders of magnitude cheaper than conventional nanofabrication. In this paper, we describe our initial results and show the promise of this technique for low-cost and high-yield nanosynthesis.

Bandyopadhyay, S.; Miller, A.E.; Yue, D.F.; Banerjee, G. [Univ. of Notre Dame, Notre Dame, IN (United States). Dept. of Electrical Engineering; Ricker, R.E.; Jones, S. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Materials Science and Engineering Laboratory; Eastman, J.A. [Argonne National Lab., IL (United States); Baugher, E.; Chandrasekhar, M. [Univ. of Missouri-Columbia, Columbia, MS (United States). Dept. of Physics and Astronomy

1994-06-01

7

Localization in a Quasi-Periodic One Dimensional System  

Microsoft Academic Search

We study mobility edges and Anderson-like localization in a disorder-free, one-dimensional quasi-periodic system. In particular, we study a bichromatic sinusoidal lattice potential where a primary periodic lattice is perturbed by a secondary lattice with a period that is incommensurate with that of the primary lattice. This interesting potential admits both extended and localized states without the presence of disorder. We

John Biddle; Donald Priour; Sankar Das Sarma

2009-01-01

8

A quasi-periodic hybrid undulator at BESSY II  

NASA Astrophysics Data System (ADS)

At BESSY II the first quasi-periodic hybrid type undulator has been installed. The magnetic structure has been optimized for higher order suppression and simultaneously for high flux in the (shifted) 5th harmonic to provide an useful energy range between 20 and 500eV. At smallest gap of 15mm the device operates as a wiggler with a /K-value of 16.

Bahrdt, J.; Frentrup, W.; Gaupp, A.; Scheer, M.; Gudat, W.; Ingold, G.; Sasaki, S.

2001-07-01

9

QUASI-PERIODIC OSCILLATIONS IN LASCO CORONAL MASS EJECTION SPEEDS  

SciTech Connect

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.

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

10

Detecting circumbinary planets: A new quasi-periodic search algorithm  

NASA Astrophysics Data System (ADS)

We present a search method based around the grouping of data residuals, suitable for the detection of many quasi-periodic signals. Combined with an efficient and easily implemented method to predict the maximum transit timing variations of a transiting circumbinary exoplanet, we form a fast search algorithm for such planets. We here target the Kepler dataset in particular, where all the transiting examples of circumbinary planets have been found to date. The method is presented and demonstrated on two known systems in the Kepler data.

Armstrong, D.; Pollacco, D.

2013-04-01

11

The quasi-periodicity of the minority game revisited  

NASA Astrophysics Data System (ADS)

We analyze two well-known related aspects regarding the sequence of minority sides from the Minority Game (MG) in its symmetric phase: period-two dynamics and quasi-periodic behavior. We also study the sequence of minority sides in a general way within a graph-theoretical framework. In order to analyze the outcome dynamics of the MG, it is useful to define the MG, namely an MG with a new choosing rule of the strategy to play, which takes into account both prior preferences and game information. In this way, each time an agent is undecided because two of her best strategies predict different choices while being equally successful so far, she selects her a priori favorite strategy to play, instead of performing a random tie-break as in the MG. This new choosing rule leaves the generic behavior of the model unaffected and simplifies the game analysis. Furthermore, interesting properties arise which are only partially present in the MG, like the quasi-periodic behavior of the sequence of minority sides, which turns out to be periodic for the MG.

Acosta, Gabriel; Caridi, Inés; Guala, Sebastián; Marenco, Javier

2013-10-01

12

Quasi-periodic oscillations in the Z source GX 340 +  

NASA Astrophysics Data System (ADS)

X-ray observations of the Z source GX 340 + 0 with the Ginga Observatory have found the source in three spectral states: the flaring branch (FB), the normal branch (NB) and the horizontal branch (HB). In accordance with previous observations, quasi-periodic oscillations (QPO) with frequencies 32-50 Hz were observed in the HB and near 6 Hz in a portion of the NB. In the HB the power spectra also showed low-frequency noise (LFN). The fractional rms variation of both types of QPO and of the LFN were strongly dependent on the X-ray energy band. Rough values for all three were about 2 percent at about 3 keV and about 8 percent at about 12 keV.

Penninx, W.; Lewin, W. H. G.; Tan, J.; Mitsuda, K.; van der Klis, M.; van Paradijs, J.

1991-03-01

13

Energy dependence of kilohertz quasi-periodic oscillations  

NASA Astrophysics Data System (ADS)

Kilohertz quasi-periodic oscillations (kHz QPOs) are the fastest variability features from the low mass X-ray binaries (LMXBs) originally discovered in 1996 with Rossi X-ray Timing Explorer (RXTE). Most of the Z sources as well as several atoll sources have shown this timing feature. The physical origin of the kHz QPOs is still unknown, although many theoretical models are available in the literature. The energy dependence of rms amplitude from the kHz QPOs could be a potentially important tool to understand the spectral origin of this timing feature. We have studied this energy dependence in details for a large number kHz QPOs from a neutron star LMXB. We have also done simulations to test basic models. Here we will present the observed results and the simulations as well as the basic implications of the results. We will briefly mention the role of ASTROSAT in this regard.

Mukherjee, Arunava; Bhattacharyya, Sudip

2012-07-01

14

Peculiar microwave quasi-periodic pulsations with zigzag pattern in a CME-related Flare on 2005-01-15  

NASA Astrophysics Data System (ADS)

A microwave quasi-periodic pulsation with zigzag pattern (Z-QPP) in a solar flare on 2005-01-15 is observed by the Chinese Solar Broadband Spectrometer in Huairou (SBRS/Huairou) at 1.10-1.34 GHz. The zigzag pulsation occurred just in the early rising phase of the flare with weakly right-handed circular polarization. Its period is only several decades millisecond. Particularly, before and after the pulsation, there are many spectral fine structures, such as zebra patterns, fibers, and millisecond spikes. The microwave Z-QPP can provide some kinematic information of the source region in the early rising phase of the flare, and the source width changes from ~1000 km to 3300 km, even if we have no imaging observations. The abundant spectral fine structures possibly reflect the dynamic features of non-thermal particles.

Tan, Baolin

2013-07-01

15

Quasi-Periodic Oscillations in AM Herculis Binaries  

NASA Astrophysics Data System (ADS)

AM Her variables are close-binary systems in which a white dwarf with a magnetic field of 20--70 MG accretes matter from a companion star. Theoretical studies of magnetically channeled accretion flows in such systems predict that the shock formed near the white dwarf should oscillate with periods of order 0.1--1 s. Optical high-speed photometry has indeed shown the existence of such rapid, quasi-periodic oscillations in some AM Her binaries, but not in others. We will use HST to obtain simultaneous UV and optical high-speed photometry of several AM Her systems, in order to explore further the nature of the oscillations, and to extend the search into the UV. HSP observations of two systems (VV Pup and ST LMi, in which the accreting magnetic pole periodically passes behind the limb of the white dwarf) will allow detailed eclipse mapping of the accretion column and the shock oscillations to be carried out. This proposal was initially accepted for Cycle 1, but ultimately received Supplementary status in the reassessment. We are therefore resubmitting it for Cycle 2.

Chanmugam, G.

1992-07-01

16

Quasi-Periodic Variably Polarizing Undulator at HiSOR  

NASA Astrophysics Data System (ADS)

A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At the minimum gap, achievable lowest photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. Observed photon energies of fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured magnetic field of undulator and the HiSOR beam parameters. Also, observed flux through a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

Sasaki, S.; Miyamoto, A.; Goto, K.; Arita, M.; Okuda, T.; Mitsuyasu, T.; Fujioka, K.; Namatame, H.; Taniguchi, M.

2013-03-01

17

Bifurcations of quasi-periodic dynamics: torus breakdown  

NASA Astrophysics Data System (ADS)

To study the dynamics of quasi-periodic bifurcations, we consider a system of two nonlinearly coupled oscillators using averaging, continuation and numerical bifurcation techniques. This relatively simple system displays considerable complexity. Assuming the internal resonance to be 1:2, we find a 2?-periodic solution which undergoes a supercritical Neimark-Sacker bifurcation, yielding a stable torus. Choosing a route in parameter space, we show by numerical bifurcation techniques how the torus gets destroyed by dynamical and topological changes in the involved manifolds (Krauskopf and Osinga in J Comput Phys 146:404-419, 1998). The 1:6 resonance turns out to be prominent in parameter space, and we detected a cascade of period doublings within the corresponding resonance tongue yielding a strange attractor. The phenomena agree with the Ruelle-Takens (Commun. Math. Phys. 20:167-192, 1971, Commun. Math. Phys. 23:343-344, 1971) scenario leading to strange attractors. Other periodic regimes are present in this system, and there is interesting evidence that two different regimes interact with each other, yielding yet another type of strange attractor. In this context, certain ?-periodic solutions emerge that are studied by continuation following the Poincaré-Lindstedt method using Mathieu functions; when the implicit function theorem breaks down, the analysis is supplemented by numerical bifurcation techniques.

Bakri, Taoufik; Verhulst, Ferdinand

2013-09-01

18

Are Flare Quasi-periodic Pulsations Signatures of Intermittent Reconnection?  

NASA Astrophysics Data System (ADS)

Flare quasi-periodic pulsations (QPPs) have been observed over a vast energy spectrum, from radio to hard x-rays. The periodicities of these fine structures range from tens of milliseconds to tens of seconds and suggest highly structured but intermittent energy release. In some cases, the sources of microwaves and thermal hard x-rays are situated near the apex of the flare loop arcades and are not stationary. Although it is unclear whether all the observed varieties of QPPs can be explained via a single, unified process, our recent high-resolution simulations of a breakout eruptive flare (Karpen et al. 2012) indicate that spatially and temporally localized reconnection is a plausible candidate for these bursts of radiation. With our null-tracking capabilities, we follow the creation and evolution of X- and O-type nulls in the flare current sheet and characterize their periodicity. QPPs located at the apex of the flare arcade may result from the interaction of downward-moving islands in the sheet with the arcade below. Each island is composed of highly twisted magnetic field lines that comprise a single reconnected flux tube. Upon arrival at the top of the flare loops, secondary reconnection events between the island and the arcade produce discrete energy release events that could be related to observed QPPs in that region. Different regimes of current-sheet reconnection (slow/fast), island sizes, rates of island coalescence, and rates of reconnection between islands and arcades may all help to explain the variety of energy and time scales exhibited by the flare QPPs.Abstract (2,250 Maximum Characters): Flare quasi-periodic pulsations (QPPs) have been observed over a vast energy spectrum, from radio to hard x-rays. The periodicities of these fine structures range from tens of milliseconds to tens of seconds and suggest highly structured but intermittent energy release. In some cases, the sources of microwaves and thermal hard x-rays are situated near the apex of the flare loop arcades and are not stationary. Although it is unclear whether all the observed varieties of QPPs can be explained via a single, unified process, our recent high-resolution simulations of a breakout eruptive flare (Karpen et al. 2012) indicate that spatially and temporally localized reconnection is a plausible candidate for these bursts of radiation. With our null-tracking capabilities, we follow the creation and evolution of X- and O-type nulls in the flare current sheet and characterize their periodicity. QPPs located at the apex of the flare arcade may result from the interaction of downward-moving islands in the sheet with the arcade below. Each island is composed of highly twisted magnetic field lines that comprise a single reconnected flux tube. Upon arrival at the top of the flare loops, secondary reconnection events between the island and the arcade produce discrete energy release events that could be related to observed QPPs in that region. Different regimes of current-sheet reconnection (slow/fast), island sizes, rates of island coalescence, and rates of reconnection between islands and arcades may all help to explain the variety of energy and time scales exhibited by the flare QPPs.

Guidoni, Silvina; Karpen, J. T.; DeVore, C. R.

2013-07-01

19

Quasi-Periodic Electron Bursts in the Jovian Magnetosphere  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

20

Chaotic Oscillations via Quasi-Periodicity Caused by Applying External Modulation in Ionization Waves  

Microsoft Academic Search

Dynamical behavior of nonlinear ionization waves excited in positive columns of glow discharge is investigated with external modulation. It is well known that competition of two frequencies leads the system into a state of chaotic motion via quasi-periodicity as mentioned in Ruelle and Takens scenario (D. Ruelle and F. Takens, Commun. Math. Phys. 20, 167 (1971)). Here, quasi-periodic route to

FUKUYAMA Takao; KOZAKOV Ruslan; TESTRICH Holger; WILKE Christian; KAWAI Yoshinobu

2004-01-01

21

All optical Schmitt trigger based on nonlinear quasi periodic photonic crystals  

NASA Astrophysics Data System (ADS)

All optical Schmitt trigger based on Kerr bistability in quasi periodic Thue-Morse photonic crystals is investigated. Finite difference time domain is used to investigate the Schmitt trigger operation in one dimensional nonlinear Thue-Morse Photonic crystals.

Teimourpour, Mohammad Hosain

2011-11-01

22

Quasi-periodic Oscillations in XMM-Newton Timing data of Blazars  

NASA Astrophysics Data System (ADS)

In the present talk, I will report our findings of Quasi-periodic Oscillations in XMM-Newton light curves of Blazars. I will also discuss the possible radio-loud active galactic nuclei models which can explain our findings.

Gupta, Alok Chandra

2012-07-01

23

Quasi-periodic Green's functions of the Helmholtz and Laplace equations  

Microsoft Academic Search

A classical problem of free-space Green's function G0Lambda representations of the Helmholtz equation is studied in various quasi-periodic cases, i.e., when an underlying periodicity is imposed in less dimensions than is the dimension of an embedding space. Exponentially convergent series for the free-space quasi-periodic G0Lambda and for the expansion coefficients DL of G0Lambda in the basis of regular (cylindrical in

Alexander Moroz

2006-01-01

24

Omnidirectional reflection from one-dimensional quasi-periodic photonic crystal containing left-handed material  

Microsoft Academic Search

In this Letter, we study the properties of one-dimensional quasi-periodic photonic crystal containing left-handed material. In the light of the dispersion relation, we show that one-dimensional quasi-periodic photonic crystal can exhibit complete reflection at a given microwave frequency for all incident angles and both polarizations (s- and p-polarizations). The influence of left-handed material's permittivity and permeability on the omnidirectional reflection

H. X. da; C. Xu; Z. Y. Li

2005-01-01

25

The global long-range order of quasi-periodic patterns in Islamic architecture.  

PubMed

Three decades after their discovery, the unique long-range structure of quasicrystals still poses a perplexing puzzle. The fact that some ancient Islamic patterns share similar quasi-periodic symmetries has prompted several scientists to investigate their underlying geometry and construction methods. However, available structural models depend heavily on local rules and hence they were unable to explain the global long-range order of Islamic quasi-periodic patterns. This paper shows that ancient designers, using simple consecutive geometry, have resolved the complicated long-range principles of quasi-periodic formations. Derived from these principles, a global multi-level structural model is presented that is able to describe the global long-range translational and orientational order of quasi-periodic formations. The proposed model suggests that the position of building units, locally and globally, is defined by one framework, and not tiled based on local rules (matching, overlapping or subdividing). In this way, quasi-periodic formations can grow rapidly ad infinitum without the need for any defects or mismatches. The proposed model, which presents a novel approach to the study of quasi-periodic symmetries, will hopefully provide a deeper understanding of the structure of quasicrystals at an atomic scale, allowing scientists to achieve improved control over their composition and structure. PMID:22338658

Al Ajlouni, Rima A

2012-01-05

26

Radiation characteristics of quasi-periodic radio bursts in the Jovian high-latitude region  

NASA Astrophysics Data System (ADS)

Ulysses had a "distant encounter" with Jupiter in February 2004. The spacecraft passed from north to south, and it observed Jovian radio waves from high to low latitudes (from +80° to +10°) for few months during its encounter. In this study, we present a statistical investigation of the occurrence characteristics of Jovian quasi-periodic bursts, using spectral data from the unified radio and plasma wave experiment (URAP) onboard Ulysses. The latitudinal distribution of quasi-periodic bursts is derived for the first time. The analysis suggested that the bursts can be roughly categorized into two types: one having periods shorter than 30 min and one with periods longer than 30 min, which is consistent with the results of the previous analysis of data from Ulysses' first Jovian flyby [MacDowall, R.J., Kaiser, M.L., Desch, M.D., Farrell, W.M., Hess, R.A., Stone, R.G., 1993. Quasi-periodic Jovian radio bursts: observations from the Ulysses radio and plasma wave. Experiment. Planet. Space Sci. 41, 1059-1072]. It is also suggested that the groups of quasi-periodic bursts showed a dependence on the Jovian longitude of the sub-solar point, which means that these burst groups are triggered during a particular rotational phase of the planet. Maps of the occurrence probability of these quasi-periodic bursts also showed a unique CML/MLAT dependence. We performed a 3D ray tracing analysis of the quasi-periodic burst emission to learn more about the source distribution. The results suggest that the longitudinal distribution of the occurrence probability depends on the rotational phase. The source region of quasi-periodic bursts seems to be located at an altitude between 0.4 and 1.4 Rj above the polar cap region ( L>30).

Kimura, Tomoki; Tsuchiya, Fuminori; Misawa, Hiroaki; Morioka, Akira; Nozawa, Hiromasa

2008-12-01

27

The Spectroscopic Signature of Quasi-periodic Upflows in Active Region Timeseries  

NASA Astrophysics Data System (ADS)

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 ~100 km s-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 & 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.

Tian, Hui; McIntosh, Scott W.; De Pontieu, Bart

2011-02-01

28

Visualization of the Laminar Separation Bubble Undergoing Quasi-Periodical Behavior near Stall  

NASA Astrophysics Data System (ADS)

Flow visualization study was conducted to investigate the quasi-periodical behavior of the laminar separation bubble formed on a NACA0012 airfoil at the angles of attack ?=11 12º. The Reynolds number based on the airfoil chord was Re=1.3×105. At ?=11.5º, the flow over the airfoil quasi-periodically switches between a large separated flow and an attached flow with small separation near the leading edge at a frequency of about 2Hz. This attached flow resembles the flow pattern with a short bubble formed near the leading edge such as at ?=10º. Ejection of large vortices downstream was observed during the quasi-periodical switching. The flow stays attached to the airfoil surface at ?=11º. As the angle of attack is increased, the large separated flow becomes dominant. At ?=12º, the flow is completely separated largely.

Tanaka, Hiroyuki; Rinoie, Kenichi; Sunada, Yasuto

29

Phase Registration of a Single Quasi-Periodic Signal Using Self Dynamic Time Warping  

Microsoft Academic Search

\\u000a This paper proposes a method for phase registration of a single non-parametric quasi-periodic signal. After a short-term period\\u000a has been detected for each sample by normalized autocorrelation, Self Dynamic Time Warping (Self DTW) between a quasi-periodic\\u000a signal and that with multiple-period shifts is applied to obtain corresponding samples of the same phase. A phase sequence\\u000a is finally estimated by the

Yasushi Makihara; Trung Ngo Thanh; Hajime Nagahara; Ryusuke Sagawa; Yasuhiro Mukaigawa; Yasushi Yagi

2010-01-01

30

A quasi-periodic oscillation in the blazar J1359+4011  

NASA Astrophysics Data System (ADS)

The Owens Valley Radio Observatory 40-m telescope has been monitoring the 15-GHz radio flux density of over 1200 blazars since 2008. The 15-GHz light curve of the flat spectrum radio quasar J1359+4011 shows a strong and persistent quasi-periodic oscillation. The time-scale of the oscillation varies between 120 and 150 d over an ˜4 year time span. We interpret this as the active galactic nucleus mass-scaled analogue of low-frequency quasi-periodic oscillations from Galactic microquasars or as evidence of modulation of the accretion flow by thermal instabilities in the `inner' accretion disc.

King, O. G.; Hovatta, T.; Max-Moerbeck, W.; Meier, D. L.; Pearson, T. J.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.; Shepherd, M. C.

2013-11-01

31

Third-harmonic generation in a general two-component quasi-periodic optical superlattice.  

PubMed

The quasi-periodic optical superlattice is a promising material for use in optical frequency conversion. We propose a method for designing a quasi-periodic structure for efficient third-harmonic generation (THG) at any given wavelength. With this method we have made a LiTaO(3) sample in which 27% THG at 0.48microm was achieved, together with a series of highly efficient multiwavelength second-harmonic generation outputs. The result is in good agreement with the theoretical prediction. PMID:18040485

Zhang, C; Wei, H; Zhu, Y Y; Wang, H T; Zhu, S N; Ming, N B

2001-06-15

32

A quasi-periodic oscillation in the blazar J1359+4011  

NASA Astrophysics Data System (ADS)

The Owens Valley Radio Observatory 40-m telescope has been monitoring the 15-GHz radio flux density of over 1200 blazars since 2008. The 15-GHz light curve of the flat spectrum radio quasar J1359+4011 shows a strong and persistent quasi-periodic oscillation. The time-scale of the oscillation varies between 120 and 150 d over an ˜4 year time span. We interpret this as the active galactic nucleus mass-scaled analogue of low-frequency quasi-periodic oscillations from Galactic microquasars or as evidence of modulation of the accretion flow by thermal instabilities in the `inner' accretion disc.

King, O. G.; Hovatta, T.; Max-Moerbeck, W.; Meier, D. L.; Pearson, T. J.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.; Shepherd, M. C.

2013-09-01

33

Quasi-periodic distribution of plasmon modes in two-dimensional Fibonacci arrays of metal nanoparticles.  

PubMed

In this paper we investigate for the first time the near-field optical behavior of two-dimensional Fibonacci plasmonic lattices fabricated by electron-beam lithography on transparent quartz substrates. In particular, by performing near-field optical microscopy measurements and three dimensional Finite Difference Time Domain simulations we demonstrate that near-field coupling of nanoparticle dimers in Fibonacci arrays results in a quasi-periodic lattice of localized nanoparticle plasmons. The possibility to accurately predict the spatial distribution of enhanced localized plasmon modes in quasi-periodic Fibonacci arrays can have a significant impact for the design and fabrication of novel nano-plasmonics devices. PMID:18542657

Dallapiccola, Ramona; Gopinath, Ashwin; Stellacci, Francesco; Dal Negro, Luca

2008-04-14

34

Quasi-periodic solutions and periodic bursters in quasiperiodically driven oscillators  

NASA Astrophysics Data System (ADS)

In this paper, we propose a perturbation method to determine an approximation and conditions of existence of quasi-periodic (QP) solutions and bursting dynamics in a quasi-periodically driven system. The QP forcing consists of two periodic excitations, one with a very slow frequency and the other with a frequency of the same order of the proper frequency of the oscillator. A first averaging is done over the fast dynamics, then the quasi-static solutions of the modulation equations of amplitude and phase are determined and their stability analyzed. We show that a necessary condition for the occurrence of periodic bursters is that the slow excitation is parametric.

Lakrad, Faouzi; Belhaq, Mohamed

2009-05-01

35

Normal-internal resonances in quasi-periodically forced oscillators: a conservative approach  

NASA Astrophysics Data System (ADS)

We perform a bifurcation analysis of normal-internal resonances in parametrized families of quasi-periodically forced Hamiltonian oscillators, for small forcing. The unforced system is a one degree of freedom oscillator, called the `backbone' system; forced, the system is a skew-product flow with a quasi-periodic driving with n basic frequencies. The dynamics of the forced system are simplified by averaging over the orbits of a linearization of the unforced system. The averaged system turns out to have the same structure as in the well-known case of periodic forcing (n = 1); for a real analytic system, the non-integrable part can even be made exponentially small in the forcing strength. We investigate the persistence and the bifurcations of quasi-periodic n-dimensional tori in the averaged system, filling normal-internal resonance `gaps' that had been excluded in previous analyses. However, these gaps cannot completely be filled up: secondary resonance gaps appear, to which the averaging analysis can be applied again. This phenomenon of `gaps within gaps' makes the quasi-periodic case more complicated than the periodic case.

Broer, Henk; Hanßmann, Heinz; Jorba, Àngel; Villanueva, Jordi; Wagener, Florian

2003-09-01

36

Methods for Probing Quasi-Periodic Oscillations on Short Time Scales.  

National Technical Information Service (NTIS)

Optimal filter analysis techniques are employed in order to set constraints on the nature of possible relationships between Low Frequency Noise (LFN) and Quasi-Periodic Oscillations (QPOs) in GX5-1 on time scales near the QPO coherence length. Simulations...

J. P. Norris P. Hertz K. S. Wood B. A. Vaughan P. F. Michelson

1989-01-01

37

Simultaneous observations of Jovian quasi-periodic radio emissions by the Galileo and Cassini spacecraft  

Microsoft Academic Search

The gravity-assist flyby by Cassini of Jupiter on 30 December 2000 and the extended Galileo orbital mission provided a unique opportunity to obtain simultaneous measurements with two spacecraft of many Jovian plasma wave and radio emissions. One of these emissions is Jovian type III radio emissions, also known as Jovian quasi-periodic (QP) emissions. The simultaneous observations of the QP emissions

G. B. Hospodarsky; W. S. Kurth; B. Cecconi; D. A. Gurnett; M. L. Kaiser; M. D. Desch; P. Zarka

2004-01-01

38

Construction of Solutions of Linear Differential Equations with Quasi-Periodic Coefficients.  

National Technical Information Service (NTIS)

The authors consider the problem of constructing a general solution of the system dx/dt = Ax + P(omega t)x, the right-hand side of which is smooth and quasi-periodic with respect to t with a frequency basis omega = (omega sub 1,...,omega sub n). When spec...

Y. A. Mitropolskii A. M. Samoilenko

1968-01-01

39

Formation and Quasi-Periodic Behavior of Outer Spiral Rainbands in a Numerically Simulated Tropical Cyclone  

NASA Astrophysics Data System (ADS)

The formation and quasi-periodic behavior of outer spiral rainbands in a tropical cyclone simulated in the cloud-resolving tropical cyclone model version 4 (TCM4) are analyzed. The outer spiral rainbands in the simulation are preferably initiated near the 60-km radius, or roughly about three times the radius of maximum wind (RMW). After initiation, they generally propagate radially outward with a mean speed of ~5 m s-1. They are reinitiated quasi-periodically with a period between 22 h and 26 h in the simulation. While the inner spiral rainbands, which form within a radius of about three times the RMW, are characterized by the convectively coupled vortex Rossby waves (VRWs), the formation of outer spiral rainbands, namely, rainbands formed outside a radius of about three times the RMW, is much more complicated. It is shown that outer spiral rainbands are triggered by the inner-rainband remnants immediately outside the rapid filamentation zone and inertial instability in the upper troposphere. The preferred radial location of initiation of outer spiral rainbands is understood as a balance between the suppression of deep convection by rapid filamentation and the favorable dynamical and thermodynamic conditions for initiation of deep convection. The quasi-periodic occurrence of outer spiral rainbands is found to be associated with the boundary layer recovery from the effect of convective downdrafts and the consumption of convective available potential energy (CAPE) by convection in the previous outer spiral rainbands. Specifically, once convection is initiated and organized in the form of outer spiral rainbands, it will produce strong downdrafts and consume CAPE. These effects weaken convection near its initiation location. As the rainband propagates outward further, the boundary layer air near the original location of convection initiation takes about 10 h to recover by extracting energy from the underlying ocean. Convection and thus new outer spiral rainbands will be initiated near a radius of about three times the RMW. This will be followed by a similar outward propagation and the subsequent boundary layer recovery, leading to a quasi-periodic occurrence of outer spiral rainbands. In response to the quasi-periodic appearance of outer spiral rainbands, the storm intensity experiences a similar quasi-periodic oscillation with its intensity or intensification rate starting to decrease after about 4 h of the initiation of an outer spiral rainband. The results provide an alternative explanation or one of the mechanisms that are responsible for the quasi-periodic (quasi-diurnal) variation in the intensity and in the area of outflow-layer cloud canopy of observed tropical cyclones.

Li, Q.; Wang, Y.

2012-04-01

40

Quasi-periodic Green's functions of the Helmholtz and Laplace equations  

NASA Astrophysics Data System (ADS)

A classical problem of free-space Green's function G0? representations of the Helmholtz equation is studied in various quasi-periodic cases, i.e., when an underlying periodicity is imposed in less dimensions than is the dimension of an embedding space. Exponentially convergent series for the free-space quasi-periodic G0? and for the expansion coefficients DL of G0? in the basis of regular (cylindrical in two dimensions and spherical in three dimension (3D)) waves, or lattice sums, are reviewed and new results for the case of a one-dimensional (1D) periodicity in 3D are derived. From a mathematical point of view, a derivation of exponentially convergent representations for Schlömilch series of cylindrical and spherical Hankel functions of any integer order is accomplished. Exponentially convergent series for G0? and lattice sums DL hold for any value of the Bloch momentum and allow G0? to be efficiently evaluated also in the periodicity plane. The quasi-periodic Green's functions of the Laplace equation are obtained from the corresponding representations of G0? of the Helmholtz equation by taking the limit of the wave vector magnitude going to zero. The derivation of relevant results in the case of a 1D periodicity in 3D highlights the common part which is universally applicable to any of remaining quasi-periodic cases. The results obtained can be useful for the numerical solution of boundary integral equations for potential flows in fluid mechanics, remote sensing of periodic surfaces, periodic gratings, and infinite arrays of resonators coupled to a waveguide, in many contexts of simulating systems of charged particles, in molecular dynamics, for the description of quasi-periodic arrays of point interactions in quantum mechanics, and in various ab initio first-principle multiple-scattering theories for the analysis of diffraction of classical and quantum waves.

Moroz, Alexander

2006-09-01

41

Quasi-periodic Activity in the Blazar 0059+581 (Poster)  

NASA Astrophysics Data System (ADS)

Our analysis of a series of 8-GHz VLBI images of the blazar 0059+581 together with integrated light curves from 8 to 37 GHz for 1994--2002 suggests the occurrence of quasi-periodic flares approximately every two years. There is evidence that alternating flares are optically thick (associated with the core) and optically thin (associated with the jet). This, in turn, suggests that the duration of the entire cycle of the quasi-periodic activity is ? 4 years, with two peaks per cycle. One possible scenario is that the first peak is associated with a disturbance at the base of the jet, while the second is associated with the evolution of the disturbance as it propagates down the jet flow.

Pyatunina, T. B.; Rachimov, I. A.; Zborovskii, A. A.; Gabuzda, D. C.; Jorstad, S. G.; Teräsranta, H.; Aller, M. F.; Aller, H. D.

2003-07-01

42

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

PubMed

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

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

2007-08-20

43

Sobolev quasi-periodic solutions of multidimensional wave equations with a multiplicative potential  

NASA Astrophysics Data System (ADS)

We prove the existence of quasi-periodic solutions for wave equations with a multiplicative potential on T^d , d ? 1, and finitely differentiable nonlinearities, quasi-periodically forced in time. The only external parameter is the length of the frequency vector. The solutions have Sobolev regularity both in time and space. The proof is based on a Nash-Moser iterative scheme as in [5]. The key tame estimates for the inverse linearized operators are obtained by a multiscale inductive argument, which is more difficult than for NLS due to the dispersion relation of the wave equation. We prove the ‘separation properties’ of the small divisors assuming weaker non-resonance conditions than in [11].

Berti, Massimiliano; Bolle, Philippe

2012-09-01

44

Diurnal Variations of Quasi-Periodic and Periodic VLF emissions in the Outer Magnetosphere  

Microsoft Academic Search

ELF-VLF receiver and search coil magnetometer data from four Antarctic stations during 1998 have been analyzed to study quasi-periodic emissions (QPs) and periodic emissions (PEs), which occur as ULF-range modulations of ELF-VLF signals between 0.5 kHz and ˜4 kHz. QPs are modulated at frequencies of 15-50 mHz, and PEs are modulated at frequencies of 100-500 mHz. The stations used covered

M. J. Engebretson; J. L. Posch; G. A. Shelburne; A. J. Halford; A. J. Smith; M. Spasojevich; R. L. Arnoldy

2003-01-01

45

Nonradial Oscillations in Neutron Star Oceans: A Source of Quasi-periodic X-Ray Oscillations?  

Microsoft Academic Search

The detection of quasi-periodic oscillations in the brightest X-ray sources has opened up a new window on the properties of accreting neutron stars. All six of the highest accretion rate (Mdot ≳ 10-9 Msun yr-1) sources have exhibited oscillations in the 5-7 Hz range. We explore the possibility that the underlying clock for this feature is a low 1 nonradial

Lars Bildsten; Curt Cutler

1995-01-01

46

Restrictions to neutron star models based on twin-peak quasi-periodic oscillations  

NASA Astrophysics Data System (ADS)

In a series of works - Török et al. (2010, 2012a) and Urbanec et al. (2010a) - we explored restrictions to neutron star properties that are implied by various models of twin-peak quasi-periodic oscillations. Here we sketch an attempt to confront the obtained mass-angular-momentum relations and limits on neutron star compactness with the parameters estimated by assuming various equations of state and the spin frequency of the atoll source 4U 1636-53.

Török, Gabriel; Urbanec, Martin; Goluchová, Kate?ina; Bakala, Pavel; Šrámková, Eva; Stuchlík, Zden?k

2013-03-01

47

Quasi-Periodicity of the Drag Coefficient and Nusselt Number Induced by Taylor-Görtler Vortices  

Microsoft Academic Search

In this article, we investigate the impact of Taylor-Görtler vortices on the drag coefficient and Nusselt number in a heated rotating channel flow using the method of large-eddy simulation (LES). We report the observation of quasi-periodicity of the drag coefficient and Nusselt number in the spanwise direction induced by Taylor-Görtler vortices. The physical conditions under which the extrema of the

Qian-Qiu Xun; Bing-Chen Wang; Eugene Yee

2010-01-01

48

Quasi-periodic dust events in the summertime south polar region of Mars  

NASA Astrophysics Data System (ADS)

A Hovmöller diagram analysis of the dust optical depth measured by the Mars Global Surveyor Thermal Emission Spectrometer shows the occurrence of quasi-periodic westwardly-propagating disturbances with timescales of 10-20 sols during summer in the south polar region of Mars. Dust clouds emerge repeatedly around the region with a latitude of around 70-80°S and a longitude of 240-300°E, move westward at speeds of 3-6 m s -1, reach the region with a longitude of 60-120°E, and finally disappear. This longitude range coincides with elevated terrains in the south polar region, and in this region an increase of dust optical depth encircling the south pole is also observed. This implies that the quasi-periodic dust events will contribute to the enhancement of the atmospheric dust loading in this region. These dust events might be related to baroclinic instability caused by the thermal contrast across the CO 2 cap edge, or the horizontal advection or vertical convection with radiative-dynamical feedback. The westward movement of the dust clouds suggests steady westward winds blowing in the near-surface layer, where the quasi-periodic dust lifting is expected to occur. Such a westward cap-edge flow will be created by the Coriolis force acting on the flow from the ice side to the regolith side.

Imamura, Takeshi; Ito, Yuko

2011-01-01

49

On the phase diagram of frustrated (quasi-)periodic cellular automata  

NASA Astrophysics Data System (ADS)

We introduce and study frustrated cellular automata (CA) obtained by quenching competing Chaté - Manneville rules. A period-two (P2) rule and a quasi-periodic one with period close to three (QP3) are frozen at random on the lattice sites. We find that the periodic and quasi-periodic cycles are resilient to internal frustration as well as to external unbounded noise. A low concentration of impurities improves the (quasi-)periodicity of the CA, damping the chaotic background noise significantly. Starting from pure QP3 CA, a first phase transition happens at a concentration of rule P2, 0305-4470/29/12/010/img1, leading to a macroscopic fixed point. A second phase transition, at 0305-4470/29/12/010/img2, brings the P2 phase. Although macroscopically stable, the central phase displays a stretched exponential relaxation of the site - site autocorrelations, indicating the presence of a new type of glass with slow dynamics superimposed on the natural cyclic dynamics of the CA rules. These results appear to be quite general and are found for many pairs of rules.

Mousseau, Normand

1996-06-01

50

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

NASA Astrophysics Data System (ADS)

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.

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

2008-03-01

51

The twoscale asymptotic error analysis for piezoelectric problems in the quasi-periodic structure  

NASA Astrophysics Data System (ADS)

Applications for piezoelectric effect have grown rapidly, and piezoelectric materials play important roles in countless areas of modern life. By means of twoscale method and coupled boundary layer, some new kinds of twoscale asymptotic expansions for solutions to the electrical potential and the displacement in quasi-periodic structure under coupled piezoelectric effect are derived, and the homogenization constants of piezoelectric materials are presented. The coupled twoscale relation between the electrical potential and the displacement is set up, and some improved asymptotic error estimates are analyzed.

Feng, YongPing; Deng, MingXiang; Guan, XiaoFei

2013-10-01

52

Methods for probing quasi-periodic oscillations on short time scales  

NASA Astrophysics Data System (ADS)

Optimal filter analysis techniques are employed in order to set constraints on the nature of possible relationships between Low Frequency Noise (LFN) and Quasi-Periodic Oscillations (QPOs) in GX5-1 on time scales near the QPO coherence length. Simulations afford comparison with theory and calibrate the high noise bias. Models in which LFN shots modulate sinusoidal QPOs are explored for shot rates approx. 400 Hz and shot clustering fractions approx. 50 percent. The models are found to be incompatible with the data.

Norris, J. P.; Hertz, P.; Wood, K. S.; Vaughan, B. A.; Michelson, P. F.; Mitsuda, Kazuhisa; Dotani, T.

1989-11-01

53

Omnidirectional phase matching of arbitrary processes by radial quasi-periodic nonlinear photonic crystal.  

PubMed

We investigate second-harmonic generation in a nonlinear photonic crystal having radial quasi-periodic order and continuous rotational symmetry. This device enables us to simultaneously phase match different nonlinear interactions in any arbitrary direction of propagation. We have fabricated such a crystal by electric field poling of a magnesium-doped stoichiometric LiTaO(3) and demonstrated frequency doubling of two different pump wavelengths at three different angles. Fourier coefficients were 10 times higher than that of a lattice-based multidirectional frequency doubler. PMID:20634876

Voloch-Bloch, Noa; Davidovich, Tomer; Ellenbogen, Tal; Ganany-Padowicz, Ayelet; Arie, Ady

2010-07-15

54

Restrictions to Neutron Star Properties Based on Twin-Peak Quasi-Periodic Oscillations  

NASA Astrophysics Data System (ADS)

We consider twin-peak quasi-periodic oscillations (QPOs) observed in the accreting low-mass neutron star (NS) binaries and explore restrictions to NS properties that are implied by various QPO models. For each model and each source, the consideration results in a specific relation between the NS mass M and the angular-momentum j rather than in their single preferred combination. Furthermore, the inferred restrictions on NS properties (or QPO models) are weaker for the low-frequency sources than for the high-frequency sources.

Török, Gabriel; Bakala, Pavel; Šrámková, Eva; Stuchlík, Zden?k; Urbanec, Martin; Goluchová, Kate?ina

2013-02-01

55

THz laser based on quasi-periodic AlGaAs superlattices  

NASA Astrophysics Data System (ADS)

The use of quasi-periodic AlGaAs superlattices as an active element of a quantum cascade laser of terahertz range is proposed and theoretically investigated. A multi-colour emission, having from three to six peaks of optical gain, is found in Fibonacci, Thue–Morse, and figurate superlattices in electric fields of intensity F = 11 – 13 kV cm-1 in the frequency range f = 2 – 4 THz. The peaks depend linearly on the electric field, retain the height of 20 cm-1, and strongly depend on the thickness of the AlGaAs-layers.

Malyshev, K. V.

2013-06-01

56

Robust absorption broadband in one-dimensional metallic-dielectric quasi-periodic structure.  

PubMed

We demonstrated that a broad and robust absorption band for a wide range of incidence angles and for both polarizations can be realized using a one-dimensional metallic-dielectric quasi-periodic structure, when the thickness of the constituent metal is comparable to its skin depth. The absorptance in such peculiar structure can exceed 99% to meet different applications. Furthermore, employing the effective medium approach, a theoretical expression has been deduced to instruct the working frequency of the absorption band. By tuning the permittivity and thickness of the constituent layers, the robust absorption band can cover the wavelength from the visible to the near-infrared. PMID:19503532

Dong, J W; Liang, G Q; Chen, Y H; Wang, H Z

2006-03-01

57

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

Microsoft Academic Search

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

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

2008-01-01

58

Quasi-periodic Oscillations and Broadband Variability in Short Magnetar Bursts  

NASA Astrophysics Data System (ADS)

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 QPOs 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 ruling out false positives. We illustrate our Bayesian method by applying it to a sample of 27 bursts from the magnetar SGR J0501+4516 observed by the Fermi Gamma-ray Burst Monitor, and we find no evidence for the presence of QPOs in any of the bursts in the unbinned spectra, but do find a candidate detection in the binned spectra of one burst. However, whether this signal is due to a genuine quasi-periodic process, or can be attributed to unmodeled effects in the noise is at this point a matter of interpretation.

Huppenkothen, Daniela; Watts, Anna L.; Uttley, Phil; van der Horst, Alexander J.; van der Klis, Michiel; Kouveliotou, Chryssa; Gö?ü?, Ersin; Granot, Jonathan; Vaughan, Simon; Finger, Mark H.

2013-05-01

59

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

SciTech Connect

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.

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

60

Periodicity analysis of Jovian quasi-periodic radio bursts based on Lomb-Scargle periodograms  

NASA Astrophysics Data System (ADS)

The Jovian polar magnetosphere has relativistic particle accelerations with quasi-periodicity (hereafter QP accelerations) that are accompanied by periodic auroral emissions and low-frequency radio bursts called quasi-periodic (QP) bursts. Some previous observations suggested a possible physical relationship between the QP accelerations and QP radio bursts. However, the cause of the QP accelerations has not been revealed yet. This study investigated the generation process of QP radio bursts that constrain the QP acceleration process. The statistical features of QP bursts' periodicity were investigated by applying Lomb-Scargle periodogram analysis to the variations of the QP bursts' spectral densities observed by the Galileo and Ulysses spacecraft. The Lomb-Scargle analysis revealed remarkable characteristics: QP bursts have statistically large amplitudes with periods of 30-50 min at all latitudes. This result suggests that 30-50 min is an "eigenfrequency" of the QP accelerations which is close to the 45 min periodicity of the pulsating X-ray hot spot in the polar cap region. In addition, it was also revealed that successive pulses sometimes exhibit periodicity transition. We discussed one possible scenario which links Jovian periodic accelerations to those in the terrestrial magnetosphere. The scenario is that particles are energized within the period of the dispersive Alfvén waves with field-aligned electric fields that obliquely propagate between the northern and southern ionospheres. The observed eigenfrequency and periodicity transition of QP bursts are consistent with the Alfvénic acceleration scenario.

Kimura, Tomoki; Tsuchiya, Fuminori; Misawa, Hiroaki; Morioka, Akira; Nozawa, Hiromasa; Fujimoto, Masaki

2011-03-01

61

Periodic and quasi-periodic behavior in resource-dependent age structured population models.  

PubMed

To describe the dynamics of a resource-dependent age structured population, a general non-linear Leslie type model is derived. The dependence on the resources is introduced through the death rates of the reproductive age classes. The conditions assumed in the derivation of the model are regularity and plausible limiting behaviors of the functions in the model. It is shown that the model dynamics restricted to its omega-limit sets is a diffeomorphism of a compact set, and the period-1 fixed points of the model are structurally stable. The loss of stability of the non-zero steady state occurs by a discrete Hopf bifurcation. Under general conditions, and after the loss of stability of the structurally stable steady states, the time evolution of population numbers is periodic or quasi-periodic. Numerical analysis with prototype functions has been performed, and the conditions leading to chaotic behavior in time are discussed. PMID:11276524

Dilão, R; Domingos, T

2001-03-01

62

QUASI-PERIODIC FORMALDEHYDE MASER FLARES IN THE MASSIVE PROTOSTELLAR OBJECT IRAS 18566+0408  

SciTech Connect

We report results of an extensive observational campaign of the 6 cm formaldehyde maser in the young massive stellar object IRAS 18566+0408 (G37.55+0.20) conducted from 2002 to 2009. Using the Arecibo Telescope, the Very Large Array, and the Green Bank Telescope, we discovered quasi-periodic formaldehyde flares (P {approx} 237 days). Based on Arecibo observations, we also discovered correlated variability between formaldehyde (H{sub 2}CO) and methanol (CH{sub 3}OH) masers. The H{sub 2}CO and CH{sub 3}OH masers are not spatially coincident, as demonstrated by different line velocities and high angular resolution MERLIN observations. The flares could be caused by variations in the infrared radiation field, possibly modulated by periodic accretion onto a young binary system.

Araya, E. D. [Physics Department, Western Illinois University, 1 University Circle, Macomb, IL 61455 (United States); Hofner, P.; Goss, W. M. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Kurtz, S. [Centro de RadioastronomIa y Astrofisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 3-72, 58089 Morelia, Michoacan (Mexico); Richards, A. M. S. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Linz, H. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Olmi, L. [University of Puerto Rico at Rio Piedras, Physics Department, P.O. Box 23343, San Juan, PR 00931 (Puerto Rico); Sewilo, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2010-07-10

63

Multiscale analysis in momentum space for quasi-periodic potential in dimension two  

NASA Astrophysics Data System (ADS)

We consider a polyharmonic operator H=(-?)l+V(xvec ) in dimension two with l >= 2, l being an integer, and a quasi-periodic potential V(xvec ). We prove that the absolutely continuous spectrum of H contains a semiaxis and there is a family of generalized eigenfunctions at every point of this semiaxis with the following properties. First, the eigenfunctions are close to plane waves ei<\\Vkgr vec ,xvec > at the high energy region. Second, the isoenergetic curves in the space of momenta \\Vkgr vec corresponding to these eigenfunctions have a form of slightly distorted circles with holes (Cantor type structure). A new method of multiscale analysis in the momentum space is developed to prove these results.

Karpeshina, Yulia; Shterenberg, Roman

2013-07-01

64

Millihertz quasi-periodic optical oscillations in 4U 0614+091  

NASA Astrophysics Data System (ADS)

We report the discovery of a 1-mHz optical quasi-periodic oscillation (QPO) in the candidate ultra-compact low-mass X-ray binary 4U 0614+091. The ultra-low-frequency QPO has no X-ray counterpart in contemporaneous RXTE/PCA data and is likely a signature of structure in the accretion disc. The QPO can be reasonably fitted with a single sine wave but with a phase jump part way through the observation, indicating that it is not coherent. We also identify a 48-min modulation, approximately consistent with the suggested orbital period of O'Brien and Shahbaz et al. If this is indeed orbital, it supports an identification of 4U 0614+091 as an ultra-compact source.

Zhang, Y.; Hynes, R. I.; Robinson, E. L.

2012-02-01

65

Fine structure of the sources of quasi-periodic pulsations in "single-loop" solar flares  

NASA Astrophysics Data System (ADS)

Analysis of the observational data obtained with a high angular resolution in the ranges of vacuum ultraviolet (1?, TRACE) and hard X-ray (4?, RHESSI) emissions in some solar flares previously considered "single-loop" ones shows that they are not such flares. The thick single loops with a diameter of 13?-21? observed in these flares in the microwave range with an angular resolution of 5?-10? (NoRH) are actually arcades of thinner loops with a diameter of less than 3?. In this case, the observed quasi-periodic pulsations of microwave emission are not a consequence of the oscillations of an isolated thick loop, as is usually assumed, but a result of the successive involvement of many relatively thinner loops in the process of flare energy release. The established facts impose significant constraints on the generation models of pulsations in flares.

Zimovets, I. V.; Kuznetsov, S. A.; Struminsky, A. B.

2013-04-01

66

Nonradial pulsations of accretion disks - The nature of quasi-periodic oscillations in dwarf novae  

NASA Astrophysics Data System (ADS)

Quasi-periodic oscillations on time scales from 30 s to 150 s, which have been observed in several dwarf novae during outburst, have been qualitatively interpreted as oscillations of the accretion disks in these systems. This is investigated quantitatively by showing that there exist nonradial oscillation modes of the disk that, being weakly coupled in the radial direction, correspond to oscillations of individual disk annuli which are periodic in phi, z, and t. The frequencies of these oscillations are directly proportional to the rotation frequency of the annulus. Because the luminosity of an annulus is largest at some intermediate radius, the oscillations are expected to be most evident for annuli near this radius.

van Horn, H. M.; Wesemael, F.; Winget, D. E.

1980-02-01

67

Quasi-periodic Wiggles of Microwave Zebra Structures in a Solar Flare  

NASA Astrophysics Data System (ADS)

Quasi-periodic wiggles of microwave zebra pattern (ZP) structures with periods ranging from about 0.5 s to 1.5 s are found in an X-class solar flare on 2006 December 13 at the 2.6-3.8 GHz with the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou). Periodogram and correlation analysis show that the wiggles have two to three significant periodicities and are almost in phase between stripes at different frequencies. The Alfvén speed estimated from the ZP structures is about 700 km s–1. We find the spatial size of the wave-guiding plasma structure to be about 1 Mm with a detected period of about 1 s. This suggests that the ZP wiggles can be associated with the fast magnetoacoustic oscillations in the flaring active region. The lack of a significant phase shift between wiggles of different stripes suggests that the ZP wiggles are caused by a standing sausage oscillation.

Yu, Sijie; Nakariakov, V. M.; Selzer, L. A.; Tan, Baolin; Yan, Yihua

2013-11-01

68

Statistical investigation of the VLF quasi-periodic emissions measured by the DEMETER spacecraft  

NASA Astrophysics Data System (ADS)

We present a survey of quasi-periodic (QP) ELF/VLF emissions detected on board the DEMETER satellite (altitude of about 700 km, nearly Sun-synchronous orbit at 10:30/22:30 LT). Five years of data have been visually inspected for the presence of QP emissions. It is found that QP events occur in about 3 percents of daytime half-orbits, while they are basically absent during the night (note that we were likely to miss QP events with the modulation periods lower than about 10 s or the frequency bandwidth lower than about 400 Hz). The events occur predominantly during quiet geomagnetic conditions following the periods of enhanced geomagnetic activity. Their occurrence and properties are systematically analyzed.

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

2013-04-01

69

Quasi-periodic frequency fluctuations observed during coronal radio sounding experiments 1991-2009  

NASA Astrophysics Data System (ADS)

Coronal radio sounding experiments were carried out using the dual-frequency signals of the spacecraft Ulysses, Galileo, Mars Express, Venus Express, and Rosetta. The change in differential frequency recorded at the NASA and ESA ground stations, a quantity sensitive only to the plasma along the radio ray path from spacecraft to receiver, has been analyzed in this work. This large volume of observational data provides evidence for the occasional presence of a quasi-periodic component (QPC) in the derived frequency fluctuation spectra. First seen in data from the Mars Express conjunction in 2004, further evidence for the QPC has now been found in data recorded at other solar conjunction opportunities from 1991 to 2009, thereby better defining the statistical characteristics of the QPC. The level of QPC spectral density is a factor of three higher than the expected power-law background level. The characteristic frequency of the spectral density maximum is roughly 4 mHz, corresponding to a QPC fluctuation period of about 4 min. The bandwidth of the spectral line is comparable to the maximum frequency. The QPC are observed at heliocentric distances between 3 and 40 solar radii, both in equatorial regions and at high heliolatitudes. The QPC is detected with an occurrence frequency of about 20% and is occasionally accompanied by its second harmonic. The most likely progenitors of the QPC are quasi-periodic electron density fluctuations associated with magnetosonic waves, which are generated locally from nonlinear interactions of 5-min band Alfvén waves propagating from the coronal base.

Efimov, A. I.; Lukanina, L. A.; Samoznaev, L. N.; Rudash, V. K.; Chashei, I. V.; Bird, M. K.; Pätzold, M.; MEX, VEX, ROS Radio Science Team

2012-02-01

70

Plasma structures responsible for sporadic E region quasi-periodic echoes  

NASA Astrophysics Data System (ADS)

We used the interferometry technique to reconstruct the spatial structures of 3-m field-aligned irregularities (FAI) in the nighttime sporadic E (Es) layer responsible for quasi-periodic (QP) echoes. We found that the scattering regions that give rise to the QP striations with positive range rates occurred in patchy patterns with zonal and vertical extents of approximately 5 20 and 3 8 km, respectively. These echo patterns appeared quasi-periodically with periods of 2 6 min and moved horizontally from southeast to northwest at an approximately constant height. One of the important findings of this study is that the zonal trace velocities of the kilometer-scale plasma structures were approximately the same as the zonal drift velocities of the 3-m FAI. The former were deduced from the temporal displacement of the echo patterns on the horizontal plane, and the latter were estimated from the observed Doppler velocities of the 3-m FAI combined with the angular positions resolved by the interferometry technique. This feature strongly implies that the small-scale FAI were “frozen” within the large-scale plasma structures responsible for the QP echoes. On the basis of this frozen-in property, the meridional component of the drift velocity of the plasma structures can be obtained from that of the 3-m FAI, irrespective of the limitations of the extraordinarily narrow width of the expected echoing region in the north south direction. Our results show that the maximum drift velocity of the plasma structures is as large as approximately 135 m/s in the direction from southeast to northwest. On the basis of the long dwelling time (greater than 6 min) and small horizontal dimension (average of approximately 10 km) of the QP scattering regions, we speculate that the configuration of the large-scale plasma structures responsible for the QP echoes is likely to be a horizontally elongate shape whose major axes are primarily aligned in the meridional direction with respect to geomagnetic north.

Chu, Yen-Hsyang; Wang, Chien-Ya; Yang, Kuo-Feng

2007-04-01

71

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

NASA Astrophysics Data System (ADS)

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.

Grant, Paul M.

2010-03-01

72

On the Nature of Quasi-periodic Oscillation Phase Lags in Black Hole Candidates  

NASA Astrophysics Data System (ADS)

Observations of quasi-periodic oscillations (QPOs) in X-ray binaries hold a key to understanding many aspects of these enigmatic systems. Complex appearance of the Fourier phase lags related to QPOs is one of the most puzzling observational effects in accreting black holes (BHs). In this Letter we show that QPO properties, including phase lags, can be explained in a framework of a simple scenario, where the oscillating media provide feedback on the emerging spectrum. We demonstrate that the QPO waveform is presented by the product of a perturbation and time-delayed response factors, where the response is energy dependent. The essential property of this effect is its nonlinear and multiplicative nature. Our multiplicative reverberation model successfully describes the QPO components in energy-dependent power spectra as well as the appearance of the phase lags between signals in different energy bands. We apply our model to QPOs observed by the Rossi X-Ray Timing Explorer in BH candidate XTE J1550-564. We briefly discuss the implications of the observed energy dependence of the QPO reverberation times and amplitudes on the nature of the power-law spectral component and its variability.

Shaposhnikov, Nikolai

2012-06-01

73

Search for Persistent Quasi-Periodicities in the Solar and Interplanetary Magnetic Fields  

NASA Astrophysics Data System (ADS)

Previous analysis of the radial component of the interplanetary magnetic field from 1962 - 1998 has revealed a dominant frequency of 27.03 days to 0.02 day accuracy (Neugebauer, et al., 2000). We have repeated and extended this analysis with OMNI data from 1963 - 2007 obtained from the Coordinated Heliospheric Observations (COHO) database. Over this longer data string we find that the 27.03 day Lomb-Scargle periodogram peak is reduced while two side peaks near 26.8 days and 27.6 days become almost as strong. In the interval 1999-2007 there are two dominant periods near 26.5 days and 27.2 days. As a solar counterpart to the above analysis we have searched for persistent rotation periods near 27 days of global patterns of photospheric magnetic fields derived from Wilcox Solar Observatory synoptic Carrington rotation maps. Techniques applied include, principal components analysis, independent component analysis, singular spectrum analysis, wavelet spectral analysis, and complex demodulation. We find a variety of quasi- periodicities between 26 and 29 days that remain coherent for 1 - 2 years. In the southern solar hemisphere the strongest periodicity is at 28.2 days, while in the northern hemisphere it is around 26.5 days. Neugebauer, M., Smith, Smith, E.J., Ruzmaikin, A., Feynman, J., Vaughan, A.H. 2000, J. Geophys. Res., 106, A5, 8363.

Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.

2007-12-01

74

A possible intrinsic mechanism for the quasi-periodic dynamics of the Jovian magnetosphere  

NASA Astrophysics Data System (ADS)

Most regions of the Jovian magnetosphere covered by the Galileo spacecraft measurements undergo quasi-periodic modulations with a time period of several Earth days. These modulations appear in various field and particle properties. Most prominent are periodically recurring ion flow bursts associated with disturbances in the meridional component of the magnetic field in the Jovian magnetotail or variations of the energy spectral shape of the particle distribution associated with the stretching and dipolarization of the magnetic field. Each individual cycle of these modulations is believed to represent a global reconfiguration of the Jovian magnetosphere. We present a simple conceptual model for these periodic processes assuming (1) ion mass loading from internal plasma sources and (2) fast planetary rotation causing magnetotail field line stretching due to centrifugal forces. This leads to a magnetotail configuration favoring magnetic reconnection. Magnetic reconnection causes plasmoid formation and release as well as dipolarization of field lines connected to the planet. Continued mass loading leads again to a stretching of the tail field lines. Our model shows that the suggested intrinsic mechanism can explain the observed periodicities of several days in Jovian substorm-like processes.

Kronberg, E. A.; Glassmeier, K.-H.; Woch, J.; Krupp, N.; Lagg, A.; Dougherty, M. K.

2007-05-01

75

ON THE NATURE OF QUASI-PERIODIC OSCILLATION PHASE LAGS IN BLACK HOLE CANDIDATES  

SciTech Connect

Observations of quasi-periodic oscillations (QPOs) in X-ray binaries hold a key to understanding many aspects of these enigmatic systems. Complex appearance of the Fourier phase lags related to QPOs is one of the most puzzling observational effects in accreting black holes (BHs). In this Letter we show that QPO properties, including phase lags, can be explained in a framework of a simple scenario, where the oscillating media provide feedback on the emerging spectrum. We demonstrate that the QPO waveform is presented by the product of a perturbation and time-delayed response factors, where the response is energy dependent. The essential property of this effect is its nonlinear and multiplicative nature. Our multiplicative reverberation model successfully describes the QPO components in energy-dependent power spectra as well as the appearance of the phase lags between signals in different energy bands. We apply our model to QPOs observed by the Rossi X-Ray Timing Explorer in BH candidate XTE J1550-564. We briefly discuss the implications of the observed energy dependence of the QPO reverberation times and amplitudes on the nature of the power-law spectral component and its variability.

Shaposhnikov, Nikolai, E-mail: nikolai.v.shaposhnikov@nasa.gov, E-mail: lev@milkyway.gsfc.nasa.gov [Department of Astronomy, CRESST/University of Maryland, College Park, MD 20742 (United States)

2012-06-20

76

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

Microsoft Academic Search

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

R. F. Elsner; M. C. Weisskopf; W. Darbro; B. D. Ramsey; A. C. Williams; P. G. Sutherland; J. E. Grindlay

1986-01-01

77

Discovery of the 0.08 Hz quasi periodic oscillation from the black hole candidate LMC X-1  

Microsoft Academic Search

Discovery is reported of the 0.0751 Hz quasi periodic oscillation from the black hole candidate LMC X-1. The observations were performed with the Ginga satellite in April and July 1987, but the QPO was detected only in the April data. The high quality energy spectra of LMC X-1 are also presented. They are extremely soft relative to those of the

K. Ebisawa; K. Mitsuda; H. Inoue; T. Dotani

1988-01-01

78

Long-Time Simulations of Astrophysical Jets: Energy Structure and Quasi-Periodic Ejection  

NASA Astrophysics Data System (ADS)

We have performed self-consistent 2.5-dimensional nonsteady MHD numerical simulations of jet formation as long as possible, including the dynamics of accretion disks. Previous simulations showed that, in the case where the calculation time of the simulations is very short as compared with the time scale of observed jets, there is no significant difference between the characteristics of the nonsteady and steady MHD simulations. Thus, we have investigated long-time evolutions of the mass-accretion rate, mass-outflow rate, jet velocity, and various energy fluxes. We found that the ejection of a jet is quasi-periodic. The period of the ejection, Tejection, is related to the time needed for the initial magnetic field, B0, to be twisted to generate a toroidal filed, Tejection ? VA-1 ? B0-1 ? Emg-1/2, where VA is the Alfvén velocity and Emg the initial magnetic energy. We compared our results with both the steady-state theory and the previous 2.5-dimensional nonsteady MHD simulations. We found that the time-averaged velocity of the jet, Vjet,avg, is ˜ 0.1 VK and ˜ 0.1 Vjet,max, where VK is the Keplerian velocity at (r, z) = (1. 0) and Vjet,max the maximum velocity of the jet. Nevertheless, the characteristics of our simulations are consistent with those of the steady solution and previous short-time simulations. We found that the dependences of the time-averaged velocity and the mass-outflow rate, dot{M}w,avg, on the initial magnetic field are approximately Vjet,avg ? B00.3 and dot{M}w,avg ? B00.32, respectively.

Ibrahim, Ahmed; Shibata, Kazunari

2008-08-01

79

SDO/AIA observations of periodic and quasi-periodic phenomenon associated with an EUV jet  

NASA Astrophysics Data System (ADS)

It has long been advocated that explosive magnetic activity is responsible for the mass-balance in the solar atmosphere, supplying the corona and the solar wind with heated plasma. The explosive events are thought to be the result of emerging bi-polar (EB) regions reconnecting with pre-existing, open fields, with the size of the EB's (i.e., granular, super-granular) being related to size of the resulting feature (i.e., spicules, EUV/X-ray jets). Recent evidence has suggested a deeper relationship between spicules and EUV jets (Sterling et al., 2010). We present here observations of a EUV jet observed with SDO/AIA close to a southern coronal hole. The jet can be considered as a 'Blowout jet' (using the terminology of Moore et al., 2010), launching vast amounts of chromospheric plasma into the atmosphere along with hotter material. The hotter part of the jet appears to be composed of multiple, (quasi-)periodic ejections that individually resemble fast moving (>100 km/s) spicules. The multiple ejections appear crucial for distributing the hotter material high into the corona, possibly suggesting that larger EUV/X-ray are composed of many smaller spicule-like events. Although the event is close to the limb, evidence for reconnection at the chromospheric level is provided. Further, evidence for helicity (or torsional motion) and the presence of slow and fast Magnetohydrodynamic waves is given, with the wave mode excitation likely due to the reconnection process. Exploiting the observed wave motion, we also use magneto-seismological techniques to determine local plasma parameters with sub-resolution accuracy along one of the jets unique features.

Morton, Richard; Verth, Gary; Erdelyi, Robertus; Srivastava, Abhi

2013-04-01

80

MICROWAVE QUASI-PERIODIC PULSATION WITH MILLISECOND BURSTS IN A SOLAR FLARE ON 2011 AUGUST 9  

SciTech Connect

A peculiar microwave quasi-periodic pulsation (QPP) accompanying a hard X-ray (HXR) QPP of about 20 s duration occurred just before the maximum of an X6.9 solar flare on 2011 August 9. The most interesting aspect is that the microwave QPP consists of millisecond timescale superfine structures. Each microwave QPP pulse is made up of clusters of millisecond spike bursts or narrowband type III bursts. There are three different frequency drift rates: the global frequency drift rate of the microwave QPP pulse group, the frequency drift rate of the microwave QPP pulse, and the frequency drift rate of individual millisecond spikes or type III bursts. The physical analysis indicates that the energetic electrons accelerating from a large-scale highly dynamic magnetic reconnecting current sheet above the flaring loop propagate downward, impact the flaring plasma loop, and produce HXR bursts. The tearing-mode (TM) oscillations in the current sheet modulate HXR emission and generate HXR QPP; the energetic electrons propagating downward produce Langmuir turbulence and plasma waves, resulting in plasma emission. The modulation of TM oscillation on the plasma emission in the current-carrying plasma loop may generate microwave QPP. The TM instability produces magnetic islands in the loop. Each X-point will be a small reconnection site and will accelerate the ambient electrons. These accelerated electrons impact the ambient plasma and trigger the millisecond spike clusters or the group of type III bursts. Possibly, each millisecond spike burst or type III burst is one of the elementary bursts (EBs). A large number of such EB clusters form an intense flaring microwave burst.

Tan Baolin; Tan Chengming, E-mail: bltan@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories of the Chinese Academy of Sciences, Datun Road A20, Chaoyang District, Beijing 100012 (China)

2012-04-10

81

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

SciTech Connect

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.

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

82

IMAGING OBSERVATIONS OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARE LOOPS WITH SDO/AIA  

SciTech Connect

Quasi-periodic pulsations (QPPs) of flaring emission with periods from a few seconds to tens of minutes have been widely detected from radio bands to {gamma}-ray emissions. However, in the past the spatial information of pulsations could not be utilized well due to the instrument limits. We report here imaging observations of the QPPs in three loop sections during a C1.7 flare with periods of P = 24 s-3 minutes by means of the extreme-ultraviolet 171 A channel of the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory. We confirm that the QPPs with the shortest period of 24 s were not of an artifact produced by the Nyquist frequency of the AIA 12 s cadence. The QPPs in the three loop sections were interconnected and closely associated with the flare. The detected perturbations propagated along the loops at speeds of 65-200 km s{sup -1}, close to those of acoustic waves in them. The loops were made up of many bright blobs arranged in alternating bright and dark changes in intensity (spatial periodical distribution) with the wavelengths 2.4-5 Mm (as if they were magnetohydrodynamic waves). Furthermore, in the time-distance diagrams, the detected perturbation wavelengths of the QPPs are estimated to be {approx}10 Mm, which evidently do not fit the above ones of the spatial periodic distributions and produce a difference of a factor of 2-4 with them. It is suggested that the short QPPs with periods P < 60 s were possibly sausage-mode oscillations and the long QPPs with periods P > 60 s were the higher (e.g., >2nd) harmonics of slow magnetoacoustic waves.

Su, J. T.; Mao, X. J. [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012 (China); Shen, Y. D.; Liu, Y. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China); Liu, Y. [W. W. Hansen Experimental Physical Laboratory, Stanford University, Stanford, CA 94305 (United States)

2012-08-20

83

Mass-Angular-momentum Relations Implied by Models of Twin Peak Quasi-periodic Oscillations  

NASA Astrophysics Data System (ADS)

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 ?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.

Török, Gabriel; Bakala, Pavel; Šrámková, Eva; Stuchlík, Zden?k; Urbanec, Martin; Goluchová, Kate?ina

2012-12-01

84

Studies of quasi-periodic oscillations in the black hole transient XTE J1817-330  

NASA Astrophysics Data System (ADS)

We have used archival Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA) data to investigate the timing and spectral characteristics of the transient XTE J1817-330. The data pertain to 160 PCA pointed observations made during the outburst period 2006 January 27 to August 2. A detailed analysis of quasi-periodic oscillations (QPOs) in this black hole X-ray binary is carried out. Power density spectra were obtained using the light curves of the source. QPOs have been detected in the 2-8 keV band in 10 of the observations. In eight of these observations, QPOs are present in the 8-14 keV and in five observations in the 15-25 keV band. XTE J1817-330 is the third black hole source from which low-frequency QPOs are clearly detected in hard X-rays. The QPO frequency lies in ?4-9 Hz and the rms amplitude in the 1.7-13.3 per cent range, the amplitude being higher at higher energies. We have fitted the power density spectra of the observations with Lorentzian and power-law models. Energy spectra are derived for those observations in which the QPOs are detected, in order to investigate any dependence of the QPO characteristic on the spectral parameters. These spectra are well fitted with a two-component model, which includes the disc blackbody component and a power-law component. The QPO characteristics and their variations are discussed and the implications on the origin of QPOs are examined.

Roy, Jayashree; Agrawal, P. C.; Paul, B.; Duorah, K.

2011-04-01

85

High-frequency quasi-periodic oscillations from GRS 1915+105  

NASA Astrophysics Data System (ADS)

We report the results of a systematic timing analysis of all archival Rossi X-Ray Timing Explorer (RXTE) observations of the bright black hole binary GRS 1915+105 in order to detect high-frequency quasi-periodic oscillations (HFQPOs). We produced power-density spectra in two energy bands and limited the analysis to the frequency range 30-1000 Hz. We found 51 peaks with a single-trial significance larger than 3?. As all but three have centroid frequencies that are distributed between 63 and 71 Hz, we consider most of them significant regardless of the number of trials involved. The average centroid frequency and full width at half-maximum are 67.3 ± 2.0 Hz and 4.4 ± 2.4 Hz, respectively. Their fractional rms varies between 0.4 and 2 per cent (total band detections) and between 0.5 and 3 per cent (hard band detections). As GRS 1915+105 shows large variability on time-scales longer than 1 s, we analysed the data in 16 s intervals and found that the detections are limited to a specific region in the colour-colour diagram, corresponding to state B of the source, when the energy spectrum is dominated by a bright accretion disc component. However, the rms spectrum of the HFQPO is very hard and does not show a flattening up to 40 keV, where the fractional rms reaches 11 per cent. We discuss our findings in terms of current proposed models and compare them with the results on other black hole binaries and neutron-star binaries.

Belloni, T. M.; Altamirano, D.

2013-06-01

86

Disk Precession and Quasi-Periodic Brightness Oscillations of V603 Aql in 2001-2002  

NASA Astrophysics Data System (ADS)

We present the photometric observations of the old nova V603 Aql with the RTT 150 Russian-Turkish telescope during eleven nights of 2001-2002. We show that the star at this time was in a state with positive superhumps and its photometric period of 0.144-0.145 day was longer than the orbital period. We found night-to-night variations in the mean brightness of the system that are consistent with disk precession periods of 3.3 and 3.0 days in 2001 and 2002, respectively. Analysis of the results and their comparison with the results of other authors using current theoretical models for disk precession lead us to suggest that the change in the disk precession period was caused by a change in the accretion rate in the system. V603 Aql in a state with negative superhumps was found to be brighter than it is in a state with positive superhumps by 0.2-0.3 mag. We hypothesize that the transition between these states could also be caused by a change in the accretion rate. Quasi-periodic oscillations (QPOs) of the brightness with typical time scales of 9-70 min were detected on each observing night. These time scales were found to change from night to night. The detection of QPOs with a period of about 0.05 of the orbital period and its multiples on certain nights provides evidence for the model of QPO generation through accretion-rate modulation by ionization-front oscillations on the surface of the donor star near the inner Lagrangian point.

Suleimanov, V.; Bikmaev, I.; Belyakov, K.; Sakhibullin, N.; Zhukov, G.; Aslan, Z.; Kiziloglu, U.; Khamitov, I.

2004-09-01

87

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

SciTech Connect

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.

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

88

Entrainment, instability, quasi-periodicity, and chaos in a compound neural oscillator.  

PubMed

We studied the dynamical behavior of a class of compound central pattern generator (CPG) models consisting of a simple neural network oscillator driven by both constant and periodic inputs of varying amplitudes, frequencies, and phases. We focused on a specific oscillator composed of two mutually inhibiting types of neuron (inspiratory and expiratory neurons) that may be considered as a minimal model of the mammalian respiratory rhythm generator. The simulation results demonstrated how a simple CPG model--with a minimum number of neurons and mild nonlinearities--may reproduce a host of complex dynamical behaviors under various periodic inputs. In particular, the network oscillated spontaneously only when both neurons received adequate and proportionate constant excitations. In the presence of a periodic source, the spontaneous rhythm was overridden by an entrained oscillation of varying forms depending on the nature of the source. Stable entrained oscillations were inducible by two types of inputs: (1) anti-phase periodic inputs with alternating agonist-antagonist drives to both neurons and (2) a single periodic drive to only one of the neurons. In-phase inputs, which exert periodic drives of similar magnitude and phase relationships to both neurons, resulted in varying disruptions of the entrained oscillations including magnitude attenuation, harmonic and phase distortions, and quasi-periodic interference. In the absence of significant phasic feedback, chaotic motion developed only when the CPG was driven by multiple periodic inputs. Apneic episodes with repetitive alternation of active (intrinsic oscillation) and inactive (cessation of oscillation) states developed when the network was driven by a moderate periodic input of low frequency. Similar results were demonstrated in other, more complex oscillator models (that is, half-center oscillator and three-phase respiratory network model). These theoretical results may have important implications in elucidating the mechanisms of rhythmogenesis in the mature and developing respiratory CPG as well as other compound CPGs in mammalian and invertebrate nervous systems. PMID:9540048

Matsugu, M; Duffin, J; Poon, C S

1998-03-01

89

Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-velocity Upflows?  

NASA Astrophysics Data System (ADS)

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 ? 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-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-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.

De Pontieu, Bart; McIntosh, Scott W.

2010-10-01

90

Diurnal Variations of Quasi-Periodic and Periodic VLF emissions in the Outer Magnetosphere  

NASA Astrophysics Data System (ADS)

ELF-VLF receiver and search coil magnetometer data from four Antarctic stations during 1998 have been analyzed to study quasi-periodic emissions (QPs) and periodic emissions (PEs), which occur as ULF-range modulations of ELF-VLF signals between 0.5 kHz and ˜4 kHz. QPs are modulated at frequencies of 15-50 mHz, and PEs are modulated at frequencies of 100-500 mHz. The stations used covered a range of magnetic latitudes from -62° (Halley) to -74° (South Pole Station); two automated geophysical observatories (AGOs) were located at intermediate latitudes. Consistent with earlier studies, most QPs were observed with magnetic pulsations of identical period in the Pc 3-4 range (type I QPs). Of those QPs not observed with simultaneous magnetic pulsations (type II QPs), nearly all were accompanied by PEs. It is also notable that no PE events simultaneous with Pc 3-4 magnetic pulsations but without QPs were observed during the entire year at any station. Diurnal patterns of all categories of QP events show occurrence maxima in the noon or post-noon sectors. The total absence of type I QP occurrences without PEs on the nightside is consistent with the expected absence of Pc 3-4 pulsations there, because of their origin at the upstream bow shock. PEs, on the other hand, could be seen at all local times. Diurnal profiles showed no latitudinal or seasonal differences for most categories, except for a clear reversal of the profile of PE occurrence with latitude. In every multistation event studied, we have found QP and/or PE modulations to be simultaneous at all stations to within the 1-s sampling time of the data. This suggests that all such events originate a single, localized region, most probably near the plasmapause. In contrast, the magnetic pulsations showed little or no detailed correlation between stations. Both statistical and single event studies support the hypothesis that highly localized field-aligned currents stimulated by echoing whistlers (PEs) may be responsible for producing type II QPs on the same flux tubes, typically in the subauroral or auroral regions. In addition, we have noted that the small number of type II QP events we have observed without accompanying PEs is tightly clustered near local noon. The existence of a set of equatorially-localized, near-noon, compressional Pc 3-4 waves that evidently do not appear in ground records suggests that this category as well might be generated by ULF wave modulation of equatorial ELF/VLF wave growth.

Engebretson, M. J.; Posch, J. L.; Shelburne, G. A.; Halford, A. J.; Smith, A. J.; Spasojevich, M.; Inan, U. S.; Arnoldy, R. L.

2003-12-01

91

The phase lags of high-frequency quasi-periodic oscillations in four black hole candidates  

NASA Astrophysics Data System (ADS)

We measured the phase-lag spectrum of the high-frequency quasi-periodic oscillations (QPO) in the black hole systems (at QPO frequencies) GRS 1915+105 (35 Hz and 67 Hz), GRO J1655-40 (300 Hz and 450 Hz), XTE J1550-564 (180 Hz and 280 Hz) and IGR J17091-3624 (67 Hz). The lag spectra of the 67-Hz QPO in, respectively, GRS 1915+105 and IGR J17091-3624, and the 450-Hz QPO in GRO J1655-40 are hard (hard photons lag the soft ones) and consistent with each other, with the hard lags increasing with energy. On the contrary, the lags of the 35- Hz QPO in GRS 1915+105 are soft, with the lags becoming softer as the energy increases; the lag spectrum of the 35-Hz QPO is inconsistent with that of the 67-Hz QPO. The lags of the 300-Hz QPO in GRO J1655-40, and the 180-Hz and the 280-Hz QPO in XTE J1550-564 are independent of energy, consistent with each other and with being zero or slightly positive (hard lags). For GRO J1655-40, the lag spectrum of the 300-Hz QPO differs significantly from that of the 450-Hz QPOs. The similarity of the lag spectra of the 180-Hz and 280-Hz QPO in XTE J1550-564 suggests that these two are the same QPO seen at a different frequency in different observations. If this is correct, the lags could provide an alternative way to identify the high-frequency QPO features in galactic black hole systems. The lag spectrum of the 67-Hz QPO in GRS 1915+105 (hard lags) is significantly different from that of the 2.7 × 10-4 Hz QPO in the narrow-line Seyfert 1 galaxy RE J1034+396 (soft lags), which disproves the suggestion that the two QPOs are the same physical phenomenon with their frequencies scaled only by the black hole mass. The lag spectrum of the QPO in RE J1034+396 is similar to that of the 35-Hz QPO in GRS 1915+105, although identifying these two QPOs as being the same physical feature remains problematic. We compare our results with those for the lags of the kilohertz QPOs in neutron-star systems and the broad-band noise component in active galactic nuclei, and discuss possible scenarios for producing the lags in these systems.

Méndez, Mariano; Altamirano, Diego; Belloni, Tomaso; Sanna, Andrea

2013-11-01

92

Evolution of the out-of-plane amplitude for quasi-periodic trajectories in the Earth-Moon system  

NASA Astrophysics Data System (ADS)

The out-of-plane amplitude along quasi-periodic trajectories in the Earth-Moon system is highly sensitive to perturbations in position and/or velocity as underscored recently by the ARTEMIS spacecraft. Controlling the evolution of the out-of-plane amplitude is non-trivial, but can be critical to satisfying mission requirements. The sensitivity of the out-of-plane amplitude evolution to perturbations due to lunar eccentricity, solar gravity, and solar radiation pressure is explored and a strategy for designing low-cost deterministic maneuvers to control the amplitude history is also examined. The method is sufficiently general and is applied to the L1 quasi-periodic orbit that serves as a baseline for the ARTEMIS P2 trajectory.

Pavlak, Thomas A.; Howell, Kathleen C.

2012-12-01

93

On the coexistence of periodic or quasi-periodic oscillations near a Hopf-pitchfork bifurcation in NFDE  

NASA Astrophysics Data System (ADS)

Normal form method is first employed to study the Hopf-pitchfork bifurcation in neutral functional differential equation (NFDE), and is proved to be an efficient approach to show the rich dynamics (periodic and quasi-periodic oscillations) around the bifurcation point. We give an algorithm for calculating the third-order normal form in NFDE models, which naturally arise in the method of extended time delay autosynchronization (ETDAS). The existence of Hopf-pitchfork bifurcation in a van der Pol's equation with extended delay feedback is given and the unfoldings near this critical point is obtained by applying our algorithm. Some interesting phenomena, such as the coexistence of several stable periodic oscillations (or quasi-periodic oscillations) and the existence of saddle connection bifurcation on a torus, are found by analyzing the bifurcation diagram and are illustrated by numerical method.

Jiang, Weihua; Niu, Ben

2013-03-01

94

Efficient generation of orange light in a quasi-periodically poled LiTaO3 crystal  

NASA Astrophysics Data System (ADS)

We present an approach to generating a tunable orange laser from 0.601 to 0.604 ?m based on a quasi-periodically poled superlattice in LiTaO3 and a Q-switched 1.064 ?m Nd:YVO4 laser as pump. The orange laser was generated in a cavity by a parametric process cascaded by a frequency mixing with a maximum output of 310 mW using 15 W pump power.

Pan, S. D.; Yu, X. Q.; Yan, Z.; Shen, Y.; Lv, X. J.; Zhu, S. N.

2008-12-01

95

Discovery of 0.08Hz quasi-periodic oscillations from the black-hole candidate LMC X-1  

Microsoft Academic Search

In the X-ray flux of LMC X-1, quasi-periodic oscillatiosn (QPO) of centroid frequency 0.0751 + or - 0.0009 Hz were discovered. Observations were made on April 22 and on July 16, 1987 with the large area proportional counters (LAC) on Ginga. QPOs were detected only in the April data. The energy spectrum of LMC X-1 is well represented by a

Ken Ebisawa; Kazuhisa Mitsuda; Hajime Inoue

1989-01-01

96

Quasi-periodic Propagating Signals in the Solar Corona: The Signature of Magnetoacoustic Waves or High-velocity Upflows?  

Microsoft Academic Search

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

Bart De Pontieu; Scott W. McIntosh

2010-01-01

97

Quasi-periodic Oscillations in Black Hole Candidates as an Indicator of Transition between Low and High States  

Microsoft Academic Search

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

Robert E. Rutledge; Walter H. G. Lewin; Michiel van der Klis; Jan van Paradijs; Tadayasu Dotani; Brian Vaughan; Tomaso Belloni; Tim Oosterbroek; Chryssa Kouveliotou

1999-01-01

98

Characterization of a non thermal plasma torch  

Microsoft Academic Search

A non thermal He plasma needle was developed and characterized. The plasma was produced using the method presented in Anghels et al., which utilizes a resonant transformer to produce the voltages necessary to breakdown the helium (He) working gas. The plasma under study was found to have an output power less than 2 watts for all flow rates used with

Barnard Onyenucheya; Jennifer L. Zirnheld; Thomas M. DiSanto; Daniel P. Muffoletto

2009-01-01

99

Tuning visible light generation based on multi-channel quasi-periodically poled LiTaO3  

NASA Astrophysics Data System (ADS)

We demonstrate broadband tuning visible light generation based on a multi-channel quasi-periodically poled LiTaO3 crystal, in which a quasi-phase matched optical parametric generation process and a quasi-phase matched sum-frequency mixing process were achieved simultaneously. The conversion characters on spectrum and energy were studied by using a nanosecond pulse laser at 1.064 ?m as pump light. We could tune the visible light over ~ 26 nm by means of changing the crystal's channel and temperature. The ratio of the output wavelength variation to that of temperature was ~ 0.07 nm/°C. The single-pass slope efficiency was 6.3% with the maximum output energy of 25 ?J.

Pan, S. D.; Yuan, Y.; Zhao, L. N.; Liu, Y. H.; Zhu, S. N.

2011-01-01

100

Discovery of a 34 Hz quasi-periodic oscillation in the X-ray emission of GRS 1915+105  

NASA Astrophysics Data System (ADS)

We report the discovery in the Rossi X-Ray Timing Explorer data of GRS 1915+105 of a second quasi-periodic oscillation at 34 Hz, simultaneous with that observed at 68 Hz in the same observation. The data corresponded to those observations from 2003 where the 68 Hz oscillation was very strong. The significance of the detection is 4.2?. These observations correspond to a very specific position in the colour-colour diagram for GRS 1915+105, corresponding to a harder spectrum compared to those where a 41 Hz oscillation was discovered. We discuss the possible implications of the new pair of frequencies comparing them with the existing theoretical models.

Belloni, T. M.; Altamirano, D.

2013-06-01

101

A 200-Second Quasi-Periodicity After the Tidal Disruption of a Star by a Dormant Black Hole  

NASA Astrophysics Data System (ADS)

Supermassive black holes are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. Supermassive black holes can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a 200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.

Reis, Ruben C.; Miller, J. M.; Reynolds, M.; Gultekin, K.; Maitra, D.; King, A. L.; Strohmayer, T. E.

2013-04-01

102

A 200-Second Quasi-Periodicity After the Tidal Disruption of a Star by a Dormant Black Hole  

NASA Astrophysics Data System (ADS)

Supermassive black holes (SMBHs; mass is greater than or approximately 105 times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe.

Reis, R. C.; Miller, J. M.; Reynolds, M. T.; Gültekin, K.; Maitra, D.; King, A. L.; Strohmayer, T. E.

2012-08-01

103

Constraining the Mass and Moment of Inertia of Neutron Stars from Quasi-Periodic Oscillations in X-ray Binaries  

NASA Astrophysics Data System (ADS)

We put some constraints on the mass and moment of inertia of neutron stars based on the interpretation of high-frequency quasi-periodic oscillations (HF-QPOs) observed in low mass X-ray binaries (LMXBs). We use available HF-QPOs observations to look for the average mass and moment of inertia of neutron stars by applying our parametric resonance model to discriminate between slow and fast rotators in relation with the innermost stable circular orbit (ISCO). We find an average mass M* ? (2.0 - 2.2) M?. The corresponding average moment of inertia is then I* ? (1 - 3) × 1038kg m2 ? (0.5 - 1.5) (10 km)2 M?.

Pétri, J.

2012-12-01

104

Multi-Resonance Orbital Model Applied to High-Frequency Quasi-Periodic Oscillations Observed in Sgr A*  

NASA Astrophysics Data System (ADS)

The multi-resonance orbital model of high-frequency quasi-periodic oscillations (HF QPOs) enables precise determination of the black hole dimensionless spin a if observed set of oscillations demonstrates three (or more) commensurable frequencies. The black hole spin a is related to the frequency ratio only, while its mass M is related to the frequency magnitude. The model is applied to the triple frequency set of HF QPOs observed in Sgr A* source with frequency ratio 3:2:1. Acceptable versions of the multi-resonance model are determined by the restrictions on the Sgr A* supermassive black hole mass. The version of strong resonances related to the black hole "magic" spin a=0.983 is acceptable but the version demonstrating the best agreement with the mass restrictions predicts spin a=0.980.

Kotrlová, A.; Stuchlík, Z.; Török, G.

2013-06-01

105

A 200-second quasi-periodicity after the tidal disruption of a star by a dormant black hole.  

PubMed

Supermassive black holes (SMBHs; mass is greater than or approximately 10(5) times that of the Sun) are known to exist at the center of most galaxies with sufficient stellar mass. In the local universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, which often comes in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-second x-ray quasi-periodicity around a previously dormant SMBH located in the center of a galaxy at redshift z = 0.3534. This result may open the possibility of probing general relativity beyond our local universe. PMID:22859817

Reis, R C; Miller, J M; Reynolds, M T; Gültekin, K; Maitra, D; King, A L; Strohmayer, T E

2012-08-02

106

Quasi-periodic backscatters from the E region at Gadanki: Evidence for Kelvin-Helmholtz billows in the lower thermosphere?  

NASA Astrophysics Data System (ADS)

Analyzing the field-aligned coherent radar backscatter observed over Gadanki, India (13.5°N, 79.2°E), with a narrow beam pointing almost vertically, we present convincing experimental evidence for the presence of low-latitudes tilted sporadic ionization layers close to 10 km in vertical extent that move horizontally through the field of view of the radar. Using the data from high temporal (˜3 s) resolution experiments, we also show that the line-of-sight Doppler velocities associated with at least some of the quasi-periodic striations have very clear vortex-like structures cutting across a vertical plane inside regions of strong horizontal wind shears. The power as well as the Doppler width peak together, and they often reach their peak values near the center of a vortex, where the magnitude of the Doppler velocity is minimum. The Doppler properties and spatial distribution of the 3 m echoes are explained in terms of a local electrodynamical process that makes ions and electrons move with the vertical neutral wind. Both the wind field and the tilt of the layers are in turn consistent with the presence of Kelvin-Helmholtz billows. We postulate that the billows themselves are triggered by a shear instability in the large ambient zonal wind; strong zonal wind shears clearly have to be present when sporadic E layers are observed. In our case, the breaking of an originally uniform and horizontal sporadic E layer into tilted pieces aligned more or less parallel to one another, and their motion through the radar field of view in the presence of a mean zonal wind, give the echoes their quasi-periodic appearance.

Choudhary, R. K.; St.-Maurice, J.-P.; Kagan, L. M.; Mahajan, K. K.

2005-08-01

107

HIGHLY COHERENT KILOHERTZ QUASI-PERIODIC OSCILLATIONS FROM THE NEUTRON STAR X-RAY BINARY EXO 1745-248  

SciTech Connect

We report the discovery (20{sigma}) of kilohertz quasi-periodic oscillations (kHz QPOs) at {approx}690 Hz from the transient neutron star low-mass X-ray binary EXO 1745-248. We find that this is a lower kHz QPO and systematically study the time variation of its properties using smaller data segments with and without the shift-and-add technique. The quality (Q) factor occasionally significantly varies within short ranges of frequency and time. A high Q-factor (264.5 {+-} 38.5) of the QPO is found for a 200 s time segment, which might be the largest value reported in the literature. We argue that an effective way to rule out kHz QPO models is to observationally find such high Q-factors, even for a short duration, as many models cannot explain a high coherence. However, as we demonstrate, the shift-and-add technique cannot find a very high Q-factor which appears for a short period of time. This shows that the coherences of kHz QPOs can be higher than the already high values reported using this technique, implying further constraints on models. We also discuss the energy dependence of fractional rms amplitude and the Q-factor of the kHz QPO.

Mukherjee, Arunava; Bhattacharyya, Sudip, E-mail: arunava@tifr.res.in, E-mail: sudip@tifr.res.in [Tata Institute of Fundamental Research, Mumbai-400005 (India)

2011-04-01

108

Simultaneous observations of quasi-periodic ELF/VLF wave emissions and energetic-electron precipitation by DEMETER  

NASA Astrophysics Data System (ADS)

One of the proposed explanations of the quasi-periodic (QP) VLF wave observed in the ionosphere is based on their generation by energetic electrons in the equatorial region of the magnetosphere. These electrons then precipitate into the ionosphere and their flux should be modulated with the same period as the QP emissions. The main attention in our study is paid to the correlation between both features. We use the DEMETER spacecraft data for this purpose. We have analyzed more than two hundred events of the QP wave measurements by DEMETER. In this large data set, we have found several cases where precipitated electrons are highly correlated with the QP wave bursts. To our knowledge, such observations made onboard satellites have not been reported earlier. We have found the cases at both low (L < 4) and high (L > 4) McIlwain parameter, however characteristics of the QP emissions (the frequencies, the dynamic spectrums, the periods) differ for different latitudes. Energetic particle data from the DEMETER satellite are supplemented by data from the NOAA-17 satellite. The orbit of this spacecraft is very similar to the orbit of DEMETER. We discuss mechanisms of removal of energetic electrons from a generation region and we compare the parameters of the observed events with the cyclotron maser model of the QP emissions.

Hayosh, M.; Pasmanik, D.; Demekhov, A.; Santolík, O.; Titova, E.; Parrot, M.

2012-04-01

109

Quasi-periodic oscillations in the X-ray flux of GX3+1 (4U 1744-26)  

NASA Astrophysics Data System (ADS)

GX 3+1, one of the brightest X-ray sources, was observed with EXOSAT in 1985 for 8.5 hr on March 24 - 25, and for 16 hr on September 4. During both observations the flux levels varied by about 20 per cent. The mean flux in September was about 8 per cent lower than in March. Throughout the March 24 - 25 observations, low-frequency noise (LFN) was observed below roughly 10 Hz, but no quasi-periodic oscillations (QPO) were detected. During the September 4 observations, LFN was again detected throughout, but this time QPO were also detected (with a mean frequency of about 8 Hz) during an approximately 3.3-hr period. QPO were only observed (but not always) when the spectral hardness was below a certain value. QPO were not observed in the so-called 'horizontal spectral branch'. It is possible that these QPO in GX 3+1 are similar in nature to the intensity-dependent 5.6-Hz QPO observed in Cyg X-2 which are also not observed in the horizontal branch.

Lewin, W. H. G.; van Paradijs, J.; Hasinger, G.; Penninx, W. H.; Langmeier, A.; van der Klis, M.; Jansen, F.; Basinska, E. M.; Sztajno, M.; Trumper, J.

1987-05-01

110

Quasi-periodic oscillations in the X-ray flux of GX 3+1 (4U 1744-26)  

NASA Astrophysics Data System (ADS)

The X-ray source GX 3+1 was observed with EXOSAT in 1985 for 8.5 hr on March 24 to 25, and for 16 hr on September 4. During both observations the flux levels vary by 20%. The mean flux in September is 8% lower than in March. Throughout the March 24 to 25 observations, low-frequency noise (LFN) is observed below 10 Hz, but no quasi-periodic oscillations (QPO) are detected. During the September 4 observations, LFN is detected throughout, but QPO are also detected (with a mean frequency of 8 Hz) during a 3.3 hr period. The strength of the QPO is 3%. The LFN strength increases from 2% to 6% for photon energies increasing from 2 to 10 keV. There appears to be no correlation between the occurrence of QPO and source intensity, however, QPO are only observed (but not always) when the spectral hardness is below a certain value. The QPO are not observed in the horizontal spectral branch.

Lewin, W. H. G.; van Paradijs, J.; Hasinger, G.; Penninx, W.; Langmeier, A.; van der Klis, M.; Jansen, F.; Basinska, E. M.; Sztjano, M.; Truemper, J.

1986-08-01

111

Renormalized entropy for one dimensional discrete maps: periodic and quasi-periodic route to chaos and their robustness  

NASA Astrophysics Data System (ADS)

We apply renormalized entropy as a complexity measure to the logistic and sine-circle maps. In the case of logistic map, renormalized entropy decreases (increases) until the accumulation point (after the accumulation point up to the most chaotic state) as a sign of increasing (decreasing) degree of order in all the investigated periodic windows, namely, period-2, 3, and 5, thereby proving the robustness of this complexity measure. This observed change in the renormalized entropy is adequate, since the bifurcations are exhibited before the accumulation point, after which the band-merging, in opposition to the bifurcations, is exhibited. In addition to the precise detection of the accumulation points in all these windows, it is shown that the renormalized entropy can detect the self-similar windows in the chaotic regime by exhibiting abrupt changes in its values. Regarding the sine-circle map, we observe that the renormalized entropy detects also the quasi-periodic regimes by showing oscillatory behavior particularly in these regimes. Moreover, the oscillatory regime of the renormalized entropy corresponds to a larger interval of the nonlinearity parameter of the sine-circle map as the value of the frequency ratio parameter reaches the critical value, at which the winding ratio attains the golden mean.

Afsar, Ozgur; Bagci, Gokhan Baris; Tirnakli, Ugur

2013-07-01

112

DISCOVERY OF HIGH-FREQUENCY QUASI-PERIODIC OSCILLATIONS IN THE BLACK HOLE CANDIDATE IGR J17091-3624  

SciTech Connect

We report the discovery of 8.5{sigma} high-frequency quasi-periodic oscillations (HFQPOs) at 66 Hz in the Rossi X-ray Timing Explorer data of the black hole candidate IGR J17091-3624, a system whose X-ray properties are very similar to those of microquasar GRS 1915+105. The centroid frequency of the strongest peak is {approx}66 Hz, its quality factor above five, and its rms is between 4% and 10%. We found a possible additional peak at 164 Hz when selecting a subset of the data; however, at the 4.5{sigma} level we consider this detection marginal. These QPOs have hard spectrum and are stronger in observations performed between 2011 September and October, during which IGR J17091-3624 displayed for the first time light curves that resemble those of the {gamma} variability class in GRS 1915+105. We find that the 66 Hz QPO is also present in previous observations (4.5{sigma}), but only when averaging {approx}235 ks of relatively high count rate data. The fact that the HFQPOs frequency in IGR J17091-3624 matches surprisingly well with that seen in GRS 1915+105 raises questions on the mass scaling of QPOs frequency in these two systems. We discuss some possible interpretations; however, they all strongly depend on the distance and mass of IGR J17091-3624, both completely unconstrained today.

Altamirano, D. [Astronomical Institute, 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098XH Amsterdam (Netherlands); Belloni, T., E-mail: d.altamirano@uva.nl [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy)

2012-03-15

113

New type of ensemble of quasi-periodic, long-lasting VLF emissions at the auroral zone  

NASA Astrophysics Data System (ADS)

A new type of the series of quasi-periodic (QP) very low frequency (VLF) emissions in frequency range of 1-5 kHz, and not associated with geomagnetic pulsations, has been discovered at auroral latitudes (L = 5.3) during the Finnish VLF campaign (held in December 2011). At least five unusually spectacular events, each with a duration of several hours, have been observed during the night under conditions of quiet geomagnetic activity (Kp = 0-1), although QPs usually occur during the daytime. Contrary to the QP emissions typically occurring during the day, the spectral structure of these QP events represented an extended, complicated sequence of repeated discrete rising VLF signals. Their duration was about 2-3 min each, with the repetition periods ranging from ~1 min to ~10 min. Two such nighttime non-typical events are reported in this paper. The fine structure of the separated QP elements may represent a mixture of the different frequency band signals, which seem to have independent origins. It was found that the periodic signals with lower frequency appear to trigger the strong dispersive upper frequency signals. The temporal dynamics of the spectral structure of the QPs studied were significantly controlled by some disturbances in the solar wind and interplanetary magnetic field (IMF). This finding is very important for future theoretical investigations because the generation mechanism of this new type of QP emissions is not yet understood.

Manninen, J.; Kleimenova, N. G.; Kozyreva, O. V.

2012-12-01

114

Simultaneous observations of quasi-periodic ELF/VLF wave emissions and electron precipitation by DEMETER satellite: A case study  

NASA Astrophysics Data System (ADS)

We present results of case studies of quasi-periodic (QP) ELF/VLF hiss emissions detected onboard the DEMETER satellite. Three events with simultaneous periodic modulation in VLF wave intensity and energetic electron precipitation are found. In each event we observe exact coincidence of one or two busts of VLF wave intensity with energetic electron precipitation peaks. To our knowledge, such observations made onboard satellites have not been reported earlier. All events are observed at fairly quiet geomagnetic conditions (Kp <3). The dynamic spectrum of the VLF waves in these QP events was characterized by a regular frequency increase in each burst, and the repetition period was less than or about 20 s. These features allow us to suggest that the observed events belong to the QP2-class, i.e., events which are not associated with geomagnetic pulsations. We also analyze energetic electron data from NOAA-17 spacecraft which has helio-synchronous circular orbit similar to DEMETER spacecraft and measured in the same region of the magnetosphere within 30 min for the analyzed events. NOAA-17 data confirm that the QP emissions were detected by DEMETER in the region of isotropization of energetic electrons, which is typically associated with the development of the cyclotron instability. Modulation of electron flux with a period close to the QP emission period is observed in two events. Based on the observed correlation between bursts of wave intensity and energetic particle flux, we estimate the location and spatial extent of the source region for QP emissions.

Hayosh, M.; Pasmanik, D. L.; Demekhov, A. G.; Santolik, O.; Parrot, M.; Titova, E. E.

2013-07-01

115

Shear instability as a source of the daytime quasi-periodic radar echoes observed by the Gadanki VHF radar  

NASA Astrophysics Data System (ADS)

High-resolution observations of the daytime quasi-periodic (QP) structures of the lower E region irregularities made using the Gadanki VHF radar are presented. The structures are found to display striations with negative altitude rates of ~10 m s-1 and periods of 1-3 minutes. More importantly, these structures are found to be associated with a descending irregularity layer having descent rate of ~0.3 m s-1. The characteristics of these structures although resemble closely to that of nighttime low altitude structures observed earlier at Gadanki as well as at mid-latitudes, the periodicities observed during daytime are found to be higher than that observed during nighttime. The Doppler velocities are mostly in the range -20-10 m s-1 and exhibit remarkable shear corresponding to the echoes of larger periodicities. The echoes being mostly confined to the collision dominated lower E region, it is possible to derive meridional neutral wind and the derived wind shows remarkable shear. It is proposed that the Kelvin-Helmholtz instability is the most likely mechanism responsible for the observed structures presented in this paper.

Sripathi, S.; Patra, A. K.; Sivakumar, V.; Rao, P. B.

2003-11-01

116

Discovery of High-frequency Quasi-periodic Oscillations in the Black Hole Candidate IGR J17091-3624  

NASA Astrophysics Data System (ADS)

We report the discovery of 8.5? high-frequency quasi-periodic oscillations (HFQPOs) at 66 Hz in the Rossi X-ray Timing Explorer data of the black hole candidate IGR J17091-3624, a system whose X-ray properties are very similar to those of microquasar GRS 1915+105. The centroid frequency of the strongest peak is ~66 Hz, its quality factor above five, and its rms is between 4% and 10%. We found a possible additional peak at 164 Hz when selecting a subset of the data; however, at the 4.5? level we consider this detection marginal. These QPOs have hard spectrum and are stronger in observations performed between 2011 September and October, during which IGR J17091-3624 displayed for the first time light curves that resemble those of the ? variability class in GRS 1915+105. We find that the 66 Hz QPO is also present in previous observations (4.5?), but only when averaging ~235 ks of relatively high count rate data. The fact that the HFQPOs frequency in IGR J17091-3624 matches surprisingly well with that seen in GRS 1915+105 raises questions on the mass scaling of QPOs frequency in these two systems. We discuss some possible interpretations; however, they all strongly depend on the distance and mass of IGR J17091-3624, both completely unconstrained today.

Altamirano, D.; Belloni, T.

2012-03-01

117

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

PubMed

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

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

2012-01-24

118

Spectral Index and Quasi-Periodic Oscillation Frequency Correlation in Black Hole Sources: Observational Evidence of Two Phases and Phase Transition in Black Holes.  

National Technical Information Service (NTIS)

Recent studies have shown that strong correlations are observed between the low frequencies (1-10 Hz) of quasi-periodic oscillations (QPOs) and the spectral power law index of several black hole (BH) candidate sources, in low (hard) states, steep power la...

L. Titarchuk R. Fiorito

2004-01-01

119

MICROWAVE QUASI-PERIODIC PULSATIONS IN MULTI-TIMESCALES ASSOCIATED WITH A SOLAR FLARE/CME EVENT  

SciTech Connect

Microwave observations of quasi-periodic pulsations (QPPs) in multi-timescales at the Solar Broadband Radio Spectrometer in Huairou (SBRS/Huairou) on 2006 December 13 are confirmed to be associated with an X3.4 flare/coronal mass ejection (CME) event. It is most remarkable that the timescales of QPPs are distributed in a broad range from hectoseconds (very long period pulsation, VLP, P>100 s), decaseconds (long period pulsation, LPP, 10 < P < 100 s), a few seconds (short period pulsation, SPP, 1 < P < 10 s), deciseconds (slow very short period pulsation, slow-VSP, 0.1 < P < 1.0 s), to centiseconds (fast very short period pulsation, fast-VSP, P < 0.1 s), and form a broad hierarchy. The statistical distribution of QPPs in logarithmic period-duration space indicates that all the QPPs can be classified into two groups: group I includes VLP, LPP, SPP, and some slow-VSPs distributed approximately around a line; group II includes fast-VSP and most of the slow-VSPs dispersively distributed away from the above line. This feature implies that the generation mechanism of group I is different from group II. Group I is possibly related to some MHD oscillations in magnetized plasma loops in the active region; e.g., VLPs may be generated by standing slow sausage mode coupling, resonating with the underlying photospheric 5 minute oscillation, with the modulation amplified and forming the main framework of the whole flare/CME process; LPPs, SPPs, and some slow-VSPs are most likely to be caused by standing fast modes or LRC-circuit resonance in current-carrying plasma loops. Group II is possibly generated by modulations of resistive tearing-mode oscillations in electric current-carrying flaring loops.

Tan Baolin; Zhang Yin; Tan Chengming; Liu Yuying, E-mail: bltan@nao.cas.c [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences (China)

2010-11-01

120

Time Delays in Quasi-periodic Pulsations Observed during the X2.2 Solar Flare on 2011 February 15  

NASA Astrophysics Data System (ADS)

We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on timescale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager channels in the range 25-100 keV lead all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the extreme-ultraviolet (EUV) channels of the Euv SpectroPhotometer (ESP) on board the Solar Dynamic Observatory. The zirconium and aluminum filter channels of the Large Yield Radiometer on board the Project for On-Board Autonomy satellite and the soft X-ray (SXR) channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite, where the channel at 1-8 Å leads the 0.5-4 Å channel by several seconds. The time lags between the first and last channels is up to ?9 s. We identified at least two distinct time intervals during the flare impulsive phase, during which the QPPs were associated with two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels showed different lags during these two intervals. To our knowledge, this is the first time that time lags are reported between EUV and SXR fluctuations on these timescales. We discuss possible emission mechanisms and interpretations, including flare electron trapping.

Dolla, L.; Marqué, C.; Seaton, D. B.; Van Doorsselaere, T.; Dominique, M.; Berghmans, D.; Cabanas, C.; De Groof, A.; Schmutz, W.; Verdini, A.; West, M. J.; Zender, J.; Zhukov, A. N.

2012-04-01

121

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

SciTech Connect

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.

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

122

Independence of short time scale fluctuations of quasi-periodic oscillations and low-frequency noise in GX 5-1  

Microsoft Academic Search

The short time-scale variability in the X-ray flux of the quasi-periodic oscillations (QPOs) and low-frequency noise (LFM) in GX 5-1 is examined, using data from Ginga observations and simulations of the GX 5-1 power spectrum, with the purpose of determining whether there is an association between the LFN and the QPO in GX 5-1 on the horizontal branch (i.e., whether

J. P. Norris; P. Hertz; K. S. Wood; B. A. Vaughan; P. F. Michelson; K. Mitsuda; T. Dotani

1990-01-01

123

On the importance of searching for oscillations of the Jovian inner radiation belt with a quasi-period of 40 minutes  

Microsoft Academic Search

Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. 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 a

Yu-Qing Lou; Chen Zheng

2003-01-01

124

The discovery of 0.2 HZ quasi-periodic oscillations in the X-ray flux of the transient 42 second pulsar EXO 2030 + 375  

Microsoft Academic Search

The discovery of about 0.2 Hz quasi-periodic oscillations (QPOs) in the 1-15 keV X-ray flux of the transient 42 s pulsar EXO 2030 + 375 is reported. The detection of QPOs in the power spectra of this pulsar was made possible by the application of a newly developed technique to decouple the power spectrum peaks. QPOs were detected during an

L. Angelini; L. Stella; A. N. Parmar

1989-01-01

125

Normal-Branch Quasi-periodic Oscillations in Scorpius X-1: Viscous Oscillations of a Spherical Shell Near the Neutron Star  

Microsoft Academic Search

We present a comprehensive classification of all observed quasi-periodic oscillations (QPOs) within the framework of the transition layer model using a large set of Rossi X-Ray Timing Explorer data for Scorpius X-1. The model assumes an optically thin material along the observer's line of sight in the horizontal branch and an increasingly optically thick material while in the other two

L. G. Titarchuk; C. F. Bradshaw; B. J. Geldzahler; E. B. Fomalont

2001-01-01

126

Direct Imaging by SDO\\/AIA of Quasi-periodic Propagating Fast Mode Magnetosonic Waves of 2000 km\\/s in the Solar Corona  

Microsoft Academic Search

Quasi-periodic, propagating fast mode magnetosonic waves in the corona were difficult to observe in the past due to relatively low instrument cadences. We report here unprecedented evidence of such waves directly imaged in EUV by the new SDO\\/AIA instrument. In the 2010 August 1 C3.2 flare\\/CME event, we find arc-shaped wave trains of 1-5% intensity variations emanating near the flare

Wei Liu; J. Zhao; L. Ofman; C. J. Schrijver; M. J. Aschwanden; B. De Pontieu; T. D. Tarbell

2011-01-01

127

Direct Imaging of Quasi-periodic Fast Propagating Waves of ~2000 km s-1 in the Low Solar Corona by the Solar Dynamics Observatory Atmospheric Imaging Assembly  

Microsoft Academic Search

Quasi-periodic propagating fast mode magnetosonic waves in the solar corona were difficult to observe in the past due to relatively low instrument cadences. We report here evidence of such waves directly imaged in EUV by the new Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory. In the 2010 August 1 C3.2 flare\\/coronal mass ejection event, we find arc-shaped

Wei Liu; Junwei Zhao; Leon Ofman; Carolus J. Schrijver; Markus J. Aschwanden; Bart De Pontieu; Theodore D. Tarbell

2011-01-01

128

Quasi-periodic regime of self-modulation oscillations with a periodic low-frequency envelope in a ring chip laser  

SciTech Connect

The dynamics of a ring chip Nd:YAG laser radiation in an external static magnetic field inducing an optical nonreciprocity of the resonator is studied experimentally. The amplitude and frequency nonreciprocities of the ring cavity induced by this magnetic field varied with moving the magnet with respect to the active element of the chip laser. A previously unknown quasi-periodic self-modulation lasing regime in which the self-modulation intensity oscillations of counterpropagating waves have an antiphase low-frequency envelope is found. The temporal and spectral characteristics of radiation are studied and the conditions of the appearance of this lasing regime are determined. (lasers)

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)

2011-01-31

129

Effects of Non-Thermal Plasma on Mammalian Cells  

PubMed Central

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.

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

2011-01-01

130

Direct Imaging of Quasi-periodic Fast Propagating Waves of ~2000 km s-1 in the Low Solar Corona by the Solar Dynamics Observatory Atmospheric Imaging Assembly  

NASA Astrophysics Data System (ADS)

Quasi-periodic propagating fast mode magnetosonic waves in the solar corona were difficult to observe in the past due to relatively low instrument cadences. We report here evidence of such waves directly imaged in EUV by the new Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory. In the 2010 August 1 C3.2 flare/coronal mass ejection event, we find arc-shaped wave trains of 1%-5% intensity variations (lifetime ~200 s) that emanate near the flare kernel and propagate outward up to ~400 Mm along a funnel of coronal loops. Sinusoidal fits to a typical wave train indicate a phase velocity of 2200 ± 130 km s-1. Similar waves propagating in opposite directions are observed in closed loops between two flare ribbons. In the k-? diagram of the Fourier wave power, we find a bright ridge that represents the dispersion relation and can be well fitted with a straight line passing through the origin. This k-? ridge shows a broad frequency distribution with power peaks at 5.5, 14.5, and 25.1 mHz. The strongest signal at 5.5 mHz (period 181 s) temporally coincides with quasi-periodic pulsations of the flare, suggesting a common origin. The instantaneous wave energy flux of (0.1-2.6) × 107 erg cm-2 s-1 estimated at the coronal base is comparable to the steady-state heating requirement of active region loops.

Liu, Wei; Title, Alan M.; Zhao, Junwei; Ofman, Leon; Schrijver, Carolus J.; Aschwanden, Markus J.; De Pontieu, Bart; Tarbell, Theodore D.

2011-07-01

131

Identification of the Infrared Non-thermal Emission in Blazars  

NASA Astrophysics Data System (ADS)

Blazars constitute the most interesting and enigmatic class of extragalactic ?-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] ?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 ?-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.

Massaro, F.; D'Abrusco, R.; Ajello, M.; Grindlay, J. E.; Smith, Howard A.

2011-10-01

132

Imaging Observations of X-Ray Quasi-periodic Oscillations at 3 - 6 keV in the 26 December 2002 Solar Flare  

NASA Astrophysics Data System (ADS)

Quasi-periodic oscillations in soft X-rays (SXR) are not well known due to the instrument limitations, especially the absence of imaging observations of SXR oscillations. We explore the quasi-periodic oscillations of SXR at 3 - 6 keV in a solar flare observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 26 December 2002. This was a B8.1 class event and showed three X-ray sources (S1, S2, and S3) at 3 - 6 keV and two sources (S1 and S2) at 12 - 25 keV. The light curves of the total fluxes display a two-minute oscillation at 3 - 6 keV, but not in the energy bands above 8 keV. To investigate imaging observations of the oscillations, we prepared CLEAN images at seven energy bands between 3 keV and 20 keV with an eight-second integration. The light curves of three sources were analyzed after integrating the flux of each source region. We used the Fourier method to decompose each source light curve into rapidly varying and slowly varying components. The rapidly varying components show seven individual peaks which are well fitted with a sine function. Then we used the wavelet method to analyze the periods in the rapidly varying component of each source. The results show that three sources display damped quasi-periodic oscillations with a similar two-minute period. The damped oscillations timescale varies between 2.5 to 6 minutes. Source S1 oscillates with the same phase as S3, but is almost in anti-phase with S2. Analyzing the flaring images in more detail, we found that these oscillation peaks are well consistent with the appearance of S3, which seems to split from or merge with S2 with a period of two minutes. The flare images with a high cadence of one second at 3 - 6 keV show that source S3 appears with a rapid period of 25 seconds. The two-minute oscillation shows the highest spectral power. Source S3 seems to shift its position along the flare loop with a mean speed of 130 km s-1, which is of the same order as the local sound speed. This connection between the oscillation peaks and emission enhancement appears to be an observational constraint on the emission mechanism at 3 - 6 keV.

Ning, Zongjun

2013-10-01

133

FEASIBILITY ANALYSIS REPORT FOR HYBRID NON-THERMAL PLASMA REACTORS  

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...

134

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...

135

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

PubMed

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

Israel, M; Zaryabova, V; Ivanova, M

2013-06-01

136

Independence of short time scale fluctuations of quasi-periodic oscillations and low-frequency noise in GX 5-1  

NASA Astrophysics Data System (ADS)

The short time-scale variability in the X-ray flux of the quasi-periodic oscillations (QPOs) and low-frequency noise (LFM) in GX 5-1 is examined, using data from Ginga observations and simulations of the GX 5-1 power spectrum, with the purpose of determining whether there is an association between the LFN and the QPO in GX 5-1 on the horizontal branch (i.e., whether the LFN shots are the envelope of the QPOs). It is shown that the GX 5-1 data contain no indication that QPOs are carried by positive shots. Simulations also revealed no indication of a correlation between the QPO and the LFN components. The results are consistent with a picture of QPOs produced independently from an intensity-symmetric LFN component.

Norris, J. P.; Hertz, P.; Wood, K. S.; Vaughan, B. A.; Michelson, P. F.; Mitsuda, K.; Dotani, T.

1990-10-01

137

Relation between the quasi-periodic oscillations and the low-frequency noise of GX 5-1 in the horizontal branch  

NASA Astrophysics Data System (ADS)

Ginga observations of quasi-periodic oscillations (QPOs) and the low-frequency noise (LFN) from GX 5-1 in its horizontal-branch spectral state are presented. Power spectral fits were attempted using model functions based on simple oscillating shot models. A clear second-harmonic peak of QPO was detected. Variations in the powers of QPO and LFN on timescales of 8-256 s were also studied. These variations were significant for all of the timescales studied, and were uncorrelated with each other on timescales shorter than a few tens of seconds, and correlated on longer timescales. From simulations based on a simple shot model, it was found that the variation amplitude and the lack of correlation on short timescales are not inconsistent with the oscillating shot models. A more complex model is necessary to fully explain the observed properties.

Mitsuda, Kazuhisa; Dotani, Tadayasu; Yoshida, Atsumasa; Vaughan, Brian; Norris, Jay P.

1991-02-01

138

Independence of short time scale fluctuations of quasi-periodic oscillations and low-frequency noise in GX 5-1  

SciTech Connect

The short time-scale variability in the X-ray flux of the quasi-periodic oscillations (QPOs) and low-frequency noise (LFM) in GX 5-1 is examined, using data from Ginga observations and simulations of the GX 5-1 power spectrum, with the purpose of determining whether there is an association between the LFN and the QPO in GX 5-1 on the horizontal branch (i.e., whether the LFN shots are the envelope of the QPOs). It is shown that the GX 5-1 data contain no indication that QPOs are carried by positive shots. Simulations also revealed no indication of a correlation between the QPO and the LFN components. The results are consistent with a picture of QPOs produced independently from an intensity-symmetric LFN component. 27 refs.

Norris, J.P.; Hertz, P.; Wood, K.S.; Vaughan, B.A.; Michelson, P.F. (E. O. Hulburt Center for Space Research, Washington, DC (USA) Stanford Univ., CA (USA))

1990-10-01

139

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

SciTech Connect

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.

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

1994-04-01

140

Direct Imaging by SDO/AIA of Quasi-periodic Propagating Fast Mode Magnetosonic Waves of 2000 km/s in the Solar Corona  

NASA Astrophysics Data System (ADS)

Quasi-periodic, propagating fast mode magnetosonic waves in the corona were difficult to observe in the past due to relatively low instrument cadences. We report here unprecedented evidence of such waves directly imaged in EUV by the new SDO/AIA instrument. In the 2010 August 1 C3.2 flare/CME event, we find arc-shaped wave trains of 1-5% intensity variations emanating near the flare kernel and propagating outward along a funnel of coronal loops. Sinusoidal fits to a typical wave train indicate a phase velocity of 2350 +/- 210 km/s. Similar waves propagating in opposite directions are observed in closed loops between two flare ribbons. In the k-omega diagram of the Fourier wave power, we find a bright ridge that represents the dispersion relation and can be well fitted with a straight line passing through the origin, giving an equal phase and group velocity of 1630 +/- 760 km/s averaged over the event. This k-omega ridge shows a broad frequency distribution with prominent power at four non-harmonic frequencies, 5.5, 14.5, 25.1, and 37.9 mHz, among which the 14.5 mHz (period: 69 s) signal is the strongest. The signal at 5.5 mHz (period: 181 s, same as chromospheric 3-minute oscillations) temporally coincides with flare pulsations, suggesting a common origin of possibly quasi-periodic magnetic reconnection. The instantaneous wave energy flux of (0.1-2.6)e7 ergs/cm2/s estimated at the coronal base is comparable to the steady-state heating requirement of active region loops.

Liu, Wei; Title, A. M.; Zhao, J.; Ofman, L.; Schrijver, C. J.; Aschwanden, M. J.; De Pontieu, B.; Tarbell, T. D.

2011-05-01

141

Non-Thermal Electromagnetic Radiation Damage to Lens Epithelium  

Microsoft Academic Search

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

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

2008-01-01

142

IDENTIFICATION OF THE INFRARED NON-THERMAL EMISSION IN BLAZARS  

SciTech Connect

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.

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

143

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

SciTech Connect

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.

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

144

The discovery of 0. 2 Hz quasi-periodic oscillations in the X-ray flux of the transient 42 second pulsar EXO 2030 + 375  

SciTech Connect

The discovery of about 0.2 Hz quasi-periodic oscillations (QPOs) in the 1-15 keV X-ray flux of the transient 42 s pulsar EXO 2030 + 375 is reported. The detection of QPOs in the power spectra of this pulsar was made possible by the application of a newly developed technique to decouple the power spectrum peaks. QPOs were detected during an outburst, when the source was close to its maximum observed luminosity. Upper limits to the QPO strength during the rest of the outburst are consistent with the mean value observed of about 3.5 percent rms. During the outburst the QPOs centroid frequency decreased by about 12 percent, as the luminosity decreased by about 25 percent. The observed QPOs strength, frequency, and frequency-luminosity dependence are all in remarkable agreement with the predictions of the beat frequency model for QPOs and provide the first quantitative confirmation of it. Simple models in which the QPOs signal is produced close to the magnetospheric boundary are ruled out as only about 0.2 percent of the total accretion luminosity can be liberated at this distance from the neutron star surface. 31 refs.

Angelini, L.; Stella, L.; Parmar, A.N. (EXOSAT Observatory, Noordwijk (Netherlands))

1989-11-01

145

Non-typical ground-based quasi-periodic VLF emissions observed at L˜5.3 under quiet geomagnetic conditions at night  

NASA Astrophysics Data System (ADS)

Non-typical long lasting quasi-periodic (QP) VLF emissions have been recorded in Northern Finland at L˜5.3 during the recent Finnish VLF campaign held in December 2011. Contrary to the typical daytime QP emissions, the night-time and early morning (00-05UT) event reported here for the first time is a sequence of 1.5-3.5kHz noise bursts lasting for several tens of seconds with an unusually long repetition period which gradually decreases from ˜700s to ˜50s. These QP emissions were observed under conditions of very quiet geomagnetic activity (Kp=0). In spite of that, the interplanetary magnetic field generally had a small southward component, and a high-latitude substorm occurred on the night-side. After this substorm, the repetition period of the VLF bursts suddenly dropped from ˜200s to˜60s and the spectral structure of QP wave changed. We attribute these QP emissions to auto-oscillations of the cyclotron instability of the Earth's radiation belts. According to the theory, the repetition period of the QP should be inversely proportional to the flux of the gyroresonant energetic electrons. Thus the increased flux of energetic electrons injected by the substorm probably led to the decreasing QP repetition periods.

Manninen, J.; Kleimenova, N. G.; Kozyreva, O. V.; Bespalov, P. A.; Kozlovsky, A. E.

2013-07-01

146

Observation of three-dimensional structures of quasi-periodic echoes associated with mid-latitude sporadic-E layers by MU radar ultra-multi-channel system  

NASA Astrophysics Data System (ADS)

Quasi-periodic (QP) backscatter observed by VHF radars associated with the mid-latitude Sporadic-E (Es) layers is characterized by distinct striations on range-time-intensity (RTI) plots. Two competing models claim to explain the structure of unstable regions that scatter the radar waves: horizontally drifting patches at an almost constant altitude and unstable regions elongated in altitude along the geomagnetic field line. We have conducted interferometric imaging observations of QP radar echoes to investigate spatial structures of QP echoes, precisely. Kyoto University's newly developed ultra-multi-channel receiving system of middle and upper atmosphere (MU) radar was used. We used 19 independent channels for the radar imaging, and determined the three-dimensional structure and the motion of the QP echoes. During the observation from 30 May to 02 June 2005, well-defined QP echoes were observed on the nights of 31 May, 01 June, and 02 June 2005. Some of QP echoes were found at altitudes higher than 120 km and appeared to descend in altitude as they approached the radar. This result suggests that backscatter regions are developed along the geomagnetic field line from Es layer altitudes to as high as 130 km and that the fluctuations in plasma density and electric field observed by Pfaff et al. (2005) using in-situ measurements form a part of QP echoes.

Saito, S.; Yamamoto, M.; Hashiguchi, H.; Maegawa, A.

2006-07-01

147

Quasi-periodic oscillations and energy spectra from the two brightest Ultra-Luminous X-ray sources in M82  

NASA Astrophysics Data System (ADS)

Ultra-Luminous X-ray sources (ULXs) are thought to be accreting black holes (BHs) that might host intermediate-mass black holes (IMBH), proposed to exist by theoretical studies, even though a firm detection (as a class) is still missing. The brightest ULX in M82 (M82 X-1) is probably one of the best candidates to host an IMBH. In this work, we analysed the data of the recent release of observations obtained from M82 X-1 taken by XMM-Newton. We performed a study of the timing and spectral properties of the source. We report on the detection of ?(46 ± 2) mHz quasi-periodic oscillations (QPOs) in the power density spectra of two observations. A comparison of the frequency of these high-frequency QPOs with previous detections supports the 1:2:3 frequency distribution as suggested in other studies. We discuss the implications if the ?(46 ± 2) mHz QPO detected in M82 X-1 is the fundamental harmonic, in analogy with the high-frequency QPOs observed in BH binaries. For one of the observations, we have detected for the first time a QPO at 8 mHz (albeit at a low significance), which coincides with a hardening of the spectrum. We suggest that the QPO is a millihertz QPO originating from the close-by transient ULX M82 X-2, with analogies to the low-frequency QPOs observed in BH binaries.

Caballero-García, M. D.; Belloni, T.; Zampieri, L.

2013-10-01

148

Non-thermal Plasma for VOC Treatment in Flue Gases  

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

149

MERCURY OXIDIZATION IN NON-THERMAL PLASMA BARRIER DISCHARGE SYSTEM  

SciTech Connect

In the past decade, the emission of toxic elements from human activities has become a matter of great public concern. Hg, As, Se and Cd typically volatilize during a combustion process and are not easily caught with conventional air pollution control techniques. In addition, there is no pollution prevention technique available now or likely be available in the foreseeable future that can prevent the emission of these trace elements. These trace elements pose additional scientific challenge as they are present at only ppb levels in large gas streams. Mercury, in particular, has attracted significant attention due to its high volatility, toxicity and potential threat to human health. In the present research work, a non-thermal plasma dielectric barrier discharge technique has been used to oxidize Hg{sup 0}(g) to HgO. The basic premise of this approach is that Hg{sup 0} in vapor form cannot be easily removed in an absorption tower whereas HgO as a particulate is amiable to water scrubbing. The work presented in this report consists of three steps: (1) setting-up of an experimental apparatus to generate mercury vapors at a constant rate and modifying the existing non-thermal plasma reactor system, (2) solving the analytical challenge for measuring mercury vapor concentration at ppb level, and (3) conducting experiments on mercury oxidation under plasma conditions to establish proof of concept.

V.K. Mathur

2003-02-01

150

Mechanism of NO reduction with non-thermal plasma.  

PubMed

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

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

2005-01-01

151

Characteristics and implications of Doppler spectra of E region quasi-periodic echoes observed by the multibeam middle and upper atmosphere radar  

NASA Astrophysics Data System (ADS)

We present multibeam middle and upper atmosphere (MU) radar observations of quasi-periodic (QP) echoes from 3.2-m field-aligned irregularities associated with plasma patches in the nighttime midlatitude sporadic E (Es) layers over Shigaraki, Japan, to give a cohesive view of the QP echo characteristics. Echo regions with zonal scales less than 50 km moved westward at altitudes near 105 km with trace velocities of 110-120 m s-1 and crossed the radar beams successively. Doppler spectra of the echoes changed in time, range, and azimuth and exhibited mostly type 2 echoes with Doppler velocities between -200 and +200 m s-1 and occasionally type 1 echoes due to the two-stream instability ("the first type 1 echo detection by the MU radar"). We find that the spectra near the middle of the drifting echo region have two type 2 peaks, one at positive Doppler velocity (motion away from the radar) and the other at negative one (motion toward the radar) and that the spectra in the west and east parts of the echo region have single type 2 peak at positive and negative Doppler velocities, respectively. Interestingly, the type 1 echoes lasting for about 4 min on a fixed beam were located near the middle of the echo region. Their Doppler shifts between 250 and 320 m s-1 are very consistent with those from previous type 1 echo observations at other midlatitude locations. Occasionally, type 1 and type 2 echoes coexisted in the same range gates. On the basis of recent observations, theories, and simulations related to QP echoes, we propose a simple model of an Es plasma patch to explain the observations. In the model, polarization electric fields with opposite polarity inside and outside the patch, elongated along the NW-SE direction, play a predominant role in exciting type 1 and type 2 echoes, and cause a variety of Doppler spectra.

Ogawa, Tadahiko; Otsuka, Yuichi; Yamamoto, Mamoru

2006-05-01

152

Low-frequency (11 mHz) Oscillations in H1743-322: A New Class of Black Hole Quasi-periodic Oscillations?  

NASA Astrophysics Data System (ADS)

We report the discovery of quasi-periodic oscillations (QPOs) at ~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 ?2.2 mHz while the intensity had changed significantly. We show that this ~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 ~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.

Altamirano, D.; Strohmayer, T.

2012-08-01

153

Discovery of Quasi-periodic X-ray Dips from the ULX NGC 5408 X-1: Implications for the Accretion Geometry  

NASA Astrophysics Data System (ADS)

The nature of ultraluminous X-ray sources (ULXs) remains mysterious. It is not clear whether they are simply scaled-up accreting binaries, i.e., intermediate-mass black holes (mass range of a few 100-1000 solar masses) in binary orbits around companion stars accreting at a sub-Eddington rate or if they are stellar-mass black holes accreting and emitting via a super-Eddington mechanism. Perhaps the ULX population comprises both categories. We present evidence from an archetypal ULX, NGC 5408 X-1 (X-ray luminosity > 10^40 ergs/sec), that the source accretes in a geometry similar to that of Roche lobe overflow binaries. Using the approximately 3.5 years of Swift/X-ray monitoring data of the source we detect two distinct phenomena: (1) a quasi-sinusoidal, energy-dependent (modulation amplitude decreases with increasing energy upto 8 keV) modulation of the X-ray flux with a period of 112 days and (2) quasi-periodic, energy-independent dips in the X-ray intensity that recur on average every 243 days and with a variance of 23 days, suggesting a moderately high inclination. These two modulations (including their phase separation) appear to be consistent with the predicted variations for Roche-lobe accreting binaries with low-mass ratios, q = M(donor)/M(accretor). The smooth component can be produced by absorption/obscuration by two spatially distinct bulges along the outer rim of the accretion disk (produced by the tidal effects of the massive companion star) while the sharp dips are possibly produced by absorption due to clumps of material produced by the accretion stream - disk impact. We present an idealized accretion geometry of ULX NGC 5408 X-1 that is consistent with these modulations.

Ranga Reddy Pasham, Dheeraj; Strohmayer, T. E.

2013-04-01

154

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

SciTech Connect

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.

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

155

Non-thermal observations using EISCAT: Aspect angle dependence  

SciTech Connect

Recent observations with the EISCAT incoherent scatter radar have shown large rises in dayside, auroral plasma velocities (>2 km s/sup -1/) over a wide range of latitudes and lasting about an hour. These are larger than the neutral thermal speed, and allow, for the first time, observations of a non-thermal plasma over a range of observing angles, revealing a clear angular dependence. The observed ion temperature anisotropy, deduced by assuming a Maxwellian line-of-sight ion velocity distribution, is at least 1.75, which exceeds the theoretical value for a bi-Maxwellian based on a realistic ion-neutral collision model. The apsect angle dependence of the signal spectra also indicates non-Maxwellian plasma. copyright American Geophysical Union 1987

Winser, K.J.; Lockwood, M.; Jones, G.O.L.

1987-09-01

156

Numerical Simulation of Non-Thermal Food Preservation  

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

157

Discovery of a quasi-periodic oscillation in the X-ray pulsar 1A 1118-615: correlated spectral and aperiodic variability  

NASA Astrophysics Data System (ADS)

Aims: Our goal is to investigate the X-ray timing and spectral variability of the high-mass X-ray binary 1A 1118-615 during a type-II outburst. Methods: We performed a detailed color, spectral, and timing analysis of a giant outburst from 1A 1118-615 using RXTE data. Results: We report the discovery of a variable quasi-periodic oscillation (QPO) in the power spectral density of 1A 1118-615, with a centroid frequency of ~0.08 Hz. The centroid frequency of the QPO correlates with the X-ray flux, as expected according to the most accredited models for QPO production. For energies above ~4 keV, the QPO rms variability decreases as the energy increases. Pulse profiles display an energy dependence with a two-peak profile at lower energies and a single peak at higher energies. From the spectral analysis we confirm the presence of a cyclotron absorption feature at ~60 keV, the highest value measured for an X-ray pulsar. We find that the spectral parameters (photon index, cutoff energy, iron fluorescence line strength) display a marked dependence with flux. We detect two different levels of neutral hydrogen column density, possibly owing to to the Be companion activity. We report for the first time a correlation between the timing and spectral parameters in an X-ray pulsar. All correlations found between spectral/timing parameters and X-ray flux are present up to a flux of ~6 × 10-9 erg cm-2 s-1, when a saturation level is reached. We propose that the observed saturation corresponds to the minimum extent of the neutron star magnetosphere. We estimate the magnetic field of the neutron star from two independent ways, using results from spectral (cyclotron line energy) and timing (QPO frequency) analysis, obtaining consistent values of ~7-8 × 1012 G. Results from the comprehensive spectral and timing analysis are discussed in comparison with other X-ray pulsars.

Nespoli, E.; Reig, P.

2011-02-01

158

The kilohertz quasi-periodic oscillations during the Z and atoll phases of the unique transient XTE J1701-462  

NASA Astrophysics Data System (ADS)

We analysed 866 observations of the neutron star low-mass X-ray binary XTE J1701-462 during its 2006-2007 outburst. XTE J1701-462 is the only example so far of a source that during an outburst showed, beyond any doubt, spectral and timing characteristics both of the Z and atoll type. There are 707 RXTE observations (~2.5 Ms) of the source in the Z phase and 159 in the atoll phase (~0.5 Ms). We found, respectively, pairs of kilohertz quasi-periodic oscillations (kHz QPOs) in eight observations during the Z phase and single kHz QPO in six observations during the atoll phase. Using the shift-and-add technique, we identified the QPO in the atoll phase as the lower kHz QPO. We found that the lower kHz QPO in the atoll phase has a significantly higher coherence and fractional rms amplitude than any of the kHz QPOs seen during the Z phase, and that in the same frequency range, atoll lower kHz QPOs show coherence and fractional rms amplitude, respectively, two and three times larger than the Z kHz QPOs. Out of the 707 observations in the Z phase, there is no single observation in which the kHz QPOs have a coherence or rms amplitude similar to those seen when XTE J1701-462 was in the atoll phase, even though the total exposure time was about five times longer in the Z than in the atoll phase. Since it is observed in the same source, the difference in QPO coherence and rms amplitude between the Z and atoll phase cannot be due to neutron star mass, magnetic field, spin, inclination of the accretion disc, etc. If the QPO frequency is a function of the radius in the accretion disc in which it is produced, our results suggest that in XTE J1701-462 the coherence and rms amplitude are not uniquely related to this radius. Here we argue that this difference is instead due to a change in the properties of the accretion flow around the neutron star. Regardless of the precise mechanism, our result shows that effects other than the geometry of space-time around the neutron star have a strong influence on the coherence and rms amplitude of the kHz QPOs, and therefore the coherence and rms amplitude of the kHz QPOs cannot be simply used to deduce the existence of the innermost stable circular orbit around a neutron star.

Sanna, Andrea; Méndez, Mariano; Altamirano, Diego; Homan, Jeroen; Casella, Piergiorgio; Belloni, Tomaso; Lin, Dacheng; van der Klis, Michiel; Wijnands, Rudy

2010-10-01

159

On the importance of searching for oscillations of the Jovian inner radiation belt with a quasi-period of 40 minutes  

NASA Astrophysics Data System (ADS)

Experiments aboard the Ulysses spacecraft discovered quasi-periodic bursts of relativistic electrons and of radio emissions with ~40-min period (QP-40) from the south polar direction of Jupiter in 1992 February. 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 a distance of ~2-3 RJ (where RJ is the radius of Jupiter), where relativistic electrons are known to be trapped using the diagnostics of synchrotron emissions, can execute global QP-40 magnetoinertial oscillations excited by arrivals of high-speed solar winds at the Jovian magnetosphere. 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 relativistic electron bursts. Highly beamed synchrotron emissions from such QP-40 burst electrons with small pitch angles relative to Jovian magnetic fields at ~30-40 RJ give rise to QP-40 radio bursts with typical frequencies <~0.2 MHz. We predict that the synchrotron brightness of the IRB should vary on QP-40 time-scales upon arrivals of high-speed solar winds with estimated magnitudes >~0.1 Jy, detectable by existing ground-based radio telescopes. The recent discovery of ~45-min pulsations of Jupiter's north polar X-ray hot spot by the High-Resolution Camera (HRC) of the Chandra spacecraft provides strong supporting circumstantial evidence that the IRB neighborhood did oscillate with QP-40 time-scales. Using the real-time solar wind data from the spacecraft Advanced Composition Explorer (ACE), we show here that such QP-40 pulsations of Jupiter's north polar X-ray hot spot did in fact coincide with the arrival of high-speed solar wind at Jupiter. We note also that properly sampled data of simultaneous far-ultraviolet images of auroral ovals obtained by the Hubble Space Telescope imaging spectrograph (HST-STIS) would have contained QP-40 oscillatory signatures. Based on our theoretical analysis, we offer several predictions that can be tested by further spacecraft and ground-based telescope observations.

Lou, Yu-Qing; Zheng, Chen

2003-09-01

160

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

Microsoft Academic Search

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

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

161

Spectral Diagnostics of Non-Thermal Particles in the Solar Chromosphere  

Microsoft Academic Search

There are at least three effects of the non-thermal particle bombardment on the solar atmosphere: (1) non-thermal ionization and excitation; (2) proton-hydrogen charge exchange; (3) impact line polarization. Due to the non-thermal ionization and excitation effects of electron bombardments in flares, Halpha line is widely broadened and shows a strong central reversal. Significant enhancements at the line wings of Lyalpha

C. Fang; Z. Xu; M. D. Ding

2003-01-01

162

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  

Microsoft Academic Search

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 Gpara(Vg) parallel to the steps and Gperp(Vg) perpendicular to them were measured at 80 K as functions of gate voltage Vg. At sufficiently high Vg, Gpara at 80 K is several times as high

Y. Akiyama; T. Kawazu; T. Noda; H. Sakaki

2010-01-01

163

SDO/AIA Observations of Quasi-periodic Fast (~1000 km/s) Propagating (QFP) Waves as Evidence of Fast-mode Magnetosonic Waves in the Low Corona: Statistics and Implications  

NASA Astrophysics Data System (ADS)

Recent EUV imaging observations from SDO/AIA led to the discovery of quasi-periodic fast (~2000 km/s) propagating (QFP) waves in active regions (Liu et al. 2011). They were interpreted as fast-mode magnetosonic waves and reproduced in 3D MHD simulations (Ofman et al. 2011). Since then, we have extended our study to a sample of more than a dozen such waves observed during the SDO mission (2010/04-now). We will present the statistical properties of these waves including: (1) Their projected speeds measured in the plane of the sky are about 400-2200 km/s, which, as the lower limits of their true speeds in 3D space, fall in the expected range of coronal Alfven or fast-mode speeds. (2) They usually originate near flare kernels, often in the wake of a coronal mass ejection, and propagate in narrow funnels of coronal loops that serve as waveguides. (3) These waves are launched repeatedly with quasi-periodicities in the 30-200 seconds range, often lasting for more than one hour; some frequencies coincide with those of the quasi-periodic pulsations (QPPs) in the accompanying flare, suggestive a common excitation mechanism. We obtained the k-omega diagrams and dispersion relations of these waves using Fourier analysis. We estimate their energy fluxes and discuss their contribution to coronal heating as well as their diagnostic potential for coronal seismology.

Liu, W.; Ofman, L.; Title, A. M.; Zhao, J.; Aschwanden, M. J.

2011-12-01

164

Non-thermal discharge processing of gaseous pollutants  

SciTech Connect

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.

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

1993-08-27

165

Airflow control by non-thermal plasma actuators  

NASA Astrophysics Data System (ADS)

Active flow control is a topic in full expansion due to associated industrial applications of huge importance, particularly for aeronautics. Among all flow control methods, such as the use of mechanical flaps, wall synthetic jets or MEMS, plasma-based devices are very promising. The main advantages of such systems are their robustness, simplicity, low power consumption and ability for real-time control at high frequency. This paper is a review of the worldwide works on this topic, from its origin to the present. It is divided into two main parts. The first one is dedicated to the recent knowledge concerning the electric wind induced by surface non-thermal plasma actuators, acting in air at atmospheric pressure. Typically, it can reach 8 m s-1 at a distance of 0.5 mm from the wall. In the second part, works concerning active airflow control by these plasma actuators are presented. Very efficient results have been obtained for low-velocity subsonic airflows (typically U? <= 30 m s-1 and Reynolds number of a few 105), and promising results at higher velocities indicate that plasma actuators could be used in aeronautics.

Moreau, Eric

2007-02-01

166

Decomposition of benzene by non-thermal plasma processing: Photocatalyst and ozone effect  

Microsoft Academic Search

Plasma technology has some shortcomings, such as higher energy consumption and byproducts produced in the reaction process. However non-thermal plasma associated with catalyst can resolve these problems. Therefore this kind of technology was paied more and more attention to treat waste gas. A hybrid system comprising a non-thermal plasma reactor and nanometer titanium dioxide catalyst was used for benzene removal

T. Zhu; J. Li; Y. Jin; Y. Liang; G. Ma

167

NATO Advanced Research Workshop on Non-Thermal Plasma Techniques for Pollution Control  

NASA Astrophysics Data System (ADS)

Acid rain, global warming, ozone depletion, and smog are preeminent environmental problems facing the world today. Non-thermal plasma techniques offer an innovative approach to the cost-effective solution of these problems. Many potential applications of non-thermal plasmas to air pollution control have already been demonstrated. On 21-25 Sept. 1992, leading experts from academia, government laboratories, and industry met at Cambridge University, England to discuss laboratory studies and industrial implementation of non-thermal plasmas for the abatement of hazardous gaseous wastes. Papers presented at the workshop are included.

1992-09-01

168

Non-Thermal Laser Ablation Model for Micro-Surgical Applications  

Microsoft Academic Search

We have developed a non-thermal laser ablation model which may reduce thermal damage to neighboring structures. Based on this model, the three critical parameters for a well controlled non-thermal microsurgery are (1) the laser wavelength with its photon energy matching closely the bond dissociation energy, (2) the energy fluence must be above threshold to avoid thermal process due to non-radiative

K. Sentrayan; A. Thorpe Jr.; C. O. Trouth

1998-01-01

169

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

Microsoft Academic Search

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

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

170

Modelling of ferro-electric packed bed non-thermal plasma reactor for NF3 treatments  

Microsoft Academic Search

Summary form only given. Ferro-electric packed bed non-thermal plasma reactor has been widely investigated for application to PFC removal etc. However, the plasma parameters of this non-thermal plasma reactor are not well understood in spite of fact that the fundamental characteristics of this reactor are relatively well known. In order to optimize operation of the ferro-electric packed bed reactor for

J. S. Chang; K. Urashima; K. Takaki

2002-01-01

171

Non-thermal modification of heat-loss responses during exercise in humans  

Microsoft Academic Search

This review focuses on the characteristics of heat-loss responses during exercise with respect to non-thermal factors. In\\u000a addition, the effects of physical training on non-thermal heat-loss responses are discussed. When a subject is already sweating\\u000a the sweating rate increases at the onset of dynamic exercise without changes in core temperature, while cutaneous vascular\\u000a conductance (skin blood flow) is temporarily decreased.

Narihiko Kondo; Takeshi Nishiyasu; Yoshimitsu Inoue; Shunsaku Koga

2010-01-01

172

DIRECT IMAGING OF QUASI-PERIODIC FAST PROPAGATING WAVES OF {approx}2000 km s{sup -1} IN THE LOW SOLAR CORONA BY THE SOLAR DYNAMICS OBSERVATORY ATMOSPHERIC IMAGING ASSEMBLY  

SciTech Connect

Quasi-periodic propagating fast mode magnetosonic waves in the solar corona were difficult to observe in the past due to relatively low instrument cadences. We report here evidence of such waves directly imaged in EUV by the new Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory. In the 2010 August 1 C3.2 flare/coronal mass ejection event, we find arc-shaped wave trains of 1%-5% intensity variations (lifetime {approx}200 s) that emanate near the flare kernel and propagate outward up to {approx}400 Mm along a funnel of coronal loops. Sinusoidal fits to a typical wave train indicate a phase velocity of 2200 {+-} 130 km s{sup -1}. Similar waves propagating in opposite directions are observed in closed loops between two flare ribbons. In the k-{omega} diagram of the Fourier wave power, we find a bright ridge that represents the dispersion relation and can be well fitted with a straight line passing through the origin. This k-{omega} ridge shows a broad frequency distribution with power peaks at 5.5, 14.5, and 25.1 mHz. The strongest signal at 5.5 mHz (period 181 s) temporally coincides with quasi-periodic pulsations of the flare, suggesting a common origin. The instantaneous wave energy flux of (0.1-2.6) x 10{sup 7} erg cm{sup -2} s{sup -1} estimated at the coronal base is comparable to the steady-state heating requirement of active region loops.

Liu Wei; Title, Alan M.; Schrijver, Carolus J.; Aschwanden, Markus J.; De Pontieu, Bart; Tarbell, Theodore D. [Lockheed Martin Solar and Astrophysics Laboratory, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Zhao Junwei [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Ofman, Leon [Catholic University of America and NASA Goddard Space Flight Center, Code 671, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

2011-07-20

173

Non-thermal plasma technologies: new tools for bio-decontamination.  

PubMed

Bacterial control and decontamination are crucial to industrial safety assessments. However, most recently developed materials are not compatible with standard heat sterilization treatments. Advanced oxidation processes, and particularly non-thermal plasmas, are emerging and promising technologies for sanitation because they are both efficient and cheap. The applications of non-thermal plasma to bacterial control remain poorly known for several reasons: this technique was not developed for biological applications and most of the literature is in the fields of physics and chemistry. Moreover, the diversity of the devices and complexity of the plasmas made any general evaluation of the potential of the technique difficult. Finally, no experimental equipment for non-thermal plasma sterilization is commercially available and reference articles for microbiologists are rare. The present review aims to give an overview of the principles of action and applications of plasma technologies in biodecontamination. PMID:18775485

Moreau, M; Orange, N; Feuilloley, M G J

2008-08-16

174

THE SWIFT BURST ALERT TELESCOPE PERSPECTIVE ON NON-THERMAL EMISSION IN HIFLUGCS GALAXY CLUSTERS  

SciTech Connect

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 {approx}5{sigma} 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 {approx}< 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.

Wik, Daniel R.; Baumgartner, Wayne H.; Tueller, Jack; Okajima, Takashi [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sarazin, Craig L. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Zhang Yuying [Argelander-Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, 53121 Bonn (Germany); Mushotzky, Richard F. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Clarke, Tracy E., E-mail: daniel.r.wik@nasa.gov [Naval Research Laboratory, 4555 Overlook Avenue SW, Code 7213, Washington, DC 20375 (United States)

2012-03-20

175

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

NASA Astrophysics Data System (ADS)

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.

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

176

BRIEF COMMUNICATION: An alternative source for generating atmospheric pressure non-thermal plasmas  

NASA Astrophysics Data System (ADS)

This communication presents an alternative source for the generation of non-thermal plasmas at atmospheric pressure. It is based on a very simple electric diagram that generates, on the plasma electrode, an electric field sufficiently high to ionize various gases (helium, argon or even air), which flow at atmospheric pressure. The dc power supply is lower than 10 V, the frequency of the electric field is in the range 0.1-1 MHz and the plasma power is less than 1 W. The plasma is generated using only one electrode. It has all the characteristics of non-thermal plasmas.

Anghel, S. D.; Simon, A.

2007-08-01

177

TOPICAL REVIEW: Non-thermal plasmas in and in contact with liquids  

NASA Astrophysics Data System (ADS)

During the last two decades atmospheric (or high) pressure non-thermal plasmas in and in contact with liquids have received a lot of attention in view of their considerable environmental and medical applications. The simultaneous generation of intense UV radiation, shock waves and active radicals makes these discharges particularly suitable for decontamination, sterilization and purification purposes. This paper reviews the current status of research on atmospheric pressure non-thermal discharges in and in contact with liquids. The emphasis is on their generation mechanisms and their physical characteristics.

Bruggeman, Peter; Leys, Christophe

2009-03-01

178

Reactive oxygen species controllable non-thermal helium plasmas for evaluation of plasmid DNA strand breaks  

NASA Astrophysics Data System (ADS)

Non-thermal, oxygen-rich helium plasmas were investigated to achieve an enhanced reactive oxygen species concentration at low voltage driving conditions. A non-thermal plasma device was fabricated based on a theta-shaped tube, and its potential was investigated for use in topological alteration of plasmid DNA. The optical emission spectra of the plasma showed that the oxygen flow affected the plasma properties, even though an oxygen plasma was not produced. The plasmid DNA strand breaks became more significant with the addition of oxygen flow to the helium in a single hollow, theta-shaped tube with other experimental conditions being unchanged.

Young Kim, Jae; Lee, Dong-Hoon; Ballato, John; Cao, Weiguo; Kim, Sung-O.

2012-11-01

179

Non-thermal plasmas as gas-phase advanced oxidation processes  

SciTech Connect

Non-thermal plasmas are useful for generating reactive species (free radicals) in a gas stream. Because radical attack reaction rate constants are very large for many chemical species, entrained pollutants are readily decomposed by radicals. Such plasmas can generate both oxidative and reductive radicals; therefore, they show promise for treating a wide variety of pollutants.

Rosocha, L.A.

1997-08-01

180

Non-thermal High-intensity Focused Ultrasound for Breast Cancer Therapy.  

National Technical Information Service (NTIS)

Several in vitro studies have demonstrated the non-thermal (< 42C) cell killing effect of HIFU, which resembles high linear energy transfer (LET) radiation cell damage that is not affected by the local biochemical environment and shows less radiation resi...

C. M. Ma

2012-01-01

181

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...

182

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...

183

EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry  

NASA Astrophysics Data System (ADS)

This special issue is based on the symposium on Non-thermal Plasma Assisted Fuel Conversion for Green Chemistry, a part of the 240th ACS National Meeting & Exposition held in Boston, MA, USA, 22-26 August 2010. Historically, the Division of Fuel Chemistry of the American Chemical Society (ACS) has featured three plasma-related symposia since 2000, and has launched special issues in Catalysis Today on three occasions: 'Catalyst Preparation using Plasma Technologies', Fall Meeting, Washington DC, USA, 2000. Special issue in Catalysis Today 72 (3-4) with 12 peer-reviewed articles. 'Plasma Technology and Catalysis', Spring Meeting, New Orleans, LA, USA, 2003. Special issue in Catalysis Today 89 (1-2) with more than 30 peer-reviewed articles. 'Utilization of Greenhouse Gases II' (partly focused on plasma-related technologies), Spring Meeting, Anaheim, CA, USA, 2004. Special issue in Catalysis Today 98 (4) with 25 peer-reviewed articles. This time, selected presentations are published in this Journal of Physics D: Applied Physics special issue. An industrial material and energy conversion technology platform is established on thermochemical processes including various catalytic reactions. Existing industry-scale technology is already well established; nevertheless, further improvement in energy efficiency and material saving has been continuously demanded. Drastic reduction of CO2 emission is also drawing keen attention with increasing recognition of energy and environmental issues. Green chemistry is a rapidly growing research field, and frequently highlights renewable bioenergy, bioprocesses, solar photocatalysis of water splitting, and regeneration of CO2 into useful chemicals. We would also like to emphasize 'plasma catalysis' of hydrocarbon resources as an important part of the innovative next-generation green technologies. The peculiarity of non-thermal plasma is that it can generate reactive species almost independently of reaction temperature. Plasma-generated reactive species are used to initiate chemical reactions at unexpectedly lower temperatures than conventional thermochemical reactions, leading to non-equilibrium product distribution or creating unconventional reaction pathways. When non-thermal plasma is combined with catalysts, a synergistic effect is frequently observed. Such unique properties of non-thermal plasma are expected to contribute excellent control over process parameters that meet the need for energy saving, environment protection, and material preservation. This special issue consists of eleven peer-reviewed papers including two invited publications. Professors Alexander Fridman and Alexander Rabinovich from Drexel University, and Dr Gutsol from the Chevron Energy Technology Company present a critical review of various industry-oriented practical plasma fuel conversion processes. Professor Richard Mallinson from University of Oklahoma describes his recent project on E85 (85%-ethanol/15%-gasoline) upgrading using non-thermal plasma and catalyst hybrid reactor, and highlights the synergistic effect on fuel conversion processes. Other papers focus on plasma/catalyst hybrid reactions for methane dry (CO2) reforming, plasma synthesis of carbon suboxide polymer from CO, the gas-to-liquid (GTL) process using a non-thermal plasma-combined micro-chemical reactor, and molecular beam characterization of plasma-generated reactive species. Much research regarding plasma catalysis is ongoing worldwide, but there is plenty of room for further development of plasma fuel processing, which could eventually provide a viable and flexible solution in future energy and material use. Finally, we would like to thank all symposium participants for their active discussion. We appreciate the sponsorship of the Division of Fuel Chemistry of the American Chemical Society. We express special thanks to the program chair of the Fuel Chemistry Division, Professor Chang-jun Liu at Tianjin University, for his dedication to the success of the symposium. We particularly express our appreciation to the Editorial Board of Journal

Nozaki, Tomohiro; Gutsol, Alexander

2011-07-01

184

The effects of non-thermal plasmas on selected mammalian cells  

NASA Astrophysics Data System (ADS)

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.

Leduc, Mathieu

185

Quasi-periodic distributed feedback laser  

NASA Astrophysics Data System (ADS)

Although lasers have found numerous applications, their design is often still based on the concept of a gain medium within a mirror cavity. Exceptions to this are distributed feedback lasers, in which feedback develops along a periodic structure, or random lasers, which do not require any form of cavity. Random lasers have very rich emission spectra, but are difficult to control. Distributed feedback devices, conversely, have the same limited design possibilities of regular lasers. We show, by making use of a quasi-crystalline structure in an electrically pumped device, that several advantages of a random laser can be combined with the predictability of a distributed feedback resonator. We have constructed a terahertz quantum cascade laser based on a Fibonacci distributed feedback sequence, and show that engineering of the self-similar spectrum of the grating allows features beyond those possible with traditional periodic resonators, such as directional output independent of the emission frequency and multicolour operation.

Mahler, Lukas; Tredicucci, Alessandro; Beltram, Fabio; Walther, Christoph; Faist, Jérôme; Beere, Harvey E.; Ritchie, David A.; Wiersma, Diederik S.

2010-03-01

186

Investigation of micro-flaring and secular and quasi-periodic variations in dMe flare stars. IV - Harmonic analysis of YZ Canis Minoris and a possible connection with the Ionson-Mullan hypothesis of coronal heating  

NASA Astrophysics Data System (ADS)

Periodograms of U-band photometric data have been examined to search for "time signatures" in YZ Canis Minoris down to periods of about 6 seconds. Quasi-periods are found at 7.1, 15.4, 33.2 and 92.9 s. From harmonic analysis the fundamental frequencies, 46.3 mHz (21.6s period) and 35.8 mHz (27.9 s) and 10.8 mHz (92.9 s), and several overtones and found. The 7.1-s "time signature" appears to be superposed overtones of these fundamentals. The 15.4-s "time signature" is very close to the 5th overtone of 10.8 mHz. Similarities with other dM4.5e stars, e.g. AT Microscopii (with "time signatures" 13.2 and 7.9 s), may be explicable in terms of a few such close fundamental frequencies. These fundamental frequencies and their overtones may have a bearing on the Ionson-Mullan hypothesis that coronal-heating is coupled to convective motion in late-type stars, and they are important new parameters possibly related to the flaring mechanism.

Andrews, A. D.

1990-03-01

187

Photon-Energy Dependence of the Phase of Quasi-Periodic Oscillations in Black Holes and Neutron Stars and the Implications for Models of Their X-Ray Emission  

NASA Astrophysics Data System (ADS)

Using a new method to determine the relative phases of quasi-periodic oscillations (QPOs) at low and high photon energies, we find that the 6 Hz oscillations of the QPOs in the black hole X-ray binary XTE J1550-564 and in the 6 Hz normal branch oscillation (NBO) in the neutron star LMXB Sco X-1 exhibit similar trends. In both oscillations, the waveforms shift to later times with increasing photon energy up to about 6--8 keV. Above this energy the trend reverses and the waveforms shift to earlier times with increasing photon energy, eventually leading the waveforms observed at low photon energies. This behavior rules out the possibility that Compton up/down scattering mechanism is the only mechanism responsible for generating the phase shifts. We discuss the implications for models of QPO X-ray spectra and the origin of spectral variability in these X-ray sources. This research was supported in part by NASA grant NAG 5-12030, NSF grant AST 0098399, and the funds of the Fortner Endowed Chair at Illinois. WY thanks M. van der Klis for stimulating comments and the support of NWO grant 614.051.002 at the University of Amsterdam where this study was initiated.

Yu, W.; Lamb, F. K.

2004-08-01

188

Constraints on kilohertz quasi-periodic oscillation models and stellar equations of state from SAX J1808.4-3658, Cyg X-2 and 4U 1820-30  

NASA Astrophysics Data System (ADS)

We test the relativistic precession model (RPM) and the magnetohydrodynamics Alfvén wave oscillation model (AWOM) for the kilohertz (kHz) quasi-periodic oscillations (QPOs) from sources with measured neutron star (NS) masses and twin kHz QPO frequencies. For the RPM, the derived NS masses of Cyg X-2, SAX J1808.4-3658 and 4U 1820-30 are 1.96 ± 0.10, 2.83 ± 0.04 and 1.85 ± 0.02 M?, respectively. These are, respectively, ˜30, 100 and 40 per cent higher than the measured results 1.5 ± 0.3, <1.4 and 1.29^{+0.19}_{-0.07} M?. For the AWOM, where the free parameter of the model is the density of the star, we infer the NS radii to be around 10-20 km for the above three sources. Based on this, we can infer the matter compositions inside the NSs with the help of the equations of state. In particular, for SAX J1808.4-3658, the AWOM shows a lower mass density for its NS than those of the other known kHz QPO sources, with a radius range of 17-20 km, which excludes the strange quark matter inside its star.

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

2013-11-01

189

Mars exospheric thermal and non-thermal components: Seasonal and local variations  

NASA Astrophysics Data System (ADS)

A model of the martian exosphere is built for average solar conditions. A Chamberlain's approach (Chamberlain, J.W. [1963]. Planet. Space Sci. 11, 901) is used to describe the O, CO, CO2, and O2 thermal exospheric components. The average thermal oxygen density at 300 km in altitude varies by about one order of magnitude with seasons. A Monte-Carlo test particle simulation is also developed in order to estimate the non-thermal oxygen component of the exosphere. The seasonal variation of the non-thermal oxygen average density is much less than the thermal component but displays clear seasonal variations of its spatial distribution. The neutral oxygen atomic escaping flux varies from 2.9 to 5.3 × 1025 s-1 in good agreement with Valeille et al. (Valeille, A., Combi, M.R., Bougher, S.W., Tenishev, V., Nagy, A.F. [2009a]. J. Geophys. Res. (Planets) 114, 11006; Valeille, A., Tenishev, V., Bougher, S.W., Combi, M.R., Nagy, A.F. [2009b]. J. Geophys. Res. (Planets) 114, 11005). Mars's oxygen exosphere is thermal below 600 km and non-thermal above 700 km at all seasons. The typical scale height is ˜45 km for thermal O and ˜500 km for the non-thermal oxygen density. The total photoionization rate above 300 km corresponds to a CO2+/O total production ratio between 0.004 and 0.02. When compared to the composition of the escaping flux measured by ASPERA-3/Mars Express, this suggests that ions formed below 300 km should significantly contribute to the escaping ion flux and/or that a significant part of the newly O+ ions reimpacts Mars. The simulated oxygen density profile is also compared to the recent observed profile by Alice/Rosetta (Feldman, P.D. et al. [2011]. Icarus 214, 394-399). Although the scale height of our simulated non-thermal oxygen exosphere and the transition from thermal to non-thermal dominated exospheres are slightly higher than suggested by Feldman et al. (Feldman, P.D. et al. [2011]. Icarus 214, 394-399), a good agreement is found when taking into account the uncertainties of Alice/Rosetta observations.

Yagi, M.; Leblanc, F.; Chaufray, J. Y.; Gonzalez-Galindo, F.; Hess, S.; Modolo, R.

2012-11-01

190

Industrial applications of atmospheric non-thermal plasma in environmental remediation  

NASA Astrophysics Data System (ADS)

Atmospheric non-thermal plasma (NTP) has been recognized as an important tool for the abatement of pollutants and for promoting various chemical reactions in gas or in liquid. Indoor air cleaners have been mass-produced and proved to be effective for the removal of odour and allergen. NTP has various potential applications in environmental remediation, such as the removal of volatile organic pollutants, simultaneous removal of NOx and soot in diesel exhaust and sterilization of air and water. To improve the efficiency of plasma chemical processes, a combination of NTP and catalysts/absorbents is effective. Synergetic effects have been recognized; however, its mechanism remains subject to further investigations. The generation of non-thermal discharge plasma and several industrial applications are presented in this paper.

Mizuno, Akira

2007-05-01

191

Non-thermal leptogenesis in supersymmetric 3-3-1 model with inflationary scenario  

NASA Astrophysics Data System (ADS)

We study a leptogenesis scenario in which the heavy Majorana neutrinos are produced non-thermally in inflaton decays in the supersymmetric economical SU(3)CotimesSU(3)LotimesU(1)X model with an inflationary scenario, and for this purpose neutrino masses play the key role. Due to the inflaton with mass in the GUT scale, the model under consideration provides successful neutrino masses, which is different from the ones without the inflationary scenario. The lepton-number-violating interactions among the inflaton and right-handed neutrinos appear at the one-loop level, and this is a reason for the non-thermal leptogenesis scenario. The bound followed from the gravitino abundance and the cosmological constraint on neutrino mass/the neutrino oscillation data is m_{\

Huong, D. T.; Long, H. N.

2011-01-01

192

Swifts BAT search for non-thermal emission in HIFLUGCS clusters  

NASA Astrophysics Data System (ADS)

Detections of diffuse inverse Compton (IC) emission at hard X-ray energies have typically been controversial and/or of low significance. Consistency of the existing limits and detections may be possible only for very extended IC spatial distributions. To test this idea, we apply a method to characterize extended, hard X-ray emission from the Swifts BAT survey. Spatially coincident spectra from XMM-Newtons and Swifts are jointly fit to simultaneously constrain both thermal and non-thermal components, but no significant IC spectral component is seen in any of the clusters in the sample. For the Coma cluster, our upper limits exclude the most recently detected fluxes, regardless of the IC spatial distribution. Spectra from all clusters are summed, to enhance marginal IC emission possibly present in many clusters, but no aggregate non-thermal excess is found, although a hint of an excess is seen in the radio halo/relic subset.

Wik, D.

193

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

SciTech Connect

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.

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

1996-01-11

194

Dust-acoustic Solitary Waves in Dusty Plasma with Non-thermal Ions  

SciTech Connect

In the present research paper, characteristics of dust-acoustic solitary waves in dusty plasma are studied. The dust charge is treated as variable. KdV equation has been derived using reductive perturbation method. The effect of relative number density, relative ion temperature, non-thermal parameter and variable charge has been numerically studied for possibility of both type of dust-acoustic solitary waves.

Saini, Nareshpal Singh; Gill, Tarsem Singh [Department of Physics, Guru Nanak Dev University, Amritsar-143005 (India); Kaur, Harvinder [Department of Physics, Khalsa College, Amritsar-143002 (India)

2005-10-31

195

Solvated Electron Technology{sup TM}. Non-Thermal Alternative to Waste Incineration  

Microsoft Academic Search

Solvated Electron Technology (SET{sup TM}) is a patented non-thermal alternative to incineration for treating Toxic Substances Control Act (TSCA) and other mixed waste by destroying organic hazardous components. SET{sup TM} is a treatment process that destroys the hazardous components in mixed waste by chemical reduction. The residual material meets land disposal restriction (LDR) and TSCA requirements for disposal. In application,

W. L. Foutz; J. E. Rogers; J. D. Mather

2008-01-01

196

DETERMINATION OF NON-THERMAL VELOCITY DISTRIBUTIONS FROM SERTS LINEWIDTH OBSERVATIONS  

SciTech Connect

Non-thermal velocities obtained from the measurement of coronal Extreme Ultraviolet (EUV) linewidths have been consistently observed in solar EUV spectral observations and have been theorized to result from many plausible scenarios including wave motions, turbulence, or magnetic reconnection. Constraining these velocities can provide a physical limit for the available energy resulting from unresolved motions in the corona. We statistically determine a series of non-thermal velocity distributions from linewidth measurements of 390 emission lines from a wide array of elements and ionization states observed during the Solar Extreme Ultraviolet Research Telescope and Spectrograph 1991-1997 flights covering the spectral range 174-418 A and a temperature range from 80,000 K to 12.6 MK. This sample includes 248 lines from active regions, 101 lines from quiet-Sun regions, and 41 lines were observed from plasma off the solar limb. We find a strongly peaked distribution corresponding to a non-thermal velocity of 19-22 km s{sup -1} in all three of the quiet-Sun, active region, and off-limb distributions. For the possibility of Alfven wave resonance heating, we find that velocities in the core of these distributions do not provide sufficient energy, given typical densities and magnetic field strengths for the coronal plasma, to overcome the estimated coronal energy losses required to maintain the corona at the typical temperatures working as the sole mechanism. We find that at perfect efficiency 50%-60% of the needed energy flux can be produced from the non-thermal velocities measured.

Coyner, Aaron J. [Department of Physics, Catholic University of America, 620 Michigan Avenue, Washington, DC 20064 (United States); Davila, Joseph M., E-mail: aaron.j.coyner@nasa.gov [Code 671, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2011-12-01

197

SOLCOST - Version 3. 0. Solar energy design program for non-thermal specialists  

SciTech Connect

The SOLCOST solar energy design program is a public domain computerized design tool intended for use by non-thermal specialists to size solar systems with a methodology based on life cycle cost. An overview of SOLCOST capabilities and options is presented. A detailed guide to the SOLCOST input parameters is included. Sample problems showing typical imput decks and resulting SOLCOST output sheets are given. Details of different parts of the analysis are appended. (MHR)

Not Available

1980-05-01

198

Non-Thermal Treatment of Hanford Site Low-Level Mixed Waste  

SciTech Connect

DOE proposes to transport contact-handled LLMW from the Hanford Site to the Allied Technology Group (ATG) Mixed Waste Facility (MWF) in Richland, Washington, for non-thermal treatment and to return the treated waste to the Hanford Site for eventual land disposal. Over a 3-year period the waste would be staged to the ATG MWF, and treated waste would be returned to the Hanford Site. The ATG MWF would be located on an 18 hectare (ha) (45 acre [at]) ATG Site adjacent to ATG's licensed low-level waste processing facility at 2025 Battelle Boulevard. The ATG MWF is located approximately 0.8 kilometers (km) (0.5 miles [mi]) south of Horn Rapids Road and 1.6 km (1 mi) west of Stevens Drive. The property is located within the Horn Rapids triangle in northern Richland (Figure 2.1). The ATG MWF is to be located on the existing ATG Site, near the DOE Hanford Site, in an industrial area in the City of Richland. The effects of siting, construction, and overall operation of the MWF have been evaluated in a separate State Environmental Policy Act (SEPA) EIS (City of Richland 1998). The proposed action includes transporting the LLMW from the Hanford Site to the ATG Facility, non-thermal treatment of the LLMW at the ATG MWF, and transporting the waste from ATG back to the Hanford Site. Impacts fi-om waste treatment operations would be bounded by the ATG SEPA EIS, which included an evaluation of the impacts associated with operating the non-thermal portion of the MWF at maximum design capacity (8,500 metric tons per year) (City of Richland 1998). Up to 50 employees would be required for non-thermal treatment portion of the MWF. This includes 40 employees that would perform waste treatment operations and 10 support staff. Similar numbers were projected for the thermal treatment portion of the MWF (City of Richland 1998).

NONE

1998-09-01

199

Miniaturized non-thermal atmospheric pressure plasma jet---characterization of self-organized regimes  

Microsoft Academic Search

The study reports for the first time on self-organization effects in a radio frequency (RF) plasma generated with a miniaturized non-thermal atmospheric pressure plasma jet. The source is configured as a capacitively coupled RF jet (27.2 MHz) with two outer ring electrodes around a quartz capillary (d = 4.0 mm) between which a gas mixture flows at typical rates of

J. Schäfer; R. Foest; A. Ohl; K.-D. Weltmann

2009-01-01

200

Thermal and non-thermal intracellular mechanical fluctuations of living cells  

NASA Astrophysics Data System (ADS)

Intracellular stresses generated by molecular motors can actively modify cytoskeletal network, which causes changes in intracellular mechanical properties. We study the out-of-equilibrium microrheology in living cells. This paper reports measurements of the intracellular mechanical properties using passive and optical tweezers-based active microrheology approaches and endogenous organelle particles as probes. Using the fluctuation-dissipation theorem, we compared the two approaches measurements and distinguished thermal and non-thermal fluctuations of mechanical properties in living cells.

Wei, Ming-Tzo; Ou-Yang, H. Daniel

2010-08-01

201

Determination of Non-thermal Velocity Distributions from SERTS Linewidth Observations  

NASA Astrophysics Data System (ADS)

Non-thermal velocities obtained from the measurement of coronal Extreme Ultraviolet (EUV) linewidths have been consistently observed in solar EUV spectral observations and have been theorized to result from many plausible scenarios including wave motions, turbulence, or magnetic reconnection. Constraining these velocities can provide a physical limit for the available energy resulting from unresolved motions in the corona. We statistically determine a series of non-thermal velocity distributions from linewidth measurements of 390 emission lines from a wide array of elements and ionization states observed during the Solar Extreme Ultraviolet Research Telescope and Spectrograph 1991-1997 flights covering the spectral range 174-418 Å and a temperature range from 80,000 K to 12.6 MK. This sample includes 248 lines from active regions, 101 lines from quiet-Sun regions, and 41 lines were observed from plasma off the solar limb. We find a strongly peaked distribution corresponding to a non-thermal velocity of 19-22 km s-1 in all three of the quiet-Sun, active region, and off-limb distributions. For the possibility of Alfvén wave resonance heating, we find that velocities in the core of these distributions do not provide sufficient energy, given typical densities and magnetic field strengths for the coronal plasma, to overcome the estimated coronal energy losses required to maintain the corona at the typical temperatures working as the sole mechanism. We find that at perfect efficiency 50%-60% of the needed energy flux can be produced from the non-thermal velocities measured.

Coyner, Aaron J.; Davila, Joseph M.

2011-12-01

202

Are Non-thermal Motions in the Solar Corona Evidence for Coronal Heating by MHD Turbulence?  

Microsoft Academic Search

Recent solar observations suggest that the solar outer atmosphere is turbulent. In the present talk, I focus on the SOHO\\/SUMER observations of non-thermal motions --- unresolved plasma motions that are required to explain the line width excess over thermal broadening --- of UV\\/EUV emitting plasma whose temperature ranges from 10^4 to 10^6 K. It has been found from a thorough

Jongchul Chae

2001-01-01

203

Non-thermal electron velocity distribution measured by electron cyclotron emission in Alcator C tokamak  

Microsoft Academic Search

The non-thermal electron velocity distribution of lower hybrid RF heated plasmas in the Alcator C tokamak is deduced from measurements of electron cyclotron emission using a specialized vertical viewing optics arrangement. At a density of anti n(sub e) = 0.7 x 10 to the 29th power\\/cu m , the reconstructed distribution function in the range 50keV less than or equal

K. Kato; I. H. Hutchinson

1985-01-01

204

Near-Infrared Irradiation Non-thermally Affects Subcutaneous Adipocytes and Bones  

PubMed Central

Objective: We previously reported that near-infrared irradiation simulating solar near-infrared with pre- and parallel-irradiational cooling can penetrate the skin and non-thermally affects dermis, superficial muscles, and so forth. To clarify the possible effect of NIR irradiation on other subcutaneous tissues, we evaluated how near-infrared non-thermally affects subcutaneous adipocytes and bones in rats. Methods: The central back tissues of rats were irradiated with a specialized near-infrared device that simulates solar radiation. The total energy emitted was equivalent to approximately 8.75 hours of sunbathing in North America. Histological evaluation was performed on subcutaneous adipocytes and the spinous process of the near-infrared-irradiated rat and compared with non-irradiated controls. Results: Subcutaneous and bone marrow adipocytes, CD34-positive hematopoietic stem cells in bone marrow, and the cortical bone mass were all significantly increased, whereas the bone marrow cell number was significantly decreased following near-infrared irradiation. Apoptotic cells were detected in the bone marrow at postirradiation days 7 and 30 but were not detected at day 60 or in the controls. Bone marrow cell numbers recovered gradually, whereas the increase in subcutaneous and bone marrow adipocytes, CD34-positive hematopoietic stem cells in bone marrow, and cortical bone mass remained elevated even at day 180. Conclusions: Near-infrared irradiation that simulated solar radiation non-thermally affected subcutaneous adipocytes and bones in rats. It induced putative, non-thermal damage of bone marrow, which was mediated by apoptosis. However, it increased subcutaneous and bone marrow adipocytes, CD34-positive hematopoietic stem cells in bone marrow, and cortical bone mass.

Tanaka, Yohei; Matsuo, Kiyoshi; Yuzuriha, Shunsuke

2011-01-01

205

Asymmetric electron cyclotron emission from non-thermal plasmas subject to a generalized Kirchhoff's law  

Microsoft Academic Search

The electron cyclotron emission (ECE) spectra characteristic of a non-thermal plasma comprising a current-carrying superthermal electron tail, for which a generalized Kirchhoff's law holds true, are evaluated for both the extraordinary (X) and ordinary (O) mode, for perpendicular as well as oblique propagation on the outboard side of the plasma; both higher order finite-Larmor-radius effects and harmonic overlap are accounted

M. Bornatici; U. Ruffina

1996-01-01

206

Ubiquitous Non-thermals in Astrophysical Plasmas: Restating the Difficulty of Maintaining Maxwellians  

NASA Astrophysics Data System (ADS)

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, Ke , the ratio of the electron mean free path to the scale length of electron pressure. Rather generally, f(v < v 2(Ke )) will be Gaussian, so that MB atomic or wave particle effects controlled by speeds v < v 2 ? w(15/8Ke )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 Ke (s) <= 0.01; this global condition pertains to the maximum value of Ke 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 Ke > 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.

Scudder, J. D.; Karimabadi, H.

2013-06-01

207

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

SciTech Connect

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.

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

208

Search for non-thermal radio emission from Eta Carina's outer blast wave with ATCA  

NASA Astrophysics Data System (ADS)

Non-thermal hard X-ray and high-energy (HE; 1 MeV < E < 100 GeV) gamma-ray emission in the direction of Eta Carina has been recently detected using the INTEGRAL, AGILE and Fermi satellites. This emission can be either interpreted in the framework of particle acceleration in the colliding wind region between the two massive stars or in the very fast moving blast wave which originates in the historical 1843 "Great Eruption". The detection of a radio shell at the location of the shock would support the latter scenario and confirm Eta Carina as prime example of a new source type, namely, an LBV star whose massive ejecta accelerates electrons to non-thermal energies. While Fermi and INTEGRAL do not provide sufficient angular resolution to resolve the blast wave, high resolution radio observations using ATCA will be able to test non-thermal radio emission from this acceleration site. The current sensitivity of ATCA is such that a relatively modest observation time of 12 hours will be sufficient to image the synchrotron emission from the blast region down to magnetic field strengths well below typical ISM values and hence prove or reject our blast-wave hypothesis for the high energy emission.

Ohm, Stefan; Urquhart, James; Skilton, Joanna Lucy; Hinton, Jim; Domainko, Wilfried

2010-10-01

209

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)

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.

Barret, Didier

2012-07-01

210

Non-thermal recombination - a neglected source of flare hard X-rays and fast electron diagnostic  

Microsoft Academic Search

Context: Flare Hard X-rays (HXRs) from non-thermal electrons are commonly treated as solely bremsstrahlung (free-free = f-f), recombination (free-bound = f-b) being neglected. This assumption is shown to be substantially in error, especially in hot sources, mainly due to recombination onto Fe ions. Aims: We analyse the effects on HXR spectra J(?) and electron diagnostics by including non-thermal recombination onto

J. C. Brown; P. C. V. Mallik

2008-01-01

211

Non-thermal radio emission from colliding-wind binaries: modelling Cyg OB2 No. 8A and No. 9  

NASA Astrophysics Data System (ADS)

Some OB stars show variable non-thermal radio emission. The non-thermal emission is due to synchrotron radiation that is emitted by electrons accelerated to high energies. The electron acceleration occurs at strong shocks created by the collision of radiatively-driven stellar winds in binary systems. Here we present results of our modelling of two colliding wind systems: Cyg OB2 No. 8A and Cyg OB2 No. 9.

Volpi, Delia; Blomme, Ronny; De Becker, Michael; Rauw, Gregor

2011-07-01

212

Formation of hydrophobic coating on glass surface using atmospheric pressure non-thermal plasma in ambient air  

Microsoft Academic Search

Non-thermal plasmas under atmospheric pressure are of great interest in material surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of a glass surface for improving hydrophobicity using a non-thermal plasma generated by a dielectric barrier corona discharge (DBCD) with a needle array-to-plane electrode arrangement in atmospheric air is conducted, and the surface properties

Z. Fang; Y. Qiu; E. Kuffel

2004-01-01

213

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

PubMed Central

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.

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

2012-01-01

214

Particle acceleration and non-thermal emission during the V407 Cygni nova outburst  

NASA Astrophysics Data System (ADS)

Context. On March 2010, the symbiotic binary V407 Cyg erupted as a result of a nova explosion. The event gave rise to a two-week long burst of ? 100 MeV ?-rays detected by Fermi/LAT, a unique observation testifying to particle acceleration in the system. Aims: The outburst can be considered a scaled-down supernova, with short dynamical time scale, and thus can constitute a test case for theories of the origin of Galactic cosmic rays. We aim at determining the properties of the accelerated particles and identifying the origin of the high-energy radiation. Methods: We developed a model for diffusive shock acceleration and non-thermal emission in V407 Cyg, complemented by an evaluation of the thermal emission from the shocked plasma. We considered both leptonic and hadronic contributions to the non-thermal processes, and investigated the effect of many binary and nova parameters. Results: The ?-ray emission is mostly of leptonic origin and arises predominantly from inverse-Compton scattering of the nova light. Matching the light curve requires gas accumulation in the vicinity of the white dwarf, as a consequence of wind accretion, while the spectrum imposes particle scattering close to the Bohm limit in the upstream equipartition magnetic field. The nova accelerated protons (respectively electrons) with energies up to ?300 GeV (respectively ?20 GeV), for a total non-thermal energy ?10 erg after two weeks, representing ?10% of the initial nova kinetic energy. The electron-to-proton ratio at injection is 6%. Conclusions: The V407 Cyg eruption can be understood from the same principles that are invoked for particle acceleration in supernova remnants, although without the need for strong magnetic field amplification. The population of novae in symbiotic systems is a negligible source of Galactic cosmic rays, and most likely not a class of TeV-emitters.

Martin, P.; Dubus, G.

2013-03-01

215

First Achievements and Opportunities for Cancer Treatment Using Non-thermal Plasma  

NASA Astrophysics Data System (ADS)

This paper summarizes the experimental results and plasma delivery strategy developed in Orléans for the evaluation of antitumor action of dielectric barrier discharge and plasma gun for cancer treatment. Detailed analysis of biological effects following non thermal plasma application for both in vitro and in vivo experiments reveals the role of ROS, DNA damage induction, cell cycle modification and apoptosis induction. Recent characterization of plasma splitting and ­mixing in different capillary geometries, using the plasma gun, together with preliminary tolerance study dealing with lung and colon treatment indicate that endoscopic plasma delivery may be a new and valuable therapy in cancerology.

Robert, Eric; Vandamme, Marc; Sobilo, Julien; Sarron, Vanessa; Ries, Delphine; Dozias, Sébastien; Brulle, Laura; Lerondel, Stéphanie; Le Pape, Alain; Pouvesle, Jean Michel

216

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

DOEpatents

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.

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

2009-04-21

217

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

SciTech Connect

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.

Charles Mones

2006-12-01

218

Relation between the Coronal Mass Ejection Acceleration and the Non-thermal Flare Characteristics  

NASA Astrophysics Data System (ADS)

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 ? -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 0 and the non-thermal flare parameters, with the highest correlation of h 0 to the spectral index ? of flare-accelerated electrons (c ? 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 (~80%), the non-thermal flare emission starts after the CME acceleration, on average delayed by ?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.

Berkebile-Stoiser, S.; Veronig, A. M.; Bein, B. M.; Temmer, M.

2012-07-01

219

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

SciTech Connect

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.

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

220

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

SciTech Connect

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.

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

2002-06-18

221

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

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.

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

222

Evaluation of Thermal and Non-thermal Effects of UHF RFID Exposure on Biological Drugs.  

PubMed

The Radio Frequency Identification (RFID) technology promises to improve several processes in the healthcare scenario, especially those related to traceability of people and things. Unfortunately, there are still some barriers limiting the large-scale deployment of these innovative technologies in the healthcare field. Among these, the evaluation of potential thermal and non-thermal effects due to the exposure of biopharmaceutical products to electromagnetic fields is very challenging, but still slightly investigated. This paper aims to setup a controlled RF exposure environment, in order to reproduce a worst-case exposure of pharmaceutical products to the electromagnetic fields generated by the UHF RFID devices placed along the supply chain. Radiated powers several times higher than recommended by current normative limits were applied (10 W and 20 W). The electric field strength at the exposed sample location, used in tests, was as high as 100 V/m. Non-thermal effects were evaluated by chromatography techniques and in vitro assays. The results obtained for a particular case study, the ActrapidTM human insulin preparation, showed temperature increases lower than 0.5°C and no significant changes in the structure and performance of the considered drug. PMID:22717524

Calcagnini, G; Censi, F; Maffia, M; Mainetti, L; Mattei, E; Patrono, L; Urso, E

2012-06-14

223

Thermal and non-thermal traces of AGN feedback: results from cosmological AMR simulations  

NASA Astrophysics Data System (ADS)

We investigate the observable effects of feedback from active galactic nuclei (AGN) on non-thermal components of the intracluster medium (ICM). We have modelled feedback from AGN in cosmological simulations with the adaptive mesh refinement code enzo, investigating three types of feedback that are sometimes called quasar, jet and radio mode. Using a small set of galaxy clusters simulated at high resolution, we model the injection and evolution of cosmic rays, as well as their effects on the thermal plasma. By comparing both the profiles of thermal gas to observed profiles from the ACCEPT sample and the secondary ?-ray emission to the available upper limits from Fermi, we discuss how the combined analysis of these two observables can constrain the energetics and mechanisms of feedback models in clusters. Those modes of AGN feedback that provide a good match to X-ray observations yield a ?-ray luminosity resulting from secondary cosmic rays that is about 10 times below the available upper limits from Fermi. Moreover, we investigate the injection of turbulent motions into the ICM from AGN, and the detectability of these motions via the analysis of line broadening of the Fe xxiii line. In the near future, deeper observations/upper limits of non-thermal emissions from galaxy clusters will yield stringent constraints on the energetics and modes of AGN feedback, even at early cosmic epochs.

Vazza, F.; Brüggen, M.; Gheller, C.

2013-01-01

224

Flare Loop Top Sources: A diagnostic for non-thermal particle injection  

NASA Astrophysics Data System (ADS)

X-ray emitting sources have often been observed at the apex of post-flare loops by the Hard X-Ray telescope (HXT) onboard the Japanese Yohkoh satellite and by NASA's Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). In order to investigate the physics behind the generation of these loop top sources we have coupled a 1D, time-dependent, hydro code with a non-thermal particle transport code. The hydro code provides temperature and density information of the target plasma to the particle code and the particle code provides the dynamic heating of the plasma to the hydro code. Previous work with a combined has shown that it is possible to create flare loop top emission sources under certain conditions. In this work we test the relationship between the pitch angle distribution of the injected non-thermal particles and the generation of loop top emission source. RHESSI, HXT and XRT datasets are synthesized from the simulations to provide a direct link between theoretical work and observables. This work is supported by NASA grant NAG5-12820.

Winter, H. D.; Martens, P. C.

2007-12-01

225

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

NASA Astrophysics Data System (ADS)

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.

Dai, S.; Xu, R.

2012-12-01

226

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

NASA Astrophysics Data System (ADS)

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.

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

227

Dark matter interpretation of the origin of non-thermal phenomena in galaxy clusters  

NASA Astrophysics Data System (ADS)

Aims: We studied the multi-frequency predictions of various annihilating dark matter (DM) scenarios in order to explore the possibility to interpret the still unknown origin of non-thermal phenomena in galaxy clusters. Methods: We consider three different DM models with light (9 GeV), intermediate (60 GeV), and high (500 GeV) neutralino mass and study their physical effects in the atmosphere of the Coma cluster. The secondary particles created in the neutralino annihilation processes produce a multi-frequency spectral energy distribution (SED) of non-thermal radiation and also heat the intracluster gas, which we test against the observations available for the Coma cluster from radio to gamma-rays. The various DM-produced SEDs are normalized by the condition to fit the Coma radio halo spectrum, thus obtaining best-fit values of the annihilation cross-section ?V and of the central magnetic field B0. Results: We find that it is not possible to interpret all the non-thermal phenomena observed in galaxy clusters in terms of DM annihilation. The light-mass DM model with 9 GeV mass produces too little power at all other frequencies, while the high-mass DM model with 500 GeV produces a large excess power at all other frequencies. The intermediate-mass DM model with 60 GeV and ? ± composition is marginally consistent with the HXR and gamma-ray observations, but narrowly fails to reproduce the EUV and soft X-ray observations. The intermediate-mass DM model with 60 GeV and b{bar b} composition is, on the other hand, always below the observed fluxes. We note that the radio halo spectrum of Coma is well fitted only in the b{bar b} or light- and intermediate-mass DM models. We also find that the heating produced by the DM annihilation in the centre of the Coma cluster is always larger than the intracluster gas cooling rate for an NFW DM density profile and it is substantially smaller than the cooling rate only for a cored DM density profile in light-mass DM model with 9 GeV. Conclusions: The possibility of interpreting the origin of non-thermal phenomena in galaxy clusters with DM annihilation scenarios requires a low neutralino mass and a cored DM density profile. If we then consider the multi-messenger constraints to the neutralino annihilation cross-section, it turns out that this scenario would also be excluded unless we introduce a substantial boost factor that represents DM substructures. If we relax the condition to fit the Coma radio halo and we consider the EUV and HXR detections as upper limits for the non-thermal emission, together with the gamma-ray limit, then the limits on ?V are less stringent than those obtained by the multi-messenger analysis.

Colafrancesco, S.; Lieu, R.; Marchegiani, P.; Pato, M.; Pieri, L.; Buonanno, R.

2011-03-01

228

The effect of blood flow on magnetic resonance imaging of non thermal irreversible electroporation.  

PubMed

To generate an understanding of the physiological significance of MR images of Non-Thermal Irreversible Electroporation (NTIRE) we compared the following MR imaging sequences: T1W, T2W, PD, GE, and T2 SPAIR acquired after NTIRE treatment in a rodent liver model. The parameters that were studied included the presence or absence of a Gd-based contrast agent, and in vivo and ex-vivo NTIRE treatments in the same liver. NTIRE is a new minimally invasive tissue ablation modality in which pulsed electric fields cause molecularly selective cell death while, the extracellular matrix and large blood vessels remain patent. This attribute of NTIRE is of major clinical importance as it allows treatment of undesirable tissues near critical blood vessels. The presented study results suggest that MR images acquired following NTIRE treatment are all directly related to the unique pattern of blood flow after NTIRE treatment and are not produced in the absence of blood flow. PMID:24169528

Hjouj, Mohammad; Lavee, Jacob; Last, David; Guez, David; Daniels, Dianne; Sharabi, Shirley; Rubinsky, Boris; Mardor, Yael

2013-10-30

229

Non-thermal Doppler-broadened Lyman-? line shape in resonant dissociation of H2  

NASA Astrophysics Data System (ADS)

The detailed Lyman-? emission line shape after resonant dissociation and excitation of H2 via collisions with Ne excimer molecules has been determined (Ne*2 + H2 ? 2Ne + H + H*(n = 2)). Pressure effects due to the high Ne pressure, required for efficient excimer formation, decrease the effective lifetime of the hydrogen excited state. The reduced effective lifetime significantly reduces the average number of elastic collisions experienced by the excited hydrogen atom before radiative decay. Excess energy imparted to the excited-state hydrogen atom by the Ne excimer, in the dissociative excitation collision, produces a non-thermal Doppler-broadened emission line shape. The full width at half maximum (FWHM) is 3.85 pm and the effective lifetime of the n = 2 state is estimated to be 14 ps at a Ne pressure of 1 atm. Results are obtained from pressure-dependent measurements of the Balmer-? absorption line shape using laser spectroscopy.

McCarthy, T. J.; Murnick, D. E.; Salvermoser, M.; Ulrich, A.

2005-08-01

230

Quasilinear Evolution of Multiple Non-thermal Ion Distributions in ICRF Heating  

SciTech Connect

The AORSA global-wave solver is combined with the CQL3D bounce-averaged Fokker-Planck code to simulate the quasilinear evolution of non-thermal distributions in ion cyclotron resonance heating of tokamak plasmas. A novel re-formulation of the quasilinear operator enables calculation of the velocity space diffusion coefficients directly from the global wave fields. To obtain self-consistency between the wave fields and particle distribution function, AORSA and CQL3D have been iteratively coupled using Python. The combined self-consistent model is applied to minority ion heating in the Alcator C-Mod tokamak. Results show the formation of a 70 keV ion tail near the minority ion cyclotron resonance layer in approximate agreement with measurements from charge exchange neutral particle analyzers.

Jaeger, Erwin Frederick [ORNL

2006-01-01

231

Decomposition of trifluoromethane in a dielectric barrier discharge non-thermal plasma reactor.  

PubMed

The decomposition of trifluoromethane (CHF3) was carried out using non-thermal plasma generated in a dielectric barrier discharge (DBD) reactor. The effects of reactor temperature, electric power, initial concentration and oxygen content were examined. The DBD reactor was able to completely destroy CHF3 with alumina beads as a packing material. The decomposition efficiency increased with increasing electric power and reactor temperature. The destruction of CHF3 gradually increased with the addition of O2 up to 2%, but further increase in the oxygen content led to a decrease in the decomposition efficiency. The degradation pathways were explained with the identified by-products. The main by-products from CHF3 were found to be COF2, CF4, CO2 and CO although the COF2 and CF4 disappeared when the plasma were combined with alumina catalyst. PMID:23513444

Gandhi, M Sanjeeva; Mok, Y S

2012-01-01

232

Identification of mechanisms for decomposition of air pollutants by non-thermal plasma processing  

NASA Astrophysics Data System (ADS)

Non-thermal plasma processing methods have been shown to be effective for treating dilute concentrations of pollutants in large-volume atmospheric-pressure air streams. This paper presents results from basic experimental and theoretical studies aimed at identifying the main reactions responsible for the decomposition of four representative compounds: carbon tetrachloride, methylene chloride, trichloroethylene and methanol. Each of these compounds is shown to be decomposed by a different plasma species: electrons, nitrogen atoms, oxygen radicals and positive ions, respectively. By understanding what plasma species is responsible for the decomposition of a pollutant molecule, it is possible to establish the electrical power requirements of the plasma reactor and help identify the initial reactions that lead to the subsequent process chemistry. These studies are essential for predicting the scaling of the process to commercial size units.

Penetrante, B. M.; Hsiao, M. C.; Bardsley, J. N.; Merritt, B. T.; Vogtlin, G. E.; Kuthi, A.; Burkhart, C. P.; Bayless, J. R.

1997-08-01

233

Sterilization of Staphylococcus Aureus by an Atmospheric Non-Thermal Plasma Jet  

NASA Astrophysics Data System (ADS)

An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus (S. aureus). The plasma jet was generated by dielectric barrier discharge (DBD), which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 106 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy (SEM) that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N2+ and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.

Liu, Xiaohu; Hong, Feng; Guo, Ying; Zhang, Jing; Shi, Jianjun

2013-05-01

234

Abatement of mixture of volatile organic compounds (VOCs) in a catalytic non-thermal plasma reactor.  

PubMed

Total oxidation of mixture of dilute volatile organic compounds was carried out in a dielectric barrier discharge reactor with various transition metal oxide catalysts integrated in-plasma. The experimental results indicated the best removal efficiencies in the presence of metal oxide catalysts, especially MnO(x), whose activity was further improved with AgO(x) deposition. It was confirmed water vapor improves the efficiency of the plasma reactor, probably due to the formation of hydroxyl species, whereas, in situ decomposition of ozone on the catalyst surface may lead to nascent oxygen. It may be concluded that non-thermal plasma approach is beneficial for the removal of mixture of volatile organic compounds than individual VOCs, probably due to the formation of reactive intermediates like aldehydes, peroxides, etc. PMID:22975253

Karuppiah, J; Reddy, E Linga; Reddy, P Manoj Kumar; Ramaraju, B; Karvembu, R; Subrahmanyam, Ch

2012-08-24

235

Inactivation of Microorganisms in Model Biofilms by an Atmospheric Pressure Pulsed Non-thermal Plasma  

NASA Astrophysics Data System (ADS)

Non-thermal plasma jet formed by self-running pulsed-periodical high-current spark generator (PPSG) was used for atmospheric pressure inactivation of microorganisms including biofilms. A distinctive feature of the PPSG is a formation of transient hot plasma clouds (plasma bullets) periodically flying out to the target. We experimented with model biofilms of E. coli and Bacillus subtilis monocultures which were grown on agar and surfaces of steel and polypropylene coupons. High efficiency of plasma inactivation was demonstrated. This effect is associated primarily with an interaction of transient hot plasma clouds with biofilms. Besides complete or partial degradation of the cell membrane, weakening of the cell wall of E.coli culture by active plasma was found.

Akishev, Yuri; Trushkin, N.; Grushin, M.; Petryakov, A.; Karal'nik, V.; Kobzev, E.; Kholodenko, V.; Chugunov, V.; Kireev, G.; Rakitsky, Yu.; Irkhina, I.

236

The Effect of Blood Flow on Magnetic Resonance Imaging of Non Thermal Irreversible Electroporation  

PubMed Central

To generate an understanding of the physiological significance of MR images of Non-Thermal Irreversible Electroporation (NTIRE) we compared the following MR imaging sequences: T1W, T2W, PD, GE, and T2 SPAIR acquired after NTIRE treatment in a rodent liver model. The parameters that were studied included the presence or absence of a Gd-based contrast agent, and in vivo and ex-vivo NTIRE treatments in the same liver. NTIRE is a new minimally invasive tissue ablation modality in which pulsed electric fields cause molecularly selective cell death while, the extracellular matrix and large blood vessels remain patent. This attribute of NTIRE is of major clinical importance as it allows treatment of undesirable tissues near critical blood vessels. The presented study results suggest that MR images acquired following NTIRE treatment are all directly related to the unique pattern of blood flow after NTIRE treatment and are not produced in the absence of blood flow.

Hjouj, Mohammad; Lavee, Jacob; Last, David; Guez, David; Daniels, Dianne; Sharabi, Shirley; Rubinsky, Boris; Mardor, Yael

2013-01-01

237

Absorption Effect of Jet on Non-thermal Radiation Spectrum of 3C 279  

NASA Astrophysics Data System (ADS)

The absorption effect on the non-thermal spectrum of 3C 279 in a jet model is considered in this paper. Based on a simple synchrotron self-Compton (SSC) model, it is assumed that a blob of radiation region in the jet is partly kept out by a cooled blob in this jet, and then the emission from the radiation region can be absorbed. This leads to the change of the spectral energy distribution. Our calculation indicates that there is a strong absorption in X-ray band, and the absorbed energy will be emitted in the form of emission lines in ultraviolet and soft X-ray bands. We reproduce the multi-band spectra of 3C 279 by using such a model and give a brief discussion.

Zhou, X. R.; Zhang, L.

2010-10-01

238

Non-thermal water loss of the early Mars: 3D multi-ion hybrid simulations  

NASA Astrophysics Data System (ADS)

In this study we analyze the non-thermal loss rates of O +, O 2+ and CO 2+ ions over the last 4.5 billion years (Gyr) in the Martian history by using a 3D hybrid model. For this reason we derived the past solar wind conditions in detail. We take into account the intensified particle flux of the early Sun as well as an Martian atmosphere, which was exposed to a sun's extreme ultraviolet (EUV) radiation flux 4.5 Gyr ago that was 100 times stronger than today. Furthermore, we model the evolution of the interplanetary magnetic field by a Weber & Davis solar wind model. The 'external' influences of the Sun's radiation flux and solar wind flux lead to the formation of an ionospheric obstacle by photoionization, charge exchange and electron impact. For the early Martian conditions we could show that charge exchange was the dominant ionization mechanism. Several hybrid simulations for different stages in the evolution of the Martian atmosphere, at 1, 2, 5, 10, 30 and 100 EUV, were performed to analyze the non-thermal escape processes by ion pick-up, momentum transfer from the solar wind to the ionosphere and detached ionospheric plasma clouds. Our results show a non-linear evolution of the loss rates. Using mean solar wind parameters the simulations result in an oxygen loss equivalent to the depth of a global Martian ocean of about 2.6 m over the last 4.5 Gyr. The induced magnetic field strength could be increased up to about 2000 nT. A simulation run with high solar wind density results in an oxygen loss of a Martian ocean up to 205 m depth during 150 million years after the sun reached the zero age mean sequence (ZAMS).

Boesswetter, A.; Lammer, H.; Kulikov, Y.; Motschmann, U.; Simon, S.

2010-12-01

239

A Wise View Of The Non-thermal Gamma-ray Sky  

NASA Astrophysics Data System (ADS)

One of the main scientific objectives of the recent Fermi mission is unveiling the nature of the unidentified gamma-ray sources (UGSs). Despite the large improvements of Fermi in the gamma-ray source localization with respect to the past gamma-ray missions, about 1/3 of the gamma-ray objects detected still do not have a low energy counterpart associated. Recently, we discovered that blazars, the rarest and the most gamma-ray detected class of Active Galactic Nuclei (AGNs), can be recognized and separated from other extragalactic sources dominated by thermal emission using the IR colors. I will present how the Wide-Field Infrared Survey Explorer (WISE) infrared data make possible to identify a distinct region of the IR color-color diagrams where the sources dominated by the thermal radiation are separated from those dominated by non-thermal emission, in particular the blazar population. This IR non-thermal region of the parameter space, so called WISE Blazar Strip (WBS), it is a powerful new diagnostic tool that can be used to extract new blazar candidates, to identify those of uncertain type and also to search for the blazar-like counterparts of unidentified gamma-ray sources. First, I will show the relation between the infrared and gamma-ray emission for a selected sample of blazars associated with Fermi sources, for which WISE archival observations are available. Then, for the first time, I will present a possible candidate counterpart for 156 out of 313 UGSs analyzed.

Massaro, Francesco; D'Abrusco, R.; Paggi, A.; Tosti, G.; Ajello, M.; Gasaparrini, D.

2012-05-01

240

Killing of adherent oral microbes by a non-thermal atmospheric plasma jet.  

PubMed

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

Rupf, Stefan; Lehmann, Antje; Hannig, Matthias; Schäfer, Barbara; Schubert, Andreas; Feldmann, Uwe; Schindler, Axel

2009-11-12

241

Eradication of Pseudomonas aeruginosa biofilms by atmospheric pressure non-thermal plasma.  

PubMed

Bacteria exist, in most environments, as complex, organised communities of sessile cells embedded within a matrix of self-produced, hydrated extracellular polymeric substances known as biofilms. Bacterial biofilms represent a ubiquitous and predominant cause of both chronic infections and infections associated with the use of indwelling medical devices such as catheters and prostheses. Such infections typically exhibit significantly enhanced tolerance to antimicrobial, biocidal and immunological challenge. This renders them difficult, sometimes impossible, to treat using conventional chemotherapeutic agents. Effective alternative approaches for prevention and eradication of biofilm associated chronic and device-associated infections are therefore urgently required. Atmospheric pressure non-thermal plasmas are gaining increasing attention as a potential approach for the eradication and control of bacterial infection and contamination. To date, however, the majority of studies have been conducted with reference to planktonic bacteria and rather less attention has been directed towards bacteria in the biofilm mode of growth. In this study, the activity of a kilohertz-driven atmospheric pressure non-thermal plasma jet, operated in a helium oxygen mixture, against Pseudomonas aeruginosa in vitro biofilms was evaluated. Pseudomonas aeruginosa biofilms exhibit marked susceptibility to exposure of the plasma jet effluent, following even relatively short (? 10's s) exposure times. Manipulation of plasma operating conditions, for example, plasma operating frequency, had a significant effect on the bacterial inactivation rate. Survival curves exhibit a rapid decline in the number of surviving cells in the first 60 seconds followed by slower rate of cell number reduction. Excellent anti-biofilm activity of the plasma jet was also demonstrated by both confocal scanning laser microscopy and metabolism of the tetrazolium salt, XTT, a measure of bactericidal activity. PMID:22952948

Alkawareek, Mahmoud Y; Algwari, Qais Th; Laverty, Garry; Gorman, Sean P; Graham, William G; O'Connell, Deborah; Gilmore, Brendan F

2012-08-31

242

Suzaku/WAM and RHESSI Observations of Non-thermal Electrons in Solar Microflares  

NASA Astrophysics Data System (ADS)

We report on hard X-ray spectroscopy of solar microflares observed by the Wide-band All-sky Monitor (WAM), on board the Suzaku satellite, and by RHESSI. WAM transient data provide wide energy band (50 keV-5 MeV) spectra over a large field of view (~2? sr) with a time resolution of 1 s. WAM is attractive as a hard X-ray solar flare monitor due to its large effective area (~800 cm2 at 100 keV, ~13 times larger than that of RHESSI). In particular, this makes it possible to search for high energy emission in microflares that is well below the RHESSI background. The WAM solar flare list contains six GOES B-class microflares that were simultaneously observed by RHESSI between the launch of Suzaku in 2005 July and 2010 March. At 100 keV, the detected WAM fluxes are more than ~20 times below the typical RHESSI instrumental background count rates. The RHESSI and WAM non-thermal spectra are in good agreement with a single power law with photon spectral indices between 3.3 and 4.5. In a second step, we also searched the RHESSI microflare list for events that should be detectable by WAM, assuming that the non-thermal power-law emission seen by RHESSI extends to >50 keV. From the 12 detectable events between 2005 July and 2007 February, 11 were indeed seen by WAM. This shows that microflares, similar to regular flares, can accelerate electrons to energies up to at least 100 keV.

Ishikawa, Shin-nosuke; Krucker, Säm; Ohno, Masanori; Lin, Robert P.

2013-03-01

243

Non-thermal plasma techniques for abatement of volatile organic compounds and nitrogen oxides  

SciTech Connect

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.

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

244

The nature of the giant diffuse non-thermal source in the A3411-A3412 complex  

NASA Astrophysics Data System (ADS)

Very Large Array deep radio images at 1.4 GHz in total intensity and polarization reveal a diffuse non-thermal source in the interacting clusters A3411-A3412. Moreover, a small-size low-power radio halo at the centre of the merging cluster A3411 is found. We present here new optical and X-ray data and discuss the nature and properties of the diffuse non-thermal source. We suggest that the giant diffuse radio source is related to the presence of a large-scale filamentary structure and to multiple mergers in the A3411-A3412 complex.

Giovannini, G.; Vacca, V.; Girardi, M.; Feretti, L.; Govoni, F.; Murgia, M.

2013-10-01

245

Large amplitude dust-acoustic double layers in non-thermal plasmas with positive and negative dust  

NASA Astrophysics Data System (ADS)

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.

Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.

2011-11-01

246

Organic pollutants abatement and biodecontamination of brewery effluents by a non-thermal quenched plasma at atmospheric pressure  

Microsoft Academic Search

A preliminary study was carried out to investigate possible decontamination of the waste waters from a Cameroonian brewery by using a non-thermal atmospheric plasma. Samples of waste waters collected during periods of intense activity of production were first analysed for organoleptic, physical–chemical and organic parameters, and then exposed to a humid air electric discharge at ambient temperature and pressure. The

A. Doubla; S. Laminsi; S. Nzali; E. Njoyim; J. Kamsu-Kom; J.-L. Brisset

2007-01-01

247

Overview of non-thermal mixed waste treatment technologies: Treatment of mixed waste (ex situ); Technologies and short descriptions  

SciTech Connect

This compendium contains brief summaries of new and developing non- thermal treatment technologies that are candidates for treating hazardous or mixed (hazardous plus low-level radioactive) wastes. It is written to be all-encompassing, sometimes including concepts that presently constitute little more than informed ``ideas``. It bounds the universe of existing technologies being thought about or considered for application on the treatment of such wastes. This compendium is intended to be the very first step in a winnowing process to identify non-thermal treatment systems that can be fashioned into complete ``cradle-to-grave`` systems for study. The purpose of the subsequent systems paper studies is to investigate the cost and likely performance of such systems treating a representative sample of U.S. Department of Energy (DOE) mixed low level wastes (MLLW). The studies are called Integrated Non-thermal Treatment Systems (INTS) Studies and are being conducted by the Office of Science and Technology (OST) of the Environmental Management (EM) of the US Department of Energy. Similar studies on Integrated Thermal Treatment Systems have recently been published. These are not designed nor intended to be a ``downselection`` of such technologies; rather, they are simply a systems evaluation of the likely costs and performance of various non- thermal technologies that have been arranged into systems to treat sludges, organics, metals, soils, and debris prevalent in MLLW.

NONE

1995-07-01

248

Gas-Phase Pollutant Decomposition with Non-Thermal Plasmas: Simple Removal Equations and Figures-of Merit.  

National Technical Information Service (NTIS)

Non-thermal plasmas (NTPs) are a type of advanced oxidation and reduction technology for treating gas-phase chemical pollutants. Such plasmas are good sources of highly reactive oxidative and reductive species (free radicals and others), e.g., O(P3), OH, ...

L. A. Rosocha

1999-01-01

249

The Relationship between Extreme Ultraviolet Non-thermal Line Broadening and High-energy Particles during Solar Flares  

NASA Astrophysics Data System (ADS)

We have studied the relationship between the location of EUV non-thermal broadening and high-energy particles during large flares using the EUV Imaging Spectrometer on board Hinode, the Nobeyama Radio Polarimeter, the Nobeyama Radioheliograph, and the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. We have analyzed five large flare events that contain thermal-rich, intermediate, and thermal-poor flares classified by the definition discussed in the paper. We found that, in the case of thermal-rich flares, the non-thermal broadening of Fe XXIV occurred at the top of the flaring loop at the beginning of the flares. The source of 17 GHz microwaves is located at the footpoint of the flare loop. On the other hand, in the case of intermediate/thermal-poor flares, the non-thermal broadening of Fe XXIV occurred at the footpoint of the flare loop at the beginning of the flares. The source of 17 GHz microwaves is located at the top of the flaring loop. We discussed the difference between thermal-rich and intermediate/thermal-poor flares based on the spatial information of non-thermal broadening, which may provide clues that the presence of turbulence plays an important role in the pitch angle scattering of high-energy electrons.

Kawate, T.; Imada, S.

2013-10-01

250

Use of fluorescent techniques for understanding the effect of non thermal plasma discharge on the E. coli cell  

Microsoft Academic Search

Summary form only given: It has been demonstrated that ambient air non-thermal plasma discharges are very effective in inactivating various microorganisms. Plasma is being considered as a potent sterilization technology. It is important to understand the biological effect of plasma on bacteria. Fluorescent techniques are often employed by cell biologists to detect cellular phenomenon. These phenomena include changes in pH,

N. Vaze; D. Staack; Y. Mukhin; S. Anandan; A. Fridman

2009-01-01

251

Young Stellar Clusters, WR-Type Phenomena and the Origin of the Galactic-Center Non-thermal Radio Filaments  

NASA Astrophysics Data System (ADS)

Recent observations of the Arches cluster located within a projected distance of 30 pc from the dynamical center of the Galaxy have shown the presence of diffuse and discrete X-ray continuum emission, diffuse 6.4keV line emission as well as thermal and non-thermal radio continuum emission. This young and dense stellar cluster is also recognized to be within the 95% error circle of an identified steady source of ?-ray emission associated with the EGRET source 3EG J1746-2851. Much of the thermal and non-thermal emission can be explained by shocked gas resulting from colliding winds originating from massive binaries within the cluster. In particular, we argue that non-thermal particles could upscatter the radiation field of the cluster by ICS (inverse-Compton scattering) and account for the ?-ray emission. We also consider that the fluorescent 6.4 keV line emission may be the result of the impact of low-energy relativistic particles on neutral gas distributed in the vicinity of the cluster. Lastly, we sketch an interpretation in which young stellar clusters and massive young binary systems are responsible for the origin of non-thermal radio filaments found throughout the inner 300pc of the Galaxy. The collimation of the non-thermal filaments may be done in the colliding-wind region by the ionized surface of individual mass-losing stars of massive binary systems. In this picture, a WR-type phenomenon is expected to power a central star burst in the Galactic center in order to account for all the observed filaments.

Yusef-Zadeh, F.

252

Phenotypic and genetic differentiation among yellow monkeyflower populations from thermal and non-thermal soils in Yellowstone National Park.  

PubMed

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

Lekberg, Ylva; Roskilly, Beth; Hendrick, Margaret F; Zabinski, Catherine A; Barr, Camille M; Fishman, Lila

2012-03-22

253

Observational Constraints of Coronal Non-Thermal Velocities from Statistical Analysis of SERTS 1991-1997 Linewidth Observations  

NASA Astrophysics Data System (ADS)

The determination of non-thermal line broadening and velocities from the spectral linewidth measurements in the EUV provide an observational limits to available energy from unresolved sources within the observed coronal structures. These non-thermal velocity components can result from a number of sources including wave motions , turbulence, and electron beam interactions among others each of which has been suggested as a possible means of generating the required energy for the coronal heating process. .This study presents the determination and statistical analysis of the non-thermal velocity components of 397 identified EUV spectral lines from the combined observations of the SERTS 1991-1997 flights covering the wavelength range from 174-418Å. Similar analysis is also presented for the distributions of active region, quiet sun, and off-limb emission lines respectively which combine to form the composite distribution. We find, for all four of these velocity distributions, a strong non-thermal velocity peak corresponding to a velocity of 20-24 km/s regardless of location or activity level. These velocities suggest the majority of SERTS observed lines do not produce sufficient energy within their non-thermal components to contribute significantly to the heating process and are likely instead to observed motions of plasma cooling into the SERTS temperature range, peaked near 1.4 MK. The active region velocity distribution, however, exhibits evidence of a multi-component distribution through the existence of a high velocity shoulder which can be fit with a secondary distribution peaking near 47 km/s. This higher velocity component, does possess enough energy to overcome typical energy losses and potentially contribute to the available energy of the observed coronal plasma.

Coyner, A. J.; Davila, J. M.

2009-12-01

254

Conversion of carbon disulfide in air by non-thermal plasma.  

PubMed

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

Yan, Xiao; Sun, Yifei; Zhu, Tianle; Fan, Xing

2013-07-31

255

Direct chemical oxidation: a non-thermal technology for the destruction of organic wastes  

SciTech Connect

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.

Balazs, G.B.; Cooper, J. F.; Lewis, P. R.; Adamson, M. G.

1998-02-01

256

Vascular smooth muscle cells ablation with endovascular non thermal irreversible electroporation  

PubMed Central

Purpose Using fundamental principles of electroporation and mathematical analyses of temperature and electrical fields of blood vessels we developed an endovascular ablation approach - non thermal irreversible electroporation (NTIRE). The purpose of this study was to evaluate the effect of endovascular NTIRE on blood vessels. Material and Methods Specially made endovascular devices with four electrodes on top of inflatable balloons were used to apply electroporation pulses. Finite element simulations were used to characterize NTIRE protocols that will not induce thermal damage to treated tissues. Right iliac arteries of eight rabbits were treated with 90 NTIRE pulses. Angiograms were preformed before and after the procedures. Arterial specimens were harvested at 7 and 35 days. Evaluation included Hematoxylin & Eosin, elastic Von Giessen, and Masson’s Trichrome stains. Immunohistochemistry of selected slides included smooth muscle actin, proliferating cell nuclear antigen, von willebrand factor and S-100 antigen. Results At 7 days, all NTIRE-treated arterial segments displayed complete, transmural ablation of vascular smooth muscle cells (VSMC). At 35 days, similar damage to VSMC was noted. In most cases, elastic lamina remained intact and endothelial layer regenerated. Occasional mural inflammation and cartilaginous metaplasia were noted. After five weeks there was no evidence of significant VSMC proliferation, with the dominant process being wall fibrosis with regenerated endothelium. Conclusions NTIRE can be applied in an endovascular approach. It efficiently ablates vessel wall within seconds and with no damage to extra-cellular structures. NTIRE has possible applications in many fields of clinical cardiology, including arterial restenosis and cardiac arrhythmias.

Maor, Elad; Ivorra, Antoni; Mitchell, James J.; Rubinsky, Boris

2010-01-01

257

Removal mechanism of elemental mercury by using non-thermal plasma.  

PubMed

The removal mechanism of elementary mercury (Hg(0)) by non-thermal plasma (NTP) has been investigated, where dielectric barrier discharge and O(3) injection methods as oxidation techniques are employed, together with the analysis of mercury species deposited on the reactor surface using temperature-programmed desorption and dissociation (TPDD) and scanning electron microscopy-energy dispersive spectroscopy. The removal of Hg(0) by NTP is found to be time-dependent and proceed through three domains; the Hg(0) concentration just slightly decreases as soon as NTP is initiated and then becomes constant for several minutes (Region 1), thereafter starts to decrease rapidly for 1h (Region 2) and, after passing fall-off region, very slowly decreases for about 4h (Region 3). The deposited mercury species on the reactor surface were conglomerated like islands, rather than dispersed uniformly, and their ratio of Hg(0) to O composition is observed to be 1:2. Additionally, the new peak in TPDD spectra observed in the region of 260-380°C is proposed as HgO(3). These results lead us to conclude that the deposited mercury species by NTP have extra O atoms to oxidize the adsorbed Hg(0), resulting in the acceleration of removal rate as the oxidation of Hg(0) proceeds. PMID:21257191

Byun, Youngchul; Koh, Dong Jun; Shin, Dong Nam

2011-01-22

258

Collisionless Shocks in Partly Ionized Plasma with Cosmic Rays: Microphysics of Non-thermal Components  

NASA Astrophysics Data System (ADS)

In this review we discuss some observational aspects and theoretical models of astrophysical collisionless shocks in partly ionized plasma with the presence of non-thermal components. A specific feature of fast strong collisionless shocks is their ability to accelerate energetic particles that can modify the shock upstream flow and form the shock precursors. We discuss the effects of energetic particle acceleration and associated magnetic field amplification and decay in the extended shock precursors on the line and continuum multi-wavelength emission spectra of the shocks. Both Balmer-type and radiative astrophysical shocks are discussed in connection to supernova remnants interacting with partially neutral clouds. Quantitative models described in the review predict a number of observable line-like emission features that can be used to reveal the physical state of the matter in the shock precursors and the character of nonthermal processes in the shocks. Implications of recent progress of gamma-ray observations of supernova remnants in molecular clouds are highlighted.

Bykov, A. M.; Malkov, M. A.; Raymond, J. C.; Krassilchtchikov, A. M.; Vladimirov, A. E.

2013-05-01

259

In vivo non-thermal irreversible electroporation impact on rat liver galvanic apparent internal resistance.  

PubMed

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. PMID:21248392

Golberg, A; Laufer, S; Rabinowitch, H D; Rubinsky, B

2011-01-20

260

In vivo non-thermal irreversible electroporation impact on rat liver galvanic apparent internal resistance  

NASA Astrophysics Data System (ADS)

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.

Golberg, A.; Laufer, S.; Rabinowitch, H. D.; Rubinsky, B.

2011-02-01

261

Non-thermal ISR scatter and auroral forms associated with a substorm expansion  

NASA Astrophysics Data System (ADS)

Ground-based observations of a poleward substorm expansion using a high-resolution CMOS camera (50 frames/sec, 50 m spatial) and the electronically steerable Poker Flat Incoherent Scatter Radar (PFISR) have clarified the relationship between fine scale auroral structure and the development of non-thermal ISR echoes commonly referred to as NEIALs (Naturally Enhanced Ion Acoustic Lines). The measurements provide an unprecedented view into the temporal development of auroral forms and the decameter scale irregularities responsible for NEIALs. The highly structured auroral forms present during this event provide insight into the filamentary current systems associated with dispersive Alfvén waves, which determine the spatial dynamics of the aurora. There are existing models of the production of NEIALs that are dependent on a large current density, which has been observed in fine scale aurora, whereas other models are dependent on beams of precipitating electrons with low energy. Explanations in terms of true density enhancements have also been suggested. The results in this paper suggest that multiple mechanisms may be required to explain the observed spectral distortions. Speculations are provided concerning the mode of magnetosphere-ionosphere coupling underlying the optical and ISR features.

Dahlgren, H.; Marshall, R. A.; Akbari, H.; Semeter, J. L.

2011-12-01

262

Evidence of Non-thermal X-Ray Emission from HH 80  

NASA Astrophysics Data System (ADS)

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-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.

López-Santiago, J.; Peri, C. S.; Bonito, R.; Miceli, M.; Albacete-Colombo, J. F.; Benaglia, P.; de Castro, E.

2013-10-01

263

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

NASA Astrophysics Data System (ADS)

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. An elevated pressure of 15 psig shows improvement of selectivity of H2 and CO to 120% and 87%, with a significant reduction of C2Hx side products. H2 selectivity increased to 127% when a high ratio (29.2) of water-to-ethanol feed was used. Increasing CO2 selectivity is observed at higher water-to-ethanol ratios indicating that the water gas shift reaction occurs. A higher productivity and lower C2Hx products were observed at larger gas gaps. The highest overall energy efficiency achieved, including electrical power consumption, was 82% for all products or 66% for H2 only.

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

2011-07-01

264

RE-ACCELERATION OF NON-THERMAL PARTICLES AT WEAK COSMOLOGICAL SHOCK WAVES  

SciTech Connect

We examine diffusive shock acceleration (DSA) of the pre-existing as well as freshly injected populations of non-thermal, cosmic-ray (CR) particles at weak cosmological shocks. Assuming simple models for thermal leakage injection and Alfvenic drift, we derive analytic, time-dependent solutions for the two populations of CRs accelerated in the test-particle regime. We then compare them with the results from kinetic DSA simulations for shock waves that are expected to form in intracluster media and cluster outskirts in the course of large-scale structure formation. We show that the test-particle solutions provide a good approximation for the pressure and spectrum of CRs accelerated at these weak shocks. Since the injection is extremely inefficient at weak shocks, the pre-existing CR population dominates over the injected population. If the pressure due to pre-existing CR protons is about 5% of the gas thermal pressure in the upstream flow, the downstream CR pressure can absorb typically a few to 10% of the shock ram pressure at shocks with a Mach number M {approx}< 3, yet the re-acceleration of CR electrons can result in a substantial synchrotron emission behind the shock. The enhancement in synchrotron radiation across the shock is estimated to be about a few to several for M {approx} 1.5 and 10{sup 2}-10{sup 3} for M {approx} 3, depending on the detail model parameters. The implication of our findings for observed bright radio relics is discussed.

Kang, Hyesung [Department of Earth Sciences, Pusan National University, Pusan 609-735 (Korea, Republic of); Ryu, Dongsu, E-mail: kang@uju.es.pusan.ac.kr, E-mail: ryu@canopus.cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2011-06-10

265

EVOLUTION OF NON-THERMAL SHELL EMISSION ASSOCIATED WITH ACTIVE GALACTIC NUCLEUS JETS  

SciTech Connect

We explore the evolution of emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei. Focusing on powerful sources which host luminous quasars, we evaluated the broadband emission spectra by properly taking into account adiabatic and radiative cooling effects on the electron distribution. The synchrotron radiation and inverse Compton (IC) scattering of various photons that are mainly produced in the accretion disk and dusty torus are considered as radiation processes. We show that the resultant radiation is dominated by the IC emission for compact sources ({approx}<10 kpc), whereas the synchrotron radiation is more important for larger sources. We also compare shell emissions with those expected from the lobe under the assumption that the fractions of the energy deposited in the shell and lobe carried by non-thermal electrons are {epsilon}{sub e} {approx} 0.01 and {epsilon}{sub e,lobe} {approx} 1, respectively. We find that shell emissions are brighter than lobe ones at infrared and optical bands when the source size is {approx}>10 kpc, and the IC emissions from the shell at {approx}>10 GeV can be observed with an absence of contamination from the lobe irrespective of the source size. In particular, it is predicted that, for most powerful nearby sources (L{sub j} {approx} 10{sup 47} erg s{sup -1}), {approx}TeV gamma-rays produced via IC emissions can be detected by modern Cherenkov telescopes such as MAGIC, HESS, and VERITAS.

Ito, Hirotaka [Department of Aerospace Engineering, Tohoku University, 6-6-01 Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8579 (Japan); Kino, Motoki [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Kawakatu, Nozomu [Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8571 (Japan); Yamada, Shoichi, E-mail: hito@rhd.mech.tohoku.ac.jp, E-mail: kawakatu@ccs.tsukuba.ac.jp [Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

2011-04-01

266

Non-thermal hot electrons ultrafastly generating hot optical phonons in graphite.  

PubMed

Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature T(el) while leaving the lattice temperature T(l) low; subsequently the hot electrons heat up the lattice until T(el) = T(l) is reached. This temporal hierarchy owes to the assumption that the electron-electron scattering rate is much larger than the electron-phonon scattering rate. We report herein that the TTM scheme is seriously invalidated in semimetal graphite. Time-resolved photoemission spectroscopy (TrPES) of graphite reveals that fingerprints of coupled optical phonons (COPs) occur from the initial moments where T(el) is still not definable. Our study shows that ultrafast-and-efficient phonon generations occur beyond the TTM scheme, presumably associated to the long duration of the non-thermal electrons in graphite. PMID:22355583

Ishida, Y; Togashi, T; Yamamoto, K; Tanaka, M; Taniuchi, T; Kiss, T; Nakajima, M; Suemoto, T; Shin, S

2011-08-19

267

Non-thermal mechanism of weak microwave fields influence on neurons  

NASA Astrophysics Data System (ADS)

A non-thermal mechanism of weak microwave field impact on a nerve fiber is proposed. It is shown that in the range of about 30-300 GHz, there are strongly pronounced resonances associated with the excitation of ultrasonic vibrations in the membrane as a result of interaction with electromagnetic radiation. The viscous dissipation limits the resonances and results in their broadening. These forced vibrations create acoustic pressure, which may lead to the redistribution of the protein transmembrane channels, and thus changing the threshold of the action potential excitation in the axons of the neural network. The influence of the electromagnetic microwave radiation on various specific areas of myelin nerve fibers was analyzed: the nodes of Ranvier, and the initial segment--the area between the neuron hillock and the first part of the axon covered with the myelin layer. It was shown that the initial segment is the most sensitive area of the myelined neurons from which the action potential normally starts.

Shneider, M. N.; Pekker, M.

2013-09-01

268

ROS implication in a new antitumor strategy based on non-thermal plasma.  

PubMed

Non-thermal plasma (NTP) is generated by ionizing neutral gas molecules/atoms leading to a highly reactive gas at ambient temperature containing excited molecules, reactive species and generating transient electric fields. Given its potential to interact with tissue or cells without a significant temperature increase, NTP appears as a promising approach for the treatment of various diseases including cancer. The aim of our study was to evaluate the interest of NTP both in vitro and in vivo. To this end, we evaluated the antitumor activity of NTP in vitro on two human cancer cell lines (glioblastoma U87MG and colorectal carcinoma HCT-116). Our data showed that NTP generated a large amount of reactive oxygen species (ROS), leading to the formation of DNA damages. This resulted in a multiphase cell cycle arrest and a subsequent apoptosis induction. In addition, in vivo experiments on U87MG bearing mice showed that NTP induced a reduction of bioluminescence and tumor volume as compared to nontreated mice. An induction of apoptosis was also observed together with an accumulation of cells in S phase of the cell cycle suggesting an arrest of tumor proliferation. In conclusion, we demonstrated here that the potential of NTP to generate ROS renders this strategy particularly promising in the context of tumor treatment. PMID:21702038

Vandamme, Marc; Robert, Eric; Lerondel, Stéphanie; Sarron, Vanessa; Ries, Delphine; Dozias, Sébastien; Sobilo, Julien; Gosset, David; Kieda, Claudine; Legrain, Brigitte; Pouvesle, Jean-Michel; Pape, Alain Le

2011-08-12

269

Pyrite-enhanced methylene blue degradation in non-thermal plasma water treatment reactor.  

PubMed

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)

Benetoli, Luís Otávio de Brito; Cadorin, Bruno Mena; Baldissarelli, Vanessa Zanon; Geremias, Reginaldo; de Souza, Ivan Gonçalvez; Debacher, Nito Angelo

2012-08-24

270

Jovian non-thermal radio emission observed by STEREO/WAVES  

NASA Astrophysics Data System (ADS)

Solar TErrestrial RElations Observatory (STEREO) consists of two 3-axis-stabilized identical spacecraft (STEREO-A and STEREO-B), launched on Oct. 25, 2006. The WAVES experiment onboard STEREO is a radio burst tracer which observes the generation and evolution of the radio disturbances from the Sun to the orbit of Earth. Being mainly dedicated for measuring solar radio bursts, SWAVES also provided unique observations of the Jovian planetary radio emission. For the first time Jovian radiation is observed stereoscopically by two identical spacecraft in a frequency range from few kHz up to 16 MHz. The data recorded during more than two years (Nov 2006 - Dec 2008) of mission operations is analyzed. A big amount of the events of non-Io and Io controlled "arc-like" decametric components of the Jovian radiation (DAM) as well as hectometric emission (HOM) has been recorded. The unique stereoscopic observations by STEREO provide the opportunity to determine the propagation characteristics of the Jovian non-thermal radiation such as directivity and beam width of the emission cone. First results will be presented.

Rucker, H. O.; Panchenko, M.; Shaposhnikov, V. E.; Melnik, V. N.; Boudjada, M. Y.; Stereo Team

2009-04-01

271

Thermal treatment and non-thermal technologies for remediation of manufactured gas plant sites  

SciTech Connect

More than 1,500 manufactured gas plant (MGP) sites exist throughout the US. Many are contaminated with coal tar from coal-fueled gas works which produced town gas from the mid-1800s through the 1950s. Virtually all old US cities have such sites. Most are in downtown areas as they were installed for central distribution of manufactured gas. While a few sites are CERCLA/Superfund, most are not. However, the contaminants and methods used for remediation are similar to those used for Superfund clean-ups of coal tar contamination from wood-treating and coke oven facilities. Clean-up of sites is triggered by regulatory pressure, property transfers and re-development as well as releases to the environment--in particular, via groundwater migration. Due to utility de-regulation, site clean-ups may also be triggered by sale of a utility or of a specific utility site to other utilities. Utilities have used two approaches in dealing with their MGP sites. The first is do nothing and hope for the best. History suggests that, sooner or later, these sites become a bigger problem via a release, citizen lawsuit or regulatory/public service commission intervention. The second, far better approach is to define the problem now and make plans /for waste treatment or immobilization. This paper describes recent experience with a high capacity/low cost thermal desorption process for this waste and reviews non-thermal technology, such as bio-treatment, capping, recycling, and dig and haul. Cost data are provided for all technologies, and a case study for thermal treatment is also presented.

McGowan, T.F.; Greer, B.A. [RMT, Inc., Atlanta, GA (United States); Lawless, M. [Draper Aden Associates, Blacksburg, VA (United States)

1996-12-31

272

Non-thermal excitation and control of magnetization in Fe/GaAs film by ultrafast laser pulses  

NASA Astrophysics Data System (ADS)

We present our recent study of non-thermal excitation and coherent control of spin reorientation in 10-nm epitaxially grown Fe thin films by low-energy femtosecond laser pulses. The magnetization dynamics and hysteresis curves were recorded by pump-probe differential magnetic Kerr (DMK) spectroscopy using linearly polarized laser beams. A sharp switching in DMK signal is observed when we rotated the pump polarization. This result indicates a non-thermal origin of magnetization excitation and reorientation in Fe films. We reveal that spins can interact coherently with the polarization induced by the pulsed laser field in magnetic metals. Such opto-magnetic interactions are instantaneous and are only limited in time by the properties of laser pulses. Our results suggest the feasibility of ultrafast optical control of both the magnetization and the demagnetization responses in magnetic films.

Gong, Y.; Kutayiah, A. R.; Zhang, X. H.; Zhao, J. H.; Ren, Y. H.

2012-04-01

273

In Vitro Hemagglutination Activity of ?-Conglycinin and Glycinin Fractions and Feeding Study of Non-Thermal Treated Soy Protein  

Microsoft Academic Search

The purpose of this study was to use non-thermal means to reduce hemagglutination activities of soy proteins and thereby improve\\u000a the feeding quality of the resulting treated proteins. Two storage proteins in soybeans, ?-conglycinin- and glycinin-rich\\u000a fractions, were shown to have in vitro hemagglutination activity. The activity of the ?-conglycinin fraction was not reduced\\u000a by hydrolysis with single proteases, but

Yating MaTong; Tong Wang; Richard Faris; Michael Spurlock

2011-01-01

274

Non-thermal cosmic backgrounds from blazars: the contribution to the CMB, X-ray and ?-ray backgrounds  

Microsoft Academic Search

We present a new assessment of the contribution of the Blazar population to the extragalactic back- ground radiation across the electromagnetic spectrum. Our calculations rely on deep Blazar radio counts that we have derived combining several radio and multi-frequency surveys. We show that Blazar emission integrated over cosmic time gives rise to a considerable broad-band non-thermal Cosmic Background that in

P. Giommi; S. Colafrancesco; E. Cavazzuti; M. Perri; C. Pittori

2006-01-01

275

Decontamination of chemical warefare agent simulator Dimethyl Methylphosphonate (DMMP) using RF large area non-thermal atmospheric pressure plasma  

Microsoft Academic Search

Experimental results of the treatment of dimethyl methylphosphonate (DMMP), which is a chemical stimulant of the sarin gas, are reported. The plasma used for the experiment was a large area non-thermal RF atmospheric pressure plasma produced in the ambient air, of which size was 15times100 mm2. Previously measured current and gas temperature were low enough for thermally-sensitive material treatments, and

Dan Bee Kim; B. Gweon; S. Y. Moon; W. Choe

2008-01-01

276

Non-thermal cosmic backgrounds from blazars: the contribution to the CMB, X-ray and gamma-ray backgrounds  

Microsoft Academic Search

We present a new assessment of the contribution of the blazar population to the extragalactic background radiation across the electromagnetic spectrum. Our calculations rely on deep blazar radio counts that we have derived by combining several radio and multi-frequency surveys. We show that blazar emission integrated over cosmic time gives rise to a considerable broad-band non-thermal cosmic background that in

P. Giommi; S. Colafrancesco; E. Cavazzuti; M. Perri; C. Pittori

2006-01-01

277

Functionalization of nanomaterials by non-thermal large area atmospheric pressure plasmas: application to flexible dye-sensitized solar cells.  

PubMed

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 Ti(3+) 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. PMID:23831925

Jung, Heesoo; Park, Jaeyoung; Yoo, Eun Sang; Han, Gill-Sang; Jung, Hyun Suk; Ko, Min Jae; Park, Sanghoo; Choe, Wonho

2013-09-01

278

Decontamination of Bacillus subtilis Spores in a Sealed Package Using a Non-thermal Plasma System  

NASA Astrophysics Data System (ADS)

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.

Keener, Kevin M.; Jensen, J. L.; Valdramidis, V. P.; Byrne, E.; Connolly, J.; Mosnier, J. P.; Cullen, P. J.

279

Thermal and non-thermal X-ray processes in the Galactic Centre  

NASA Astrophysics Data System (ADS)

Recent observations have demonstrated that a diverse range of processes contribute to the extended X-ray emission observed from the central 100pc of our Galaxy. The region to the north-east of Sgr A* is characterized by bright knots of 6.4-keV iron-line emission arising from the X-ray fluorescence of dense molecular material. The variability of this emission establishes X-ray illumination as the excitation mechanism and links the line emission directly to an associated non-thermal continuum arising from the Thomson scattering of the incident X- ray photons. The Galactic Centre SMBH (Sgr A*) is the most likely origin of the X-ray flux and, in fact, the X-ray fluorescence provides a crude record of the outburst activity of Sgr A* over the past 150 years. Strong He-like and H-like iron-K line emission at 6.7 and 6.9 keV indicative of a very hot (~7 keV) thermal component is evident throughout the Galactic Centre. Recent work suggests the bulk of this emission can be explained in terms of the integrated emission of low-luminosity point sources (eg CVs). It now seems unlikely that the region is pervaded by a truly diffuse and highly energetic ultra-hot thermal plasma. Thermal emission at kT ~ 0.8 keV, traced by He-like Sulphur (2.4 keV) and Argon (3.1 keV) lines, is strongly concentrated in the same north-eastern region. This component most likely originates in multiple supernova explosions, although it is difficult to identify individual remnants within the region of enhanced surface brightness. For a few localized regions the He-like Fe/S ratio suggests a temperature closer to ~1.5 keV. Intriguingly one such X-ray hot-spot is spatially coincident with the so-called Radio Arc region, a site of cosmic-ray particle acceleration. Various aspects of the above picture will be reviewed in this talk.

Warwick, Bob; Heard, Victoria; Capelli, Renzo

2012-09-01

280

Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma  

PubMed Central

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.

Schafer, J.; Foest, R.; Reuter, S.; Kewitz, T.; Sperka, J.; Weltmann, K.-D.

2012-01-01

281

Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma.  

PubMed

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

Schäfer, J; Foest, R; Reuter, S; Kewitz, T; Šperka, J; Weltmann, K-D

2012-10-01

282

Laser schlieren deflectometry for temperature analysis of filamentary non-thermal atmospheric pressure plasma  

SciTech Connect

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.

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

283

Efficiency of Removing Sulfur Dioxide in the Air by Non-Thermal Plasma Along with the Application of the Magnetic Field  

Microsoft Academic Search

The non-thermal plasma created by high voltage pulsed power supply can be used to remove sulfur dioxide in the air, but how to increase the removing efficiency is not clear. It is novel to apply the magnetic field in removing SO2 as discussed in this paper. The mechanisms of removing sulfur dioxide by non-thermal plasma along with the application of

Jingjing Liu; Xiaohua Wang; Xingcheng Yuan; Mingzhe Rong

2005-01-01

284

Non-Thermal X-ray Emission from the Galactic Supernova Remnants G156.2+5.7 and G266.2-1.2  

NASA Astrophysics Data System (ADS)

A small but growing number of Galactic supernova remnants (SNRs) are known to feature non-thermal components in their X-ray spectra. Some of these SNRs also exhibit thermal X-ray emission, while the X-ray emission from the other SNRs is exclusively non-thermal. The study of non-thermal X-ray emission from SNRs has attracted a considerable amount of interest from both theoretical and observational perspectives, but our understanding of this phenomenon is still incomplete. Unresolved issues include the process responsible for producing this emission (synchrotron or non-thermal bremsstrahlung) and the physical conditions which are conducive to its production. We are conducting a broadband (approximately 0.5-20 keV) study of non-thermal X-ray emission from a sample of Galactic SNRs, as observed by the ROSAT, ASCA, RXTE, Chandra and XMM-Newton observatories. We will present the results of our study of the non-thermal X-ray emission from the SNRs G156.2+5.7 (as observed by ROSAT, ASCA and RXTE) and G266.2-1.2 (as observed by ROSAT, ASCA, RXTE and Chandra): the former SNR is known to exhibit both thermal and non-thermal X-ray emission, while the latter SNR exhibits non-thermal X-ray emission exclusively. Preliminary results and initial conclusions from this work will be presented and discussed. T.G.P. acknowledges support for this work from NASA LTSA grant NAG5-9237.

Pannuti, T. G.; Allen, G. E.

2003-05-01

285

Non-thermal recombination - a neglected source of flare hard X-rays and fast electron diagnostic  

NASA Astrophysics Data System (ADS)

Context: Flare Hard X-rays (HXRs) from non-thermal electrons are commonly treated as solely bremsstrahlung (free-free = f-f), recombination (free-bound = f-b) being neglected. This assumption is shown to be substantially in error, especially in hot sources, mainly due to recombination onto Fe ions. Aims: We analyse the effects on HXR spectra J(?) and electron diagnostics by including non-thermal recombination onto heavy elements in our model. Methods: Using Kramers hydrogenic cross sections with effective Z=Z_eff, we calculate f-f and f-b spectra for power-law electron spectra within both thin and thick target limits and for Maxwellians with summation over all important ions. Results: We find that non-thermal electron recombination, especially onto Fe, must, in general, be included with f-f for reliable spectral interpretation, when the HXR source is hot, such as occulted loops containing high ions of Fe (f-b cross-section ? Z^4). The f-b contribution is greatest when the electron spectral index ? is large and any low energy cut-off Ec is small, because the electron flux spectrum F(E) emitting f-b photon energy ? is ? (E=?-V_Z)-? (VZ is the ionisation potential) and not ? (E=?)-?+1 as for f-f. The f-b spectra recombination edges mean a cut-off Ec in F(E) appears as an HXR feature at ? = Ec + V_Z, offering an Ec diagnostic. For thick target sources, the presence of Ec appears as edges in J'(?), not in J(?), but it is still detectable. Including f-b lowers the F(E) needed for prescribed HXR fluxes greatly in some cases; and even when small, it seriously distorts F(E) as inferred by inversion or forward fitting of J(?) based on f-f alone. Conclusions: The f-b recombination from non-thermal electrons can be an important contributor to HXR spectra, so it should be included in spectral analyses, especially for hot sources. Accurate results will require use of better cross sections than ours and consideration of source ionisation structure.

Brown, J. C.; Mallik, P. C. V.

2008-04-01

286

Existence domains of large amplitude dust-acoustic solitons in non-thermal plasmas with positive and negative dust  

NASA Astrophysics Data System (ADS)

Using the traditional Sagdeev pseudopotential approach, the existence of large amplitude solitons is investigated for a plasma composed of cold negative dust, adiabatic positive dust, non-thermal ions and Boltzmann electrons. The lower and upper soliton Mach number limitations are determined as a function of various parameters and physical reasons are provided as to why these Mach number limits occur. Some regions in parameter space have been identified where only negative or positive solitons occur, whereas, other regions support the coexistence of both positive and negative potential solitons.

Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.

2011-11-01

287

Non-thermal hard X-ray emission in galaxy clusters observed with the BeppoSAX PDS  

Microsoft Academic Search

We study the X-ray emission in a sample of galaxy clusters using the BeppoSAX\\u000aPDS instrument in the 20 -- 80 keV energy band. The non-thermal hard X-ray\\u000acluster emission (HXR) is detected at a 2 sigma level in 50% of the\\u000anon-significantly AGN-contaminated clusters: A2142, A2199, A2256, A3376, Coma,\\u000aOphiuchus and Virgo. The data are consistent with a scenario

J. Nevalainen; T. Oosterbroek; M. Bonamente; S. Colafrancesco

2003-01-01

288

Non-thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration  

NASA Astrophysics Data System (ADS)

This paper reviews our recent research results of using non-thermal ­atmospheric plasmas for oral bacterial deactivation and for composite restoration improvement. Oral bacteria of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. The plasma exposure time for a 99.9999% cell reduction was less than 15 s for S. mutans and within 5 min for L. acidophilus. To evaluate the dentin/composite interfacial bonding, extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. After dental composite application and light curing, the teeth were then sectioned into micro-bars as the specimens for microtensile test. Student Newman Keuls (SNK) tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment of the dentin surfaces. These findings indicated that non-thermal atmospheric plasma technology is very promising for dental clinical applications.

Yu, Qing Song; Li, H.; Ritts, A. C.; Yang, B.; Chen, M.; Hong, L.; Xu, C.; Yao, X.; Wang, Y.

289

Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE: non-thermal component detection  

NASA Astrophysics Data System (ADS)

We report results of a one-year monitoring of the low-mass X-ray binary (LMXB) source (atoll type) 4U 1728-34 with INTEGRAL and RXTE. Three time intervals were covered by INTEGRAL, during which the source showed strong spectral evolution. We studied the broad-band X-ray spectra in detail by fitting several models in the different sections of the hardness-intensity diagram. The soft states are characterized by prominent blackbody emission plus a contribution from a Comptonized emission. The hard states are characterized by the presence of an excess flux with respect to the Comptonization model above 50 keV, while the soft component is fainter. To obtain an acceptable fit to the data, this excess is modelled either with a power law with photon index ?˜ 2 or a Comptonization (CompPS) spectrum implying the presence of hybrid thermal and non-thermal electrons in a corona. This makes 4U 1728-34 one of the few LMXBs of atoll type showing non-thermal emission at high energy. From our analysis, it is also apparent that the presence of the hard tail is more prominent as the overall spectrum becomes harder. We also discuss alternative models which can describe these hard states.

Tarana, A.; Belloni, T.; Bazzano, A.; Méndez, M.; Ubertini, P.

2011-09-01

290

A Search for Evidence of Non-Thermal Emission from the Supernova Remnants 37A/B  

NASA Astrophysics Data System (ADS)

The ADP grant NAG5-9211 entitled 'A Search for Evidence of Non-Thermal Emission from the Supernova Remnants 37 A/B' was not used to support an analysis of the ASCA data for these two remnants because the ASCA mission ended before the remnants were observed. The grant was used to support similar research on two remnants in the Large Magellanic Cloud, N132D and N 103B. An analysis of the Chandra data for these two remnants exhibits some evidence of non-thermal emission from small regions in the remnants. The X-ray spectra for these regions can not be adequately described by a single thermal X-ray emission model. However, if an X-ray synchrotron component is also included, the spectral data can be well described by the model and the values of the fit parameters are consistent with the values expected. These results were presented at the 199th Meeting of the American Astronomical Society. In summary, the grant has enabled us to strengthen the evidence that supernova remnants outside our Galaxy can also accelerate electrons to very-high energies. The results of this analysis will be published soon in the Astrophysical Journal,

Oliversen, R.

2002-01-01

291

Absence of synergistic enhancement of non-thermal effects of ultrasound on cell killing induced by ionizing radiation.  

PubMed

The present study was performed to elucidate the role of non-thermal effects (cavitation and direct effects) of ultrasound, in simultaneous combination with X-irradiation on the cytotoxicity of mouse L cells. Firstly, mouse L cells were exposed to X-rays and ultrasound (1 MHz continuous wave, spatial peak temporal average intensity; 3.7 W/cm2) simultaneously at 37 degrees C under O2 or Ar saturated conditions to examine the cavitational effect of ultrasound. Secondly, cells were exposed to X-rays and ultrasound at 37 degrees C under N2O saturated conditions, which suppresses the cavitation, to examine the direct effects of ultrasound. The cavitational effect under O2 and Ar saturated conditions induced an exponential decrease in cell survival, and resulted in an additive effect on cell killing with the combination of X-rays and ultrasound. The direct effect in the N2O conditions induced no cell killing and did not modify the cell killing induced by X-rays. These results suggested that the non-thermal effects of ultrasound did not interact synergistically with X-rays for cell killing. PMID:3499413

Kondo, T; Kano, E

1987-10-01

292

Solar off-limb line widths with SUMER: revised value of the non-thermal velocity and new results  

NASA Astrophysics Data System (ADS)

Alfvén waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in the solar wind and in the upper corona. In the lower corona, one can use the line profiles to infer the ion temperatures. But the value of the so-called "non-thermal" (or "unresolved") velocity, potentially related to the amplitude of Alfvén waves propagating in the corona, is critical in firmly identifying ion-cyclotron preferential heating. In a previous paper, we proposed a method to constrain both the Alfvén wave amplitude and the preferential heating, above a polar coronal hole observed with the SUMER/SOHO spectrometer. Taking into account the effect of instrumental stray light before analysing the line profiles, we ruled out any direct evidence of damping of the Alfvén waves and showed that ions with the lowest charge-to-mass ratios were preferentially heated. We re-analyse these data here to correct the derived non-thermal velocity, and we discuss the consequences on the main results. We also include a measure of the Fe VIII 1442.56 Å line width (second order), thus extending the charge-to-mass ratio domain towards ions more likely to experience cyclotron resonance.

Dolla, L.; Solomon, J.

2009-09-01

293

Bactericidal effects of non-thermal argon plasma in vitro, in biofilms and in the animal model of infected wounds.  

PubMed

Non-thermal (low-temperature) physical plasma is under intensive study as an alternative approach to control superficial wound and skin infections when the effectiveness of chemical agents is weak due to natural pathogen or biofilm resistance. The purpose of this study was to test the individual susceptibility of pathogenic bacteria to non-thermal argon plasma and to measure the effectiveness of plasma treatments against bacteria in biofilms and on wound surfaces. Overall, Gram-negative bacteria were more susceptible to plasma treatment than Gram-positive bacteria. For the Gram-negative bacteria Pseudomonas aeruginosa, Burkholderia cenocepacia and Escherichia coli, there were no survivors among the initial 10(5) c.f.u. after a 5 min plasma treatment. The susceptibility of Gram-positive bacteria was species- and strain-specific. Streptococcus pyogenes was the most resistant with 17?% survival of the initial 10(5) c.f.u. after a 5 min plasma treatment. Staphylococcus aureus had a strain-dependent resistance with 0 and 10?% survival from 10(5) c.f.u. of the Sa 78 and ATCC 6538 strains, respectively. Staphylococcus epidermidis and Enterococcus faecium had medium resistance. Non-ionized argon gas was not bactericidal. Biofilms partly protected bacteria, with the efficiency of protection dependent on biofilm thickness. Bacteria in deeper biofilm layers survived better after the plasma treatment. A rat model of a superficial slash wound infected with P. aeruginosa and the plasma-sensitive Staphylococcus aureus strain Sa 78 was used to assess the efficiency of argon plasma treatment. A 10 min treatment significantly reduced bacterial loads on the wound surface. A 5-day course of daily plasma treatments eliminated P. aeruginosa from the plasma-treated animals 2 days earlier than from the control ones. A statistically significant increase in the rate of wound closure was observed in plasma-treated animals after the third day of the course. Wound healing in plasma-treated animals slowed down after the course had been completed. Overall, the results show considerable potential for non-thermal argon plasma in eliminating pathogenic bacteria from biofilms and wound surfaces. PMID:20829396

Ermolaeva, Svetlana A; Varfolomeev, Alexander F; Chernukha, Marina Yu; Yurov, Dmitry S; Vasiliev, Mikhail M; Kaminskaya, Anastasya A; Moisenovich, Mikhail M; Romanova, Julia M; Murashev, Arcady N; Selezneva, Irina I; Shimizu, Tetsuji; Sysolyatina, Elena V; Shaginyan, Igor A; Petrov, Oleg F; Mayevsky, Evgeny I; Fortov, Vladimir E; Morfill, Gregor E; Naroditsky, Boris S; Gintsburg, Alexander L

2010-09-09

294

Optimal filter techniques for quasi-periodic oscillations.  

NASA Astrophysics Data System (ADS)

Optimal filter analysis techniques are employed in order to set constraints on the nature of possible relationships between low frequency noise (LFN) and quasiperiodic oscillations (QPOs) in GX 5-1 on timescales near the QPO coherence length. Models are explored in which LFN shots modulate sinusoidal QPOs for shot rates up to 400 Hz and shot clustering fractions up to ?50%. Such models are found to be constrained by comparison with the data.

Norris, J. P.; Hertz, P.; Wood, K. S.; Vaughan, B. A.; Michelson, P. F.; Mitsuda, K.; Dotani, T.

295

Quasi-Periodicity in Medieval and Islamic architecture and ornament  

Microsoft Academic Search

A recent article in Science by Lu and Steinhardt has caused a controversy over whether Medieval Islamic tilings are examples of aperiodic and quasiperiodic tilings. The tilings have five- or ten-fold symmetry, which cannot occur in traditional crystallography. Such tilings were only recently discovered in the West. The goal of this project is to read several articles and write a

Ser Zheng; Helmer Aslaksen

296

Electrochemical synthesis of quasi-periodic quantum dot arrays  

SciTech Connect

The conventional route to nanosynthesis involves beam nanolithography (electron beam, ion beam or-x-ray lithography). Exposure to these beams during pattern delineation however causes severe radiation damage to nanostructures which is further compounded during later post-processing such as reactive ion etching. Consequently, finished nanostructures become replete with traps, vacancies, spurious charges and surface states. To circumvent this problem, we are developing a ``gentle`` electrochemical technique for the fabrication of periodic quantum dot arrays. It does not damage the structures through harsh processing steps, offers a minimum feature size down to {approximately} 40 {Angstrom}, allows the fabrication of structures on non-planar surfaces (e.g. spherical or cylindrical substrates), is amenable to mass production (millions of wafers can be processed simultaneously) and is potentially orders of magnitude cheaper than conventional nanofabrication. This paper describes initial results and show that this technique bears significant promise for future applications in nanostructure synthesis.

Miller, A.E.; Yue, D.F.; Banerjee, G.; Bandyopadhyay, S. [Univ. of Notre Dame, Notre Dame, IN (United States). Dept. of Electrical Engineering; Ricker, R.E.; Jones, S. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Materials Science and Engineering Laboratory; Eastman, J.A. [Argonne National Lab., IL (United States)

1994-06-01

297

Non-thermal excitation and control of dynamic magnetization in a Fe/GaAs heterojunction by ultrafast laser pulses  

NASA Astrophysics Data System (ADS)

Control carrier injection in metal semiconductor heterojunctions and therefore their magnetic dynamics is a major challenge in modern solid-state electronic devices. We report on our recent study of non-thermally excitation and coherently control the spin reorientation by utilizing low-energy femtosecond laser pulses to induce a photo- current through a Fe/GaAs interface. The magnetization dynamics and hysteresis curves were recorded by the pump-probe differential magnetic Kerr (DMK) technique. We show that magnetization excitation and reorientation strongly depend on the polarization of pump pulses. A clear four-fold switching is identified in DMK signal when we rotate the polarization of pump pulses. Our results show that the dynamic magnetization can be induced and controlled by ultrafast laser pulses, and therefore indicate the feasibility of next generation femtosecond-switching magnetic storage devices.

Gong, Yu; Kutayiah, A. R.; Cevher, Z.; Zhang, X. H.; Zhao, J. H.; Ren, Y. H.

2013-03-01

298

Non-thermal dark matter production from the electroweak phase transition: multi-TeV WIMPs and "baby-zillas"  

NASA Astrophysics Data System (ADS)

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.

Falkowski, Adam; No, Jose M.

2013-02-01

299

[Dependence of the non-thermal radiofrequency electromagnetic field bioeffects on the typological features of electroencephalogram in humans].  

PubMed

In researches with participation of volunteers bioeffects of short-term non-thermal radiofrequency electromagnetic field (RF EMF) exposure were studied. The basic form of brain's reaction was the amplification of energy in a-range in electroencephalogram (EEG) spectra. Dependence of these changes, not only due to the changes of the exposure parameters, but also due to personal EEG typological features was shown. Moderate degree of the alpha frequencies domination in the background promoted development of reaction of a brain to the RF EMF exposure. To a lesser degree it was shown at hyperactivity of this range and, practically, was absent in the conditions of theta- or beta2-range domination in the EEG background with the open and closed eyes. The combination of RF EMF exposure and monotonous activity has authentically strengthened result, keeping the basic form of reaction (energy amplification in the alpha range of EEG spectrum) and dependence on EEG typological features. PMID:21434398

Luk'ianova, S N; Grigor'ev, Iu G; Grigor'ev, O A; Merkulov, A V

300

Non-thermal radio emission from O-type stars. IV. Cygnus OB2 No. 8A  

NASA Astrophysics Data System (ADS)

Context. Several early-type colliding-wind binaries are known to emit synchrotron radiation due to relativistic electrons, which are most probably accelerated by the Fermi mechanism. By studying such systems we can learn more about this mechanism, which is also relevant in other astrophysical contexts. Colliding-wind binaries are furthermore important for binary frequency determination in clusters and for understanding clumping and porosity in stellar winds. Aims: We study the non-thermal radio emission of the binary Cyg OB2 No. 8A, to see if it is variable and if that variability is locked to the orbital phase. We investigate if the synchrotron emission generated in the colliding-wind region of this binary can explain the observations and we verify that our proposed model is compatible with the X-ray data. Methods: We use both new and archive radio data from the Very Large Array (VLA) to construct a light curve as a function of orbital phase. We also present new X-ray data that allow us to improve the X-ray light curve. We develop a numerical model for the colliding-wind region and the synchrotron emission it generates. The model also includes free-free absorption and emission due to the stellar winds of both stars. In this way we construct artificial radio light curves and compare them with the observed one. Results: The observed radio fluxes show phase-locked variability. Our model can explain this variability because the synchrotron emitting region is not completely hidden by the free-free absorption. In order to obtain a better agreement for the phases of minimum and maximum flux we need to use stellar wind parameters for the binary components which are somewhat different from typical values for single stars. We verify that the change in stellar parameters does not influence the interpretation of the X-ray light curve. Our model has trouble explaining the observed radio spectral index. This could indicate the presence of clumping or porosity in the stellar wind, which - through its influence on both the Razin effect and the free-free absorption - can considerably influence the spectral index. Non-thermal radio emitters could therefore open a valuable pathway to investigate the difficult issue of clumping in stellar winds. Partly based on observations with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).Appendices are only available in electronic form at http://www.aanda.org

Blomme, R.; De Becker, M.; Volpi, D.; Rauw, G.

2010-09-01

301

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide. Quarterly Report April 1-June 30, 2004.  

National Technical Information Service (NTIS)

The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H2S) in a non-thermal plasma and recover hydrogen (H2) through a superpermeable multi-layer membrane. Superpermeability of hy...

M. D. Argyle J. F. Ackerman S. Muknahallipatna J. C. Hamann S. Legowski

2004-01-01

302

Can Electromagnetic Exposure Cause a Change in Behaviour? Studying Possible Non-Thermal Influences on Honey Bees - An Approach within the Framework of Educational Informatics  

Microsoft Academic Search

In recent years the public discussion has been focused increasingly on possible unhealthy effects of high-frequency electromagnetic fields (particularly of mobile-phones) on human beings. Whereas thermal effects of this radiation could be explained very well, non-thermal effects could hardly be clarified. In our last works, we pointed out that - from view of Educational Informatics - honey bees are suitable

Wolfgang Harst; Jochen Kuhn; Hermann Stever

303

Non-thermal plasma-assisted NOx reduction over Na-Y zeolites: The promotional effect of acid sites  

SciTech Connect

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

Kwak, Ja Hun; Peden, Charles HF; Szanyi, Janos

2006-06-01

304

Electrostatic solitary structures in presence of non-thermal electrons and a warm electron beam on the auroral field lines  

SciTech Connect

Electrostatic solitary waves (ESWs) have been observed by satellites in the auroral region of the Earth's magnetosphere. These ESWs are found to be having both positive and negative electrostatic potentials. Using the Sagdeeev psuedo-potential technique, arbitrary amplitude electron-acoustic solitary waves/double layers are studied in an unmagnetized plasma consisting of non-thermally distributed hot electrons, fluid cold electrons, a warm electron beam, and ions. The inertia of the warm electrons, and not the beam speed, is essential for the existence of positive potential solitary structures. Existence domains for positive as well as negative potential electrostatic solitons/double layers are obtained. For the typical auroral region parameters, the electric field amplitude of the negative potential solitons is found to be in the range {approx}(3-30) mV/m and {approx}(5-80) mV/m for the positive potential solitons. For the negative potential solitons/double layers, the amplitudes are higher when their widths are smaller. On the other hand, the amplitude of the positive potential structures increase with their widths.

Singh, S. V. [Indian Institute of Geomagnetism, Navi Mumbai (India); School of Physics, University of Kwazulu-Natal, Durban (South Africa); Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Bharuthram, R. [University of the Western Cape, Bellville (South Africa); Pillay, S. R. [School of Physics, University of Kwazulu-Natal, Durban (South Africa)

2011-12-15

305

Effects of background fluid on the efficiency of inactivating yeast with non-thermal atmospheric pressure plasma.  

PubMed

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

Ryu, Young-Hyo; Kim, Yong-Hee; Lee, Jin-Young; Shim, Gun-Bo; Uhm, Han-Sup; Park, Gyungsoon; Choi, Eun Ha

2013-06-14

306

Use of atmospheric non-thermal plasma as a disinfectant for objects contaminated with methicillin-resistant Staphylococcus aureus  

PubMed Central

Background Health-care associated infections due to methicillin-resistant strains of Staphylococcus aureus (MRSA) are increasing worldwide despite current infection control measures. Novel methods for disinfection of MRSA would be useful. Methods We tested the effectiveness of atmospheric, non-thermal plasma discharge at killing S. aureus, including USA300 strains, and at disinfecting experimentally contaminated hospital pagers. Results Exposure of S. aureus to plasma at different concentrations and for varying lengths of time resulted in up to a 4–5 log10 kill on tryptic soy agar plates within 10 minutes and was not toxic to epithelial cells. USA300 strains of MRSA were more resistant to plasma-based killing than other tested strains. Disinfection of hospital pagers experimentally coated with clinically relevant amounts of MRSA could be achieved in as little as 30 seconds. Conclusions Generation of plasma is a promising method for disinfection of objects or surfaces that warrants further study in hospital settings. The USA300 strains of S. aureus may be more resistant to disinfection than other strains.

Burts, Monica L.; Alexeff, Igor; Meek, Eric T.; McCullers, Jonathan A

2010-01-01

307

Studies on a non-thermal pulsed corona plasma between two parallel-plate electrodes in water  

NASA Astrophysics Data System (ADS)

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 discharge. The dependence of hydrogen peroxide formation as an indicator for the generation of most important oxidative species OH radicals on the pulse repetition rate, the solution conductivity and the pH of the solution was investigated. The highest yield of H2O2 (3.5 mg L-1) was obtained at 20 pps in a NaCl solution with a conductivity of 400 µS cm-1 and pH 7 in 90 min. The maximum energy efficiency of ˜0.1 g kWh-1 H2O2 was obtained. The surface of the coated electrodes, before and after applying of electrical discharges, was analysed by scanning electron microscopy. During the discharge process, the coating was destroyed and the formation of H2O2 decreased to 10% after discharging of nearly 35 h.

Sein, M. M.; Nasir, Z. Bin; Telgheder, U.; Schmidt, T. C.

2012-06-01

308

Non-thermal atmospheric-pressure plasma can influence cell adhesion molecules on HaCaT-keratinocytes.  

PubMed

Non-thermal atmospheric-pressure plasmas provide new hope for improvement in chronic wound management because of their potency in killing microorganisms. However, the effectiveness of the procedure has to be verified and negative effects on healthy tissues have to be excluded. In wound healing adhesion molecules play a crucial role for cell migration and proliferation. We investigated whether an atmospheric-pressure plasma jet (kINPen09) influences the expression of adhesion molecules responsible for cell-cell and cell-matrix interactions after treatment of HaCaT-keratinocytes for 10 and 30 s. Twenty-four hours after plasma treatment expression of ?(2) - and ?(1)-integrin, E-cadherin and the epidermal growth factor receptor (EGFR) was determined by flow cytometry. Plasma-treated HaCaT-cells were characterized by normal ?(2)-integrin and increased ?(1)-integrin expression. E-cadherin and EGFR expression was reduced after the 30-s treatment. We did not observe any effects following the 10-s plasma treatment. In conclusion, short-term plasma treatment can be applied without effects for cell-cell and cell-matrix adhesion. PMID:21054557

Haertel, Beate; Wende, Kristian; von Woedtke, Thomas; Weltmann, Klaus Dieter; Lindequist, Ulrike

2010-11-05

309

NO{sub X} REDUCTION BEHAVIOR OF ALUMINA AND ZEOLITE CATALYSTS IN COMBINATION WITH NON-THERMAL PLASMA  

SciTech Connect

Lean burn gasoline and diesel engines provide improved fuel economy when compared to engines operating under stoichiometric fuel/air conditions. At the same time, lean burn and diesel engines present a problem for emission control. Because they operate under oxidizing conditions, the conventional three-way catalyst is not effective in NOx reduction [1,2]. In addition, the wide temperature range of automobile exhaust gases present a challenge for catalyst design. The temperature of exhaust gases from a light duty diesel engine can vary from 150 to 500 C, depending on the operating conditions. To date, a catalyst that operates with high NOx conversion efficiency over the entire operating range has not been found. Non-thermal plasma assisted catalysis has been shown to be a promising technology for NOx reduction in lean burn and diesel exhaust gases [3,4]. The approach exploited in this paper is to use a plasma in combination with several catalysts, each of which are active over unique temperature ranges. It was reported in the literature, that the one of the essential roles of plasma treatment is to oxidize NO to easier reducible NO2 [7]. In this contribution, the other important function of plasma treatment, namely partial oxidation of propylene, will be demonstrated.

Panov, A.G.

2000-08-20

310

A combined process of non-thermal plasma with sludge stabilization for the simultaneous reduction of odor and organic waste.  

PubMed

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

Shin, S; Hwang, H-J; Song, J

2011-01-01

311

Effects of Background Fluid on the Efficiency of Inactivating Yeast with Non-Thermal Atmospheric Pressure Plasma  

PubMed Central

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.

Ryu, Young-Hyo; Kim, Yong-Hee; Lee, Jin-Young; Shim, Gun-Bo; Uhm, Han-Sup; Park, Gyungsoon; Choi, Eun Ha

2013-01-01

312

Non-thermal "Burst-on-Tail" of Long-Duration Solar Event on 26 October 2003  

NASA Astrophysics Data System (ADS)

Observations of a rare long-duration solar event of GOES class X1.2 from 26 October 2003 are presented. This event showed a pronounced burst of hard X-ray and microwave emission, which was extremely delayed (> 60 min) with respect to the main impulsive phase and did not have any significant response visible in soft X-ray emission. We refer to this phenomenon as a "burst-on-tail". Based on TRACE observations of the growing flare arcade and some simplified estimation, we explain why a reaction of active region plasma to accelerated electrons may change drastically over time. We suggest that, during the "burst-on-tail", non-thermal electrons were injected into magnetic loops of larger spatial scale than during the impulsive phase bursts, thus resulting in much smaller values of plasma temperature and emission measure in their coronal volume, and hence little soft X-ray flux. The nature of the long gap between the main impulsive phase and the "burst-on-tail" is, however, still an open question.

Zimovets, I.; Struminsky, A.

2012-12-01

313

Search for Non-Thermal Emissions from an Isolated Magnetic White Dwarf, EUVE J0317-855, with Suzaku  

NASA Astrophysics Data System (ADS)

To search for possible non-thermal emissions from magnetic white dwarfs (WDs), we selected the most suitable candidates from among magnetic cataclysmic variables and isolated WDs. After the magnetic cataclysmic variable AE Aquarii, which emits hard X-ray pulses, the isolated WD EUVE J0317-855 is expected to emit the second most powerful magnetic dipole radiation with energies reaching ˜ 1.1 × 1029 erg s-1 . EUVE J0317-855 was observed with Suzaku from 2009 July 16 to 2009 July 17 for about 60 ks. No significant emissions were detected from the object in the 0.5-10 keV band, and the upper limit of the X-ray flux was estimated to be 1.7 × 10-13 erg cm-2 s-1 in the 2-10 keV band. This value corresponds to less than 0.05% of the calculated spin-down energy. It excludes the possibility of explaining soft gamma-ray repeaters and anomalous X-ray pulsars as WDs, but may indicate that the activity in the magnetosphere of WDs is not so different from that occurring in radio pulsars. Curvature radiation, which is one of the suggested mechanism for emissions from the magnetosphere of compact objects, may explain the observed X-ray flux of AE Aquarii, and is consistent with the non-detection of EUVE J0317-855.

Harayama, Atsushi; Terada, Yukikatsu; Ishida, Manabu; Hayashi, Takayuki; Bamba, Aya; Tashiro, Makoto S.

2013-08-01

314

Non-thermal Emission from the Photospheres of Gamma-ray Burst Outflows. I. High-Frequency Tails  

NASA Astrophysics Data System (ADS)

We study the spectrum of high-frequency radiation emerging from mildly dissipative photospheres of long-duration gamma-ray burst outflows. Building on the results of recent numerical investigations, we assume that electrons are heated impulsively to mildly relativistic energies by either shocks or magnetic dissipation at Thomson optical depths of several and subsequently cool by inverse Compton, scattering off the thermal photons of the photosphere. We show that even in the absence of magnetic field and non-thermal leptons, inverse Compton scattering produces power-law tails that extend from the peak of the thermal radiation, at several hundred keV, to several tens of MeV, and possibly up to GeV energies. The slope of the high-frequency power law is predicted to vary substantially during a single burst, and the model can easily account for the diversity of high-frequency spectra observed by BATSE. Our model works in baryonic as well as in magnetically dominated outflows, as long as the magnetic field component is not overwhelmingly dominant.

Lazzati, Davide; Begelman, Mitchell C.

2010-12-01

315

Surface molecules on HaCaT keratinocytes after interaction with non-thermal atmospheric pressure plasma.  

PubMed

Non-thermal atmospheric-pressure plasmas have been developed that will be used in future for several purposes, e.g. medicine. Living tissues and cells are at the focus of plasma treatment, e.g. to improve wound healing, or induce apoptosis and growth arrest in tumour cells. Detailed investigations of plasma-cell interactions are needed. Cell surface adhesion molecules as integrins, cadherins or the EGFR (epidermal growth factor receptor) are of importance in wound healing and also for development of cancer metastasis. This study has focused on measurement of cell surface molecules on human HaCaT keratinocytes (human adult low calcium temperature keratinocytes) promoting adhesion, migration and proliferation as one important feature of plasma-cell interactions. HaCaT keratinocytes were treated with plasma by a surface dielectric barrier discharge in air. Cell surface molecules and induction of intracellular ROS (reactive oxygen species) were analysed by flow cytometry 24 h after plasma treatment. Besides a reduction of cell viability a significant down-regulation of E-cadherin and the EGFR expression occurred. The influence on ?2- and ?1-integrins was less pronounced, and expression of ICAM-1 (intercellular adhesion molecule 1) was unaffected. The extent of effects depended on the exposure time of cells to the plasma and the treatment regimen. Intracellular level of ROS detected by the fluorescent dye H2DCFDA (2',7'-dichlorodihydrofluorescein diacetate) increased by plasma treatment, but it was neither dependent on the treatment time nor related to the different treatment regimens. Two-dimensional cultures of HaCaT keratinocytes appear to be a suitable method of investigating plasma-cell interactions. PMID:22973947

Haertel, Beate; Hähnel, Marcel; Blackert, Susanne; Wende, Kristian; von Woedtke, Thomas; Lindequist, Ulrike

2012-01-01

316

Novel non-thermal atrial fibrillation treatment with photosensitization reaction: possibility of permanent electrical blockade in rat chronic model  

NASA Astrophysics Data System (ADS)

We demonstrated a possibility of electrical conduction block by ex vivo and in vivo experiments using rat models to establish a non-thermal treatment for atrial fibrillation by photosensitization reaction (PR). One hour after the injection of 2 mg/kg Talaporfin sodium to Wistar rat, the right ventricle (1.4 mmT) was extracted. Paced with a stimulation electrode, this tissue was placed in a tissue bath and immersed in irrigated Tyrode's solution of 37°C with 8 ?g/ml Talaporfin sodium and the gas mixture bubbling of 95% CO2 and 5% O2. The propagated electrical signal was measured by two bipolar electrodes. Exciting light of 670 nm in wavelength was irradiated to the tissue between the bipolar electrodes by the power density of 1 W/cm2. After this irradiation, propagation signal blockade was obtained and continued up to three hours. Rat atrioventricular (AV) node was employed as a target region for chronic model. The heart of Wistar rat was surgically exposed. External four-lead electrocardiogram of this rat was measured. Thirty minutes after the injection of 10 mg/kg Talaporfin sodium to the rat, exciting light of 663 nm in wavelength was irradiated to the AV node by the power density of 500 mW/cm2 for ten minutes. Acute AV block was obtained during the irradiation. Two weeks after this procedure, complete AV block was confirmed. The rat was sacrificed to obtain the tissue specimen. We found that the AV node was replaced by scarring tissue under the microscopic observation of the specimen. We verified possibility of permanent electrical conduction block using PR.

Matsuo, Hiroki; Ito, Arisa; Miyoshi, Shunichiro; Soejima, Kyoko; Ogawa, Satoshi; Arai, Tsunenori

2009-06-01

317

Diagnostics of non-thermal processes in chromospheric flares. 1. Hoe and Call K line profiles of an atmosphere bombarded by 10-500 keV electrons  

NASA Astrophysics Data System (ADS)

The significance of non-thermal excitation and ionization of hydrogen and CaII, by an electron beam, on the line profiles of H? and CaII K line has been investigated. Non-LTE Hot and CaII K line profiles have been calculated for the temperature distributions of semi-empirical flares models F1 and F2 (Machado et al. t980). For reasonable values of the beam energy flux and power index, the hydrogen lines are greatly strengthened and broadened, and an obvious central reversal appears. The effects are weaker for the CaII K line. These effects can be used to diagnose electron beam bombardment during a solar flare, especially at its early phase. Any semi-empirical flare model that does not take into account non-thermal effects overestimates the heating of the solar atmosphere.

Fang, C.; Henoux, J. C.; Gan, W. Q.

1993-07-01

318

Hawking non-thermal and thermal radiations of Reissner Nordström anti-de Sitter black hole by Hamilton-Jacobi method  

NASA Astrophysics Data System (ADS)

We have investigated Hawking non-thermal and purely thermal Radiations of Reissner Nordström anti-de Sitter (RNAdS) black hole by massive particles tunneling method. The spacetime background has taken as dynamical, incorporate the self-gravitation effect of the emitted particles the imaginary part of the action has derived from Hamilton-Jacobi equation. We have supposed that energy and angular momentum are conserved and have shown that the non-thermal and thermal tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The results for RNAdS black hole is also in the same manner with Parikh and Wilczek's opinion and explored the new result for Hawking radiation of RNAdS black hole.

Ilias Hossain, M.; Atiqur Rahman, M.

2013-09-01

319

Non-thermal processes in standard big bang nucleosynthesis: II. Two-body disintegration of D, 7Li, 7Be nuclei by fast neutrons  

Microsoft Academic Search

Continuing the analysis of non-thermal effects in standard big bang nucleosynthesis (JCAP05(2008)010), we examine the role of suprathermal nuclear reactions induced in the early universe plasma by energetic nucleons of various origins. The processes of present interest are break-ups of D, 7Li, 7Be nuclei induced by 14-MeV neutrons generated in the plasma via the T(d, n)4He reaction. It is shown

Victor T. Voronchev; Makoto Nakamura; Yasuyuki Nakao

2009-01-01

320

Efficient models for photoionization produced by non-thermal gas discharges in air based on radiative transfer and the Helmholtz equations  

Microsoft Academic Search

This paper presents formulation of computationally efficient models of photoionization produced by non-thermal gas discharges in air based on three-group Eddington and improved Eddington (SP3) approximations to the radiative transfer equation, and on effective representation of the classic integral model for photoionization in air developed by Zheleznyak et al (1982) by a set of three Helmholtz differential equations. The reported

A. Bourdon; V. P. Pasko; N. Y. Liu; S. Célestin; P. Ségur; E. Marode

2007-01-01

321

Higher-order growth rate of instability of obliquely propagating kinetic Alfvén and ion-acoustic solitons in a magnetized non-thermal plasma  

Microsoft Academic Search

The higher-order growth rate of instability for obliquely propagating kinetic Alfvén and ion-acoustic solitons in a magnetized non-thermal plasma have been obtained by the multiple-scale perturbation expansion method developed by Allen and Rowlands (1993). The growth rate of instability is obtained correct to order k2, where k is the wave number of a long-wavelength plane-wave perturbation. The corresponding lowest-order stability

Anup Bandyopadhyay; K. P. Das

2001-01-01

322

Ion-acoustic solitons and double-layers in a plasma consisting of positive and negative ions with non-thermal electrons  

Microsoft Academic Search

In this research paper, the authors have studied the properties of ion-acoustic solitons and double-layers in a plasma consisting of warm positive and negative ions with different concentration of masses, charged states and non-thermal electrons using small amplitude approximation. Reductive perturbation method is used to derive KdV and m-KdV equations. Existence of ion-acoustic solitons and double-layer is explored over a

T. S. Gill; P. Bala; H. Kaur; N. S. Saini; S. Bansal; J. Kaur

2004-01-01

323

Shape effect of ferro-electric pellet in packed bed non-thermal plasma reactor for C2F6 treatments  

Microsoft Academic Search

Ferro-electric packed bed non-thermal plasma reactor has been widely investigated for application to PFC removal, NOx removal, VOC treatment, etc. The spherical shapes are generally used as the ferro-electric pellets to produce extremely high electric field near the contact points of the pellets. However, the spherical pellets packed bed reactor causes large pressure drop between the inlet and the outlet

K. Takaki; K. Urashima; J. S. Chang

2003-01-01

324

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide  

SciTech Connect

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.

Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibing Zhao; Sanil John

2006-09-30

325

Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide  

SciTech Connect

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.

Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

2005-10-01

326

Non-thermal insights on mass and energy flows through the Galactic Centre and into the Fermi bubbles  

NASA Astrophysics Data System (ADS)

We construct a simple model of the star-formation- (and resultant supernova-) driven mass and energy flows through the inner ˜200 pc (in diameter) of the Galaxy. Our modelling is constrained, in particular, by the non-thermal radio continuum and ?-ray signals detected from the region. The modelling points to a current star formation rate of 0.04-0.12 M? yr-1 at 2? confidence within the region with best-fitting value in the range 0.08-0.12 M? yr-1 which - if sustained over 10 Gyr - would fill out the ˜109 M? stellar population of the nuclear bulge. Mass is being accreted on to the Galactic Centre (GC) region at a rate ? yr-1. The region's star formation activity drives an outflow of plasma, cosmic rays and entrained, cooler gas. Neither the plasma nor the entrained gas reaches the gravitational escape speed, however, and all this material fountains back on to the inner Galaxy. The system we model can naturally account for the recently observed ?106 M?'halo' of molecular gas surrounding the Central Molecular Zone out to 100-200 pc heights. The injection of cooler, high-metallicity material into the Galactic halo above the GC may catalyze the subsequent cooling and condensation of hot plasma out of this region and explain the presence of relatively pristine, nuclear-unprocessed gas in the GC. This process may also be an important ingredient in understanding the long-term stability of the GC star formation rate. The plasma outflow from the GC reaches a height of a few kpc and is compellingly related to the recently discovered Fermi bubbles by a number of pieces of evidence. These include that the outflow advects precisely (i) the power in cosmic rays required to sustain the bubbles'?-ray luminosity in saturation; (ii) the hot gas required to compensate for gas cooling and drop-out from the bubbles and (iii) the magnetic field required to stabilize the walls of these structures. Our modelling demonstrates that ˜109 M? of hot gas is processed through the GC over 10 Gyr. We speculate that the continual star formation in the GC over the age of the Milky Way has kept the supermassive black hole in a quiescent state thus preventing it from significantly heating the coronal gas, allowing for the continual accretion of gas on to the disc and the sustenance of star formation on much wider scales in the Galaxy. In general, our investigations explicitly reveal the GC's important role in the Milky Way's wider stellar ecology.

Crocker, R. M.

2012-07-01

327

Non-thermal activation of the hsp27\\/p38MAPK stress pathway by mobile phone radiation in human endothelial cells: Molecular mechanism for cancer- and blood-brain barrier-related effects  

Microsoft Academic Search

We have examined whether non-thermal exposures of cultures of the human endothelial cell line EA.hy926 to 900 MHz GSM mobile phone microwave radiation could activate stress response. Results obtained demonstrate that 1-hour non-thermal exposure of EA.hy926 cells changes the phosphorylation status of numerous, yet largely unidentified, proteins. One of the affected proteins was identified as heat shock protein-27 (hsp27). Mobile

Dariusz Leszczynski; Sakari Joenväärä; Jukka Reivinen; Reetta Kuokka

2002-01-01

328

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

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.

Cooper, J.F.

1998-01-01

329

Nano-droplet ejection and nucleation of materials submitted to non-thermal plasma filaments  

NASA Astrophysics Data System (ADS)

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 droplets ejected from melted craters as well as nucleated primary particles and subsequent 10-100 nm agglomerates, by nucleation and coagulation in expanding vapor jets. With smaller energy per filament, 0.1-10 ?J micro-discharges and 0.1-100 ?J streamers, the initial local vapor fluxes emitted from spots of interaction between plasma filaments and electrodes are reduced. Subsequent smaller primary particle density limits the local coagulation in the vapor plume since 2-10 nm non-agglomerated crystalline metal nano-particles are produced in mono-DBD with Au, Ag and Cu electrode. Besides, the evolution of the aerosol size from primary nano-particles to agglomerates with transit time suggests slow coagulation of these primary metal particles in mono-DBD. Aerosol properties depend on the energy per filament and on the electrode. The final size is controlled by plasma parameters and transit time in and after the plasma. The aim is to underline emerging applications of atmospheric pressure plasmas for the production of tailored particles with tunable size, composition and structure with non-thermal plasma filaments to control the resulting properties of nano-powders and materials. Production rates and related energetic yields are compared.

Borra, J.-P.; Jidenko, N.; Dutouquet, C.; Aguerre, O.; Hou, J.; Weber, A.

2011-11-01

330

Ultraviolet light and Ultrasound as non-thermal treatments for the inactivation of microorganisms in fresh ready-to-eat foods.  

PubMed

The effects of two non thermal disinfection processes, Ultraviolet light (UV 254nm) 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 1.21logCFU/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 1-1.4logCFU/g. The maximum reductions of microorganisms, observed in strawberries after treatment with US, were 3.04, 2.41, 5.52 and 6.12logCFU/g for E. coli, S. aureus, S. Enteritidis and L. innocua, respectively. Treatment with UV and US, for time periods (up to 45min) 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

Birmpa, Angeliki; Sfika, Vasiliki; Vantarakis, Apostolos

2013-06-14

331

Preferential induction of apoptotic cell death in melanoma cells as compared with normal keratinocytes using a non-thermal plasma torch.  

PubMed

Selective induction of apoptosis in melanoma cells is optimal for therapeutic development. To achieve this goal, a non-thermal helium plasma torch was modified for use on cultured cells in a temperature-controlled environment. Melanoma cells were targeted with this torch (1) in parallel cultures with keratinocytes, (2) in co-culture with keratinocytes and (3) in a soft agar matrix. Melanoma cells displayed high sensitivity to reactive oxygen species generated by the torch and showed a 6-fold increase in cell death compared with keratinocytes. The extent of cell death was compared between melanoma cells and normal human keratinocytes in both short-term (5 min) co-culture experiments and longer assessments of apoptotic cell death (18-24 h). Following a 10 sec plasma exposure there was a 4.9-fold increase in the cell death of melanoma vs. keratinocytes as measured after 24 h at the target site of the plasma beam. When the treatment time was increased to 30 sec, a 98% cell death was reported for melanoma cells, which was 6-fold greater than the extent of cell death in keratinocytes. Our observations further indicate that this preferential cell death is largely due to apoptosis.. In addition, we report that this non-thermal plasma torch kills melanoma cells growing in soft agar, suggesting that the plasma torch is capable of inducing melanoma cell death in 3D settings. We demonstrate that the presence of gap junctions may increase the area of cell death, likely due to the "bystander effect" of passing apoptotic signals between cells. Our findings provide a basis for further development of this non-invasive plasma torch as a potential treatment for melanoma. PMID:22895073

Zucker, Shoshanna N; Zirnheld, Jennifer; Bagati, Archis; DiSanto, Thomas M; Des Soye, Benjamin; Wawrzyniak, Joseph A; Etemadi, Kasra; Nikiforov, Mikhail; Berezney, Ronald

2012-08-16

332

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

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.

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

333

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)

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.

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

334

The fast and slow H? chromospheric responses to non-thermal particles produced during the 1991 March 13 hard X-ray/gamma-ray flare at ~ 08 UTC  

NASA Astrophysics Data System (ADS)

We present a multi-wavelength analysis of the X1.3/2B solar flare at 8 UTC on 1991 March 13 which includes H? images obtained by the fast digital H? -camera at Locarno-Monti at a rate of five images per second, full disk microwave measurements made with a time resolution of 0.1 s by the radiotelescopes in Bern and hard X-ray/gamma-ray data with a <= 1 s time resolution by PHEBUS on board the GRANAT satellite. This set of multispectral data is used to investigate alternate forms of energy transport from the hot flare corona to the chromosphere. During this large flare, which exhibits two successive episodes of acceleration, energy transport took place within four loop systems of different sizes which expand with time and whose foot points were materialized by four H? kernels. It is shown that accelerated particles, most probably electrons, are the dominant form of energy transport, so that slower processes, such as conduction fronts, only play little role if any. Such a conlusion is demonstrated by the fact that the time evolution in intensity from the four observed kernels is well reproduced by a linear combination of the hard X-ray count rate and its time integral. Such a relationship, which is first established in this work, indicates that the H? response to non-thermal electrons consists of two components which evolve on different time scales, typically a few seconds and a few tens of seconds. The amplitude of the slow response is similar for the four kernels during the whole flare. In contrast, the amplitude of the fast response varies from one kernel to the other and is found to be the greater for the larger loop systems during the second and strongest episode of acceleration. Finally, during the first episode of acceleration, the fast H? response exhibits time variations with typical rise times of ~ 0.4-1.5 s which are nearly coincident with fast hard X-ray pulses of similar rise times. This is, so far, the most convincing evidence for correlated fast time structures in H? and hard X-rays. The ensemble of these results are discussed in the framework of models which simulate the chromospheric response of a loop atmosphere to heating by non-thermal electrons.

Trottet, G.; Rolli, E.; Magun, A.; Barat, C.; Kuznetsov, A.; Sunyaev, R.; Terekhov, O.

2000-04-01

335

DEVELOPMENT OF SCALING ALGORITHMS AND ECONOMIC EVALUATION FOR NON-THERMAL PLASMA REACTORS - ADSORBANT/CATALYZER HYBRID SYSTEM FOR CONTROL OF NOX RELEASED DURING ARMY AND RELATED U.S. DEPARTMENT OF DEF  

EPA Science Inventory

Computer code (SUENTP-J) to predict scale-up and economic evaluation of several eligible non-thermal plasma processes for air pollution control - electron beam process, pulsed corona process, and corona radical shower process - was developed for a commercial power plant. This cod...

336

AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR  

SciTech Connect

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.

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

337

Evaluation of extra- and intracellular OH radical generation, cancer cell injury, and apoptosis induced by a non-thermal atmospheric-pressure plasma jet  

NASA Astrophysics Data System (ADS)

In this study, we investigated the effects of a non-thermal atmospheric-pressure plasma jet inducing extracellular and intracellular OH radical generation as well as cell injury and apoptosis for the cultured human breast cancer cells. Increased OH radical generation in the extracellular culture medium (liquid phase) was observed with increased irradiation time, distance to the liquid surface, and voltage. From the voltage-response relationships for two breast cancer cell lines (invasive MDA-MB-231 cells and non-invasive MCF-7 cells) and normal breast cells (HMEC), the half-maximal effective peak-to-peak voltage (EV50) values were 16.7 ± 0.3 kV, 15.0 ± 0.4 kV and 11.2 ± 0.7 kV for MDA-MB-231, MCF-7 and HMEC cells, respectively. This indicated that there was almost no selective cancer cell injury induced by plasma jet irradiation under these conditions. Compared with control condition without a plasma jet, intracellular OH radical accumulation and apoptotic cells were observed with a plasma jet using conditions that induced injury to 50% of cells irrespective of the cancer cell line.

Ninomiya, Kazuaki; Ishijima, Tatsuo; Imamura, Masatoshi; Yamahara, Takayuki; Enomoto, Hiroshi; Takahashi, Kenji; Tanaka, Yasunori; Uesugi, Yoshihiko; Shimizu, Nobuaki

2013-10-01

338

Non-thermal exposure to radiofrequency energy from digital wireless phones does not affect ornithine decarboxylase activity in L929 cells.  

PubMed

L929 murine fibroblast cells were exposed to radiofrequency (RF) radiation from a time division multiple access wireless phone operating at 835 MHz frequency to determine the effect of RF-radiation energy emitted by wireless phones on ornithine decarboxylase (ODC) activity in cultured cells. Exposure was for 8 h to an average specific absorption rate (SAR) from <1 W/kg up to 15 W/kg. After exposure, cells were harvested and ODC activity was measured. No statistically significant difference in ODC activity was found between RF-radiation-exposed and sham-exposed cells at non-thermal specific absorption rates. At SARs which resulted in measurable heating of the medium, a dose-dependent decrease in enzymatic activity was observed and was shown to be consistent with a comparable decrease caused by non-RF-radiation heating. Thus we observed only the well-known enzyme inhibition due to heating, rather than the previously reported enhancement attributed to RF-radiation exposure. PMID:12968926

Desta, Abiy B; Owen, Russell D; Cress, Larry W

2003-10-01

339

NOx remediation in oxygen-rich exhaust gas using atmospheric pressure non-thermal plasma generated by a pulsed nanosecond dielectric barrier discharge  

NASA Astrophysics Data System (ADS)

It is clearly seen that the application of non-thermal plasmas (NTP) to remove NOx from gas mixture containing a large amount of oxygen (O2) is dominated by NO to NO2 oxidation. Experiments have been conducted using a NTP generated by a nanosecond pulsed dielectric barrier discharge in synthetic exhaust gas, prepared from N2, O2, NO, H2O, and C3H6, over a large range of gas temperature (20-300\\r{}C). Results show that the NOx removal rate significantly increased with increasing specific energy deposition. For example, at a temperature of 100\\r{}C and an energy deposition of 27 J l-1, 92% of the NO molecules have been removed. The W values for NO is dramatically reduced to values scaling from ?15 eV at 27 J l-1 down to ?4 eV at 7 J l-1. NOx removal efficiency around 43% was obtained at a temperature of 260\\r{}C and a space velocity of 60 000 h-1 for a specific input energy of 27 J l-1. W values for NOx were less than ?30 eV. Such treatments in exhaust gas with and without the presence of water vapour induced reactions leading to the production of a large variety of by-products such as acetaldehyde, propylene oxide, formic acid, methyl nitrate, and nitromethane.

Khacef, A.; Cormier, J. M.; Pouvesle, J. M.

2002-07-01

340

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)

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.

Kwon, Jae-Sung; Kim, Yong Hee; Choi, Eun Ha; Kim, Kyoung-Nam

2013-05-01

341

Cylindrical and spherical Gardner solitons and double layers in a dusty electronegative non-thermal plasma with two-temperature electrons  

NASA Astrophysics Data System (ADS)

A precise theoretical investigation has been made on the cylindrical and spherical (nonplanar) Gardner solitons (GSs) and double layers (DLs) in a dusty electronegative plasma (composed of inertial positive and negative ions, Maxwellian cold electrons, non-thermal hot electrons, and negatively charged static dust). The reductive perturbation method has been used in derivation of the modified Gardner (MG) equation describing the nonlinear propagation of the dust ion-acoustic (DIA) waves. The MG equation admits solitary waves (SWs) and DLs solutions for ? around its critical value ?c (where ?c is the value of ? corresponding to the vanishing of the nonlinear coefficient of the Korteweg de-Vries (K-dV) equation). The nonplanar SWs and DLs solutions are numerically analyzed and the parametric regimes for the existence of the positive as well as negative SWs and negative DLs are obtained. The basic features of nonplanar DIA SWs and DLs, which are found to be different from planar ones, are also identified. The implications of our results to different space and laboratory dusty plasma situations, are discussed.

Akhter, T.; M. Hossain, M.; A. Mamun, A.

2013-07-01

342

NON-THERMAL X-RAY EMISSION FROM THE NORTHWESTERN RIM OF THE GALACTIC SUPERNOVA REMNANT G266.2-1.2 (RX J0852.0-4622)  

SciTech Connect

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 {mu}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 ({approx}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.

Pannuti, Thomas G.; Agrawal, Rashika [Space Science Center, Department of Earth and Space Sciences, 235 Martindale Drive, Morehead State University, Morehead, KY 40351 (United States); Allen, Glenn E. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, NE80-6025, Cambridge, MA 02139 (United States); Filipovic, Miroslav D.; De Horta, Ain [University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797 (Australia); Stupar, Milorad, E-mail: t.pannuti@moreheadstate.ed, E-mail: gea@space.mit.ed, E-mail: m.filipovic@uws.edu.a, E-mail: a.dehorta@uws.edu.a, E-mail: mstupar@ics.mq.edu.a, E-mail: agar01@ipfw.ed [Department of Physics, Macquarie University, Sydney, NSW 2109 (Australia)

2010-10-01

343

Non-thermal myocardial electrical conduction block by photosensitization reaction with catheterization in right atrium isthmus of porcine heart in vivo  

NASA Astrophysics Data System (ADS)

We have studied a new type of myocardial catheter ablation with photosensitization reaction to realize non-thermal therapy for atrial arrhythmia, such as atrial fibrillation. Photochemically-generated reactive oxygen species may induce myocardial electrophysiological damage without heat generation. In this study, to demonstrate photosensitization reaction-induced myocardial electrical conduction block, the inferior vena cava to tricuspid annulus (IVC-TA) isthmus linear ablation was conducted with photosensitization reaction in porcine heart in vivo, using a newly developed laser catheter (7 Fr.). The end point of the procedure was the production of IVC-TA isthmus block under the electrophysiological analysis by diagnostic catheter with 10-bipole electrodes placed in right atrium along the isthmus. Talaporfin sodium (NPe6) as a photosensitizer was injected intravenously to pigs at 2.5-5.0 mg/kg. About 15 min after the injection, the laser light at the wavelength of 663 nm with a catheter output power density of 40-60 W/cm2 in about 1.4 mm spot size was irradiated through the laser catheter point by point in line crossing the isthmus under the fluoroscopic guidance. Before the photosensitization procedure, pacing signal from the distal electrodes of the diagnostic catheter, propagated through the isthmus in order. During the irradiation, electrical potential at the irradiated area was diminished. After the completion of the irradiation line, the bidirectional conduction block on the IVC-TA isthmus was validated by pacing from the distal and proximal bipole. These results indicated that photosensitization reaction could achieve the electrical conduction block of myocardial tissue immediately after the irradiation. We think that photosensitization reaction could become a novel therapy for atrial arrhythmia.

Ito, Arisa; Kajihara, Takuro; Suenari, Tsukasa; Takahashi, Mei; Kimura, Takehiro; Fukumoto, Kotaro; Takatsuki, Seiji; Miyoshi, Shunichiro; Arai, Tsunenori

2011-02-01

344

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)

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.

Akishev, Y.; Grushin, M.; Karalnik, V.; Kochetov, I.; Napartovich A.; Trushkin N.

2010-07-01

345

LoCuSS: A Comparison of Cluster Mass Measurements from XMM-Newton and Subaru—Testing Deviation from Hydrostatic Equilibrium and Non-thermal Pressure Support  

NASA Astrophysics Data System (ADS)

We compare X-ray hydrostatic and weak-lensing mass estimates for a sample of 12 clusters that have been observed with both XMM-Newton and Subaru. At an over-density of ? = 500, we obtain 1 - M X/M WL = 0.01 ± 0.07 for the whole sample. We also divided the sample into undisturbed and disturbed sub-samples based on quantitative X-ray morphologies using asymmetry and fluctuation parameters, obtaining 1 - M X/M WL = 0.09 ± 0.06 and -0.06 ± 0.12 for the undisturbed and disturbed clusters, respectively. In addition to non-thermal pressure support, there may be a competing effect associated with adiabatic compression and/or shock heating which leads to overestimate of X-ray hydrostatic masses for disturbed clusters, for example, in the famous merging cluster A1914. Despite the modest statistical significance of the mass discrepancy, on average, in the undisturbed clusters, we detect a clear trend of improving agreement between M X and M WL as a function of increasing over-density, M^X/M^WL=(0.908 ± 0.004)+(0.187 ± 0.010) \\cdot log_{10} (? /500). We also examine the gas mass fractions, f gas = M gas/M WL, finding that they are an increasing function of cluster radius, with no dependence on dynamical state, in agreement with predictions from numerical simulations. Overall, our results demonstrate that XMM-Newton and Subaru are a powerful combination for calibrating systematic uncertainties in cluster mass measurements. This work is based on observations made with the XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the USA (NASA), and data collected at Subaru Telescope and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan.

Zhang, Yu-Ying; Okabe, Nobuhiro; Finoguenov, Alexis; Smith, Graham P.; Piffaretti, Rocco; Valdarnini, Riccardo; Babul, Arif; Evrard, August E.; Mazzotta, Pasquale; Sanderson, Alastair J. R.; Marrone, Daniel P.

2010-03-01

346

CO2 reforming of CH4 over CeO2-doped Ni/Al2O3 nanocatalyst treated by non-thermal plasma.  

PubMed

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

Rahemi, Nader; Haghighi, Mohammad; Babaluo, Ali Akbar; Jafari, Mahdi Fallah; Estifaee, Pooya

2013-07-01

347

First Analysis of Quasi-Periodic Whistler Mode Emissions in Saturn's Inner Magnetosphere  

NASA Astrophysics Data System (ADS)

In Saturn's magnetosphere, the electron density inside of 5-6 RS has been shown to vary with longitude. When Cassini passes through this space, the Radio and Plasma Wave Science (RPWS) instrument occasionally observes a series of whistler mode emissions that each rise in frequency over a period of five to ten minutes and repeat every five to ten minutes. These waves are present in the RPWS data set starting in 2005 and continuing through to the present date, and are seen over a large range of L shells and latitudes. In this study, we perform a first analysis of these waves in which we study their occurrence and propagation characteristics. We focus on source mechanisms and correlations with known aspects of the Saturnian system, such as position relative to the moon Enceladus and position within the magnetosphere. Lastly, we examine possible implications that the generation of these waves has for longitudinal asymmetries in the electron population beyond the known density structure.

Leisner, J. S.; Cinar, G.; Hospodarsky, G. B.; Schippers, P.; Gurnett, D. A.; Santolik, O.; Coates, A. J.

2010-12-01

348

Characterization of Periodic or Quasi Periodic Rough Surfaces by Ultrasonic Spectroscopy.  

National Technical Information Service (NTIS)

The scattering of wide-band ultrasonic pulses from rough surfaces is investigated with an ultrasonic spectroscopy technique. The spectral content of the echo is correlated to the quality of the surface. Some periodic defects can be distinguished from rand...

F. Cohen Tenoudji M. Joveniaux A. Jungman G. Quentin

1976-01-01

349

Long-Term Prediction of Large Earthquakes: When Does Quasi-Periodic Behavior Occur?  

NASA Astrophysics Data System (ADS)

I argue that the prediction of large earthquakes for time scales of a few decades is possible for a number of fault segments along transform and subduction plate boundaries. A key parameter in ascertaining if forecasting is feasible is the size of the coefficient of variation, CV, the standard deviation of inter-event times of large earthquakes that rupture all or most of a given fault segment divided by T, the average repeat time. I address only large events, ones that rupture all or most of the downdip width of the seismogenic zone where velocity-weakening behavior occurs. Historic and paleoseismic data indicate that the segment that ruptured in the great 1946 Nankaido, Japan, earthquake broke 9 times in the previous 1060 years yielding T=118 years and CV=0.16. The adjacent zone that broke in 1944 exhibits similar behavior as does the Copper River delta, the site of 8 paleoseismic events dated by Plafker and Rubin (1994) above the rupture zone of the 1964 Alaska earthquake. Lindh (preceding abstract) finds that many fault segments in California have similar small values of CV. Paleoseismic data for inter-event times at Pallet Creek and Wrightwood, however, indicate a large CV. Those sites at situated along the San Andreas fault near the end of the 1857 rupture zone where slip was much smaller than in the Carrizo plain, rupture in large events to the northwest and southeast overlap and deformation is multibranched as plate motion is transferred in part to the San Jacinto fault. Plate boundary slip is confined to narrow zones along the 1944 and 1946 segments of the Nankai trough but is more diffuse in the Tokai-Suruga Bay region where the Izu Peninsula is colliding with the rest of Honshu and repeat times appear to be longer (and CV perhaps is larger). Dates of uplifted terraces likely give repeat times of inter-plate thrust events that are too long and large estimates of CV since imbricate faults within the upper plate that generate terraces do not rupture in every great earthquake. The 2002 Working Group on large earthquakes in the San Francisco Bay region followed Ellsworth et al. (1999) in adopting much larger values of CV for several critical fault segments and underestimating their likelihood of rupture in the next 30 years. The Working Group also gives considerable weight to a Poisson model, which is in conflict with both renewal processes involving slow stress accumulation and with values of CV near 0.2. The failure of the Parkfield prediction has greatly influenced views in the U.S. about long-term forecasts. The model of the repeated breaking of a single asperity is incorrect since past Parkfield shocks of about magnitude 6 likely did not rupture the same part of the San Andreas fault.

Sykes, L. R.

2003-12-01

350

On the origin of quasi-periodic radar backscatter from midlatitude sporadic E  

Microsoft Academic Search

We describe a newly discovered polarization process that appears to be induced by an atmospheric gravity wave (AGW) when it altitude-modulates a sporadic E (E(sub S)) layer in the nighttime, midlatitude ionosphere. This large-scale polarization process appears capable of accounting for three as yet unexplained features found in radar backscatter from field-aligned irregularities in E(sub S) layers: (1) kilometer-scale, wavelike

Roland T. Tsunoda; Shoichiro Fukao; Mamoru Yamamoto

1994-01-01

351

The Design and Fabrication of Fibonacci Quasi-Periodic Superstructure Fiber Bragg Gratings  

Microsoft Academic Search

Superstructure fiber Bragg gratings constructed following the Fibonacci sequence were designed and fabricated in photosensitive single mode optical fiber by phase mask scanning technique. The reflectivity of the gratings showed the six-cycle property with respect to the Fibonacci sequence order at the central wavelength 1541.86 nm. The reflection spectra were multi-fractal and self-similar with scaling. The fabricated device is compact,

Jian Zhang; Aiwu Li; Chuannan Li; Li Xia; P. Shum

2010-01-01

352

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

Microsoft Academic Search

\\u000a Time series discord has proven to be a useful concept for time-series anomaly identification. To search for discords, various\\u000a algorithms have been developed. Most of these algorithms rely on pre-building an index (such as a trie) for subsequences.\\u000a Users of these algorithms are typically required to choose optimal values for word-length and\\/or alphabet-size parameters\\u000a of the index, which are not

Wei Luo; Marcus Gallagher

353

Power spectra of quasi-periodic oscillations in luminous X-ray stars  

NASA Astrophysics Data System (ADS)

A variety of partial random processes are considered in order to study the effects on the power-density spectrum of several physical phenomena that may occur in the beat-frequency modulated accretion (BFMA) model of QPOs. The relevant physical properties of BFMA model are summarized, and the class of random processes used to represent the X-ray intensity time series predicted by the model are introduced. The dependence of the power-density spectrum on pulse shape is discussed. Pulse-lifetime and orbital-frequency distributions are introduced, illustrating how these affect the power-density spectrum. The effect of nonuniform initial-pulse phase distributions and of nonuniform pulse-time distributions are considered. The effects of a particular type of pulse-to-pulse correlation that may be natural in the context of the BFMA model and that greatly increases the power of the oscillations relative to that in the red noise is analyzed.

Shibazaki, N.; Lamb, F. K.

1987-07-01

354

On the use of Fourier averages to compute the global isochrons of (quasi)periodic dynamics.  

PubMed

The concept of isochrons is crucial for the analysis of asymptotically periodic systems. Roughly, isochrons are sets of points that partition the basin of attraction of a limit cycle according to the asymptotic behavior of the trajectories. The computation of global isochrons (in the whole basin of attraction) is however difficult, and the existing methods are inefficient in high-dimensional spaces. In this context, we present a novel (forward integration) algorithm for computing the global isochrons of high-dimensional dynamics, which is based on the notion of Fourier time averages evaluated along the trajectories. Such Fourier averages in fact produce eigenfunctions of the Koopman semigroup associated with the system, and isochrons are obtained as level sets of those eigenfunctions. The method is supported by theoretical results and validated by several examples of increasing complexity, including the 4-dimensional Hodgkin-Huxley model. In addition, the framework is naturally extended to the study of quasiperiodic systems and motivates the definition of generalized isochrons of the torus. This situation is illustrated in the case of two coupled Van der Pol oscillators. PMID:23020451

Mauroy, A; Mezi?, I

2012-09-01

355

Multipoint observations of quasi-periodic substorms associated with ULF pulsations  

NASA Astrophysics Data System (ADS)

Using auroral images from the IMAGE WIC instrument, geomagnetic data from various ground stations, and geosynchronous particle data, we have identified six consecutive substorms separated by about 45 min to 1.6 hr on November 8, 2000. Most of these substorms are of small to medium size and occurred under a weakly northward IMF condition: IMF Bz was near zero to about +5 nT prior to each substorm. IMF By was also weak, being within about ¢®¨ú3 nT. Most interestingly, we have found that for most of the substorms, about 10-15 min period ULF pulsation begins to amplify prior to each onset and tends to decline near the time of onset. The pulsation features are clearly seen at auroral zone and some higher latitude stations of the CANOPUS magnetic network when they cover morning side MLT regions. Similar features are also seen in the GOES magnetic field observations in similar MLT regions. For the first two substorms, the IMAGE magnetic network stations were at postnoon MLT regions and indicated similar ULF pulsation features. The SuperDARN data show that for most of the substorms, the ionospheric convection within the polar cap shows high-amplitude oscillations with a period of about 15 min that tend to amplify prior to onset and to decline after the onset. Based on the results, we will discuss the possible association between substorm triggering and convection associated with large-amplitude ULF pulsations.

Lee, D.; Lyons, L.; Zou, S.; Kim, K.; Ruohoniemi, J. M.; Weygand, J. M.

2007-12-01

356

Quasi-Periodic Recurrence of Large Earthquakes on the San Andreas Fault (Invited)  

NASA Astrophysics Data System (ADS)

Paleoseismic trenching investigations provide data on the recurrence of large prehistoric earthquakes. Although every effort is made to correctly identify all ground-rupturing earthquakes, including multiple exposures of complicated structures, detailed examination of stratigraphic evidence of past ruptures, and objective measures of the quality of earthquake evidence, the structural setting and depositional history of a site can still contribute uncertainty in a paleoseismic record. To explore the consequences of geologic uncertainty on seismic hazard estimates, we studied the statistical characteristics of the combined, 29-earthquake record from the Wrightwood paleoseismic site and 23 variations of this record. The analyses included nonparametric tests determine if the earthquake timing was random, periodic, or clustered and comparison of the coefficient of variation. We vary the master record by removing up to three earthquakes categorized as “possible” due to lower quality evidence, and adding five hypothetical earthquakes in time periods when low sedimentation rates could result in missed earthquakes. All variations are more periodic than would be expected from a random distribution and showed no evidence of clustering at the 80% confidence level. Estimates of the COV for the Wrightwood record and new dating of the Pallett Creek record center around 0.68, providing further evidence that although not perfectly periodic, earthquake hazards on the southern San Andreas fault are best forecast using a time-dependent renewal model.

Scharer, K. M.; Biasi, G. P.; Weldon, R. J.; Fumal, T.

2010-12-01

357

A low-dimensional model system for quasi-periodic plasma perturbations  

SciTech Connect

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.

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

358

Intensity-Modulated Radiotherapy Optimization in a Quasi-Periodically Deforming Patient Model  

SciTech Connect

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.

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

359

Large Ampltiude, Quasi-Periodic Variability of a Cool Brown Dwarf  

NASA Astrophysics Data System (ADS)

We present continuous photometric monitoring of an early T-type brown dwarf in the near-infrared. Observations over 7 nights indicate that the target is variable with a period of 7.7 hours and peak-to-peak amplitudes of up to 30% in the J band, the largest ever reported for a field brown dwarf. The evolving nature of the light curve, which displays phase changes in multi-epoch observations over months, suggests that atmospheric surface features --most likely heterogeneous clouds---are responsible. We also discuss our attempts to use combinations of current 1D 'cloudy' and 'clear' model atmospheres to reproduce simultaneously both the J, H, Ks light curve amplitudes as well as the target's observed spectral energy distribution. This object joins the T2.5 dwarf SIMP0136 discovered by Artigau and coworkers as the second L/T transition brown dwarf to display large-amplitude variability on rotational timescales, suggesting that the fragmentation of dust clouds at the L/T transition may contribute to the abrupt decline in condensate opacity and J-band brightening observed to occur over this regime. Furthermore, the presence of discrete, long-lived cloud features on these objects offers the potential to map evolving weather patterns, and hence extend studies of atmospheric circulation beyond our solar system, to a substellar mass regime never before probed.

Radigan, Jacqueline; Jayawardhana, R.; Lafreniere, D.; Artigau, E.

2011-05-01

360

Diagnostics of non-thermal processes in chromospheric flares. II. HOC and Call K line profiles for an atmosphere bombarded by 100 keV-1 MeV protons  

NASA Astrophysics Data System (ADS)

The effects on the H? line profile of non-thermal excitation and ionization of hydrogen by a 100 KeV- 1 MeV proton beam have been investigated. Non-LTE H? line profiles have been calculated for the temperature distributions of semi- empirical flares models F1 and F2 (Machado et al. 1980). For reasonable values of the beam energy flux and power index, the hydrogen lines are greatly strengthened. However, contrary to the case of an electron bombarded atmosphere, the line is not broadened, and no central reversal appears. These effects, alone or in conjunction with linear polarization measurements or Ly? red wing observations, can be used to diagnose proton beam bombardment.

Henoux, J. C.; Fang, C.; Gan, W. Q.

1993-07-01

361

Forecasting pulsatory motion for non-invasive cardiac radiosurgery: an analysis of algorithms from respiratory motion prediction  

Microsoft Academic Search

Objective  Recently, radiosurgical treatment of cardiac arrhythmia, especially atrial fibrillation, has been proposed. Using the CyberKnife,\\u000a focussed radiation will be used to create ablation lines on the beating heart to block unwanted electrical activity. Since\\u000a this procedure requires high accuracy, the inevitable latency of the system (i.e., the robotic manipulator following the motion\\u000a of the heart) has to be compensated for.

Floris Ernst; Ralf Bruder; Alexander Schlaefer; Achim Schweikard

2011-01-01

362

The Non-thermal Intracluster Medium  

NASA Astrophysics Data System (ADS)

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 ?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 Alfvén wave sweeping, with accompanying in situ Fermi acceleration.

Lieu, Richard; Quenby, John; Bonamente, Massimiliano

2010-10-01

363

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

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.

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

364

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

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.

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

365

Quasi-periodic modulations of the Saturnian Kilometric Radiation and their relation to varying solar wind parameters  

NASA Astrophysics Data System (ADS)

We consider possible connection between modulations of the SKR radio emission recorded by Cassini RPWS instrument and varying solar wind parameters measured by different spacecraft. "Sliding window" Fourier analysis and nonlinear Wigner- Ville transform have been applied. The data sets from Cassini-RPWS (SKR radio emission measurements), Cassini-CAPS (solar wind plasma measurements), Cassini- MAG (magnetic field), Ulysses-SWOOP (solar wind plasma measurements), Ulysses- VHM/FGM (Vector Helium Magnetometer/Flux Gate Magnetometer), and Wind SWE (Solar Wind Experiment) experiments were used. The analyzed SKR time profile has been produced by integration of the Stokes parameters spectra of the SKR over frequency range from 20 to 1000 kHz. Profiles of the solar wind parameters measured by Wind and Ulysses were projected onto Cassini orbit by means of an MHD simulation of the solar wind evolution between 1 and 9.5 AU. Performed study confirms strong correlation between solar wind plasma parameters and SKR and shows evident existences of 7-8, 9-10, 12-13 and 25-27 days modulation lines in the spectra of the SKR and solar wind profiles. These modulations are very likely to be manifestation of the typical periodicities in the solar surface magnetic activity.

Panchenko, M.; Rucker, H. O.; Khodachenko, M. L.; Kislyakov, A. G.; Taubenschuss, U.

2007-08-01

366

Beach-ridge development in Lake Michigan: shoreline behavior in response to quasi-periodic lake-level events  

Microsoft Academic Search

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

Todd A. Thompson; Steve J. Baedke

1995-01-01

367

Testing the No-hair Theorem with Observations in the Electromagnetic Spectrum. III. Quasi-periodic Variability  

Microsoft Academic Search

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

Tim Johannsen; Dimitrios Psaltis

2011-01-01

368

Normal Branch Quasi-Periodic Oscillations in Sco X-1: Viscous Oscillations of a Spherical Shell Near the Neutron Star  

Microsoft Academic Search

We present a comprehensive classification of all observed QPOs within the\\u000aframework of the transition layer model using a large set of Rossi X-ray Timing\\u000aExplorer (RXTE) data for Sco X-1. The model assumes an optically thin material\\u000aalong the observer's line of sight in the horizontal branch and an increasingly\\u000aoptically thick material while in the other two branches

L. G. Titarchuk; C. F. Bradshaw; B. J. Geldzahler; E. B. Fomalont

2001-01-01

369

Ultralow threshold and single-mode lasing in microgear lasers and its fusion with quasi-periodic photonic crystals  

Microsoft Academic Search

The GaInAsP microgear laser is a kind of microdisk laser but has a rotationally symmetric grating, which matches with the profile of the whispering gallery mode. In this study, we achieved the room temperature continuous-wave lasing with a threshold photopump power of 14 ?W for the smallest gear diameter of 2.02 ?m. We also observed the single-mode lasing in a

Kengo Nozaki; Atsuo Nakagawa; Daisuke Sano; Toshihiko Baba

2003-01-01

370

Spontaneous pulsing, period doubling, and quasi-periodicity in a unidirectional, single-mode, inhomogeneously broadened ring laser  

SciTech Connect

Studies of a unidirectional ring laser using the 3.51-..mu..m transition in xenon reveal a well-defined second threshold above the threshold for cw lasing at which spontaneous self-pulsing is observed. Higher excitation thresholds are found for transitions through a sequence of period doublings or to quasi-peridoic behavior (two independent pulsing frequencies). Detuning the laser cavity from resonance does not lead to the dramatic complications in the pulsing structure that were observed in Fabry-Perot lasers. Instead, with increasing detuning we find a smooth reduction in complexity of the dynamical behavior that seems to correspond principally to the reduction in the gain and the laser intensity with detuning. We also find some evidence that transverse beam profiles cause qualitative and quantitative changes in the location and nature of the various transitions.

Hoffer, L.M.; Chyba, T.H.; Abraham, N.B.

1985-01-01

371

Quasi-periodic Oscillations of Solar Active Regions in Connection with Their Flare Activity - NoRH Observations  

NASA Astrophysics Data System (ADS)

The sunspot-associated sources at the frequency of 17 GHz give information on plasma parameters in the regions of magnetic field about B=2000 G at the level of the chromosphere-corona transition region. The observations of short period (from one to ten minutes) oscillations in sunspots reflect propagation of magnetohydrodynamic (MHD) waves in the magnetic flux tubes of the sunspots. We investigate the oscillation parameters in active regions in connection with their flare activity. We confirm the existence of a link between the oscillation spectrum and flare activity. We find differences in the oscillations between pre-flare and post-flare phases. In particular, we demonstrate a case of powerful three-minute oscillations that start just before the burst. This event is similar to the cases of the precursors investigated by Sych et al. ( Astron. Astrophys. 505, 791, 2009). We also found well-defined eight-minute oscillations of microwave emission from sunspot. We interpret our observations in terms of a relationship between MHD waves propagating from sunspots and flare processes.

Abramov-Maximov, V. E.; Gelfreikh, G. B.; Shibasaki, K.

2011-11-01

372

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

Microsoft Academic Search

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

K. Pruess

2004-01-01

373

Orbitally-Induced, Quasi-Periodic Climate Change on Mars: Modelling Changes in the Global Cycling of Water and Carbon Dioxide  

Microsoft Academic Search

Mars' orbital parameters (obliquity, eccentricity and argument of perihelion) are thought to have varied substantially on time scales >105 years. Such variations, especially in obliquity, may drastically affect the circulation of the atmosphere and volatile cycling. In this study, we focus on the response of the water and carbon dioxide cycles to changes in these orbital parameters, chiefly obliquity. The

M. A. Mischna; M. I. Richardson; R. J. Wilson

2002-01-01

374

Dayside magnetosphere-ionosphere coupling during IMF clock angle ?90°: Longitudinal cusp bifurcation, quasi-periodic cusp-like auroras, and traveling convection vortices  

Microsoft Academic Search

In spite of the great progress achieved in the understanding the Earth's magnetosphere-ionosphere system, its configuration and dynamics during periods with large horizontal interplanetary magnetic field (IMF ?By? $\\\\gg$ 0) is still poorly investigated. In such time intervals, the cusp\\/low-latitude boundary layer (LLBL) entry regions are characterized by a more complex magnetic reconnection topology, than during IMF Bz-dominated periods, which

S. Massetti

2005-01-01

375

Multi-resonance orbital model of high-frequency quasi-periodic oscillations: possible high-precision determination of black hole and neutron star spin  

NASA Astrophysics Data System (ADS)

Context. Using known frequencies of the twin-peak high-frequency quasiperiodic oscillations (HF QPOs) and known mass of the central black hole, the black-hole dimensionless spin a can be determined by assuming a concrete version of the resonance model. However, a wide range of observationally limited values of the black hole mass implies low precision of the spin estimates. Aims: We discuss the possibility of higher precision for the black hole spin a measurements in the framework of a multi-resonance model inspired by observations of more than two HF QPOs in the black hole systems, which are expected to occur at two (or more) different radii of the accretion disc. This framework is also applied in a modified form to the neutron star systems. Methods: We determine the spin and mass dependence of the twin-peak frequencies with a general rational ratio n:m, assuming a non-linear resonance of oscillations with the epicyclic and Keplerian frequencies or their combinations. In the multi-resonant model, the twin-peak resonances are combined properly to give the observed frequency set. For the black hole systems we focus on the special case of duplex frequencies, when the top, bottom, or mixed frequency is common at two different radii where the resonances occur giving triple frequency sets. Results: The sets of triple frequency ratios and the related spin a are given. The resonances are considered up to n = 5 since excitation of higher order resonances is improbable. The strong resonance model for "magic" values of the black hole spin means that two (or more) versions of resonance could occur at the same radius, allowing cooperative effects between the resonances. For neutron star systems we introduce a resonant switch model that assumes switching of oscillatory modes at resonant points. Conclusions: In the case of doubled twin-peak HF QPOs excited at two different radii with common top, bottom, or mixed frequency, the black hole spin a is given by the triple frequency ratio set. The spin is determined precisely, but not uniquely, because the same frequency set could correspond to more than one concrete spin a. The black hole mass is given by the magnitude of the observed frequencies. The resonant switch model puts relevant limits on the mass and spin of neutron stars, and we expect a strong increase in the fitting procedure precision when different twin oscillatory modes are applied to data in the vicinity of different resonant points. We expect the multi-resonance model to be applicable to data from the planned LOFT or similar X-ray satellite observatory. Appendices are available in electronic form at http://www.aanda.org

Stuchlík, Z.; Kotrlová, A.; Török, G.

2013-04-01

376

Modeling of non-thermal plasma in flammable gas mixtures  

Microsoft Academic Search

An idea of using plasma-assisted methods of fuel ignition is based on non-equilibrium generation of chemically active species that speed up the combustion process. It is believed that gain in energy consumed for combustion acceleration by plasmas is due to the non-equilibrium nature of discharge plasma, which allows radicals to be produced in an above-equilibrium amount. Evidently, the size of

A. P. Napartovich; I. V. Kochetov; S. B. Leonov

2008-01-01

377

Non-thermal processes in large solar flares  

Microsoft Academic Search

We analyze particle acceleration processes in large solar flares, using observations of the August, 1972, series of large events. The energetic particle populations are estimated from the hard X-ray and ?-ray emission, and from direct interplanetary particle observations. The collisional energy losses of these particles are computed as a function of height, assuming that the particles are accelerated high in

R. P. Lin; H. S. Hudson

1976-01-01

378

Cell permeabilization using a non-thermal plasma  

NASA Astrophysics Data System (ADS)

The atmospheric pressure glow discharge torch (APGD-t) is a miniature pulsed RF (13.56 MHz) plasma source specifically designed to efficiently produce and transport reactive species to and interact with biological samples. When applied to adherent cell cultures, the APGD-t is capable of inducing temporary cell permeabilization. In this work, we evaluate the maximum radius of macromolecules able to enter into HeLa cells following a plasma treatment using a size exclusion approach with dextran molecules. We observe that this maximum radius is below 6.5 nm. We also show that no degradation occurs when a plasmid DNA suspended in culture media is plasma-treated at the operating conditions leading to cell permeabilization. The plasma-assisted DNA transfection of the HeLa cells with the hrGFP-II-1 plasmid using the APGD-t is demonstrated. Local transfection efficiencies obtained are as high as 35%.

Leduc, M.; Guay, D.; Leask, R. L.; Coulombe, S.

2009-11-01

379

Study of non-thermal phenomena with Suzaku and beyond  

Microsoft Academic Search

Suzaku is the fifth in a series of Japanese X-ray astronomy satellite with important US instrument contributions. Its scientific payload consists of two kinds of co-aligned instruments, the X-ray Imaging Spectrometers (XIS) and the Hard X-ray Detector (HXD). The HXD extends the bandpass of the observatory to much higher energies with its 10-600 keV bandpass. The detectors onboard Suzaku show

Tadayuki Takahashi

2008-01-01

380

Neptune's non-thermal radio emissions - Phenomenology and source locations  

NASA Astrophysics Data System (ADS)

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.

Rabl, Gerald K. F.; Ladreiter, H.-P.; Rucker, Helmut O.; Kaiser, Michael L.

381

Non-thermal plasma BioPrinter with nano-scale precision  

Microsoft Academic Search

Summary form only given. Techniques for patterning of biochemical molecules on different, possibly non-planar, surfaces can be applied in tissue engineering to control adhesion of cells and tissue assembly. Most existing methods of biochemical patterning are suitable only for planar surfaces. No suitable method has been demonstrated for patterning of different chemical materials on non-planar substrates such as those incorporating

Gregory Fridman; M. Li; G. Friedman; A. Gutsol; P. I. Lelkes; A. Fridman

2004-01-01

382

Thermal treatment and non-thermal technologies for remediation of manufactured gas plant sites  

Microsoft Academic Search

More than 1500 manufactured gas plant (MGP) sites exist throughout the U.S. Many are contaminated with coal tar from coal-fueled gas works which produced ‘town gas’ from the mid-1800s through the 1950s.1,2 Virtually all old U.S. cities have such sites. Most are in downtown areas as they were installed for central distribution of manufactured gas. While a few sites are

Thomas F. McGowan; Bruce A. Greer; Mike Lawless

1996-01-01

383

Subtle consequences of exposure to weak microwave fields: Are there non-thermal effects?  

NASA Astrophysics Data System (ADS)

When we speak of subtle consequences of exposure we mean only that the effects were observed in the absence of changes in core temperature due to microwave exposure. When we measure + delta T degree C in core temperature consequent to microwave exposure, we are witnessing a breakdown of thermoregulatory mechanisms. Short of this event, the exposed subject makes a number of thermoregulatory and metabolic accommodations to maintain a constant body temperature and to deal effectively with the energy being deposited in its tissues. These latter changes should interest us for they are the subtle consequences exposure to weak microwave fields. The long-term accommodations, which accompany subchronic exposure, can lead to a number of interesting effects some of which are described below. Two fundamentally different types of experimental protocol were employed. In Experiment 1A, independent groups of male rats were either exposed or sham-exposed to 915 MHz microwaves for 10 hr/night for up to 4 mo. In Experiment 1B, independent groups of rats were similarly exposed, or sham-exposed, to 2450 MHz microwaves for 10 hr/night for 4 mo. In Experiment 2, using a different type of protocol, pregnant female rats were exposed for 20 hr/day for 19 days of gestation. Control groups were either sham-exposed or served as caged controls. The main focus of the study attended to assessment of various functions and the developmental status of the gravid rats' progeny.

Lovely, R. H.; Mizumori, S. J. Y.; Johnson, R. B.; Guy, A. W.

384

Study of SO\\/sub 2\\/ removal using non-thermal plasma induced by corona discharge  

Microsoft Academic Search

Summary form only given. Application of plasma chemistry for gas cleaning is gaining prominence in recent years, mainly from the energy consideration point of view. Normally, the gas treatment is carried out at or above room temperature by the conventional dry-type corona reactor. However, this treatment is still inadequate for the removal of certain stable gases present in the flue

Dong Limin; Han Zhidong; Zhang Xianyou

2006-01-01

385

Ozone synthesis in a cylindrical dry air-fed ozonizer by non thermal gas discharges  

Microsoft Academic Search

Ozone is increasingly being used as an alternative oxidant to chlorination processes in various industrial applications without any objectionable by products to the environment and requiring less energy for its production. Therefore, it is necessary to investigate the effects of various parameters on the production of ozone both experimentally and theoretically. A theoretical study focused on numerical simulation was performed

W. J. M. Samaranayake; R. Hackam; H. Akiyama

2003-01-01

386

Neutron Signatures of Non-Thermal Ion Distributions in Z-Pinch Driven ICF Plasmas  

NASA Astrophysics Data System (ADS)

In preparation for upcoming ICF experiments on the 26 MA Z machine (e.g., D2 gas puff, MagLIF [1]), we are studying the neutron energy spectra produced by magnetically-driven loads beyond the archetypal single temperature, uniform plasma. Z-pinch sources frequently exhibit evidence of unusual neutron spectra [2], which can be attributed to three-dimensional turbulent motion, high-energy beams, and other phenomena leading to non-Maxwellian ion distributions. Understanding the nature of our plasma neutron sources is critical for understanding how they scale with increasing current. We will show Monte Carlo and analytic calculations for plausible scenarios and discuss the corresponding signatures for the existing set of time-of-flight diagnostics on Z.[4pt] [1] S. A. Slutz et al. Phys. Plasmas 17, 056303 (2010)[0pt] [2] V.V. Vikhrev and V.D. Korolev, Plasma Dynamics, Vol. 33, No. 5 (2007)

Knapp, Patrick; Jennings, Christopher; Sinars, Daniel

2012-10-01

387

Bactericial effect of a non-thermal plasma needle against Enterococcus faecalis biofilms  

NASA Astrophysics Data System (ADS)

Up to 3 cm long submillimeter-in-scale plasma needle was generated in ambient atmosphere for root canal disinfection. Powered with 1-2 kHz, multi-kilovolt nanosecond electric pulses, this He/(1%)O2 plasma jet consists of ionization fronts propagating at speeds of the order of 10^7 cm/s. Plasma treatment of Enterococcus faecalis biofilms on hydroxyapatite (HA) discs for 5 min resulted in severe damage of the bacterial cells and sterilized HA surfaces of more than 3 mm in diameter, observed by the scanning electron microscopy. With a curing dielectric microtube placed 1 cm or less below the nozzle, the plasma jet entered even at a sharp angle and followed the curvature of the tube, and reached the bottom of the tube. The bactericidal effect of the plasma needle against E. faecalis biofilm grown on the inner surfaces of the tube was demonstrated. However, the bactericidal effect weakens or diminishes for the bacteria grown deeper in the tube, indicating improvement of the plasma treatment scheme is needed. Mechanisms of the plasma bactericidal effects are discussed.

Jiang, Chunqi; Schaudinn, C.; Jaramillo, D. E.; Sedghizadeh, P. P.; Webster, P.; Costerton, J. W.

2011-11-01

388

NOx Reduction Behavior of Alumina and Zeolite Catalysts in Combination with Non-Thermal Plasma.  

National Technical Information Service (NTIS)

Lean burn gasoline and diesel engines provide improved fuel economy when compared to engines operating under stoichiometric fuel/air conditions. At the same time, lean burn and diesel engines present a problem for emission control. Because they operate un...

A. G. Panov R. Tonkyn S. Yoon A. Kolwaite S. Barlow M. L. Balmer

2004-01-01

389

A non-thermal chemical synthesis of hydrophilic and amorphous cobalt oxide films for supercapacitor application  

NASA Astrophysics Data System (ADS)

Present work explored a room temperature, simple and low cost chemical route for the preparation of hydrophilic cobalt oxide films from alkaline cobalt chloride (CoCl 2:6H 2O) and double distilled water precursor solutions. As-deposited cobalt oxide films showed amorphous nature, which is one of the prime requirements for supercapacitor, as confirmed from X-ray diffraction studies. Changes in direct band gap energy and electrical resistivity of as-deposited cobalt oxide films were confirmed after annealing. Spherical grains of about 40-50 nm diameters were uniformly distributed over the substrate surface. Surface wettability studied in contact with liquid interface, showed hydrophilic nature as water contact angle was <90°. Finally, presence of cobalt-oxygen covalent bond was observed from Raman shift experiment.

Kandalkar, Sunil G.; Lokhande, C. D.; Mane, R. S.; Han, Sung-Hwan

2007-02-01

390

Thermally Activated Martensite: Its Relationship to Non-Thermally Activated (Athermal) Martensite  

SciTech Connect

The classification of martensitic displacive transformations into athermal, isothermal or anisothermal is discussed. Athermal does not mean 'no temperature dependence' as is often thought, but is best considered to be short for the notion of no thermal activation. Processes with no thermal activation do not depend on time, as there is no need to wait for sufficient statistical fluctuations in some specific order parameter to overcome an activation barrier to initiate the process. Clearly, this kind of process contrasts with those that are thermally activated. In the literature, thermally activated martensites are usually termed isothermal martensites, suggesting a constant temperature. Actually such martensites also typically occur with continuous cooling. The important distinctive feature of these martensites is that they are thermally activated and hence are distinguishable in principle from athermal martensites. A third type of process, anisothermal, has been introduced to account for those transformations which are thought to be thermally activated but which occur on continuous cooling. They may occur so rapidly that they do not appear to have an incubation time, and hence could be mistakenly called an athermal transformation. These designations will be reviewed and discussed in terms of activation energies and kinetic processes of the various martensitic transformations.

Laughlin, D E; Jones, N J; Schwartz, A J; Massalski, T B

2008-10-21

391

Limits on non-thermal radio emission from Nova Cephei 2013  

NASA Astrophysics Data System (ADS)

Nova Cephei 2013, discovered on 2013 Feb. 02 (CBET #3397), was observed at low radio frequency with the Giant Metrewave Radio Telescope (GMRT) on 2013 June 1 (at 1.3 GHz) and Aug 23 (610 MHz) using director's discretionary time. No radio emission was detected in either epochs down to the rms noise level of 120 microJy at 1.3 GHz and 70 microJy at 610 MHz. Observations at other wavelengths earlier reported no detectable X-ray emission (ATel #4950), but clear indication of ongoing dust formation (ATel #4893, #5026 and #5269).

Dutta, Prasun; Kantharia, Nimisha G.; Roy, Nirupam; Anupama, G. C.; Ashok, N. M.; Banerjee, Dipankar P. K.

2013-09-01

392

Anisotropic illumination of AGN's accretion disk by a non thermal source. II. General relativistic effects.  

NASA Astrophysics Data System (ADS)

In a previous paper (Henri & Petrucci, 1997A&A...326...87H, hereafter Paper I), we have derived a new model in order to explain the UV and X-ray emission of radio quiet AGNs. This model assumes that a point source of relativistic leptons (e^+^,e^-^) illuminates the accretion disk of the AGN by Inverse Compton process. This disk is supposed to be simply represented by a finite slab which radiates only the energy reprocessed from the hot source. The radiation field within the hot source region is therefore highly anisotropic, which strongly influences the Inverse Compton process. The different Eddington parameters characterizing the radiative balance of this system have been calculated self-consistently in the Newtonian case (Paper I) giving a universal spectrum for a given inclination angle. In this paper, we take into account relativistic effects by including the gravitational redshift, the Doppler boosting and the gravitational focusing due to the central supermassive black hole. This has the effect of modifying the radial temperature profile in the innermost region of the disk (at some gravitational radii). However, the spectrum is hardly different from that obtained in the Newtonian case, unless the hot source is very close to the black hole. These results are clearly different from standard accretion disk models where the gravitational energy is mainly released in the vicinity of the black hole.

Petrucci, P. O.; Henri, G.

1997-10-01

393

Surface Modification of Polyester Fabric by Non-Thermal Plasma Treatment  

NASA Astrophysics Data System (ADS)

In the present study it was carried out a surface modification of polyester fabric by plasma treatment with aim of providing hidrophilicity to fabric. In the process it were used three different gaseous atmosphere with mixtures of argon, nitrogen and/or oxygen [(1) Ar + N2 (4:2), (2) Ar + N2 + O2 (4:2:2) and N2 + O2 (2:0.6)] and maintained others parameters such as pressure, current and time of treatment fixed at 1.35 mBar, 0.08 A and 30 minutes, respectively. The plasma treatment was monitored by optical emission spectroscopy (OES) to identify the species presents in the plasma reactor. Chemical changes in the fabric surface after plasma treatments were determined by Fourier Transform Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Wicking properties were used to evaluate hydrophilicity of the fabric. Wicking measurement showed that the hydrophilicity of polyester fabric was remarkably improved after treatment and was explained by XPS analysis indicating higher presence of functional groups containing nitrogen and oxygen.

Lima da Silva, R. C.; Alves, C., Jr.; Nascimento, J. H.; Neves, J. R. O.; Teixeira, V.

2012-12-01

394

Investigating the potential of non-thermal microwave as a novel skin penetration enhancement method.  

PubMed

Microwaves (MW), a part of the electromagnetic spectrum at 0.3-300GHz, affect human body in different ways through its thermal and athermal effects, including fluidization of cell membranes and liquid crystalline systems. Due to presence of such structures in skin barrier, it was decided here to investigate the potential of athermal MW as skin penetration enhancer. In this investigation, nitrofurazone was chosen as the model penetrant and its permeation through rat skin was studied in vitro at 45 and 90min exposure intervals using MW intensities of 3, 15, 30, 60, 120W at 2450MHz. Results revealed that at 30°C and 45min exposure, 3W MW does not affect permeation of nitrofurazone (P=0.148), while higher intensities increased its flux significantly (P<0.05) in a intensity-dependent manner up to 2.7 times. When the duration of exposure increased to 90min, the enhancement ratio also increased to reach a maximum of 3.3. Applying 60W MW at 25, 30, 37 and 42°C resulted in a parabolic relationship between temperature and enhancement ratio. The present results reveal that microwave can act as a skin penetration enhancement method and that its effect depends on applied intensities, exposure time and temperature. PMID:20854885

Moghimi, Hamid R; Alinaghi, Azadeh; Erfan, Mohammad

2010-09-18

395

Is the effect of mobile phone radiofrequency waves on human skin perfusion non-thermal?  

PubMed

OBJECTIVE: to establish whether skin micro blood flow can be modified by exposure to the radiofrequency waves emitted by a mobile phone when the latter is held against the jaw and ear. METHODS: Variations in skin micro blood flow and skin temperature in adult volunteers were simultaneously recorded with a thermostatic laser Doppler system during a 20-minute "radiofrequency" exposure session and a 20-minute "sham" session. The skin microvessels' vasodilatory reserve was assessed with a heat challenge at the end of the protocol. RESULTS: During the radiofrequency exposure session, skin micro blood flow increased (vs. baseline) more than during the sham exposure session. The sessions did not differ significant in terms of the skin temperature time-course response. The skin microvessels' vasodilatory ability was found to be greater during radiofrequency exposure than during sham exposure. CONCLUSIONS: Our results reveal the existence of a specific vasodilatory effect of mobile phone radiofrequency emission on skin perfusion. This article is protected by copyright. All rights reserved. PMID:23590124

Loos, Nathalie; György, Thuróczy; Ghosn, Rania; Brenet-Dufour, Valérie; Liabeuf, Sophie; Selmaoui, Brahim; Jean-Pierre, Libert; Bach, Véronique; Diouf, Momar; de Seze, René

2013-04-17

396

Kinetic model of non-thermal plasma flue gas desulfurization in a wet reactor  

Microsoft Academic Search

A model of the process in a wet reactor for flue gas desulfurization by corona discharges is provided. Through deriving dependences of chain length ?, desulfurization rate of the flue gas upon the parameters of injected energy density q, pH values of the liquid absorbents and mass transfer efficiency factor ? it is found that under the conditions of given

Xue Dong Jiang; Ruinian Li; Ruichang Qiu; Xuaotu Hu; Hui Liang

2006-01-01

397

[Non-thermal effect of GSM electromagnetic radiation on quality of pea seeds].  

PubMed

The seeds with low level of room temperature phosphorescence (RTP) were selected from a lot of air-dry peas (Pisum sativum) with 62% germination. These strong seeds (95-97% germination percentage) in air-dry, imbibed or emerged states were exposed to 905 MHz GSM-band electromagnetic radiation (EMR). The following effects of EMR were observed. Fraction II with higher RTP level appeared in the air-dry seeds. The germination rate decreased 2-3 fold in the air-dry, swollen and sprouting seeds due to an increase in the ratio of the seedlings with morphological defects (from 3 to 38%) and suffocated seeds (from 1 to 15%). We suggest tentative mechanisms to account for the decreased fitness of peas under GSM-band EMR (905 MHz); also discussed is the role of non-enzymatic hydrolysis of carbohydrates and amino-carbonyl reaction in this process. PMID:23033800

Veselova, T V; Veselovski?, V A; Deev, L I; Ba?zhumanov, A A

398

Mechanism of Blood Coagulation by Non-Thermal Atmospheric Pressure Dielectric Barrier Discharge  

Microsoft Academic Search

Summary form only given. Blood coagulation by direct contact of nonthermal atmospheric pressure Dielectric Barrier Discharge (DBD) plasma in vitro has been reported previously. This discharge appears to promote rapid blood coagulation by enhancing natural coagulation processes. However, there is no detailed understanding of the specific mechanisms by which this nonthermal plasma coagulates blood. In this paper we investigate few

S. Kalghatgi; G. Fridman; M. Balasubramanian; A. Brooks; V. Vasilets; A. Fridman; A. Gutsol; G. Friedman

2007-01-01

399

Non-thermal photodesorption of N{sub 2} from Ag(111)  

SciTech Connect

The authors have measured translational and rotational energy distributions of N{sub 2} molecules following desorption from a Ag(111) surface by infrared (1,064 nm) radiation. The observed desorption yields were large even at laser fluences far below that required for laser induced thermal desorption. State resolved laser techniques using coherent VUV radiation showed that the rotational and translational energy distributions of the desorbing N{sub 2} molecules are not consistent with the predictions of the heat diffusion model governing laser induced surface heating. These results suggest that physisorbed adsorbates can couple directly to the nascent phonon distribution or the nascent electron-hole pairs in the photoexcited substrate without heating of the surface.

Rao, R.M.; Beuhler, R.J.; White, M.G.

1998-02-01

400

Degradation of antibiotics in water by non-thermal plasma treatment.  

PubMed

The decomposition of three ?-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses. PMID:21514950

Magureanu, M; Piroi, D; Mandache, N B; David, V; Medvedovici, A; Bradu, C; Parvulescu, V I

2011-04-06

401

The thermal and non-thermal gaseous halo of NGC 5775  

NASA Astrophysics Data System (ADS)

In this letter we present first results from spectroscopic observations of Diffuse Ionized Gas (DIG) in the halo of NGC 5775 obtained with FORS11 attached to UT1/Antu of the Very Large Telescope (VLT). At our slit position perpendicular to the disk (41\\arcsec \\ SE of the nucleus) the emission of [N Ii]lambda 6583, [O Iii]lambda 5007, and [O Ii]lambda 3727 is detected out to 9 kpc into the halo, allowing possible ionization mechanisms of the DIG to be examined. Photoionization models which assume a dilute radiation field are able to fit the data for the disk, but they cannot account for the line ratios measured in the halo (e.g., [O I]/H? or [O Ii]/H? ). In particular they fail to predict the observed increase of [O Iii]lambda 5007/H? with increasing |z|. The most striking result concerns the kinematics of the halo gas. Velocities at high galactic latitudes drop from the midplane value to reach the systemic velocity at z ~\\ 9 kpc. An analysis of VLA archive data of the polarized radio-continuum emission at 4.86 GHz and 1.49 GHz reveals that magnetic fields in the halo have a strong component perpendicular to the disk and are aligned with the H? and radio-continuum spurs in the halo. This can result either from a strong wind action or, more likely, from the generation of dipolar magnetic fields. We briefly discuss the interrelation of the magnetic field structure and gas dynamics, in particular the role of magnetic fields in gas outflows, as well as the possible heating of DIG by magnetic reconnection. Based on observations collected at the European Southern Observatory, Paranal (Chile); Proposal No.: 63.N-0573(A)

Tüllmann, R.; Dettmar, R.-J.; Soida, M.; Urbanik, M.; Rossa, J.

2000-12-01

402

Ultrafast dynamics of non-thermal hot electrons in chemical vapor deposited graphene  

NASA Astrophysics Data System (ADS)

The relaxation dynamics of photoexcited carriers in a chemical vapor deposited graphene transferred on quartz substrate are investigated using ultrafast optical-pump terahertz (THz)-probe spectroscopy. Terahertz transmission through graphene sample is reduced by optical pumping. The change of transmission decays exponentially after the optical pulse. We find the decay time is insensitive to the substrate temperatures from 10 K to 300 K, but increases sublinearly with pump flunce. We model the relaxation process involving electron-phonon coupling together with a set of rate equations to describe the transient responses of quasi-particals and optical phonons. We can fit the observered transient terahertz transmission very well. The extracted carrier temperature follows the same trend of decay time as a function of fluence. High pump fluence can significantly increase the carrier temperature and broaden the carrier distributions, consequently causing the reduction of optical phonon emission efficiency and slowing down cooling rate. The differences of our results in comparison to similar measurements of expitaxial graphene on SiC will be disscussed.

Lin, Kuan-Chun; Li, Ming-Yang; Chi, Cheng-Chung; Chen, Jeng-Chung

2013-03-01

403

Direct Observation of Ultrafast Non-thermal Melting by Ultrafast X-ray Diffraction  

Microsoft Academic Search

Ultrafast nonthermal melting of femtosecond laser-irradiated germanium was observed directly for the first time using sub-picosecond, 1.54-angstrom x-ray diffraction. Such measurements allow the study of transient atomic motion fundamental to many processes in physics, chemistry, and biology.

C. W. Siders; T. Guo; K. R. Wilson

404

MHD POWER GENERATION BY NON-THERMAL IONIZATION AND ITS APPLICATION TO NUCLEAR ENERGY CONVERSION  

Microsoft Academic Search

One of the most severe limitations of MHD power generation is the high ; temperatures required for thermal ionization. Two alternative, nonthermal ; ionization methods are considered: electron-bearn injection and fission-product ; radiation. Electron-beam injection appears to be the most promising method. The ; thermodynamic cycle of a power plant incorporating a MHD generator and a reactor ; is considered.

E. J. Sternglass; T. C. Tsu; G. L. Griffith; J. H. Wright

1963-01-01

405

Irradiation as a non-thermal process for beverages, juices and fluid foods  

Technology Transfer Automated Retrieval System (TEKTRAN)

Irradiation is a nonthermal process that can effectively inactivate human pathogens in a variety of foods. A successful commercial application of this technology to fluid foods such as juices and beverages must balance the antimicrobial effects of the treatment with potential negative effects on sen...

406

The energy partitioning of non-thermal particles in a plasma: the Coulomb logarithm revisited  

NASA Astrophysics Data System (ADS)

The charged particle stopping power in a highly ionized and weakly to moderately coupled plasma has been calculated exactly to leading and next-to-leading accuracy in the plasma density by Brown, Preston and Singleton (BPS). Since the calculational techniques of BPS might be unfamiliar to some, and since the same methodology can also be used for other energy transport phenomena, we will review the main ideas behind the calculation. BPS used their stopping power calculation to derive a Fokker-Planck equation, also accurate to leading and next-to-leading orders, and we will also review this. We use this Fokker-Planck equation to compute the electron-ion energy partitioning of a charged particle traversing a plasma. The motivation for this application is ignition for inertial confinement fusion—more energy delivered to the ions means a better chance of ignition, and conversely. It is therefore important to calculate the fractional energy loss to electrons and ions as accurately as possible. One method by which one calculates the electron-ion energy splitting of a charged particle traversing a plasma involves integrating the stopping power dE/dx. However, as the charged particle slows down and becomes thermalized into the background plasma, this method of calculating the electron-ion energy splitting breaks down. As a result, it suffers a systematic error that may be as large as T/E0, where T is the plasma temperature and E0 is the initial energy of the charged particle. The formalism presented here is designed to account for the thermalization process and it provides results that are near-exact.

Singleton, Robert L., Jr.; Brown, Lowell S.

2008-12-01

407

Structure and physics of solar faculae. II - The non-thermal velocity field above faculae  

NASA Astrophysics Data System (ADS)

The OSO-8 satellite enabled the study of various characteristics of the profiles of Si II, Si IV, C IV, and O VI lines above active areas of the sun, as well as above quiet areas, and the derivation of some physical properties of the transition region between chromosphere and corona (CCT). The study of the lines shows a general tendency for the microvelocity fields on the average to be nearly constant for the heights corresponding to a temperature greater than 100,000 K; however they seem to slightly increase with height in quiet areas, and decrease in active areas. A multicomponent model of the CCT is necessary, and its geometry is far from being a set of plane-parallel columns. It is similar to an association of moving knots within the nonmoving principal component of the matter. The proportion of mass, in the knots relative to that in the nonmoving component, is several times larger in active regions than in quiet regions. In the knots, the nonthermal microvelocity fields are smaller in active regions and seem to decrease for temperature increasing above 100,000 K, contrary to what happens in the steady principal component.

Mouradian, Z.; Dumont, S.; Pecker, J.-C.; Chipman, E.; Artzner, G. E.; Vial, J. C.

1982-05-01

408

Mode tuning of photonic crystal nanocavities by photoinduced non-thermal oxidation  

NASA Astrophysics Data System (ADS)

A method to achieve photoinduced tuning of PhC nanocavity modes is discussed and implemented. It is based on light induced oxidation in air atmosphere with very low thermal budget which produces a local reduction of the GaAs membrane effective thickness and a large blueshift of the nanocavity modes. It is also shown that green light is much more efficient in inducing the micro-oxidation with respect to near infrared light. The observed behaviour is attributed to oxide growth promoted by photoenhanced reactivity.

Intonti, Francesca; Caselli, Niccolò; Vignolini, Silvia; Riboli, Francesco; Kumar, Santosh; Rastelli, Armando; Schmidt, Oliver G.; Francardi, Marco; Gerardino, Annamaria; Balet, Laurent; Li, Lianhe H.; Fiore, Andrea; Gurioli, Massimo

2012-01-01

409

Solar heating and cooling computer analysis - A simplified sizing design method for non-thermal specialists  

Microsoft Academic Search

Emphasis on solar energy for use in space heating and cooling presents a problem for many architects, heating, ventilating and air conditioning engineers, and contractors because they lack expertise in solar applications. This paper describes two public-domain computer design programs, written for use by the solar community. SOLCOST, a simplified sizing design method for nonthermal specialist users, computes an optimum

M. Connolly; R. Giellis; C. Jensen; R. McMordie

1976-01-01

410

DNA strand scission induced by a non-thermal atmospheric pressure plasma jet.  

PubMed

The DNA molecule is observed to be very susceptible to short-term exposures to an atmospheric pressure plasma jet. The DNA damage induced by plasma-generated species, i.e. excited atoms, charged particles, electrons and UV light is determined. PMID:20556293

Ptasi?ska, Sylwia; Bahnev, Blagovest; Stypczy?ska, Agnieszka; Bowden, Mark; Mason, Nigel J; Braithwaite, Nicholas St J

2010-06-16

411

Experimental investigation of a non-thermal atmospheric pressure plasma jet  

Microsoft Academic Search

The main objective of this dissertation is to understand the formation of the plasma jet from the plasma pencil, and the propagation of the plasma jet in the ambient atmosphere where the effect of the external electric field is almost zero. Before investigating the formation and propagation phenomenon of the plasma jet, common physical properties of plasma jets are determined

Asma Begum

2010-01-01

412

Propeller spin-down and the non-thermal emission from AE Aquarii  

NASA Astrophysics Data System (ADS)

To explain the observed multiwavelength emission from the cataclysmic variable star AE Aquarii, we propose a model based upon the assumption that the compact component of this binary consists of a white dwarf with a surface field strength of 1MG, rotating through a clumpy ring near the circularization radius. We argue that MHD instabilities like the Kelvin-Helmholtz instabilities will result in the white dwarf field mixing with the gas in this region and becoming highly sheared. The Poynting flux pumped into the region, and hence angular momentum transferred in the process, is enough to accelerate material centrifugally from the system. We also show that magnetic reconnection in this region will result in runaway electron acceleration to energies of 300MeV or more, which will radiate through the synchrotron process up to frequencies of the order of ?~1015Hz. We show that, because the radiation is emitted in a gaseous medium, the spectrum will be suppressed below the so-called Razin-Tsytovich frequency, which is ?R~2000GHz, which agrees with the observations. Magnetic shear in the ejection region will also induce field-aligned currents in the magnetosphere. Huge potential differences (double layers) can be generated in the circuit where the gas density becomes very low. This will occur close to the white dwarf. In this region potentials of the order of ??=300TV (TV=teravolt) can be generated. Synchrotron losses on electrons will restrict them to energies of the order of E<=50keV. As protons and ions are not affected by synchrotron losses, energies in excess of 1TeV are possible. Very high-energy (VHE) ?-ray emission can be produced if these proton and ion beams collide with the clumpy gas in, or outside, the ejection zone. We show that pulsed VHE ?-ray emission is possible, if the gas particle density of the target m