WorldWideScience

Sample records for plasma potential fluctuations

  1. Extension of the coherence function to quadratic models. [applied to plasma density and potential fluctuations

    Science.gov (United States)

    Kim, Y. C.; Wong, W. F.; Powers, E. J.; Roth, J. R.

    1979-01-01

    It is shown how the use of higher coherence functions can recover some of the lost coherence due to nonlinear relationship between two fluctuating quantities whose degree of mutual coherence is being measured. The relationship between the two processes is modeled with the aid of a linear term and a quadratic term. As a specific example, the relationship between plasma density and potential fluctuations in a plasma is considered. The fraction of power in the auto-power spectrum of the potential fluctuations due to a linear relationship and to a quadratic relationship between the density and potential fluctuations is estimated.

  2. Investigation of multifractal nature of floating potential fluctuations obtained from a dc glow discharge magnetized plasma

    Science.gov (United States)

    Shaw, Pankaj Kumar; Saha, Debajyoti; Ghosh, Sabuj; Janaki, M. S.; Iyengar, A. N. Sekar

    2017-03-01

    In this paper, multifractal detrended fluctuation analysis (MF-DFA) has been used to analyze the floating potential fluctuations obtained with a Langmuir probe from a dc glow discharge magnetized plasma device. The generalized Hurst exponents (h(q)) , local fluctuation function (Fq(s)) , the Rényi exponents (τ(q)) and the multifractal spectrum F(α) have been calculated by applying the MF-DFA method. The result of the MF-DFA shows the multifractal nature of these fluctuations. We have investigated the influence of magnetic field on the multifractal nature of the fluctuations and it is seen that degree of multifractality is reduced with the increase in the magnetic field strength. The values of h(q) have been restricted between 0.7 and 1 for the magnetized fluctuations. This result is evidence of the existence of long-range correlations in the fluctuations. Furthermore, we employed shuffle and surrogate approaches to analyze the origins of multifractality. Comparing the MF-DFA results for the data set to those for shuffled and surrogate series, we have found that its multifractal nature is due to the existence of significant long-term correlation.

  3. RP and RQA Analysis for Floating Potential Fluctuations in a DC Magnetron Sputtering Plasma

    Science.gov (United States)

    Sabavath, Gopikishan; Banerjee, I.; Mahapatra, S. K.

    2016-04-01

    The nonlinear dynamics of a direct current magnetron sputtering plasma is visualized using recurrence plot (RP) technique. RP comprises the recurrence quantification analysis (RQA) which is an efficient method to observe critical regime transitions in dynamics. Further, RQA provides insight information about the system’s behavior. We observed the floating potential fluctuations of the plasma as a function of discharge voltage by using Langmuir probe. The system exhibits quasi-periodic-chaotic-quasi-periodic-chaotic transitions. These transitions are quantified from determinism, Lmax, and entropy of RQA. Statistical investigations like kurtosis and skewness also studied for these transitions which are in well agreement with RQA results.

  4. Asymptotic behavior of correlation functions for electric potential and field fluctuations in a classical one-component plasma

    NARCIS (Netherlands)

    Suttorp, L.G.

    1992-01-01

    The correlations of the electric potential fluctuations in a classical one-component plasma are studied for large distances between the observation points. The two-point correlation function for these fluctuations is known to decay slowly for large distances, even if exponential clustering holds for

  5. Synchronous imaging of coherent plasma fluctuations

    Science.gov (United States)

    Haskey, S. R.; Thapar, N.; Blackwell, B. D.; Howard, J.

    2014-03-01

    A new method for imaging high frequency plasma fluctuations is described. A phase locked loop and field programmable gate array are used to generate gating triggers for an intensified CCD camera. A reference signal from another diagnostic such as a magnetic probe ensures that the triggers are synchronous with the fluctuation being imaged. The synchronous imaging technique allows effective frame rates exceeding millions per second, good signal to noise through the accumulation of multiple exposures per frame, and produces high resolution images without generating excessive quantities of data. The technique can be used to image modes in the MHz range opening up the possibility of spectrally filtered high resolution imaging of MHD instabilities that produce sufficient light fluctuations. Some examples of projection images of plasma fluctuations on the H-1NF heliac obtained using this approach are presented here.

  6. Nonlocally of plasma fluctuations and transport in magnetically confined plasmas theoretical background of nonlocality in fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae-I.; Yagi, Masatoshi [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    2002-09-01

    Nonlocal properties of fluctuations in confined plasmas are briefly surveyed. Contributions to understanding the bifurcation phenomena, improved confinement, and transient transport problem are explained. The theoretical progress in this aspect is addressed: Namely, the fluctuations are not excited by linear instabilities but are dressed with other turbulent fluctuations or fluctuations of meso-scale. Nonlinear interactions of fluctuations with different scale lengths are essential in dictating the dynamics of turbulence and turbulent transport. There are activators and suppressers in global inhomogeneities for evolution of turbulence. Turbulent fluctuations, on the other hand, induce or destroy these global inhomogeneities. Finally, statistical nature of turbulence is addressed. (author)

  7. Equilibrium fluctuation energy of gyrokinetic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Krommes, J.A.; Lee, W.W.; Oberman, C.

    1985-11-01

    The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed, and found to be smaller than the well-known result (k)/8..pi.. = 1/2T/(1 + (klambda/sub D/)/sup 2/) valid for arbitrarily magnetized plasmas. It is shown that, in a certain sense, the equilibrium electric field energy is minimum in the gyrokinetic regime. 13 refs., 2 figs.

  8. A theory of fluctuations in plasmas

    NARCIS (Netherlands)

    Felderhof, B.U.

    1964-01-01

    A theory of thermal fluctuations in plasmas is developed based on a probability ensemble for one-particle distribution functions ƒ(r, ν). The probability for a specific ƒ(r, ν) is obtained from the canonical ensemble with the aid of the continuum approximation. Subsequently the probability distribut

  9. Influence of plasma resistance and fluctuation on probe characteristics in detached recombining plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, N.; Tanaka, N.; Nishijima, D.; Takamura, S. [Nagoya Univ. (Japan). Dept. of Energy Engineering and Science; Ezumi, N. [Dept. of Electronics and Control Engineering, Nagano National Coll. of Technology, Tokuma (Japan)

    2001-07-01

    In order to find the causes of the strong anomaly of current-voltage characteristics of Langmuir probe observed in detached recombining plasmas in a linear divertor plasma simulator, NAGDIS-II, we have investigated plasma resistance along a magnetic field and potential fluctuations in the detached recombining plasmas. Simple calculation on the ratio between the plasma length, at which plasma resistance and resistance of ion sheath formed around a probe tip become equal, and an electron collection length indicates that the evaluation of electron temperature T{sub e} becomes inaccurate at T{sub e} of less than 0.6 eV when plasma density and neutral pressure are 1.0 x 10{sup 18} m{sup -3} and 10 mtorr, respectively. The potential fluctuation in detached recombining plasmas was found to be so large compared to T{sub e}/e, which can also modify the probe characteristics. (orig.)

  10. Theory of electromagnetic fluctuations for magnetized multi-species plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Roberto E., E-mail: roberto.navarro@ug.uchile.cl; Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Araneda, Jaime [Departamento de Física, Universidad de Concepción, Concepción 4070386 (Chile); Moya, Pablo S. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Department of Physics, Catholic University of America, Washington, D. C. 20064 (United States); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Valdivia, Juan A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro de Estudios Interdisciplinarios Básicos y Aplicados en Complejidad, CEIBA complejidad, Bogotá (Colombia)

    2014-09-15

    Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians.

  11. Study of Coupling between a Plasma Source and Plasma Fluctuations

    Science.gov (United States)

    Berumen, Jorge; Chu, Feng; Hood, Ryan; Mattingly, Sean; Rogers, Anthony; Skiff, Fred

    2014-10-01

    An experimental study on the coupling between a plasma source and plasma fluctuations in a cylindrical, magnetized, singly-ionized Argon inductively-coupled gas discharge plasma that is weakly collisional is presented. Typical plasma conditions are n ~1010 cm-3 Te ~ 3 eV and B ~ 1 kG. Amplitude Modulation (AM) of the inductively-coupled RF plasma source is produced near the fundamental-mode ion-acoustic wave frequency (~1 kHz) to study the effects of the source-wave interaction and plasma production. Density fluctuation measurements are implemented using Laser-Induced Fluorescence techniques and Langmuir probes. We apply coherent detection with respect to the wave frequency to obtain the perturbed ion distribution function associated with the waves. Measurements of fluctuating I-V traces from a Langmuir probe array and antenna current load are also used to show the effects of the interaction. We would like to acknowledge DOE DE-FG02-99ER54543 for their financial support throughout this research.

  12. Influence of temperature fluctuations on plasma turbulence investigations with Langmuir probes

    CERN Document Server

    Nold, B; Ramisch, M; Huang, Z; Müller, H W; Scott, B D; Stroth, U

    2011-01-01

    The reliability of Langmuir probe measurements for plasma-turbulence investigations is studied on GEMR gyro-fluid simulations and compared with results from conditionally sampled I-V characteristics as well as self-emitting probe measurements in the near scrape-off layer of the tokamak ASDEX Upgrade. In this region, simulation and experiment consistently show coherent in-phase fluctuations in density, plasma potential and also in electron temperature. Ion-saturation current measurements turn out to reproduce density fluctuations quite well. Fluctuations in the floating potential, however, are strongly influenced by temperature fluctuations and, hence, are strongly distorted compared to the actual plasma potential. These results suggest that interpreting floating as plasma-potential fluctuations while disregarding temperature effects is not justified near the separatrix of hot fusion plasmas. Here, floating potential measurements lead to corrupted results on the ExB dynamics of turbulent structures in the cont...

  13. Runaway electrons as a diagnostic of plasma internal magnetic fluctuations

    Institute of Scientific and Technical Information of China (English)

    Zheng Yong-Zhen; Ding Xuan-Tong; Li Wen-Zhong

    2006-01-01

    The transport of runaway electrons in a high-temperature plasma is relatively easy to measure in a steady state experiment and a perturbation experiment, which provides runaway electron diffusion coefficient Dr. This diffusion coefficient is determined by internal magnetic fluctuations, so it can be interpreted in terms of a magnetic fluctuation level. The internal magnetic fluctuation level (br/BT) is estimated to be about (2-4)×-4 in the HL-1M plasma. The results presented here demonstrate the effectiveness of using runaway electron transport techniques to determine internal magnetic fluctuations. A profile of magnetic fluctuation level in the HL-1M plasma can be estimated from Dr.

  14. Plasma density fluctuations observed during Space Shuttle Orbiter water releases

    Science.gov (United States)

    Pickett, J. S.; D'Angelo, N.; Kurth, W. S.

    1989-01-01

    Observations by the Langmuir probe on the Plasma Diagnostics Package flown as part of the Spacelab 2 mission in the summer of 1985 show a strong increase in the level of turbulence near the Shuttle Orbiter during operations in which liquid water is released. The spectrum of the plasma density fluctuations peaks at the lowest frequencies measured (a few Hz) and extends up to a few kHz, near the lower hybrid frequency. Two potential mechanisms for generating the plasma turbulence are suggested which are both based on the production of water ions as a result of charge exchange with the ambient oxygen ions in the ionosphere. The first mechanism proposed is the ion-plasma instability which arises from the drift of the contaminant with respect to the ambient oxygen ions. The other mechanism proposed is the Ott-Farley instability, which is a result of the ring distribution formed by the 'pick-up' water ions.

  15. Collective fluctuations in magnetized plasma: Transition probability approach

    Energy Technology Data Exchange (ETDEWEB)

    Sosenko, P.P. [International Centre of Physics and M.M.Boholiubov Inst. for Theoretical Physics, Kyiv (Ukraine)]|[Ecole Polytechnique, Palaiseau (France)]|[Univ. Henri Poincare, Vandoeuvre (France)

    1997-10-01

    Statistical plasma electrodynamics is elaborated with special emphasis on the transition probability approach and quasi-particles, and on modern applications to magnetized plasmas. Fluctuation spectra in the magnetized plasma are calculated in the range of low frequencies (with respect to the cyclotron one), and the conditions for the transition from incoherent to collective fluctuations are established. The role of finite-Larmor-radius effects and particle polarization drift in such a transition is explained. The ion collective features in fluctuation spectra are studied. 63 refs., 30 figs.

  16. Zero-frequency magnetic fluctuations in homogeneous cosmic plasma revisited

    CERN Document Server

    Caruso, Francisco

    2011-01-01

    Magnetic fluctuations in a non-magnetized gaseous plasma is revisited and calculated without approximations, based on the fluctuation-dissipation theorem. It is argued that the present results are qualitative and quantitative different form previous one based on the same theorem. In particular, it is shown that it is not correct that the spectral intensity does not vary sensitively with $k_{cut}$. Also the simultaneous dependence of this intensity on the plasma and on the collisional frequencies are discussed.

  17. Zero-frequency magnetic fluctuations in homogeneous cosmic plasma revisited

    OpenAIRE

    Caruso, Francisco; Oguri, Vitor

    2011-01-01

    Magnetic fluctuations in a non-magnetized gaseous plasma is revisited and calculated without approximations, based on the fluctuation-dissipation theorem. It is argued that the present results are qualitative and quantitative different form previous one based on the same theorem. In particular, it is shown that it is not correct that the spectral intensity does not vary sensitively with $k_{cut}$. Also the simultaneous dependence of this intensity on the plasma and on the collisional frequenc...

  18. Fluctuation of the electric field in a plasma

    Science.gov (United States)

    Lee, Hee J.

    2015-04-01

    The theory of electric field fluctuations in a plasma is reviewed. The fluctuations of an electric field can be assumed to be due to the Cerenkov radiation, which is emitted by single particles that satisfy the Landau wave-particle resonance conditions. This view naturally agrees with the picture that a plasma can be considered to be an aggregate of non-interacting dressed particles. A simple classical derivation of the fluctuation-dissipation theorem is presented to show that the fluctuations of the Cerenkov electric field agree with the fluctuation-dissipation theorem. A quasilinear-like solution of the Liouville equation is shown to derive an electric field fluctuation with the same form as that obtained by using the dressed particle approach. We suggest that the fluctuation can be traced to the causality that gives rise to collisionless dissipation (imaginary part of the dielectric function). Therefore, the fluctuation in a plasma has a philosophical implication in that its existence is fundamentally due to the causal principle that the effect cannot be precedent to the cause, thus defining the direction of time.

  19. Fluctuations in the relativistic plasma and primordial magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Lemoine, D. (Institut d' Astrophysique de Paris, CNRS, 98bis Bd Arago, F-75014 Paris (France) DAEC, Observatoire de Paris, Universite Paris VII, CNRS (UA173), F-92195 Meudon Cedex (France))

    1995-03-15

    The stochastic fluctuations of the electromagnetic field in a relativistic electron-positron plasma are studied. The correlation functions of the fluctuating four-current, electric and magnetic fields are computed to leading order using the Schwinger-Keldysh closed time path formulation of thermal field theory. As an application, we consider the scenario proposed by Tajima [ital et] [ital al]. for generating a primordial magnetic field from thermal fluctuations in the prerecombination plasma. We compute the level of magnetic fluctuations sustained by the pair plasma at or before the epoch of big bang nucleosynthesis and conclude that the early Universe was pervaded by a strong low-frequency, albeit small-scale, random magnetic field. The astrophysical implications are briefly discussed.

  20. Synchronization of Geodesic Acoustic Modes and Magnetic Fluctuations in Toroidal Plasmas

    Science.gov (United States)

    Zhao, K. J.; Nagashima, Y.; Diamond, P. H.; Dong, J. Q.; Itoh, K.; Itoh, S.-I.; Yan, L. W.; Cheng, J.; Fujisawa, A.; Inagaki, S.; Kosuga, Y.; Sasaki, M.; Wang, Z. X.; Wei, L.; Huang, Z. H.; Yu, D. L.; Hong, W. Y.; Li, Q.; Ji, X. Q.; Song, X. M.; Huang, Y.; Liu, Yi.; Yang, Q. W.; Ding, X. T.; Duan, X. R.

    2016-09-01

    The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a dominant GAM, and m /n =6 /2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m /n =6 /2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m /n =6 /2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. Such nonlinear synchronization may also contribute to low-frequency zonal flow formation, reduction of turbulence level, and thus confinement regime transitions.

  1. Charge density fluctuation of low frequency in a dusty plasma

    Institute of Scientific and Technical Information of China (English)

    李芳; 吕保维; O.Havnes

    1997-01-01

    The charge density fluctuation of low frequency in a dusty plasma, which is derived from the longitudinal dielectric permittivity of the dusty plasma, has been studied by kinetic theory. The results show that the P value, which describes the relative charge density on the dust in the plasma, and the charging frequency of a dust particle Ωc, which describes the ratio of charge changing of the dust particles, determine the character of the charge density fluctuation of low frequency. For a dusty plasma of P<<1, when the charging frequency Ωc is much smaller than the dusty plasma frequency wd, there is a strong charge density fluctuation which is of character of dust acoustic eigen wave. For a dusty plasma of P>>1, when the frequency Ωc, is much larger than wd there are weaker fluctuations with a wide spectrum. The results have been applied to the ionosphere and the range of radius and density of dust particles is found, where a strong charge density fluctuation of low frequency should exist.

  2. Observation of Radial Propagation of Electrostatic Fluctuations in Edge Plasma of the Sino United Spherical Tokamak

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-Ping; HE Ye-Xi; WANG Wen-Hao; GAO Zhe; ZENG Li; XIE Li-Feng; FENG Chun-Hua

    2004-01-01

    @@ Radial propagation of electrostatic fluctuations in the edge plasma of Sino-United Spherical Tokamak (SUNIST) has been measured using Langmuir probes. The propagation characteristics of the floating potential fluctuations are analysed by the two-point correlation technique. The results show radially outward propagation of the turbulent fluctuations at all measured radial positions. The power-average wavenumber profile is approximately constant in plasma edge region and suddenly increases to the limiter. These results are in good agreement with the model predictions proposed by Mattor which suggests that the drift wave propagation may be a source of edge turbulence.

  3. Magnetic Fluctuation Measurement in Sino United Spherical Tokamak Plasma

    Institute of Scientific and Technical Information of China (English)

    LIU Fei; WANG Wen-Hao; HE Ye-Xi; LIU Jun; TAN Yi; XIE Li-Feng; ZENG Long

    2007-01-01

    To investigate the magnetic fluctuations and for further transport study, the poloidal and radial magnetic field measurement is conducted on the Sino United Spherical Tokamak (SUNIST). Auto-power spectral density indicates that the magnetic fluctuation energy mainly concentrates in the frequency region lower than 10kHz. The magnetic field oscillations, which are characterized by harmonic frequencies of 40 kHz, are observed in the scrapeoff layer; by contrast, in the plasma core, the magnetic fluctuations are of Gaussian type. The time-frequency profiles show that the poloidal magnetic fluctuations are temporally intermittent. The autocorrelation calculation indicates that the fluctuations in decorrelation time vary between the core and the edge.

  4. Perturbing microwave beams by plasma density fluctuations

    Directory of Open Access Journals (Sweden)

    Köhn Alf

    2017-01-01

    Full Text Available The propagation of microwaves across a turbulent plasma density layer is investigated with full-wave simulations. To properly represent a fusion edge-plasma, drift-wave turbulence is considered based on the Hasegawa-Wakatani model. Scattering and broadening of a microwave beam whose amplitude distribution is of Gaussian shape is studied in detail as a function of certain turbulence properties. Parameters leading to the strongest deterioration of the microwave beam are identified and implications for existing experiments are given.

  5. Charge fluctuations for particles on a surface exposed to plasma

    CERN Document Server

    Sheridan, T E

    2011-01-01

    We develop a stochastic model for the charge fluctuations on a microscopic dust particle resting on a surface exposed to plasma. We find in steady state that the fluctuations are normally distributed with a standard deviation that is proportional to $CT_{e})^{1/2}$, where $C$ is the particle-surface capacitance and $T_{e}$ is the plasma electron temperature. The time for an initially uncharged ensemble of particles to reach the steady state distribution is directly proportional to $CT_{e}$.

  6. Potential Fluctuation Equality for Free Energy Evaluation

    CERN Document Server

    Ngo, Van

    2011-01-01

    Jarzynski's equality [1] allows us to investigate free energy landscapes (FELs) by constructing distributions of work performed on a system from an initial ensemble of states to final states. This work is experimentally measured by extension-versus-force (EVF) curves. We proposed a new approach that enables us to reconstruct such FELs without necessity of measuring EVF curves. We proved that any free energy changes could be computed by measuring the fluctuations of a harmonic external potential in final states. The main assumption of our proof is that one should probably treat a potential's minimum {\\lambda} (thought to be control parameter) and time in separate and independent manners. We recovered Jarzynski's equality from the introduction of a double Heaviside function. We then applied the approach in molecular dynamics (MD) simulations to compute the free energy barrier of breaking DNA base pairs (bps). The free energy barrier for breaking a CG bp in our simulations is identified as 1.7 +/- 0.2 kcal/mol t...

  7. Dynamic properties of small-scale solar wind plasma fluctuations.

    Science.gov (United States)

    Riazantseva, M O; Budaev, V P; Zelenyi, L M; Zastenker, G N; Pavlos, G P; Safrankova, J; Nemecek, Z; Prech, L; Nemec, F

    2015-05-13

    The paper presents the latest results of the studies of small-scale fluctuations in a turbulent flow of solar wind (SW) using measurements with extremely high temporal resolution (up to 0.03 s) of the bright monitor of SW (BMSW) plasma spectrometer operating on astrophysical SPECTR-R spacecraft at distances up to 350,000 km from the Earth. The spectra of SW ion flux fluctuations in the range of scales between 0.03 and 100 s are systematically analysed. The difference of slopes in low- and high-frequency parts of spectra and the frequency of the break point between these two characteristic slopes was analysed for different conditions in the SW. The statistical properties of the SW ion flux fluctuations were thoroughly analysed on scales less than 10 s. A high level of intermittency is demonstrated. The extended self-similarity of SW ion flux turbulent flow is constantly observed. The approximation of non-Gaussian probability distribution function of ion flux fluctuations by the Tsallis statistics shows the non-extensive character of SW fluctuations. Statistical characteristics of ion flux fluctuations are compared with the predictions of a log-Poisson model. The log-Poisson parametrization of the structure function scaling has shown that well-defined filament-like plasma structures are, as a rule, observed in the turbulent SW flows.

  8. Low-frequency fluctuations in a pure toroidal magnetized plasma

    Indian Academy of Sciences (India)

    P K Sharma; R Singh; D Bora

    2009-12-01

    A magnetized, low- plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼ 1011 cm-3, ∼ 4 × 1010 cm-3 and ∼ 2 × 1010 cm−3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations ( < ci) are observed and identified as flute modes. Here ci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute modes to understand the relevance of some of our experimental observations.

  9. Electrostatic fluctuations and turbulent plasma transport in low-β plasmas

    DEFF Research Database (Denmark)

    Nielsen, A.H.; Pécseli, H.L.; Juul Rasmussen, J.

    1995-01-01

    Low frequency electrostatic fluctuations are studied experimentally in a low-beta plasma, with particular attention to their importance for the anomalous plasma transport across magnetic field lines. The presence of large coherent structures in a turbulent background is demonstrated by a conditio......Low frequency electrostatic fluctuations are studied experimentally in a low-beta plasma, with particular attention to their importance for the anomalous plasma transport across magnetic field lines. The presence of large coherent structures in a turbulent background is demonstrated...

  10. Fluctuating Potential Barrier System with Correlated Spatial Noises

    Institute of Scientific and Technical Information of China (English)

    LI Jing-Hui

    2004-01-01

    In this paper, we study a fluctuating potential barrier system with correlated spatial noises. Study shows that for this system, there is the resonant activation over the fluctuating potential barrier, and that the correlation between the different spatial noises can enhance (or weaken) the resonant activation.

  11. Measurements of plasma density fluctuations and electric wave fields using spherical electrostatic probes

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, A.I.; Bostroem, R.

    1995-04-01

    Spherical electrostatic probes are in wide use for the measurements of electric fields and plasma density. This report concentrates on the measurements of fluctuations of these quantities rather than background values. Potential problems with the technique include the influence of density fluctuations on electric field measurements and vice versa, effects of varying satellite potential, and non-linear rectification in the probe and satellite sheaths. To study the actual importance of these and other possible effects, we simulate the response of the probe-satellite system to various wave phenomena in the plasma by applying approximate analytical as well as numerical methods. We use a set of non-linear probe equations, based on probe characteristics experimentally obtained in space, and therefore essentially independent of any specific probe theory. This approach is very useful since the probe theory for magnetized plasmas is incomplete. 47 refs.

  12. Slow electrostatic fluctuations generated by beam-plasma interaction

    CERN Document Server

    Pommois, Karen; Pezzi, Oreste; Veltri, Pierluigi

    2016-01-01

    Eulerian simulations of the Vlasov-Poisson equations have been employed to analyze the excitation of slow electrostatic fluctuations (with phase speed close to the electron thermal speed), due to a beam-plasma interaction, and their propagation in linear and nonlinear regime. In 1968, O'Neil and Malmberg [Phys. Fluids {\\bf 11}, 1754 (1968)] dubbed these waves "beam modes". In the present paper, it is shown that, in the presence of a cold and low density electron beam, these beam modes can become unstable and then survive Landau damping unlike the Langmuir waves. When an electron beam is launched in a plasma of Maxwellian electrons and motionless protons and this initial equilibrium is perturbed by a monochromatic density disturbance, the electric field amplitude grows exponentially in time and then undergoes nonlinear saturation, associated with the kinetic effects of particle trapping and phase space vortex generation. Moreover, if the initial density perturbation is setup in the form of a low amplitude rand...

  13. Rotation shear induced fluctuation decorrelation in a toroidal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hahm, T.S.

    1994-06-01

    The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

  14. Correlation between density fluctuations and plasma gradients at the edge of the TORE SUPRA tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Devynck, P.; Garbet, X.; Laviron, C.; Payan, J.; Haas, J. de; Clairet, F.; Talvard, M. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Gervais, F.; Gresillon, D.; Hennequin, P.; Quemeneur, A.; Truc, A. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1993-12-31

    The ALTAIR diagnostic uses scattering on the plasma electrons with the help of an IR laser beam to obtain information on the density fluctuations. This diagnostic can simultaneously record fluctuations from two independent wave numbers. Two experiments are carried out: study of the density fluctuations during strong plasma heating that combined both low hybrid waves and ion cyclotron heating; density fluctuations associated to the tokamak gas-feed modulation. 6 figs., 5 refs.

  15. Magnetic fluctuations in anisotropic space plasmas: The effect of the plasma environment

    Science.gov (United States)

    Valdivia, J. A.; Toledo, B. A.; Gallo, N.; Muñoz, V.; Rogan, J.; Stepanova, M.; Moya, P. S.; Navarro, R. E.; Viñas, A. F.; Araneda, J.; López, R. A.; Díaz, M.

    2016-11-01

    The observations in the solar wind, which are usually organized in a beta-anisotropy diagram, seem to be constrained by linear instability thresholds. Unexpectedly, under these quasi-stable conditions, there is a finite level of electromagnetic fluctuations. A relevant component of these fluctuations can be understood in terms of the electromagnetic fields produced by the thermal motion of the charged particles. For the simple case of parallel propagating fields in an electron-proton plasma, we study the effect of the parameter ωpp /Ωc that characterizes the different space physics environments, and can affect the continuum spectrum produced by these fluctuations, which in turn may be used to understand the relevance of these processes occurring in a specific plasma environment.

  16. Measurements of conductivity nonuniformities and fluctuations in combustion MHD plasmas

    Science.gov (United States)

    Kowalik, R. M.

    1980-03-01

    Diagnostics for the characterization of electrical conductivity nonuniformities in combustion magnetohydrodynamic (MHD) plasmas were developed. An initial characterization of nonuniformities in the Stanford M-2 linear generator was obtained and recommendations were made concerning the use of the diagnostics in practical MHD generator configurations. A laser induced fluorescene (LIF) diagnostic for nonintrusive measurements of local conductivity fluctuations was developed. This diagnostic and other line of sight averaged optical nonuniformity diagnostics were successfully demonstrated in several experiments in the Standford M-2 combustion systems. Results were used to characterize the nonuniformities in the M-2 system and to compare and evaluate the diagnostics. Conductivity nonuniformities were found to be predominantly streamers which had relatively long length scales of the order of l m in the axial flow direction. Shortet transverse length scales of the order of 0.1 m were found perpendicular to the flow direction. A combination of LIF and plasma luminosity diagnostics is recommended for future characterizations of conductivity uniformities in combustion MHD plasmas.

  17. Nonextensive entropy approach to space plasma fluctuations and turbulence

    CERN Document Server

    Leubner, M P; Baumjohann, W

    2006-01-01

    Spatial intermittency in fully developed turbulence is an established feature of astrophysical plasma fluctuations and in particular apparent in the interplanetary medium by in situ observations. In this situation the classical Boltzmann-Gibbs extensive thermo-statistics, applicable when microscopic interactions and memory are short ranged, fails. Upon generalization of the entropy function to nonextensivity, accounting for long-range interactions and thus for correlations in the system, it is demonstrated that the corresponding probability distributions (PDFs) are members of a family of specific power-law distributions. In particular, the resulting theoretical bi-kappa functional reproduces accurately the observed global leptokurtic, non-Gaussian shape of the increment PDFs of characteristic solar wind variables on all scales. Gradual decoupling is obtained by enhancing the spatial separation scale corresponding to increasing kappa-values in case of slow solar wind conditions where a Gaussian is approached i...

  18. Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

    Energy Technology Data Exchange (ETDEWEB)

    Schlickeiser, R., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yoon, P. H., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)

    2015-07-15

    Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.

  19. Plasma heating inside ICMEs by Alfvenic fluctuations dissipation

    CERN Document Server

    Li, Hui; He, Jiansen; Zhang, Lingqian; Richardson, John D; Belcher, John W; Tu, Cui

    2016-01-01

    Nonlinear cascade of low-frequency Alfvenic fluctuations (AFs) is regarded as one candidate of the energy sources to heat plasma during the non-adiabatic expansion of interplanetary coronal mass ejections (ICMEs). However, AFs inside ICMEs were seldom reported in the literature. In this study, we investigate AFs inside ICMEs using observations from Voyager 2 between 1 and 6 au. It is found that AFs with high degree of Alfvenicity frequently occurred inside ICMEs, for almost all the identified ICMEs (30 out of 33 ICMEs), and 12.6% of ICME time interval. As ICMEs expand and move outward, the percentage of AF duration decays linearly in general. The occurrence rate of AFs inside ICMEs is much less than that in ambient solar wind, especially within 4 au. AFs inside ICMEs are more frequently presented in the center and at the boundaries of ICMEs. In addition, the proton temperature inside ICME has a similar distribution. These findings suggest significant contribution of AFs on local plasma heating inside ICMEs.

  20. A Nonlinear Dynamic Characterization of The Universal Scrape-off Layer Plasma Fluctuations

    CERN Document Server

    Mekkaoui, A

    2012-01-01

    A stochastic differential equation of plasma density dynamic is derived, consistent with the experimentally measured pdf and the theoretical quadratic nonlinearity. The plasma density evolves on the turbulence correlation time scale and is driven by a stochastic white noise proportional to the turbulence fluctuations amplitude, while the linear growth is quadratically damped by the fluctuation level $n_e(t)/\\bar{n}_e$.

  1. Cross-diagnostic comparison of fluctuation measurements in a linear plasma column

    Science.gov (United States)

    Light, Adam D.; Archer, Nicholas A. A.; Bashyal, Atit; Chakraborty Thakur, Saikat; Tynan, George R.

    2015-11-01

    The advent of fast imaging diagnostics, which provide two-dimensional measurements on relevant plasma time scales, has proven invaluable for interpreting plasma dynamics in laboratory devices. Despite its success, imaging remains a qualitative aid for many studies, because intensity is difficult to map onto a single physical variable for use in a theoretical model. This work continues our exploration of the relationship between visible-light and electrostatic probe measurements in the Controlled Shear Decorrelation Experiment (CSDX). CSDX is a well-characterized linear machine producing dense plasmas relevant to the tokamak edge (Te ~ 3 eV, ne ~1013 /cc). Visible light from ArI and ArII line emission is collected at high frame rates using a fast digital camera. Floating potential and ion-saturation current are measured by an array of electrostatic probe tips. We present a detailed comparison between imaging and probe measurements of fluctuations, including temporal, spatial, and spectral properties in various operational regimes.

  2. Hysteresis of fluctuation dynamics associated with a fireball in a magnetized glow discharge plasma in a currentless toroidal assembly

    Science.gov (United States)

    Ghosh, Sabuj; Shaw, Pankaj Kumar; Saha, Debajyoti; Janaki, M. S.; Sekar Iyengar, A. N.

    2016-09-01

    Floating potential fluctuations associated with an anode fireball in a glow discharge plasma in the toroidal vacuum vessel of the SINP tokamak are found to exhibit different kinds of oscillations under the action of vertical magnetic field of different strengths. While increasing the vertical magnetic field, the fluctuations have shown transitions as: chaotic oscillation → inverse homoclinic transition → intermittency → chaotic oscillation. However, on decreasing the magnetic field, the fluctuations are seen to follow: chaotic oscillations → homoclinic transition → chaotic oscillation; that is the intermittent feature is not observed. Fireball dynamics is found to be closely related to the magnetic field applied; results of visual inspection with a high speed camera are in close agreement with the fluctuations, and the fireball dynamics is found to be closely related to the transitions. The statistical properties like skewness, kurtosis, and entropy of the fluctuations are also found to exhibit this hysteresis behaviour.

  3. The MDF technique for the analysis of tokamak edge plasma fluctuations

    Science.gov (United States)

    Lafouti, M.; Ghoranneviss, M.; Meshkani, S.; Elahi, A. Salar; Elahi

    2014-02-01

    Tokamak edge plasma was analyzed by applying the multifractal detrend fluctuation analysis (MF-DFA) technique. This method has found wide application in the analysis of correlations and characterization of scaling behavior of the time-series data in physiology, finance, and natural sciences. The time evolution of the ion saturation current (Is ), the floating potential fluctuation (Vf ), the poloidal electric field (Ep ), and the radial particle flux (Γ r ) has been measured by using a set of Langmuir probes consisting of four tips on the probe head. The generalized Hurst exponents (h(q)), local fluctuation function (Fq(s)), the Rényi exponents (τ(q)) as well as the multifractal spectrum f(α h ) have been calculated by applying the MF-DFA method to Is , Vf , and the magnetohydrodynamic (MHD) fluctuation signal. Furthermore, we perform the shuffling and the phase randomization techniques to detect the sources of multifractality. The nonlinearity shape of τ(q) reveals a multifractal behavior of the time-series data. The results show that in the presence of biasing, Is , Vf , Ep , and Γ r reduce about 25%, 90%, 70%, and 50%, respectively, compared with the situation with no biasing. Also, they reduce about 15%, 90%, 35%, and 25%, respectively, after resonant helical magnetic field (RHF) application. In the presence of biasing or RHF, the amplitude of the power spectrum of Is , Vf , Γ r , and MHD activity reduce remarkably in all the ranges of frequency, while their h(q) increase. The values of h(q) have been restricted between 0.6 and 0.68. These results are evidence of the existence of long-range correlations in the plasma edge turbulence. They also show the self-similar nature of the plasma edge fluctuations. Biasing or RHF reduces the amount of Fq(s). The multifractal spectrum width of Is , Vf , and MHD fluctuation amplitude reduce about 60%, 70%, and 42%, respectively, by applying biasing. In the presence of RHF, their width reduces about 60%, 85%, and 75

  4. Bistable Intrinsic Charge Fluctuations of a Dust Grain Subject to Secondary Electron Emission in a Plasma

    CERN Document Server

    Shotorban, Babak

    2015-01-01

    A master equation was formulated to study intrinsic charge fluctuations of a grain in a plasma as ions and primary electrons are attached to the grain through collisional collection, and secondary electrons are emitted from the grain. Two different plasmas with Maxwellian and non-Maxwellian distributions were considered. The fluctuations could be bistable in either plasma when the secondary electron emission is present, as two stable macrostates, associated with two stable roots of the charge net current, may exist. Metastablity of fluctuations, manifested by the passage of the grain charge between two macrostates, was shown to be possible.

  5. Bistable intrinsic charge fluctuations of a dust grain subject to secondary electron emission in a plasma.

    Science.gov (United States)

    Shotorban, B

    2015-10-01

    A master equation was formulated to study intrinsic charge fluctuations of a grain in a plasma as ions and primary electrons are attached to the grain through collisional collection, and secondary electrons are emitted from the grain. Two different plasmas with Maxwellian and non-Maxwellian distributions were considered. The fluctuations could be bistable in either plasma when the secondary electron emission is present, as two stable macrostates, associated with two stable roots of the charge net current, may exist. Metastablity of fluctuations, manifested by the passage of the grain charge between two macrostates, was shown to be possible.

  6. Energy change of a heavy quark in a viscous quark–gluon plasma with fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bing-feng, E-mail: jiangbf@mails.ccnu.edu.cn [Center for Theoretical Physics and School of Sciences, Hubei University for Nationalities, Enshi, Hubei 445000 (China); Hou, De-fu, E-mail: houdf@mail.ccnu.edu.cn [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, Hubei 430079 (China); Li, Jia-rong, E-mail: ljr@mail.ccnu.edu.cn [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan, Hubei 430079 (China)

    2016-09-15

    When a heavy quark travels through the quark–gluon plasma, the polarization and fluctuating chromoelectric fields will be produced simultaneously in the plasma. The drag force due to those fields exerting in return on the moving heavy quark will cause energy change to it. Based on the dielectric functions derived from the viscous chromohydrodynamics, we have studied the collisional energy change of a heavy quark traversing the viscous quark–gluon plasma including fluctuations of chromoelectric field. Numerical results indicate that the chromoelectric field fluctuations lead to an energy gain of the moving heavy quark. Shear viscosity suppresses the fluctuation-induced energy gain and the viscous suppression effect for the charm quark is much more remarkable than that for the bottom quark. While, the fluctuation energy gain is much smaller than the polarization energy loss in magnitude and the net energy change for the heavy quark is at loss.

  7. CO{sub 2} laser diagnostics for measurements of the plasma density profile and plasma density fluctuations on LHD

    Energy Technology Data Exchange (ETDEWEB)

    Vyacheslavov, L.N. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Tanaka, K.; Kawahata, K. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2001-04-01

    A CO{sub 2} laser based diagnostics complimentary to the existing FIR interferometer is proposed. It combines interferometry for plasma density profile measurement under conditions of large density gradients, and both imaging and scattering techniques for observation of plasma fluctuations. Two-colour interferometer with a slablike probe beam and a single multichannel linear detector array provide observation of plasma density profile and density fluctuations at two locations along the probe beam. Basic characteristics of the diagnostics are considered as well as some effects that include dispersion and are critical for two colour imaging technique. The results of the bench-top experiments with the prototype of the interferometer are presented. (author)

  8. Dynamics of Fluctuations, Flows and Global Stability Under Electrode Biasing in a Linear Plasma Device

    Science.gov (United States)

    Desjardins, Tiffany

    2015-11-01

    Various bias electrodes have been inserted into the Helicon-Cathode (HelCat) device at the University of New Mexico, in order to affect intrinsic drift-wave turbulence and flows. The goal of the experiments was to suppress and effect the intrinsic turbulence and with detailed measurements, understand the changes that occur during biasing. The drift-mode in HelCat varies from coherent at low magnetic field (1kG). The first electrode consists of 6 concentric rings set in a ceramic substrate; these rings act as a boundary condition, sitting at the end of the plasma column 2-m away from the source. A negative bias has been found to have no effect on the fluctuations, but a positive bias (Vr>5Te) is required in order to suppress the drift-mode. Two molybdenum grids can also be inserted into the plasma and sit close to the source. Floating or grounding a grid results in suppressing the drift-mode of the system. A negative bias (>-5Te) is found to return the drift-mode, and it is possible to drive a once coherent mode into a broad-band turbulent one. From a bias voltage of -5Tenew mode, which is identified as a parallel-driven Kelvin-Helmholtz mode. At high positive bias, Vg>10Te, a new large-scale global mode is excited. This mode exhibits fluctuations in the ion saturation current, as well as in the potential, with a magnitude >50%. This mode has been identified as the potential relaxation instability (PRI). In order to better understand the modes and changes observed in the plasma, a linear stability code, LSS, was employed. As well, a 1D3V-PIC code utilizing Braginskii's equations was also utilized to understand the high-bias instability.

  9. Large daily fluctuations in plasma tyrosine in treated patients with phenylketonuria

    NARCIS (Netherlands)

    vanSpronsen, FJ; vanDijk, T; Smit, GPA; vanRijn, M; Reijngoud, DJ; Berger, Ruud; Heymans, HSA

    1996-01-01

    In patients with phenylketonuria (PKU), extra tyrosine supplementation is advocated in addition to tyrosine-enriched amino acid mixtures. PKU patients have low fasting plasma tyrosine concentrations, but little is known about tyrosine fluctuations during the day. Plasma tyrosine concentrations were

  10. Multifield measurement of magnetic fluctuation-induced particle flux in a high-temperature toroidal plasma

    Science.gov (United States)

    Lin, L.; Ding, W. X.; Brower, D. L.

    2016-12-01

    Magnetic fluctuation-induced particle transport is explored in the high-temperature, high-beta interior of the Madison symmetric torus (MST) reversed-field pinch by performing a multifield measurement of the correlated product of magnetic and density fluctuations associated with global resistive tearing modes. Local density fluctuations are obtained by inverting the line-integrated interferometry data after resolving the mode helicity through correlation techniques. The local magnetic and current density fluctuations are then reconstructed using a parameterized fit of Faraday-effect polarimetry measurements. Reconstructed 2D images of density and current density perturbations in a poloidal cross section exhibit significantly different spatial structure. Combined with their relative phase, the magnetic-fluctuation-induced particle transport flux and its spatial distribution are resolved. The convective magnetic fluctuation-induced particle flux profile is measured for both standard and high-performance plasmas in MST with tokamak-like confinement, showing large reduction in the flux during improved confinement.

  11. Statistics of magnetic field fluctuations in a partially ionized space plasma

    Energy Technology Data Exchange (ETDEWEB)

    Shaikh, Dastgeer, E-mail: dastgeer.shaikh@uah.ed [Department of Physics and Center for Space Plasma and Aeronomy Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2010-07-05

    Voyager 1 and 2 data reveals that magnetic field fluctuations are compressive and exhibit a Gaussian distribution in the compressed heliosheath plasma, whereas they follow a lognormal distribution in a nearly incompressible supersonic solar wind plasma. To describe the evolution of magnetic field, we develop a nonlinear simulation model of a partially ionized plasma based on two-dimensional time-dependent multifluid model. Our model self-consistently describes solar wind plasma ions, electrons, neutrals and pickup ions. It is found from our simulations that the magnetic field evolution is governed by mode conversion process that leads to the suppression of vortical modes, whereas the compressive modes are amplified. An implication of the mode conversion process is to quench the Alfvenic interactions associated with the vortical motions. Consequently anisotropic cascades are reduced. This is accompanied by the amplification of compressional modes that tend to isotropize the plasma fluctuations and lead to a Gaussian distribution of the magnetic field.

  12. Flow shear induced fluctuation suppression in finite aspect ratio shaped tokamak plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hahm, T.S. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Burrell, K.H. [General Atomics, San Diego, CA (United States)

    1995-01-01

    The suppression of turbulence by the E {times} B flow shear and parallel flow shear is studied in an arbitrary shape finite aspect ratio tokamak plasma using the two point nonlinear analysis previously utilized in a high aspect rat& tokamak plasma. The result shows that only the E {times} B flow shear is responsible for the suppression of flute-like fluctuations. This suppression occurs regardless of the plasma rotation direction and is therefore, relevant for the VH mode plasma core as well as for the H mode plasma edge. Experimentally observed in-out asymmetry of fluctuation reduction behavior can be addressed in the context of flux expansion and magnetic field pitch variation on a given flux surface. The adverse effect of neutral particles on confinement improvement is also discussed in the context of the charge exchange induced parallel momentum damping.

  13. Multiscale Gyrokinetics for Rotating Tokamak Plasmas: Fluctuations, Transport and Energy Flows

    CERN Document Server

    Abel, I G; Wang, E; Barnes, M; Cowley, S C; Dorland, W; Schekochihin, A A

    2012-01-01

    This paper presents a complete theoretical framework for plasma turbulence and transport in tokamak plasmas. The fundamental scale separations present in plasma turbulence are codified as an asymptotic expansion in the ratio of the gyroradius to the equilibrium scale length. Proceeding order-by-order in this expansion, a framework for plasma turbulence is developed. It comprises an instantaneous equilibrium, the fluctuations driven by gradients in the equilibrium quantities, and the transport-timescale evolution of mean profiles of these quantities driven by the fluctuations. The equilibrium distribution functions are local Maxwellians with each flux surface rotating toroidally as a rigid body. The magnetic equillibrium is obtained from the Grad-Shafranov equation for a rotating plasma and the slow (resistive) evolution of the magnetic field is given by an evolution equation for the safety factor q. Large-scale deviations of the distribution function from a Maxwellian are given by neoclassical theory. The flu...

  14. Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction

    OpenAIRE

    Watari, Eriko; Taketani, Yutaka; Kitamura, Tomoyo; Tanaka, Terumi; Ohminami, Hirokazu; Abuduli, Maerjianghan; Harada, Nagakatsu; Yamanaka-Okumura, Hisami; Yamamoto, Hironori; Takeda, Eiji

    2014-01-01

    High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16...

  15. Linear and nonlinear excitations in complex plasmas with nonadiabatic dust charge fluctuation and dust size distribution

    Institute of Scientific and Technical Information of China (English)

    Zhang Li-Ping; Xue Ju-Kui; Li Yan-Long

    2011-01-01

    Both linear and nonlinear excitation in dusty plasmas have been investigated including the nonadiabatic dust charge fluctuation and Gaussian size distribution dust particles.A linear dispersion relation and a Korteweg-de VriesBurgers equation governing the dust acoustic shock waves are obtained.The relevance of the instability of wave and the wave evolution to the dust size distribution and nonadiabatic dust charge fluctuation is illustrated both analytically and numerically.The numerical results show that the Gaussian size distribution of dust particles and the nonadiabatic dust charge fluctuation have strong common influence on the propagation of both linear and nonlinear excitations.

  16. Self-similarity of fluctuation particle fluxes in the plasma edge of the stellarator L-2M

    Energy Technology Data Exchange (ETDEWEB)

    Saenko, V.V. [Ulyanovsk State University, Leo Tolstoy str., 42, Ulyanovsk (Russian Federation)

    2010-05-15

    Results are presented of statistical studies of probability density of fluctuations of plasma density, floating potential, and turbulent particle fluxes measured by a Langmuir probe in the edge plasma of the L-2M stellarator. Empirical probability densities differ from Gaussian distributions. The empirical probability density distributions have heavy tails decreasing as x{sup -{alpha}}{sup -1} and are leptokurtic. Fractional stable distributions were successfully applied to describing such distributions. It is shown that fractional stable distributions give good fit to the distri-butions of increments of fluctuation amplitudes of physical variables under study. The distribution parameters are statistically estimated from measured time sequences (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Scattering of diffracting beams of electron cyclotron waves by random density fluctuations in inhomogeneous plasmas

    Science.gov (United States)

    Weber, Hannes; Maj, Omar; Poli, Emanuele

    2015-03-01

    The physics and first results of the new WKBeam code for electron cyclotron beams in tokamak plasmas are presented. This code is developed on the basis of a kinetic radiative transfer model which is general enough to account for the effects of diffraction and density fluctuations on the beam. Our preliminary numerical results show a significant broadening of the power deposition profile in ITER due to scattering from random density fluctuations at the plasma edge, while such scattering effects are found to be negligible in medium-size tokamaks like ASDEX upgrade.

  18. Theory of density fluctuations in strongly radiative plasmas

    Science.gov (United States)

    Cross, J. E.; Mabey, P.; Gericke, D. O.; Gregori, G.

    2016-03-01

    Derivation of the dynamic structure factor, an important parameter linking experimental and theoretical work in dense plasmas, is possible starting from hydrodynamic equations. Here we obtain, by modifying the governing hydrodynamic equations, a new form of the dynamic structure factor which includes radiative terms. The inclusion of such terms has an effect on the structure factor at high temperatures, which suggests that its effect must be taken into consideration in such regimes.

  19. Fluctuation Phenomenon Analysis of an Arc Plasma Spraying Jet

    Institute of Scientific and Technical Information of China (English)

    赵文华; 田阔; 刘笛; 张冠忠

    2001-01-01

    The effects of three factors, including the power supply, the arc behaviour in the arc channel and the fluid dynamic process of the jet, on a plasma spraying jet have been experimentally detected by means of spectroscopic diagnostic techniques. The fast Fourier transform method has been applied to the analysis of the arc voltage and spectral line intensity of the jet. The three factors have been studied and distinguished from each other.

  20. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Yuan; Wang Jun; Yu Yi; Wen Yi-Zhi; Yu Chang-Xuan; Liu Wan-Dong; Wan Bao-Nian; Gao Xiang; N. C. Luhmann; C. W. Domier; Jian Wang; Z. G. Xia; Zuowei Shen

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number kg is calculated to be about 1.58 cm-1, or keps ≈0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation.

  1. Stochastic Resonance of Single (Independent of Each Other) Protein Motor System with Fluctuating Potential Barrier

    Institute of Scientific and Technical Information of China (English)

    MA Song-Hua; LI Jing-Hui; JIANG Yong-Qing; FANG Jian-Ping

    2008-01-01

    A single (independent of each other) protein motor system with fluctuating potential barrier and subject to sine electric field is investigated. We first derive the approximate Langevin equation of this system with fluctuating potential barrier. Then from this approximate Langevin equation, we calculate the signal-to-noise ratio (SNR) in the adiabatic limit. The phenomenon of stochastic resonance is found for this protein motor system with fluctuating potential barrier.

  2. Equilibrium fluctuations formulas for the quantum one-component plasma in a magnetic field

    NARCIS (Netherlands)

    John, P.; Suttorp, L.G.

    1993-01-01

    The authors derive a complete set of equilibrium fluctuation formulae for the charge density, the current density and the energy density of the quantum one-component plasma in a magnetic field. The derivation is based on the use of imaginary-time-dependent Green functions and their Kubo transforms.

  3. Equilibrium fluctuations formulas for the quantum one-component plasma in a magnetic field

    NARCIS (Netherlands)

    John, P.; Suttorp, L.G.

    1993-01-01

    The authors derive a complete set of equilibrium fluctuation formulae for the charge density, the current density and the energy density of the quantum one-component plasma in a magnetic field. The derivation is based on the use of imaginary-time-dependent Green functions and their Kubo transforms.

  4. The effect of plasma fluctuations on parallel transport parameters in the SOL

    DEFF Research Database (Denmark)

    Havlíčková, E.; Fundamenski, W.; Naulin, Volker

    2011-01-01

    in the scrape-off layer (SOL) taking into account these fluctuations is presented. Plasma transport in the SOL along the magnetic field between two targets is calculated by a one-dimensional fluid code in order to estimate the response to transient conditions along the SOL and the attention is given...

  5. Fluctuations properties and collective modes of quantum plasmas in a magnetic field

    NARCIS (Netherlands)

    Suttorp, L.G.; Van Horn, H.M.; Ichimaru, S.

    1993-01-01

    A complete set of equilibrium fluctuation formulas for the charge density, the momentum density and the energy density of a magnetized one-component quantum plasma is presented. The derivation is based on the use of equations of motion for Fourier-transformed imaginary-time Green functions. The resu

  6. Collisionless Isotropization of the Solar-wind Protons by Compressive Fluctuations and Plasma Instabilities

    Science.gov (United States)

    Verscharen, Daniel; Chandran, Benjamin D. G.; Klein, Kristopher G.; Quataert, Eliot

    2016-11-01

    Compressive fluctuations are a minor yet significant component of astrophysical plasma turbulence. In the solar wind, long-wavelength compressive slow-mode fluctuations lead to changes in {β }\\parallel {{p}}\\equiv 8π {n}{{p}}{k}{{B}}{T}\\parallel {{p}}/{B}2 and in {R}{{p}}\\equiv {T}\\perp {{p}}/{T}\\parallel {{p}}, where {T}\\perp {{p}} and {T}\\parallel {{p}} are the perpendicular and parallel temperatures of the protons, B is the magnetic field strength, and {n}{{p}} is the proton density. If the amplitude of the compressive fluctuations is large enough, {R}{{p}} crosses one or more instability thresholds for anisotropy-driven microinstabilities. The enhanced field fluctuations from these microinstabilities scatter the protons so as to reduce the anisotropy of the pressure tensor. We propose that this scattering drives the average value of {R}{{p}} away from the marginal stability boundary until the fluctuating value of {R}{{p}} stops crossing the boundary. We model this “fluctuating-anisotropy effect” using linear Vlasov-Maxwell theory to describe the large-scale compressive fluctuations. We argue that this effect can explain why, in the nearly collisionless solar wind, the average value of {R}{{p}} is close to unity.

  7. Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma

    DEFF Research Database (Denmark)

    Ionita, Codrina; Vianello, Nicola; Müller, H.W.

    2009-01-01

    in such a way that simultaneously the poloidal and radial electric field components, the ion saturation current and the current-voltage characteristic can be registered. During the AUG discharges of 7 s lengths the probe head is inserted two to three times for 100 ms each by the midplane manipulator......In ASDEX Upgrade (AUG) electrostatic and magnetic fluctuations in the edge plasma region were measured simultaneously during ELMy H-mode (high confinement) plasmas and L-mode (low confinement) plasmas and during a transition between the two modes. A special probe was used containing six Langmuir...

  8. Derivation of stochastic differential equations for scrape-off layer plasma fluctuations from experimentally measured statistics

    Energy Technology Data Exchange (ETDEWEB)

    Mekkaoui, A. [Institute for Energy and Climate Research-Plasma Physics, Research Center Juelich GmbH, Association FZJ-Euratom, D-52425 Juelich (Germany)

    2013-01-15

    A stochastic differential equation for intermittent plasma density dynamics in magnetic fusion edge plasma is derived, which is consistent with the experimentally measured gamma distribution and the theoretically expected quadratic nonlinearity. The plasma density is driven by a multiplicative Wiener process and evolves on the turbulence correlation time scale, while the linear growth is quadratically damped by the fluctuation level. The sensitivity of intermittency to the nonlinear dynamics is investigated by analyzing the nonlinear Langevin representation of the beta process, which leads to a root-square nonlinearity.

  9. Neutral Beam Source and Target Plasma for Development of a Local Electric Field Fluctuation Diagnostic

    Science.gov (United States)

    Bakken, M. R.; Burke, M. G.; Fonck, R. J.; Lewicki, B. T.; Rhodes, A. T.; Winz, G. R.

    2016-10-01

    A new diagnostic measuring local E-> (r , t) fluctuations is being developed for plasma turbulence studies in tokamaks. This is accomplished by measuring fluctuations in the separation of the π components in the Hα motional Stark spectrum. Fluctuations in this separation are expected to be Ẽ / ẼEMSE 10-3EMSE 10-3 . In addition to a high throughput, high speed spectrometer, the project requires a low divergence (Ω 0 .5°) , 80 keV, 2.5 A H0 beam and a target plasma test stand. The beam employs a washer-stack arc ion source to achieve a high species fraction at full energy. Laboratory tests of the ion source demonstrate repeatable plasmas with Te 10 eV and ne 1.6 ×1017 m-3, sufficient for the beam ion optics requirements. Te and ne scalings of the ion source plasma are presented with respect to operational parameters. A novel three-phase resonant converter power supply will provide 6 mA/cm2 of 80 keV H0 at the focal plane for pulse lengths up to 15 ms, with low ripple δV / 80 keV 0.05 % at 280 kHz. Diagnostic development and validation tests will be performed on a magnetized plasma test stand with 0.5 T field. The test chamber will utilize a washer-stack arc source to produce a target plasma comparable to edge tokamak plasmas. A bias-plate with programmable power supply will be used to impose Ẽ within the target plasma. Work supported by US DOE Grant DE-FG02-89ER53296.

  10. First in-situ observations of neutral and plasma density fluctuations within a PMSE layer

    Science.gov (United States)

    Lubken, Franz-Josef; Lehmacher, Gerald; Blix, Tom; Hoppe, Ulf-Peter; Thrane, Eivind; Cho, John; Swartz, Wesley

    1993-01-01

    The NLC-91 rocket and radar campaign provided the first opportunity for high resolution neutral and plasma turbulence measurements with simultaneous observations of PMSE (Polar Mesospheric Summer Echoes). During the flight of the TURBO payload on August 1, 1991, Cornell University Portable Radar Interferometer (CUPRI) and European Incoherent Scattter facility (EISCAT) observed double PMSE layers located at 86 and 88 km altitude, respectively. Strong neutral density fluctuations were observed in the upper layer but not in the lower layer. The fluctuation spectra of the ions and neutrals within the upper layer are consistent with standard turbulence theories. However, we show that there is no neutral turbulence present in the lower layer and that something else must have been operating here to create the plasma fluctuations and hence the radar echoes. Although the in situ measurements of the electron density fluctuations are much stronger in the lower layer, the higher absolute electron density of the upper layer more than compensated for the weaker fluctuations yielding comparable radar echo powers.

  11. Stability Dust-Ion-Acoustic Wave in Dusty Plasmas With Stream -Influence of Charge Fluctuation of Dust Grains

    CERN Document Server

    Atamaniuk, B; Atamaniuk, Barbara; Zuchowski, Krzysztof

    2007-01-01

    There is a quickly increasing wealth of experimental data on so-called dusty plasmas i. e. ionized gases or usual plasmas that contain micron sized charged particles. Interest in these structures is driven both by their importance in many astrophysical as well as commercial situations. Among them are linear and nonlinear wave phenomena. We consider the influence of dust charge fluctuations on stability of the ion-acoustic waves when the stream of particles is present. It is assumed that all grains of dust have equal masses but charges are not constant in time-they may fluctuate in time. The dust charges are not really independent of the variations of the plasma potentials. All modes will influence the charging mechanism, and feedback will lead to several new interesting and unexpected phenomena. The charging of the grains depends on local plasma characteristics. If the waves disturb these characteristic, then charging of the grains is affected and the grain charge is modified, with a resulting feedback on the...

  12. Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction.

    Science.gov (United States)

    Watari, Eriko; Taketani, Yutaka; Kitamura, Tomoyo; Tanaka, Terumi; Ohminami, Hirokazu; Abuduli, Maerjianghan; Harada, Nagakatsu; Yamanaka-Okumura, Hisami; Yamamoto, Hironori; Takeda, Eiji

    2015-01-01

    High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16 days (control group), or a diet alternating between 0.02% P and 1.2% P (LH group) or between 1.2% P and 0.02% P (HL group) every 2 days; the total amount of P intake among the groups during the feeding period was similar. In the LH and HL groups, endothelial-dependent vasodilation significantly decreased plasma 8-(OH)dG level significantly increased, and the expression of inflammatory factors such as MCP-1 increased in the endothelium as compared with the control group. These data indicate that repetitive fluctuations of plasma P caused by varying dietary P intake can impair endothelial function via increased oxidative stress and inflammatory response. Taken together, these results suggest that habitual fluctuation of dietary P intake might be a cause of cardiovascular disease through endothelial dysfunction, especially in chronic kidney disease patients.

  13. Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction

    Science.gov (United States)

    Watari, Eriko; Taketani, Yutaka; Kitamura, Tomoyo; Tanaka, Terumi; Ohminami, Hirokazu; Abuduli, Maerjianghan; Harada, Nagakatsu; Yamanaka-Okumura, Hisami; Yamamoto, Hironori; Takeda, Eiji

    2015-01-01

    High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16 days (control group), or a diet alternating between 0.02% P and 1.2% P (LH group) or between 1.2% P and 0.02% P (HL group) every 2 days; the total amount of P intake among the groups during the feeding period was similar. In the LH and HL groups, endothelial-dependent vasodilation significantly decreased plasma 8-(OH)dG level significantly increased, and the expression of inflammatory factors such as MCP-1 increased in the endothelium as compared with the control group. These data indicate that repetitive fluctuations of plasma P caused by varying dietary P intake can impair endothelial function via increased oxidative stress and inflammatory response. Taken together, these results suggest that habitual fluctuation of dietary P intake might be a cause of cardiovascular disease through endothelial dysfunction, especially in chronic kidney disease patients. PMID:25678749

  14. Controlling fluctuations and transport in the reversed field pinch with edge current drive and plasma biasing

    Energy Technology Data Exchange (ETDEWEB)

    Craig, D.J.G.

    1998-09-01

    Two techniques are employed in the Madison Symmetric Torus (MST) to test and control different aspects of fluctuation induced transport in the Reversed Field Pinch (RFP). Auxiliary edge currents are driven along the magnetic field to modify magnetic fluctuations, and the particle and energy transport associated with them. In addition, strong edge flows are produced by plasma biasing. Their effect on electrostatic fluctuations and the associated particle losses is studied. Both techniques are accomplished using miniature insertable plasma sources that are biased negatively to inject electrons. This type of emissive electrode is shown to reliably produce intense, directional current without significant contamination by impurities. The two most important conclusions derived from these studies are that the collective modes resonant at the reversal surface play a role in global plasma confinement, and that these modes can be controlled by modifying the parallel current profile outside of the reversal surface. This confirms predictions based on magnetohydrodynamic (MHD) simulations that auxiliary current drive in the sense to flatten the parallel current profile can be successful in controlling magnetic fluctuations in the RFP. However, these studies expand the group of magnetic modes believed to cause transport in MST and suggest that current profile control efforts need to address both the core resonant magnetic modes and those resonant at the reversal surface. The core resonant modes are not significantly altered in these experiments; however, the distribution and/or amplitude of the injected current is probably not optimal for affecting these modes. Plasma biasing generates strong edge flows with shear and particle confinement likely improves in these discharges. These experiments resemble biased H modes in other magnetic configurations in many ways. The similarities are likely due to the common role of electrostatic fluctuations in edge transport.

  15. Derivation of stochastic differential equations for scrape-off layer plasma fluctuations from experimentally measured statistics

    Energy Technology Data Exchange (ETDEWEB)

    Mekkaoui, Abdessamad [IEK-4 Forschungszentrum Juelich 52428 (Germany)

    2013-07-01

    A method to derive stochastic differential equations for intermittent plasma density dynamics in magnetic fusion edge plasma is presented. It uses a measured first four moments (mean, variance, Skewness and Kurtosis) and the correlation time of turbulence to write a Pearson equation for the probability distribution function of fluctuations. The Fokker-Planck equation is then used to derive a Langevin equation for the plasma density fluctuations. A theoretical expectations are used as a constraints to fix the nonlinearity structure of the stochastic differential equation. In particular when the quadratically nonlinear dynamics is assumed, then it is shown that the plasma density is driven by a multiplicative Wiener process and evolves on the turbulence correlation time scale, while the linear growth is quadratically damped by the fluctuation level. Strong criteria for statistical discrimination of experimental time series are proposed as an alternative to the Kurtosis-Skewness scaling. This scaling is broadly used in contemporary literature to characterize edge turbulence, but it is inappropriate because a large family of distributions could share this scaling. Strong criteria allow us to focus on the relevant candidate distribution and approach a nonlinear structure of edge turbulence model.

  16. Linear metric and temperature fluctuations of a charged plasma in a primordial magnetic field

    CERN Document Server

    Haba, Z

    2015-01-01

    We discuss tensor metric perturbations in a magnetic field around the homogeneous Juttner equilibrium of massless particles in an expanding universe. We solve the Liouville equation and derive the energy-momentum tensor up to linear terms in the metric and in the magnetic field.The term linear in the magnetic field is different from zero if the total charge of the primordial plasma is non-zero. We obtain an analytic formula for temperature fluctuations treating the tensor metric perturbations and the magnetic field as independent random variables. Assuming a cutoff on large momenta of the magnetic spectral function we show that the presence of the magnetic field can discriminate only low multipoles in the multipole expansion of temperature fluctuations. In such a case the term linear in the magnetic field can be more important than the quadratic one (corresponding to the fluctuations of the pure magnetic field).

  17. Energy loss of ions by electric-field fluctuations in a magnetized plasma.

    Science.gov (United States)

    Nersisyan, Hrachya B; Deutsch, Claude

    2011-06-01

    The results of a theoretical investigation of the energy loss of charged particles in a magnetized classical plasma due to the electric-field fluctuations are reported. The energy loss for a test particle is calculated through the linear-response theory. At vanishing magnetic field, the electric-field fluctuations lead to an energy gain of the charged particle for all velocities. It has been shown that in the presence of strong magnetic field, this effect occurs only at low velocities. In the case of high velocities, the test particle systematically loses its energy due to the interaction with a stochastic electric field. The net effect of the fluctuations is the systematic reduction of the total energy loss (i.e., the sum of the polarization and stochastic energy losses) at vanishing magnetic field and reduction or enhancement at strong field, depending on the velocity of the particle. It is found that the energy loss of the slow heavy ion contains an anomalous term that depends logarithmically on the projectile mass. The physical origin of this anomalous term is the coupling between the cyclotron motion of the plasma electrons and the long-wavelength, low-frequency fluctuations produced by the projectile ion. This effect may strongly enhance the stochastic energy gain of the particle.

  18. Stable explicit coupling of the Yee scheme with a linear current model in fluctuating magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Filipe da, E-mail: tanatos@ipfn.ist.utl.pt [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal); Pinto, Martin Campos, E-mail: campos@ann.jussieu.fr [CNRS, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); Després, Bruno, E-mail: despres@ann.jussieu.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); CNRS, UMR 7598, Laboratoire Jacques-Louis Lions, F-75005, Paris (France); Heuraux, Stéphane, E-mail: stephane.heuraux@univ-lorraine.fr [Institut Jean Lamour, UMR 7198, CNRS – University Lorraine, Vandoeuvre (France)

    2015-08-15

    This work analyzes the stability of the Yee scheme for non-stationary Maxwell's equations coupled with a linear current model with density fluctuations. We show that the usual procedure may yield unstable scheme for physical situations that correspond to strongly magnetized plasmas in X-mode (TE) polarization. We propose to use first order clustered discretization of the vectorial product that gives back a stable coupling. We validate the schemes on some test cases representative of direct numerical simulations of X-mode in a magnetic fusion plasma including turbulence.

  19. Propagation of dust-acoustic waves in weakly ionized plasmas with dust-charge fluctuation

    Indian Academy of Sciences (India)

    K K Mondal

    2004-11-01

    For an unmagnetized partially ionized dusty plasma containing electrons, singly charged positive ions, micron-sized massive negatively charged dust grains and a fraction of neutral atoms, dispersion relations for both the dust-ion-acoustic and the dust-acoustic waves have been derived, incorporating dust charge fluctuation. The dispersion relations, under various conditions, have been exhaustively analysed. The explicit expressions for the growth rates have also been derived.

  20. A Probe Head for Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma

    DEFF Research Database (Denmark)

    Schrittwieser, R W; Ionita, C; Vianello, N

    2010-01-01

    For ASDEX Upgrade (AUG) a new probe head was developed for simultaneous measurements of electric and magnetic fluctuations in the edge plasma region. The probe head consists of a cylindrical graphite case. On the front side six graphite pins are mounted. With this arrangement the poloidal and rad...... is inserted up to three times for 100 ms each by the midplane manipulator into the scrape-off layer. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim....

  1. Kinetic parameters and intraindividual fluctuations of ochratoxin A plasma levels in humans

    Energy Technology Data Exchange (ETDEWEB)

    Studer-Rohr, I. [Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland); Dept. of Food Science, Swiss Federal Inst. of Tech., Zurich (Switzerland); Schlatter, J. [Toxicology Section, Div. of Food Science, Swiss Federal Office of Public Health, Zurich (Switzerland); Dietrich, D.R. [Dept. of Environmental Toxicology, Univ. of Konstanz, Konstanz (Germany); Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland)

    2000-11-01

    The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic profile of OTA was studied in one human volunteer following ingestion of 395 ng {sup 3}H-labeled OTA (3.8 {mu}Ci). A two-compartment open model consisting of a central compartment was found to best describe the in vivo data. This two-compartment model consisted of a fast elimination and distribution phase (T{sub 1/2} about 20 h) followed by a slow elimination phase (renal clearance about 0.11 ml/min.) and a calculated plasma half-life of 35.55 days. This half-life was approximately eight times longer than that determined previously in rats. In addition, the intraindividual fluctuation of OTA plasma levels was investigated in eight individuals over a period of 2 months. The concentrations determined ranged between 0.2 and 0.9 ng OTA/ml plasma. The plasma levels in some individuals remained nearly constant over time, while others varied considerably (e.g. increase of 0.4 ng/ml within 3 days, decrease of 0.3 ng/ml within 5 days) during the observation period. This intraindividual fluctuation in OTA plasma levels, which may represent differences in OTA exposure and/or metabolism, as well as the large difference in plasma half-life in humans compared to rats must be taken into consideration when the results of rat cancer study data are extrapolated to humans for risk assessment purposes. (orig.)

  2. Collisionless Isotropization of the Solar Wind by Compressive Fluctuations and Plasma Instabilities

    CERN Document Server

    Verscharen, Daniel; Klein, Kristopher G; Quataert, Eliot

    2016-01-01

    Compressive fluctuations are a minor yet significant component of astrophysical plasma turbulence. In the solar wind, compressive slow-mode fluctuations lead to changes in $\\beta_{\\parallel \\mathrm p}\\equiv 8\\pi n_{\\mathrm p}k_{\\mathrm B}T_{\\parallel \\mathrm p}/B^2$ and in $R_{\\mathrm p}\\equiv T_{\\perp \\mathrm p}/T_{\\parallel \\mathrm p}$, where $T_{\\perp \\mathrm p}$ and $T_{\\parallel \\mathrm p}$ are the perpendicular and parallel temperatures of the protons, $B$ is the magnetic field strength, and $n_{\\mathrm p}$ is the proton density. If the amplitude of the compressive fluctuations is large enough, $R_{\\mathrm p}$ crosses one or more instability thresholds for anisotropy-driven micro-instabilities. The excitation of these micro-instabilities leads to partial isotropization of the pressure tensor, driving the average value of $R_{\\mathrm p}$ away from the marginal stability boundary until the fluctuating value of $R_{\\mathrm p}$ stops crossing the boundary. We model this "fluctuating-anisotropy effect" using...

  3. Evidence for the interplanetary electric potential? WIND observations of electrostatic fluctuations

    Directory of Open Access Journals (Sweden)

    C. Lacombe

    Full Text Available In the solar wind at 1 AU, coherent electrostatic waveforms in the ion acoustic frequency range (~ 1 kHz have been observed by the Time Domain Sampler (TDS instrument on the Wind spacecraft. Small drops of electrostatic potential (Df > 10-3 V have been found across some of these waveforms, which can thus be considered as weak double layers (Mangeney et al., 1999. The rate of occurrence of these potential drops, at 1 AU, is estimated by a comparison of the TDS data with simultaneous data of another Wind instrument, the Thermal Noise Receiver (TNR, which measures continuously the thermal and non-thermal electric spectra above 4 kHz. We assume that the potential drops have a constant amplitude and a constant rate of occurrence between the Sun and the Earth. The total potential drop between the Sun and the Earth, which results from a succession of small potential drops during the Sun-Earth travel time, is then found to be about 300 V to 1000 V, of the same order of magnitude as the interplanetary potential implied by a two-fluid or an exospheric model of the solar wind: the interplanetary potential may manifest itself as a succession of weak double layers. We also find that the hourly average of the energy of the non-thermal ion acoustic waves, observed on TNR between 4 and 6 kHz, is correlated to the interplanetary electrostatic field, parallel to the spiral magnetic field, calculated with a two-fluid model: this is another evidence of a relation between the interplanetary electrostatic field and the electrostatic fluctuations in the ion acoustic range. We have yet to discuss the role of the Doppler effect, which is strong for ion acoustic waves in the solar wind, and which can bias the measure of the ion acoustic wave energy in the narrow band 4–6 kHz.

    Key words. Interplanetary physics (plasma waves and turbulence; solar wind plasma Space plasma physics (electro-static structures

  4. Numerical Study of Microwave Reflectometry in Plasmas with 2D Turbulent Fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    E. Mazzucato

    1998-02-01

    This paper describes a numerical study of the role played by 2D turbulent fluctuations in microwave reflectometry -- a radar technique for density measurements using the reflection of electromagnetic waves from a plasma cutoff. The results indicate that, if the amplitude of fluctuations is below a threshold which is set by the spectrum of poloidal wavenumbers, the measured backward field appears to originate from a virtual location behind the reflecting layer, and to arise from the phase modulation of the probing wave, with an amplitude given by 1D geometric optics. These results suggest a possible scheme for turbulence measurements in tokamaks, where the backward field is collected with a wide aperture antenna, and the virtual reflecting layer is imaged onto the plane of an array of detectors. Such a scheme should be capable of providing additional information on the nature of the short-scale turbulence observed in tokamaks, which still remains one of the unresolved issues in fusion research.

  5. Fluctuation-induced shear flow and energy transfer in plasma interchange turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Li, B. [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Sun, C. K.; Wang, X. Y.; Zhou, A.; Wang, X. G. [School of Physics, State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); Ernst, D. R. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-11-15

    Fluctuation-induced E × B shear flow and energy transfer for plasma interchange turbulence are examined in a flux-driven system with both closed and open magnetic field lines. The nonlinear evolution of interchange turbulence shows the presence of two confinement regimes characterized by low and high E × B flow shear. In the first regime, the large-scale turbulent convection is dominant and the mean E × B shear flow is at a relatively low level. By increasing the heat flux above a certain threshold, the increased turbulent intensity gives rise to the transfer of energy from fluctuations to mean E × B flows. As a result, a transition to the second regime occurs, in which a strong mean E × B shear flow is generated.

  6. Suppression of turbulence and subcritical fluctuations in differentially rotating gyrokinetic plasmas

    CERN Document Server

    Schekochihin, A A; Cowley, S C

    2011-01-01

    Differential rotation is known to suppress linear instabilities in fusion plasmas. However, even in the absence of growing eigenmodes, subcritical fluctuations that grow transiently can lead to sustained turbulence. Here transient growth of electrostatic fluctuations driven by the parallel velocity gradient (PVG) and the ion temperature gradient (ITG) in the presence of a perpendicular ExB velocity shear is considered. The maximally simplified case of zero magnetic shear is treated in the framework of a local shearing box. There are no linearly growing eigenmodes, so all excitations are transient. The maximal amplification factor of initial perturbations and the corresponding wavenumbers are calculated as functions of q/\\epsilon (=safety factor/aspect ratio), temperature gradient and velocity shear. Analytical results are corroborated and supplemented by linear gyrokinetic numerical tests. For sufficiently low values of q/\\epsilon (<7 in our model), regimes with fully suppressed ion-scale turbulence are po...

  7. Gas Temperature Measurements of Fluctuating Coal - MHD Plasmas Using Modified Line Reversal.

    Science.gov (United States)

    Winkleman, Bradley Carl

    The technique of modified line reversal is investigated and developed to allow accurate measurements on fluctuating coal fired magnetohydrodynamic plasmas and flows. Generalized modified line reversal equations applicable to any geometry and optical system are developed and presented. The generalized equations are specialized to the two most common optical systems, focussed and collimated, employed for modified line reversal measurements. Approximations introduced by specializing to the specific optical systems are investigated. Vignetting of the optical system images is shown to introduce large biases in the temperature measurement for certain optical configurations commonly applied. It is shown that symmetric optical systems are unacceptable for line reversal measurements. The errors introduced by non-simultaneous measurement of the required line reversal parameters due to rapidly fluctuating plasma characteristics are characterized. Line reversal signal and temperature measurements made on a coal fired MHD plasma are used to quantify the error in the temperature measurement due to non-simultaneous sampling of the measured line reversal parameters. A simple modified line reversal system based on interference filters and photodiodes that employs spatial separation to obtain the required line reversal parameters is described. Gas temperatures measured with devices using both the spatial and temporal separation techniques are compared. Modified line reversal temperature measurements are compared to theoretically predicted temperatures as well as CARS and high velocity thermocouple temperature measurements.

  8. Role of magnetic field fluctuations in the Evolution of the kappa Distribution Functions in the Plasma Sheet

    Science.gov (United States)

    Espinoza, Cristobal; Antonova, Elizaveta; Stepanova, Marina; Valdivia, Juan Alejandro

    2016-07-01

    The evolution with the distance to Earth of ion and electron distribution functions in the plasma sheet, approximated by kappa distributions, was studied by Stepanova and Antonova (2015, JGRA 120). Using THEMIS data for 5 events of satellite alignments along the tail, covering between 5 and 30 Earth radii, they found that the kappa parameter increases tailwards, for both ions and electrons. In this work we analyse the magnetic fluctuations present in THEMIS data for the same 5 events. The aim is to explore the hypothesis proposed by Navarro et al. (2014, PRL 112), for solar wind plasmas, that the observed magnetic fluctuations could be closely related to spontaneous fluctuations in the plasma, if this can be described by stable distributions. Here we present our first results on the correlation between the spectral properties of the magnetic fluctuations and the observed parameters of the kappa distributions for different distances from Earth.

  9. Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

    DEFF Research Database (Denmark)

    Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

    2013-01-01

    We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity, and bil......We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity......, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties...... fluctuations. The effect of the applied electric potential on the bending rigidity is non-existent within error bars. However, when the membrane is stretched there is a point where the bending rigidity is lowered due to a decrease of the thickness of the membrane. All these effects should prove important...

  10. [Fluctuations and transport in fusion plasma]: Progress report, October 1, 1989--September 30, 1990

    Energy Technology Data Exchange (ETDEWEB)

    1995-12-31

    In the study of plasma collection by obstacles in a tokamak edge plasma, the effect of anomalous transport have been examined using an extension of the 2D fluid code developed here previously (Appendices A and B). The origin of the anomalous transport is assumed to be a randomly fluctuating electric field such as would be caused by drift waves. As before, the magnetic field is assumed to be uniform and perpendicular to the obstacle, which is taken to be an infinite strip. In the absence of ambient plasma flow, the numerical results indicate that ion viscous heating is important near the tip of the obstacle, where there is a large velocity gradient in the flow. For typical plasma parameters, the maximum ion temperature near the tip is up to 85% higher than the ambient ion temperature. When there is a subsonic plasma flow past the obstacle, the numerical results indicate that, near the tip of the obstacle, the ions on the downstream side are hotter than those on the upstream side. Furthermore, the ion density is higher on the upstream side. A detailed report of this work has been prepared and will be submitted as part of the Annual Progress Report. Recently, the 2D parallel electrostatic plasma particle-in-cell (PIC) code described in reference (9) (Appendix B) has been upgraded to a 2D fully electromagnetic PIC code. This code has been successfully tested on the JPL/Caltech Mark III Hypercube concurrent computers and can be used to simulate interactions of electromagnetic waves with a magnetized plasma. It is currently applied to investigate the decay of large amplitude Alfven waves, such as those observed in the solar wind. Large amplitude Alfven waves, propagating parallel to the magnetic field, are predicted to decay into obliquely propagating daughter waves and standing magnetosonic waves. Results from the simulations will be compared with theoretical predictions.

  11. 3D simulations of fluctuation spectra in the hall-MHD plasma.

    Science.gov (United States)

    Shaikh, Dastgeer; Shukla, P K

    2009-01-30

    Turbulent spectral cascades are investigated by means of fully three-dimensional (3D) simulations of a compressible Hall-magnetohydrodynamic (H-MHD) plasma in order to understand the observed spectral break in the solar wind turbulence spectra in the regime where the characteristic length scales associated with electromagnetic fluctuations are smaller than the ion gyroradius. In this regime, the results of our 3D simulations exhibit that turbulent spectral cascades in the presence of a mean magnetic field follow an omnidirectional anisotropic inertial-range spectrum close to k(-7/3). The latter is associated with the Hall current arising from nonequal electron and ion fluid velocities in our 3D H-MHD plasma model.

  12. Effects of plasma collisionality on power balance and magnetic fluctuations in the T1 reversed-field pinch

    Science.gov (United States)

    Hedin, G.; Brzozowski, J. H.; Hörling, P.; Mazur, S.; Nordlund, P.; Drake, J. R.

    1996-05-01

    The effects of plasma collisionality on power balance and magnetic fluctuations have been studied on the Extrap T1 reversed-field pinch. A characteristic minimum in loop voltage is observed as the plasma collisionality decreases. The minimum is caused by an increase in the anomalous input power and coincides with a change of scaling of the magnetic fluctuations and a rapid increase of the electron mean free path. However, the increase of anomalous input power in the low collisional regime appears to have little influence on the total amount of energy stored in the plasma.

  13. Experimental Measurement of Asymmetric Fluctuations of Poloidal Magnetic Field in Damavand Tokomak at Different Plasma Currents

    Science.gov (United States)

    Moslehi-Fard, Mahmoud; Alinejad, Naser; Rasouli, Chapar; Sadigzadeh, Asghar

    2012-08-01

    Toroidal and Poloidal magnetic fields have an important effect on the tokomak topology. Damavand Tokomak is a small size tokomak characterized with k = 1.2, B t = 1T, R 0 = 36 cm, maximum plasma current is about 35 KA with a discharge time of 21 ms. In this experimental work, the variation of poloidal magnetic field on the torodial cross section is measured and analyzed. In order to measure the polodial magnetic field, 18 probes were installed on the edge of tokomak plasma with ∆θ = 18°, while a limiter was installed inside the torus. Plasma current, I p, induces a polodial magnetic field, B p, smaller than the torodial magnetic field B t. Magnetic lines B produced as a combination of B t and B p, are localized on the nested toroidal magnetic surfaces. The presence of polodial magnetic field is necessary for particles confinement. Mirnov oscillations are the fluctuations of polodial magnetic field, detected by magnetic probes. Disrupted instability in Tokomak typically starts with mirnov oscillations which appear as fluctuations of polodial magnetic field and is detected by magnetic probes. Minor disruptions inside the plasma can contain principal magnetic islands and their satellites can cause the annihilation of plasma confinement. Production of thin layer of turbulent magnetic field lines cause minor disruption. Magnetic limiter may cause the deformation of symmetric equilibrium configuration and chaotic magnetic islands reveal in plasma occurring in thin region of chaotic field lines close to their separatrix. The width of this chaotic layer in the right side of poloidal profile of Damavand Tokomak is smaller than the width in the left side profile because of Shafranov displacement. Ergodic region in the left side of profile develops a perturbation on the magnetic polodial field lines, B p, that are greater in magnitude than that in the right side, although the values of B p on the left side are smaller than that on the right side of the profile. The Left

  14. Fluctuations in the interplanetary electric potential and energy coupling between the solar-wind and the magnetosphere

    CERN Document Server

    Badruddin,

    2013-01-01

    We utilize solar rotation average geomagnetic index ap and various solar wind plasma and field parameters for four solar cycles 20-23. We perform analysis to search for a best possible coupling function at 27-day time resolution. Regression analysis using these data at different phases of solar activity (increasing including maximum/decreasing including minimum) led us to suggest that the time variation of interplanetary electric potential is a better coupling function for solar wind-magnetosphere coupling. We suspect that a faster rate of change in interplanetary electric potential at the magnetopause might enhance the reconnection rate and energy transfer from the solar wind into the magnetosphere. The possible mechanism that involves the interplanetary potential fluctuations in influencing the solar wind-magnetosphere coupling is being investigated.

  15. Fluctuation in Plasma 5-Fluorouracil Concentration During Continuous 5-Fluorouracil Infusion for Colorectal Cancer.

    Science.gov (United States)

    Matsumoto, Hideo; Okumura, Hideo; Murakami, Haruaki; Kubota, Hisako; Higashida, Masaharu; Tsuruta, Atsushi; Tohyama, Kaoru; Hirai, Toshihiro

    2015-11-01

    It is generally believed that the plasma concentration of 5-fluorouracil (5-FU) is constant when 5-FU is continually administered for chemotherapy. The aim of the present study was to verify whether this is true. Nine patients with colorectal cancer were enrolled in this study. All patients received chemotherapy; four patients received FOLFIRI (leucovorin, 5-fluorouracil, irinotecan) and five received FOLFOX (leucovorin, 5-fluorouracil, oxaliplatin). 5-FU was administered continuously (2400 mg/m(2)) for 46 h. Serum was collected at 12 points after the start of administration. The concentration of 5-FU was evaluated using a new immunoassay method and gas chromatography-mass spectrometric (GC/MS) method. The concentrations of 5-FU fluctuated dramatically over time, with greater than 3-fold changes in each individual, and the pattern was not constant. Because the serum concentration of 5-FU fluctuates and displays various patterns, the dosage should not be based on body surface area. A new individualized method for determining the 5-FU dosage should be developed. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  16. Fluctuation Analysis of Redox Potential to Distinguish Microbial Fe(II) Oxidation

    Science.gov (United States)

    Enright, A. M. L.; Ferris, F. G.

    2016-11-01

    We developed a novel method for distinguishing abiotic and biological iron oxidation in liquid media using oxidation-reduction (redox) potential time series data. The instrument and processing algorithm were tested by immersing the tip of a Pt electrode with an Ag-AgCl reference electrode into an active iron-oxidizing biofilm in a groundwater discharge zone, as well as in two abiotic systems: a killed sample and a chemical control from the same site. We used detrended fluctuation analysis to characterize average root mean square fluctuation behavior, which was distinct in the live system. The calculated α value scaling exponents determined by detrended fluctuation analysis were significantly different at p < 0.001. This indicates that time series of electrode response data may be used to distinguish live and abiotic chemical reaction pathways. Due to the simplicity, portability, and small size, it may be suitable for characterization of extraterrestrial environments where water has been observed, such as Mars and Europa.

  17. Dust-lower-hybrid instability with fluctuating charge in quantum plasmas

    Science.gov (United States)

    Jamil, M.; Ali, M.; Rasheed, A.; Zubia, K.; Salimullah, M.

    2015-03-01

    The instability of Dust-Lower-Hybrid (DLH) wave is examined in detail in the uniform dusty magnetoplasmas. The time dependent charging effects on dust particles around its equilibrium charge Qd0 are taken into account based on Orbit-Limited Probe theory. The quantum characteristics of the system like Bohm potential and Fermi degenerate pressure are dealt using the quantum hydrodynamic model of plasmas. The external magnetic field and size of the dust particles have new physical effects over the dissipative instability of DLH wave in the quantum plasma regime.

  18. Dust-lower-hybrid instability with fluctuating charge in quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, M. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Ali, M. [Department of Physics, School of Natural Sciences, NUST, Islamabad 44000 (Pakistan); Rasheed, A. [Department of Physics, GC University, Faisalabad 38000 (Pakistan); Zubia, K. [Department of Physics, GC University, Lahore 54000 (Pakistan); Salimullah, M. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)

    2015-03-15

    The instability of Dust-Lower-Hybrid (DLH) wave is examined in detail in the uniform dusty magnetoplasmas. The time dependent charging effects on dust particles around its equilibrium charge Q{sub d0} are taken into account based on Orbit-Limited Probe theory. The quantum characteristics of the system like Bohm potential and Fermi degenerate pressure are dealt using the quantum hydrodynamic model of plasmas. The external magnetic field and size of the dust particles have new physical effects over the dissipative instability of DLH wave in the quantum plasma regime.

  19. Ionization-potential depression and dynamical structure factor in dense plasmas

    Science.gov (United States)

    Lin, Chengliang; Röpke, Gerd; Kraeft, Wolf-Dietrich; Reinholz, Heidi

    2017-07-01

    The properties of a bound electron system immersed in a plasma environment are strongly modified by the surrounding plasma. The modification of an essential quantity, the ionization energy, is described by the electronic and ionic self-energies, including dynamical screening within the framework of the quantum statistical theory. Introducing the ionic dynamical structure factor as the indicator for the ionic microfield, we demonstrate that ionic correlations and fluctuations play a critical role in determining the ionization potential depression. This is, in particular, true for mixtures of different ions with large mass and charge asymmetry. The ionization potential depression is calculated for dense aluminum plasmas as well as for a CH plasma and compared to the experimental data and more phenomenological approaches used so far.

  20. Density Fluctuations in the Yukawa One Component Plasma: An accurate model for the dynamical structure factor

    CERN Document Server

    Mithen, James P; Crowley, Basil J B; Gregori, Gianluca

    2011-01-01

    Using numerical simulations, we investigate the equilibrium dynamics of a single component fluid with Yukawa interaction potential. We show that, for a wide range of densities and temperatures, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. Since the Yukawa potential can describe the ion-ion interactions in a plasma, the model has significant applicability for both analyzing and interpreting the results of x-ray scattering data from high power lasers and fourth generation light sources.

  1. On Improving Impedance Probe Plasma Potential Measurements

    Science.gov (United States)

    2014-02-21

    assumption of a collisionless, stationary Maxwellian plasma and are seen to work well in non -flowing plasmas of sufficient density. However, as plasma...collection area. For Maxwellian electrons, np = n exp(Vp-φp)/Te and so at low frequency from Eq. (1) above, the resistive component of the ac

  2. Measuring long wavelength plasma density fluctuations by CO2 laser scattering (abstract)

    Science.gov (United States)

    Evans, D. E.

    1985-05-01

    Long wavelength density fluctuations can be observed by scattering even with a probe beam of much shorter wavelength provided the scattering angle is small enough. This paper is concerned with experiments in which the scattering angle is comparable with the probe beam divergence so the scattered and incident radiation never achieve spatial separation. Under these circumstances, the role of diffraction is preeminent and Fourier optics methods are used to describe the propagation of the beam, which is taken to be TEM00 mode Gaussian. Interaction between the probe beam and the plasma disturbance is described by refraction and no appeal is made to explicit scattering theory. Analysis of the effect of a monochromatic wave disturbance confined to a plane perpendicular to the probe beam (a plane grating in effect) reveals oscillations at the wave frequency induced on the probe with an intensity varying over the beam profile in a regular pattern symmetric about the beam axis. Detail of the pattern depends on the wavelength of the disturbance, its direction, and its axial position relative to a local beam waist. These oscillations are readily identified as due to radiation scattered by the plasma wave into diffraction orders, beating with the unperturbed part of the beam. Indeed, it can be shown1 that Fourier optics plus refraction produce almost the same result as conventional scattering theory,2 the small discrepancy being traceable to the neglect in the latter of incident beam wavefront curvature. The results of the two approaches coincide in the Fraunhofer limit. Computations of this sort have been confirmed by experiments using transducer-driven waves in air3 and by plasma experiments where the same regular patterns are observed from spontaneous plasma waves.4,5 Calculation suggests and experiments have demonstrated6 that additional information, such as the absolute direction of wave propagation, can be deduced from phase, measured with a multichannel detector array

  3. Nematic fluctuations, fermiology and the pairing potential in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, Florian

    2015-08-18

    The thesis comprises a systematic study on the doping, temperature and momentum dependent electron dynamics in iron-based superconductors using inelastic light scattering. The observation of Bardasis-Schrieffer modes in the excitation spectrum of superconducting Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} is reported and the energy and symmetry dependence of the modes are analyzed. The analysis yields the identification of a strong subdominant component of the interaction potential V(k,k{sup '}). Strong nematic fluctuations are investigated in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. The nature of the fluctuations and the origin of nematicity in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} are identified.

  4. Influence of dust charge fluctuation and polarization force on radiative condensation instability of magnetized gravitating dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Prajapati, R.P., E-mail: prajapati_iter@yahoo.co.in; Bhakta, S.

    2015-10-30

    The influence of dust charge fluctuation, thermal speed and polarization force due to massive charged dust grains is studied on the radiative condensation instability (RCI) of magnetized self-gravitating astrophysical dusty (complex) plasma. The dynamics of the charged dust and inertialess electrons are considered while the Boltzmann distributed ions are assumed to be thermal. The dusty fluid model is formulated and the general dispersion relations are derived analytically using the plane wave solutions under the long wavelength limits in both the presence and the absence of dust charge fluctuations. The combined effects of polarization force, dust thermal speed, dust charge fluctuation and dust cyclotron frequency are observed on the low frequency wave modes and radiative modified Jeans Instability. The classical criterion of RCI is also derived which remains unaffected due to the presence of these parameters. Numerical calculations have been performed to calculate the growth rate of the system and plotted graphically. We find that dust charge fluctuation, radiative cooling and polarization force have destabilizing while dust thermal speed and dust cyclotron frequency have stabilizing influence on the growth rate of Jeans instability. The results have been applied to understand the radiative cooling process in dusty molecular cloud when both the dust charging and polarization force are dominant. - Highlights: • We study combined influence of dust charge fluctuation and polarization force on RCI of dusty plasma. • The modified dispersion characteristics and conditions of Jeans and radiative instabilities are obtained. • In the photo-association region various parameters are numerically estimated. • The dust charge fluctuation, radiative cooling and polarization force have destabilizing influence on the growth rate.

  5. Double Layers: Potential Formation and Related Nonlinear Phenomena in Plasmas: Proceedings of the 5th Symposium

    Science.gov (United States)

    Iizuka, S.

    1998-02-01

    Potential Modification Due to C60- Production * Modifications of the Floating Potential and the Plasma Potential in a C60 Plasma * Properties of Strongly Electronegative Plasma Produced at Afterglow of Electron Cyclotron Resonance Chlorine Plasma * 2.2 Particle Accelerations * Potential Structures Due to an Electron Beam-Excited Localized HF-Discharge (Invited) * Experiments and Computer Simulations of Electric Field Spikes in Electron Beam-Plasma Interaction * Magnetosonic Waves in Multi-Ion-Species Plasmas: Nonlinear Evolution and Ion Acceleration * Observation of Repetitive Electric Field Pulses Accompanying a Short Wave Train Near the Lower Hybrid Frequency in a High-Voltage Linear Plasma Discharge * Control of Potential Profile and Energy Transport to Machine Ends along Open Magnetic Field Lines in a Tandem Mirror * Observation of Ion Acceleration in Picosecond Laser Produced Plasma Expanding across a Magnetic Field * Pellet Ablation Characteristics and the Effect on the Potential in Toroidal Plasmas (Invited) * CHAPTER 3: CROSS-FIELD ELECTRIC FIELDS, VELOCITY SHEAR, AND VORTEX FORMATION * 3.1 Cross-Field Potential Structures * Laboratory Simulation of Transverse Magnetic Field Effects on Dynamics of Plasma Streams in Magnetosphere * Double-Layer-like and Sheath-like Potential Structures across Magnetic Field Lines * Relaxation of Virtual Cathode Oscillations due to Transverse Effects in a Crossed-Field Diode * Control of Radial Potential Profile and Related Low-Frequency Fluctuations in an ECR-Produced Plasma * Potential Formation in Magnetized Dusty Plasma * Potential Measurement Using Electrostatic Probe in Tokamak Boundary Plasma * Studies on Radial Electric Field and Confinement in Toroidal Plasmas (Invited) * 3.2 Velocity Shear * Space Chamber Investigations of Transverse Velocity Shear Driven Plasma Waves * Observations of the Velocity-Shear-Driven Instability in a Sodium Plasma (Invited) * The Effect of Negative Ions and Neutral Particle Collisions on the

  6. Parameters influencing plasma column potential in a reflex discharge

    Science.gov (United States)

    Liziakin, G. D.; Gavrikov, A. V.; Murzaev, Y. A.; Usmanov, R. A.; Smirnov, V. P.

    2016-12-01

    Distribution of electrostatic potential in direct current reflex discharge plasma has been studied experimentally. Measurements have been conducted by the single floating probe method. The influence of 0-0.2 T magnetic field, 1-200 mTorr pressure, 0-2 kV discharge voltage, and electrodes geometry on plasma column electrostatic potential was investigated. The possibility for the formation of a preset potential profile required for the realization of plasma separation of spent nuclear fuel was demonstrated.

  7. The influence of the local volume fluctuations on the equation-of-state of hot and dense plasmas

    Science.gov (United States)

    Salzmann, David; Fisher, Dima; Barshalom, Avraham; Oreg, Joseph

    2008-04-01

    Generally, equation-of-state (EOS) of hot and dense plasmas is computed under the assumption that there is a constant volume available to every ion/atom in the plasma. In the present paper we combined two recently developed models to evaluate the influence of local density fluctuations around the ions on the corresponding EOS. The first of these is the so-called Ion Ellipsoid Model (IEM). IEM assumes that the local volume of the ion is a 3-dimensional ellipsoidal enclosure. Full description of the model is given in Ref. [1]. From IEM semi-empirical formulas were derived for the ions volume distribution function [1] for 0INFERNO models to calculate opacities and EOS on the same footing. We will describe the model and present preliminary results indicating the effect of the volume fluctuations around the ions on EOS results.

  8. Radial profile measurements of plasma pressure-like fluctuations with the heavy ion beam diagnostic on the tokamak ISTTOK

    Energy Technology Data Exchange (ETDEWEB)

    Henriques, R. B., E-mail: rhenriques@ipfn.ist.utl.pt; Malaquias, A.; Nedzelskiy, I. S.; Silva, C.; Coelho, R.; Figueiredo, H.; Fernandes, H. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2014-11-15

    The Heavy Ion Beam Diagnostic (HIBD) on the tokamak ISTTOK (Instituto Superior Técnico TOKamak) has been modified, in terms of signal conditioning, to measure the local fluctuations of the n{sub e}σ{sub 1,2}(T{sub e}) product (plasma density times the effective ionization cross-section) along the tokamak minor diameter, in 12 sample volumes in the range of −0.7a < r < 0.7a, with a maximum delay time of 1 μs. The corresponding signals show high correlation with the magnetic Mirnov coils in the characteristic MHD frequency range of ISTTOK plasmas and enable the identification of tearing modes. This paper describes the HIBD signal conditioning system and presents a preliminary analysis of the radial profile measurements of local n{sub e}σ{sub 1,2}(T{sub e}) fluctuations.

  9. The Role of Higher-Order Modes on the Electromagnetic Whistler-Cyclotron Wave Fluctuations of Thermal and Non-Thermal Plasmas

    Science.gov (United States)

    Vinas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto; Araneda, Jamie A.

    2014-01-01

    Two fundamental challenging problems of laboratory and astrophysical plasmas are the understanding of the relaxation of a collisionless plasmas with nearly isotropic velocity distribution functions and the resultant state of nearly equipartition energy density with electromagnetic plasma turbulence. Here, we present the results of a study which shows the role that higher-order-modes play in limiting the electromagnetic whistler-like fluctuations in a thermal and non-thermal plasma. Our main results show that for a thermal plasma the magnetic fluctuations are confined by regions that are bounded by the least-damped higher order modes. We further show that the zone where the whistler-cyclotron normal modes merges the electromagnetic fluctuations shifts to longer wavelengths as the beta(sub e) increases. This merging zone has been interpreted as the beginning of the region where the whistler-cyclotron waves losses their identity and become heavily damped while merging with the fluctuations. Our results further indicate that in the case of nonthermal plasmas, the higher-order modes do not confine the fluctuations due to the effective higher-temperature effects and the excess of suprathermal plasma particles. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic bi-Maxwellian and Tsallis-kappa-like magnetized electron-proton plasma. Our results indicate that the spontaneously emitted electromagnetic fluctuations are in fact enhanced over these quasi modes suggesting that such modes play an important role in the emission and absorption of electromagnetic fluctuations in thermal or quasi-thermal plasmas.

  10. (Quasi-)collisional Magneto-optic Effects in Collisionless Plasmas with sub-Larmor-scale Electromagnetic Fluctuations

    CERN Document Server

    Keenan, Brett D; Medvedev, Mikhail V

    2015-01-01

    High-amplitude, chaotic/turbulent electromagnetic fluctuations are ubiquitous in high-energy-density laboratory and astrophysical plasmas, where they can be excited by various kinetic-streaming and/or anisotropy-driven instabilities, such as the Weibel instability. These fields typically exist on "sub-Larmor scales" -- scales smaller than the electron Larmor radius. Electrons moving through such magnetic fields undergo small-angle stochastic deflections of their pitch-angles, thus establishing diffusive transport on long time-scales. We show that this behavior, under certain conditions, is equivalent to Coulomb collisions in collisional plasmas. The magnetic pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasicollisionality", may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified mag...

  11. Cross-diagnostic comparison of fluctuation measurements in a cylindrical argon plasma

    Science.gov (United States)

    Light, Adam; Chakraborty Thakur, Saikat; Tynan, George

    2016-10-01

    The advent of fast imaging diagnostics, which provide two-dimensional measurements on relevant plasma time scales, has proven invaluable for interpreting plasma dynamics in laboratory devices. Despite its success, imaging remains a qualitative aid for many studies, because intensity is difficult to map onto a single physical variable for use in a theoretical model. This work continues our exploration of the relationship between visible-light imaging and other diagnostics in the Controlled Shear Decorrelation Experiment (CSDX). CSDX is a well-characterized linear machine producing dense plasmas relevant to the tokamak edge (Te 5 eV, ne 1013 /cc). Visible light from ArI and ArII line emission is collected at high frame rates using a fast digital camera, floating potential and ion-saturation current are measured by an array of electrostatic probe tips, and average profiles of ion temperature and velocity are obtained using laser-induced fluorescence (LIF). We present a detailed comparison between these measurements, including temporal, spatial, and spectral properties in various operational regimes.

  12. On a theory of temporal fluctuations in the electrostatic potential structures associated with auroral arcs

    Science.gov (United States)

    Silevitch, M. B.

    1981-01-01

    A possible mechanism is presented for the generation of large-amplitude temporal fluctuations in the structure of the electron energization region associated with auroral arcs. The mechanism is based on the observation that the auroral arc system resembles a laboratory circuit consisting of the series connection of battery, resistance and a forward biased diode containing collisionless plasma in which large-amplitude relaxation oscillations are sometimes observed to be superimposed on the steady-state current. It is shown that in both the laboratory and auroral systems, in which a localized auroral arc dynamo, the ionosphere and the electron energization region are involved, the oscillations are controlled by the times for ions and electrons to traverse the acceleration region, which also characterize the low- and high-frequency structure of the fluctuating waveform. It is demonstrated that a plausible one-dimensional double-layer model of the auroral arc acceleration region exhibits the dynamic negative resistance necessary for the generation of oscillations by the present mechanism. Finally, consideration is given to two kinds of auroral phenomena which might be associated with the mechanism: the 10-Hz quasi-periodic flickering aurora and 10-Hz modulations in the intensity of electrostatic hydrogen cyclotron waves.

  13. New plasma measurements with a multichannel millimeter-wave fluctuation diagnostic system in the DIII-D tokamak (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Hillesheim, J. C.; Peebles, W. A.; Rhodes, T. L.; Schmitz, L.; Carter, T. A. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095-1547 (United States); White, A. E. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States)

    2010-10-15

    A novel multichannel, tunable Doppler backscattering (DBS)/reflectometry system has recently been developed and applied to a variety of DIII-D plasmas. Either DBS or reflectometry can be easily configured for use in a wide range of plasma conditions using a flexible quasi-optical antenna system. The multiple closely spaced channels, when combined with other fluctuation diagnostic systems, have opened up new measurements of plasma properties. For example, the toroidal and fine-scale radial structure of coherent plasma oscillations, such as geodesic acoustic modes, have been probed simultaneously in the core of high temperature plasmas by applying correlation analysis between two toroidally separated DBS systems, as well as within the multichannel array. When configured as a reflectometer, cross-correlation with electron cyclotron emission radiometry has uncovered detailed information regarding the crossphase relationship between density and temperature fluctuations. The density-temperature crossphase measurement yields insight into the physics of tokamak turbulence at a fundamental level that can be directly compared with predictions from nonlinear gyrokinetic simulations.

  14. New plasma measurements with a multichannel millimeter-wave fluctuation diagnostic system in the DIII-D tokamak (invited).

    Science.gov (United States)

    Hillesheim, J C; Peebles, W A; Rhodes, T L; Schmitz, L; White, A E; Carter, T A

    2010-10-01

    A novel multichannel, tunable Doppler backscattering (DBS)/reflectometry system has recently been developed and applied to a variety of DIII-D plasmas. Either DBS or reflectometry can be easily configured for use in a wide range of plasma conditions using a flexible quasi-optical antenna system. The multiple closely spaced channels, when combined with other fluctuation diagnostic systems, have opened up new measurements of plasma properties. For example, the toroidal and fine-scale radial structure of coherent plasma oscillations, such as geodesic acoustic modes, have been probed simultaneously in the core of high temperature plasmas by applying correlation analysis between two toroidally separated DBS systems, as well as within the multichannel array. When configured as a reflectometer, cross-correlation with electron cyclotron emission radiometry has uncovered detailed information regarding the crossphase relationship between density and temperature fluctuations. The density-temperature crossphase measurement yields insight into the physics of tokamak turbulence at a fundamental level that can be directly compared with predictions from nonlinear gyrokinetic simulations.

  15. Fluctuation signatures of rotation reversals and non-local transport events in KSTAR L-mode plasmas

    CERN Document Server

    Shi, Yuejiang

    2016-01-01

    Experiments in KSTAR tokamak show that non-local heat transport (NLT) is closely connected to toroidal rotation reversal. We demonstrate that NLT can be affected by electron cyclotron resonance heating (ECH), and the intrinsic rotation direction follows the changes of NLT. The cut-off density of NLT can be significantly extended by ECH. Without ECH, NLT disappears as the line averaged density ne increases above 1.25*10e19me-3. By applying ECH, NLT reappears with the ne= 2.4*10e19me-3. At the same density level, the core toroidal rotation also changes from counter-current to co-current direction by applying ECH. The poloidal flow of turbulence in core plasma estimated from MIR is in electron diamagnetic direction in ECH plasmas and ion diamagnetic direction in high density OH plasma. The auto-power spectra of density fluctuation measured by MIR are almost the same in the outer region for ECH and OH plasma. On the other hand, in the core region of ECH plasmas, the power spectra of the density fluctuations are b...

  16. Spectroscopic imaging of photopotentials and photoinduced potential fluctuations in a bulk heterojunction solar cell film.

    Science.gov (United States)

    Luria, Justin L; Hoepker, Nikolas; Bruce, Robert; Jacobs, Andrew R; Groves, Chris; Marohn, John A

    2012-11-27

    We present spatially resolved photovoltage spectra of a bulk heterojunction solar cell film composed of phase-separated poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFB) polymers prepared on ITO/PEDOT:PSS and aluminum substrates. Over both PFB- and F8BT-rich domains, the photopotential spectra were found to be proportional to a linear combination of the polymers' absorption spectra. Charge trapping in the film was studied using photopotential fluctuation spectroscopy, in which low-frequency photoinduced electrostatic potential fluctuations were measured by observing noise in the oscillation frequency of a nearby charged atomic force microscope cantilever. Over both F8BT- and PFB-rich regions, the magnitude, distance dependence, frequency dependence, and illumination wavelength dependence of the observed cantilever frequency noise are consistent with photopotential fluctuations arising from stochastic light-driven trapping and detrapping of charges in F8BT. Taken together, our findings suggest a microscopic mechanism by which intermixing of phases leads to charge trapping and thereby to suppressed open-circuit voltage and decreased efficiency in this prototypical bulk heterojunction solar cell film.

  17. Fluctuation pressure on a bio-membrane confined within a parabolic potential well

    Institute of Scientific and Technical Information of China (English)

    L. B. Freund

    2012-01-01

    A compliant bio-membrane with a nominally flat reference configuration is prone to random transverse deflections when placed in water,due primarily to the Brownian motion of the water molecules.On the average,these fluctuations result in a state of thermodynamic equilibrium between the entropic energy of the water and the total free energy of the membrane.When the membrane is in close proximity to a parallel surface,that surface restricts the fluctuations of the membrane which,in turn,results in an increase in its free energy.The amount of that increase depends on the degree of confinement,and the resulting gradient in free energy with degree of confinement implies the existence of a confining pressure.In the present study,we assume that the confinement is in the form of a continuous parabolic potential well resisting fluctuation.Analysis leads to a closed form expression for the mean pressure resulting from this confinement,and the results are discussed within the broader context of results in this area.In particular,the results provide insights into the roles of membrane stiffness,number of degrees of freedom in the model of the membrane and other system parameters.

  18. Bending and Focusing with Plasmas and Crystals - Potential and Challenges

    CERN Document Server

    Zimmermann, F

    2013-01-01

    This talk review the potential of plasmas and crystals for focusing and bending high-energy charged particle beams. It covers topics like plasma lenses, plasma wigglers, plasma dipoles, crystal channeling & reflection, radiation in crystals, crystal accelerators, crystalline beams and ultimate limitations. Past, ongoing or required R&D efforts are highlighted. Invited presentation at EuCARD'13 "Visions for the Future of Particle Accelerators," CERN, 11 June 2013.

  19. Dust ion-acoustic shock waves due to dust charge fluctuation in a superthermal dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Alinejad, H., E-mail: alinejad@nit.ac.ir [Department of Physics, Faculty of Basic Science, Babol University of Technology, Babol 47148-71167 (Iran, Islamic Republic of); Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Tribeche, M. [Plasma Physics Group, Faculty of Sciences – Physics, University of Bab-Ezzouar (Algeria); Mohammadi, M.A. [Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2011-11-14

    The nonlinear propagation of dust ion-acoustic (DIA) shock waves is studied in a charge varying dusty plasma with electrons having kappa velocity distribution. We use hot ions with equilibrium streaming speed and a fast superthermal electron charging current derived from orbit limited motion (OLM) theory. It is found that the presence of superthermal electrons does not only significantly modify the basic properties of shock waves, but also causes the existence of shock profile with only positive potential in such plasma with parameter ranges corresponding to Saturn's rings. It is also shown that the strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. -- Highlights: ► The presence of superthermal electrons causes the existence of shock waves with only positive potential. ► The strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. ► As the electrons evolve toward their thermodynamic equilibrium, the shock structures are found with smaller amplitude.

  20. 2D spatial profile measurements of potential fluctuation with heavy ion beam probe on the Large Helical Device

    Science.gov (United States)

    Shimizu, A.; Ido, T.; Nishiura, M.; Kato, S.; Ogawa, K.; Takahashi, H.; Igami, H.; Yoshimura, Y.; Kubo, S.; Shimozuma, T.

    2016-11-01

    Two-dimensional spatial profiles of potential fluctuation were measured with the heavy ion beam probe (HIBP) in the Large Helical Device (LHD). For 2D spatial profile measurements, the probe beam energy has to be changed, which requires the adjustment of many deflectors in the beam transport line to optimize the beam trajectory, since the transport line of LHD-HIBP system is long. The automatic beam adjustment system was developed, which allows us to adjust the beam trajectory easily. By analyzing coherence between potential fluctuation and magnetic probe signal, the noise level of the mode power spectrum of the potential fluctuation can be reduced. By using this method, the 2D spatial profile of potential fluctuation profile was successfully obtained.

  1. Effect of self-gravitation and dust-charge fluctuations on the shielding and energy loss of N×M projectiles in a collisional dusty plasma

    Science.gov (United States)

    Sarwar, M. Adnan; Mirza, Arshad M.

    2007-03-01

    A simple derivation of the electrostatic potential and energy loss of N×M test charge projectiles traveling through dusty plasma has been presented. The effect of dust-charge fluctuations, dust neutral collisions, and self-gravitation on the shielded potential and energy loss of charge projectiles has been investigated both analytically as well as numerically. An interference contribution of these projectiles to the shielded potential and energy loss has been observed, which depends upon their relative orientation and separation distance. A comparison has been made for correlated and uncorrelated motion of the two projectiles. The amplitude of the shielded potential is enhanced with the increase of dust Jeans frequency for separation less than the effective Debye length. The dust-charge fluctuations produce a potential well for a slow charge relaxation rate and energy is gained, not lost, by the test charge projectiles. However, a fast charge relaxation rate with a fixed value of Jeans frequency enhances the energy loss. The dust neutral collisions are also found to enhance the energy loss for the test charge velocities greater than the dust acoustic speeds. The present investigation might be useful to explain the coagulation of dust particles such as those in molecular clouds, the interstellar medium, comet tails, planetary rings, etc.

  2. Potential applications of an electron cyclotron resonance multicusp plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C.; Berry, L.A.; Gorbatkin, S.M.; Haselton, H.H.; Roberto, J.B.; Stirling, W.L. (Oak Ridge National Laboratory, Oak Ridge, TN (USA))

    1990-05-01

    An electron cyclotron resonance (ECR) multicusp plasmatron has been developed by feeding a multicusp bucket arc chamber with a compact ECR plasma source. This novel source produces large (about 25 cm diam), uniform (to within {plus minus}10%), dense ({gt}10{sup 11} cm{sup {minus}3}) plasmas of argon, helium, hydrogen, and oxygen. It has been operated to produce an oxygen plasma for etching 12.7 cm (5 in.) positive photoresist-coated silicon wafers with uniformity within {plus minus}8%. Results and potential applications of this new ECR plasma source for plasma processing of thin films are discussed.

  3. The Potential for Ambient Plasma Wave Propulsion

    Science.gov (United States)

    Gilland, James H.; Williams, George J.

    2016-01-01

    A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at

  4. Stochastic heating of a single Brownian particle by charge fluctuations in a radio-frequency produced plasma sheath.

    Science.gov (United States)

    Schmidt, Christian; Piel, Alexander

    2015-10-01

    The Brownian motion of a single particle in the plasma sheath is studied to separate the effect of stochastic heating by charge fluctuations from heating by collective effects. By measuring the particle velocities in the ballistic regime and by carefully determining the particle mass from the Epstein drag it is shown that for a pressure of 10 Pa, which is typical of many experiments, the proper kinetic temperature of the Brownian particle remains close to the gas temperature and rises only slightly with particle size. This weak effect is confirmed by a detailed model for charging and charge fluctuations in the sheath. A substantial temperature rise is found for decreasing pressure, which approximately shows the expected scaling with p(-2). The system under study is an example for non-equilibrium Brownian motion under the influence of white noise without corresponding dissipation.

  5. Progress Toward a Technique for Measuring Electric Field Fluctuations in Tokamak Core Plasmas

    Science.gov (United States)

    Thompson, D. S.; Bakken, M. R.; Burke, M. G.; Couto, H. P.; Fonck, R. J.; Lewicki, B. T.; Winz, G. R.

    2014-10-01

    Measurements of electric field fluctuations in magnetic confinement experiments are desired for validating turbulence and transport models. A new diagnostic to measure Ez (r , t) fluctuations is in development on the Pegasus Toroidal Experiment. The approach is based on neutral beam emission spectroscopy using a high-throughput, high-resolution spectrometer to resolve fluctuations in wavelength separation between components of the motional Stark effect spectrum. Fluctuations at mid-minor-radius, normalized to an estimated MSE field, are estimated to be δE /EMSE ~ 10-3. In order to resolve fluctuations at turbulent time scales (fNy ~ 500 kHz), beam and spectrometer designs minimize broadening and maximize signal-to-noise ratio. The diagnostic employs a Fabry-Pérot spectrometer with étendue-matched collection optics and low noise detectors. The interferometer spacing is varied across the face of the etalon to mitigate geometric Doppler broadening. An 80 keV H0 beam from PBX-M with a divergence Ω deployment on larger fusion facilities. Work supported by US DOE Grant DE-FG02-89ER53296.

  6. The shear viscosity of gauge theory plasma with chemical potentials

    CERN Document Server

    Benincasa, P; Naryshkin, R; Benincasa, Paolo; Buchel, Alex; Naryshkin, Roman

    2007-01-01

    We consider strongly coupled gauge theory plasma with conserved global charges that allow for a dual gravitational description. We study the shear viscosity of the gauge theory plasma in the presence of chemical potentials for these charges. Using gauge theory/string theory correspondence we prove that at large 't Hooft coupling the ratio of the shear viscosity to the entropy density is universal.

  7. The shear viscosity of gauge theory plasma with chemical potentials

    Science.gov (United States)

    Benincasa, Paolo; Buchel, Alex; Naryshkin, Roman

    2007-02-01

    We consider strongly coupled gauge theory plasma with conserved global charges that allow for a dual gravitational description. We study the shear viscosity of the gauge theory plasma in the presence of chemical potentials for these charges. Using gauge theory/string theory correspondence we prove that at large 't Hooft coupling the ratio of the shear viscosity to the entropy density is universal.

  8. Potential flux landscapes determine the global stability of a Lorenz chaotic attractor under intrinsic fluctuations.

    Science.gov (United States)

    Li, Chunhe; Wang, Erkang; Wang, Jin

    2012-05-21

    We developed a potential flux landscape theory to investigate the dynamics and the global stability of a chemical Lorenz chaotic strange attractor under intrinsic fluctuations. Landscape was uncovered to have a butterfly shape. For chaotic systems, both landscape and probabilistic flux are crucial to the dynamics of chaotic oscillations. Landscape attracts the system down to the chaotic attractor, while flux drives the coherent motions along the chaotic attractors. Barrier heights from the landscape topography provide a quantitative measure for the robustness of chaotic attractor. We also found that the entropy production rate and phase coherence increase as the molecular numbers increase. Power spectrum analysis of autocorrelation function provides another way to quantify the global stability of chaotic attractor. We further found that limit cycle requires more flux and energy to sustain than the chaotic strange attractor. Finally, by detailed analysis we found that the curl probabilistic flux may provide the origin of the chaotic attractor.

  9. Studies of Particle Wake Potentials in Plasmas

    Science.gov (United States)

    Ellis, Ian; Graziani, Frank; Glosli, James; Strozzi, David; Surh, Michael; Richards, David; Decyk, Viktor; Mori, Warren

    2011-10-01

    Fast Ignition studies require a detailed understanding of electron scattering, stopping, and energy deposition in plasmas with variable values for the number of particles within a Debye sphere. Presently there is disagreement in the literature concerning the proper description of these processes. Developing and validating proper descriptions requires studying the processes using first-principle electrostatic simulations and possibly including magnetic fields. We are using the particle-particle particle-mesh (PPPM) code ddcMD and the particle-in-cell (PIC) code BEPS to perform these simulations. As a starting point in our study, we examine the wake of a particle passing through a plasma in 3D electrostatic simulations performed with ddcMD and with BEPS using various cell sizes. In this poster, we compare the wakes we observe in these simulations with each other and predictions from Vlasov theory. Prepared by LLNL under Contract DE-AC52-07NA27344 and by UCLA under Grant DE-FG52-09NA29552.

  10. Potential applications of an electron cyclotron resonance multicusp plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C.; Berry, L.A.; Gorbatkin, S.M.; Haselton, H.H.; Roberto, J.B.; Schechter, D.E.; Stirling, W.L.

    1990-03-01

    An electric cyclotron resonance (ECR) multicusp plasmatron has been developed by feeding a multicusp bucket arc chamber with a compact ECR plasma source. This novel source produces large (about 25-cm- diam), uniform (to within {plus minus}10%), dense (>10{sup 11}--cm{sup {minus}3}) plasmas of argon, helium, hydrogen, and oxygen. It has been operated to produce an oxygen plasma for etching 12.7-cm (5-in.) positive photoresist-coated silicon wafers with uniformity within {plus minus}8%. Following a brief review of the large plasma source developed at Oak Ridge National Laboratory, the configuration and operation of the source are described and a discharge model is presented. Results from this new ECR plasma source and potential applications for plasma processing of thin films are discussed. 21 refs., 10 figs.

  11. Negative plasma potential relative to electron-emitting surfaces.

    Science.gov (United States)

    Campanell, M D

    2013-09-01

    Most works on plasma-wall interaction predict that with strong electron emission, a nonmonotonic "space-charge-limited" (SCL) sheath forms where the plasma potential is positive relative to the wall. We show that a fundamentally different sheath structure is possible where the potential monotonically increases toward a positively charged wall that is shielded by a single layer of negative charge. No ion-accelerating presheath exists in the plasma and the ion wall flux is zero. An analytical solution of the "inverse sheath" regime is demonstrated for a general plasma-wall system where the plasma electrons and emitted electrons are Maxwellian with different temperatures. Implications of the inverse sheath effect are that (a) the plasma potential is negative, (b) ion sputtering vanishes, (c) no charge is lost at the wall, and (d) the electron energy flux is thermal. To test empirically what type of sheath structure forms under strong emission, a full plasma bounded by strongly emitting walls is simulated. It is found that inverse sheaths form at the walls and ions are confined in the plasma. This result differs from past particle-in-cell simulation studies of emission which contain an artificial "source sheath" that accelerates ions to the wall, leading to a SCL sheath at high emission intensity.

  12. Characteristics of the NASA Lewis bumpy torus plasma generated with high positive or negative applied potentials

    Science.gov (United States)

    Roth, J. R.; Gerdin, G. A.

    1976-01-01

    The toroidal ring of plasma contained in the NASA Lewis bumpy-torus superconducting magnet facility may be biased to positive or negative potentials approaching 50 kilovolts by applying direct-current voltages of the respective polarity to 12 or fewer of the midplane electrode rings. The electric fields which are responsible for heating the ions by E/B drift then point radially outward or inward. The low-frequency fluctuations below the ion cyclotron frequency appeared to be dominated by rotating spokes.

  13. Effect of ion radiative cooling on Jeans instability of partially ionized dusty plasma with dust charge fluctuation

    Science.gov (United States)

    Sharma, Prerana; Patidar, Archana

    2017-01-01

    In this paper, the effect of ion radiative cooling on the gravitational instability of dusty plasma is studied, incorporating dust charge fluctuation with dust-neutral, neutral-ion, and ion-neutral collisions. The basic equations are linearized using normal mode analysis to obtain a general dispersion relation. The general dispersion relation is analytically and numerically discussed to explain the role of ion radiative cooling in the structure formation through gravitational instability. The Jeans collapse criteria are found to be modified due to ion and electron radiative cooling, dust charge fluctuations, and collisions effects. It is determined from the analytical and numerical calculations that the support of radiative cooling of ions drives thermal fluctuations and gives instability to the system. The electron cooling effect remains dominating over ion cooling effect, and thus, it enhances the collapse more efficiently than ion cooling effect. Although the radiative cooling is slow, it may precede the collapse in molecular cloud, which further leads to the structure formation. The present work is relevance for the structure formation in the molecular cloud.

  14. Higher order quark number fluctuations via imaginary chemical potentials in Nf=2 +1 QCD

    Science.gov (United States)

    D'Elia, Massimo; Gagliardi, Giuseppe; Sanfilippo, Francesco

    2017-05-01

    We discuss analytic continuation as a tool to extract the cumulants of the quark number fluctuations in the strongly interacting medium from lattice QCD simulations at imaginary chemical potentials. The method is applied to Nf=2 +1 QCD, discretized with stout improved staggered fermions, physical quark masses and the tree level Symanzik gauge action, exploring temperatures ranging from 135 up to 350 MeV and adopting mostly lattices with Nt=8 sites in the temporal direction. The method is based on a global fit of various cumulants as a function of the imaginary chemical potentials. We show that it is particularly convenient to consider cumulants up to order two, and that below Tc the method can be advantageous, with respect to a direct Montecarlo sampling at μ =0 , for the determination of generalized susceptibilities of order four or higher, and especially for mixed susceptibilities, for which the gain is well above one order of magnitude. We provide cumulants up to order eight, which are then used to discuss the radius of convergence of the Taylor expansion and the possible location of the second-order critical point at real μ : no evidence for such a point is found in the explored range of T and for chemical potentials within present determinations of the pseudocritical line.

  15. Linear response and modified fluctuation-dissipation relation in random potential

    Science.gov (United States)

    Sakuldee, Fattah; Suwanna, Sujin

    2015-11-01

    In this work, a physical system described by the Hamiltonian Hω=H0+Vω(t ) consisting of a solvable model H0 and external random and time-dependent potential Vω(t ) is investigated. Under the conditions in which, for each realization, the potential changes smoothly so that the evolution of the system follows the Schrödinger dynamics, and that the average external potential with respect to all realizations is constant in time, an adjusted equilibrium state can be defined as a reference state and the mean dynamics can be derived from taking the average of the equation with respect to the configuration parameter ω . It provides extra contributions from the deviations of the Hamiltonian and evolves the state along the time by the Heisenberg and Liouville-von Neumann equations. Consequently, the Kubo formula and the fluctuation-dissipation relation (FDR) are modified in the sense that the contribution from the information of randomness and memory effects from the time dependence is also present. The modified Kubo formula now has a contribution from two terms. The first term is an antisymmetric cross correlation between two observables measured by a probe as expected, and the latter term is an accumulation of the propagation of the effects from the randomness. When the considered system is in the adjusted equilibrium state at the time the measurement probe interacts, the latter contribution vanishes, and the standard FDR is recovered.

  16. Linear response and modified fluctuation-dissipation relation in random potential.

    Science.gov (United States)

    Sakuldee, Fattah; Suwanna, Sujin

    2015-11-01

    In this work, a physical system described by the Hamiltonian H(ω)=H(0)+V(ω)(t) consisting of a solvable model H(0) and external random and time-dependent potential V(ω)(t) is investigated. Under the conditions in which, for each realization, the potential changes smoothly so that the evolution of the system follows the Schrödinger dynamics, and that the average external potential with respect to all realizations is constant in time, an adjusted equilibrium state can be defined as a reference state and the mean dynamics can be derived from taking the average of the equation with respect to the configuration parameter ω. It provides extra contributions from the deviations of the Hamiltonian and evolves the state along the time by the Heisenberg and Liouville-von Neumann equations. Consequently, the Kubo formula and the fluctuation-dissipation relation (FDR) are modified in the sense that the contribution from the information of randomness and memory effects from the time dependence is also present. The modified Kubo formula now has a contribution from two terms. The first term is an antisymmetric cross correlation between two observables measured by a probe as expected, and the latter term is an accumulation of the propagation of the effects from the randomness. When the considered system is in the adjusted equilibrium state at the time the measurement probe interacts, the latter contribution vanishes, and the standard FDR is recovered.

  17. Awakening the potential of plasma acceleration

    CERN Multimedia

    Katarina Anthony

    2014-01-01

    Civil engineering has begun for the new AWAKE experiment, which looks to push the boundaries of particle acceleration. This proof-of-principle experiment will harness the power of wakefields generated by proton beams in plasma cells, producing accelerator gradients hundreds of times higher than those used in current RF cavities.   Civil engineering works are currently ongoing at the AWAKE facility. As one of CERN's accelerator R&D experiments, the AWAKE project is rather unique. Like all of CERN's experiments, AWAKE is a collaborative endeavour with institutes and organisations participating around the world. "But unlike fixed-target experiments, where the users take over once CERN has delivered the facility, in AWAKE, the synchronised proton, electron and laser beams provided by CERN are an integral part of the experiment," explains Edda Gschwendtner, CERN AWAKE project leader. "So, of course, CERN's involvement in the project goes well...

  18. Characteristics of nonlinear dust acoustic waves in a Lorentzian dusty plasma with effect of adiabatic and nonadiabatic grain charge fluctuation

    Directory of Open Access Journals (Sweden)

    Raicharan Denra

    2016-12-01

    Full Text Available In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.

  19. Measurement and interpretation of the velocity space correlation of a laboratory plasma fluctuation with laser induced fluorescence

    Science.gov (United States)

    Mattingly, S. W.; Berumen, J.; Chu, F.; Hood, R.; Skiff, F.

    2013-11-01

    A technique for probing velocity space correlations has been developed using laser-induced fluorescence. In this paper, a description of the experimental setup is given, with results to follow in a later publication. The experiment consists of a cylindrical plasma column 3 m long and radius ~ 0.25 cm, holding singly-charged argon ions (Ar II) with density n ~ 109 cm-3, Te ~ 5 eV, Ti,|| ~ .06 eV, and a 1 kG axial magnetic field. Two separate metastable lines are excited by single frequency lasers at 611 nm and 668 nm. These lasers may tune with a precision of .01 pm. The separate lasers are used to measure independent slices of the velocity distribution function. To confirm the velocity distribution and magnetic field, the Doppler-broadened, sigma-polarized Zeeman line for each transition is measured. With this, the absolute parallel component of ion velocity subject to LIF can be determined. The two separate lasers then give us a signal as a function of two separate parallel ion velocities. Two point correlation is used to reduce the noise floor on the plasma fluctuation. This fluctuation is then investigated as a function of the difference in velocity.

  20. Effects of solar wind ultralow-frequency fluctuations on plasma sheet electron temperature: Regression analysis with support vector machine

    Science.gov (United States)

    Wang, Chih-Ping; Kim, Hee-Jeong; Yue, Chao; Weygand, James M.; Hsu, Tung-Shin; Chu, Xiangning

    2017-04-01

    To investigate whether ultralow-frequency (ULF) fluctuations from 0.5 to 8.3 mHz in the solar wind and interplanetary magnetic field (IMF) can affect the plasma sheet electron temperature (Te) near geosynchronous distances, we use a support vector regression machine technique to decouple the effects from different solar wind parameters and their ULF fluctuation power. Te in this region varies from 0.1 to 10 keV with a median of 1.3 keV. We find that when the solar wind ULF power is weak, Te increases with increasing southward IMF Bz and solar wind speed, while it varies weakly with solar wind density. As the ULF power becomes stronger during weak IMF Bz ( 0) or northward IMF, Te becomes significantly enhanced, by a factor of up to 10. We also find that mesoscale disturbances in a time scale of a few to tens of minutes as indicated by AE during substorm expansion and recovery phases are more enhanced when the ULF power is stronger. The effect of ULF powers may be explained by stronger inward radial diffusion resulting from stronger mesoscale disturbances under higher ULF powers, which can bring high-energy plasma sheet electrons further toward geosynchronous distance. This effect of ULF powers is particularly important during weak southward IMF or northward IMF when convection electric drift is weak.

  1. Characteristics of nonlinear dust acoustic waves in a Lorentzian dusty plasma with effect of adiabatic and nonadiabatic grain charge fluctuation

    Science.gov (United States)

    Denra, Raicharan; Paul, Samit; Sarkar, Susmita

    2016-12-01

    In this paper, characteristics of small amplitude nonlinear dust acoustic wave have been investigated in a unmagnetized, collisionless, Lorentzian dusty plasma where electrons and ions are inertialess and modeled by generalized Lorentzian Kappa distribution. Dust grains are inertial and equilibrium dust charge is negative. Both adiabatic and nonadiabatic fluctuation of charges on dust grains have been taken under consideration. For adiabatic dust charge variation reductive perturbation analysis gives rise to a KdV equation that governs the nonlinear propagation of dust acoustic waves having soliton solutions. For nonadiabatic dust charge variation nonlinear propagation of dust acoustic wave obeys KdV-Burger equation and gives rise to dust acoustic shock waves. Numerical estimation for adiabatic grain charge variation shows the existence of rarefied soliton whose amplitude and width varies with grain charges. Amplitude and width of the soliton have been plotted for different electron Kappa indices keeping ion velocity distribution Maxwellian. For non adiabatic dust charge variation, ratio of the coefficients of Burger term and dispersion term have been plotted against charge fluctuation for different kappa indices. All these results approach to the results of Maxwellian plasma if both electron and ion kappa tends to infinity.

  2. Effect of Substrate Potential on Plasma Parameters of Magnetic Multicusp Plasma Source

    Science.gov (United States)

    Ueda, Yoshio; Goto, Masahiro

    1998-06-01

    The effect of substrate potential on plasmas produced in a magnetic multicusp plasma source has been studied experimentally. Plasma parameters such as electron temperature and plasma potential are estimated from electron energy distribution function numerically calculated from probe current-voltage characteristics. For a substrate potential of -150 V with respect to the source chamber, which is much lower than substrate floating potentials, the plasma parameters are not affected by the application of the potential. However, for the case where the substrate is shorted with the source chamber, the high energy component of electrons significantly decreases in comparison with the floating case leading to the reduction of electron temperature. In this case, plasma potential is positive with respect to the substrate to suppress electron loss but its absolute value is only of the order of electron temperature in eV, which is much lower than the potential between the plasma and the substrate in the floating case. This discharge mode could be advantageous in significantly reducing the ion impact energy to the substrate plate.

  3. The potential impact of turbulent velocity fluctuations on drizzle formation in Cumulus clouds in an idealized 2D setup

    CERN Document Server

    Andrejczuk, M; Blyth, A

    2015-01-01

    This article discusses a potential impact of turbulent velocity fluctuations of the air on a drizzle formation in Cumulus clouds. Two different representations of turbulent velocity fluctuations for a microphysics formulated in a Lagrangian framework are discussed - random walk model and the interpolation, and its effect on microphysical properties of the cloud investigated. Turbulent velocity fluctuations significantly enhances velocity differences between colliding droplets, especially those having small sizes. As a result drizzle forms faster in simulations including a representation of turbulence. Both representations of turbulent velocity fluctuations, random walk and interpolation, have similar effect on droplet spectrum evolution, but interpolation of the velocity does account for a possible anisotropy in the air velocity. All discussed simulations show relatively large standard deviation ($\\sim$1${\\mu}m$) of the cloud droplet distribution from the onset of cloud formation is observed. Because coalesen...

  4. Interaction potential of microparticles in a plasma: role of collisions with plasma particles.

    Science.gov (United States)

    Khrapak, S A; Ivlev, A V; Morfill, G

    2001-10-01

    The interaction potential of two charged microparticles in a plasma is studied. Violation of the plasma equilibrium around the dust particles due to plasma-particle inelastic collisions results in three effects: long-range (non-Yukawa) electrostatic repulsion, attraction due to ion shadowing, and attraction or repulsion due to neutral shadowing (depending on the sign of the temperature difference between the particle surface and neutral gas). An analytical expression for the total potential is obtained and compared with previous theoretical results. The relative contribution of these effects is studied in two limiting cases-an isotropic bulk plasma and the plasma sheath region. The results obtained are compared with existing experimental results on pair particle interaction. The possibility of the so-called dust molecule formation is discussed.

  5. The shear viscosity of gauge theory plasma with chemical potentials

    Energy Technology Data Exchange (ETDEWEB)

    Benincasa, Paolo [Department of Applied Mathematics, University of Western Ontario, London, Ontario N6A 5B7 (Canada); Buchel, Alex [Department of Applied Mathematics, University of Western Ontario, London, Ontario N6A 5B7 (Canada) and Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2J 2W9 (Canada)]. E-mail: abuchel@perimeterinstitute.ca; Naryshkin, Roman [Department of Applied Mathematics, University of Western Ontario, London, Ontario N6A 5B7 (Canada); Physics Department, Taras Shevchenko Kiev National University, Prosp. Glushkova 6, Kiev 03022 (Ukraine)

    2007-02-08

    We consider strongly coupled gauge theory plasma with conserved global charges that allow for a dual gravitational description. We study the shear viscosity of the gauge theory plasma in the presence of chemical potentials for these charges. Using gauge theory/string theory correspondence we prove that at large 't Hooft coupling the ratio of the shear viscosity to the entropy density is universal.

  6. Direct Measurement of the Phase Space Ion Fluctuation Spectrum of a Laboratory Plasma Using Two Independently Tunable Lasers

    Science.gov (United States)

    Mattingly, Sean; Berumen, Jorge; Chu, Feng; Hood, Ryan; Skiff, Fred

    2013-10-01

    A novel technique for probing velocity space correlations has been developed using laser-induced fluorescence. The experiment consists of a 3 m cylindrical plasma column of singly-charged Argon ions (Ar II) with density ~ 109 cm-3 , Te ~ 5 eV , Ti ~ . 06 eV , and a 1 kG axial magnetic field. Separate metastable lines of the Ar II ions are excited using two separate narrow bandwidth lasers. The LIF response from each laser is measured through an independently moveable periscope. These periscopes may be focused on the same localized region (~ 0 . 1 cm3) or separated to view different parts of the plasma simultaneously. By adjusting these lasers independently, one may measure a correlation function as a function of the difference in measured velocities. This measurement may be repeated for different periscope positions in the plasma to obtain a two-dimensional correlation function in space and velocity difference. This correlation is directly related to the fluctuation spectrum through a Fourier transform. Measurements of these correlations are reported and discussed. NSF DOE Grant DE-FG02-99ER54543.

  7. Excitation and Propagetion of Modified Fluctuation in a Toroidal Plasma in KT-5C Device

    Institute of Scientific and Technical Information of China (English)

    孙玄; 王之江; 陆荣华; 闻一之; 万树德; 俞昌旋; 刘万东; 王成; 潘阁生; 王文浩; 王俊

    2002-01-01

    Understanding the propagation of the turbulent perturbation in the tokamak edge plasma is an important issue to actively modify or control the turbulence, reduce the anomalous transport and improve plasma confmement. To realize active modification of the edge perturbation, a high dynamic output, broad-band, low-cost power amplifier is set up, and used to drive the active probes in the experiments on KT-5C Tokmak. By using small-size magnetic probes together with Langmiur probes, It is observed that the modified perturbation by the active probes with sufficiently driving power may spread with electrostatic mode, and electromagnetic mode as well.

  8. Transient plasma potential in pulsed dual frequency inductively coupled plasmas and effect of substrate biasing

    Science.gov (United States)

    Mishra, Anurag; Yeom, Geun Young

    2016-09-01

    An electron emitting probe in saturated floating potential mode has been used to investigate the temporal evolution of plasma potential and the effect of substrate RF biasing on it for pulsed dual frequency (2 MHz/13.56 MHz) inductively coupled plasma (ICP) source. The low frequency power (P2MHz) has been pulsed at 1 KHz and a duty ratio of 50%, while high frequency power (P13.56MHz) has been used in continuous mode. The substrate has been biased with a separate bias power at (P12.56MHz) Argon has been used as a discharge gas. During the ICP power pulsing, three distinct regions in a typical plasma potential profile, have been identified as `initial overshoot', pulse `on-phase' and pulse `off-phase'. It has been found out that the RF biasing of the substrate significantly modulates the temporal evolution of the plasma potential. During the initial overshoot, plasma potential decreases with increasing RF biasing of the substrate, however it increases with increasing substrate biasing for pulse `on-phase' and `off-phase'. An interesting structure in plasma potential profile has also been observed when the substrate bias is applied and its evolution depends upon the magnitude of bias power. The reason of the evolution of this structure may be the ambipolar diffusion of electron and its dependence on bias power.

  9. Marshall N. Rosenbluth Outstanding Doctoral Thesis Award Talk: Simultaneous Measurement of Electron Temperature and Density Fluctuations in the Core of DIII-D Plasmas

    Science.gov (United States)

    White, A. E.

    2009-11-01

    Multi-field fluctuation measurements provide opportunities for rigorous comparison between experiment and nonlinear gyrokinetic turbulence simulations. A unique set of diagnostics on DIII-D allows for simultaneous study of local, long-wavelength (0 < kθρs< 0.5) electron temperature and density fluctuations in the core plasma (0.4 < ρ< 0.8). Previous experiments in L-mode indicate that normalized electron temperature fluctuation levels (40 < f < 400,kHz) increase with radius from ˜0.4% at ρ= 0.5 to ˜2% at ρ=0.8, similar to simultaneously measured density fluctuations. Electron cyclotron heating (ECH) is used to increase Te, which increases electron temperature fluctuation levels and electron heat transport in the experiments. In contrast, long wavelength density fluctuation levels change very little. The different responses are consistent with increased TEM drive relative to ITG-mode drive. A new capability at DIII-D is the measurement of phase angle between electron temperature and density fluctuations using coupled correlation electron cyclotron emission radiometer and reflectometer diagnostics. Linear and nonlinear GYRO runs have been used to design validation experiments that focus on measurements of the phase angle. GYRO shows that if Te and ∇Te increase 50% in a beam-heated L-mode plasma (ρ=0.5), then the phase angle between electron temperature and density fluctuations decreases 30%-50% and electron temperature fluctuation levels increase a factor of two more than density fluctuations. Comparisons between these predictions and experimental results will be presented.

  10. Dust acoustic and drift waves in a non-Maxwellian dusty plasma with dust charge fluctuation

    Science.gov (United States)

    Zakir, U.; Haque, Q.; Imtiaz, N.; Qamar, A.

    2015-12-01

    > ) on the wave dispersion and instability are presented. It is found that the presence of the non-thermal electron and ion populations reduce the growth rate of the instability which arises due to the dust charging effect. In addition, the nonlinear vortex solutions are also obtained. For illustration, the results are analysed by using the dusty plasma parameters of Saturn's magnetosphere.

  11. SNS potential with exchange field in quantum dusty plasmas

    Science.gov (United States)

    Zeba, I.; Batool, Maryam; Khan, Arroj A.; Jamil, M.; Rozina, Ch

    2017-02-01

    The shielding potential of a static test charge is studied in quantum dusty plasmas. The plasma system consisting upon electrons, ions and negatively static charged dust species, is embedded in an ambient magnetic field. The modified equation of dispersion is derived using quantum hydrodynamic model (QHD) for magnetized plasmas. The quantum effects are inculcated through Fermi degenerate pressure, tunneling effect and exchange-correlation effects. The study of shielding is important to know the existence of the silence zones in space and astrophysical objects as well as crystal formation. The graphical description of the normalized potential depict the significance of the exchange and correlation effects arising through spin and other variables on the shielding potential.

  12. Screened Coulomb potential in a flowing magnetized plasma

    CERN Document Server

    Joost, Jan-Philip; Kählert, Hanno; Arran, Christopher; Bonitz, Michael

    2014-01-01

    The electrostatic potential of a moving dust grain in a complex plasma with magnetized ions is computed using linear response theory, thereby extending our previous work for unmagnetized plasmas [P. Ludwig et al., New J. Phys. 14, 053016 (2012)]. In addition to the magnetic field, our approach accounts for a finite ion temperature as well as ion-neutral collisions. Our recently introduced code \\texttt{Kielstream} is used for an efficient calculation of the dust potential. Increasing the magnetization of the ions, we find that the shape of the potential crucially depends on the Mach number $M$. In the regime of subsonic ion flow ($M1$ the magnetic field effectively suppresses the plasma wakefield.

  13. Solitary waves in a dusty plasma with charge fluctuation and dust size distribution and vortex like ion distribution

    Energy Technology Data Exchange (ETDEWEB)

    Roy Chowdhury, K. [Department of Physics, J.C.C. College, Kolkata 700 033 (India); Mishra, Amar P. [High Energy Physics Division, Department of Physics Jadavpur University, Kolkata 700 032 (India); Roy Chowdhury, A. [High Energy Physics Division, Department of Physics Jadavpur University, Kolkata 700 032 (India)

    2006-07-15

    A modified KdV equation is derived for the propagation of non-linear waves in a dusty plasma, containing N different dust grains with a size distribution and charge fluctuation with electrons in the background. The ions are assumed to obey a vortex like distribution due to their non-isothermal nature. The standard distribution for the dust size is a power law. The variation of the soliton width is studied with respect to normalized size of the dust grains. A numerical solution of the equation is done by considering the soliton solution of the modified KdV as the initial pulse. It shows considerable broadening of the pulse variation of width with {beta} {sub 1} is shown.

  14. Interaction potentials and thermodynamic properties of two component semiclassical plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T. S.; Moldabekov, Zh. A.; Ismagambetova, T. N. [Al-Farabi Kazakh National University, IETP, 71 al-Farabi Av., Almaty 050040 (Kazakhstan); Gabdullin, M. T. [Al-Farabi Kazakh National University, NNLOT, 71 al-Farabi Av., Almaty 050040 (Kazakhstan)

    2014-01-15

    In this paper, the effective interaction potential in two component semiclassical plasma, taking into account the long-range screening and the quantum-mechanical diffraction effects at short distances, is obtained on the basis of dielectric response function method. The structural properties of the semiclassical plasma are considered. The thermodynamic characteristics (the internal energy and the equation of state) are calculated using two methods: the method of effective potentials and the method of micropotentials with screening effect taken into account by the Ornstein-Zernike equation in the HNC approximation.

  15. Magnetic fluctuation behavior during the transition between quasi-single helicity and multi helicity states in the reversed-field pinch plasma

    Science.gov (United States)

    Yambe, Kiyoyuki; Sakakita, Hajime; Hirano, Yoichi; Koguchi, Haruhisa

    2016-11-01

    We measured the variation of magnetic and electrostatic fluctuations observed during the transition between the quasi-single helicity (QSH) and multi helicity (MH) states in the edge region of the Toroidal Pinch Experiment-Reversed eXperiment reversed-field pinch plasma [Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. The high-frequency magnetic fluctuations largely decrease at the start of the QSH state. During the QSH state, the toroidal and radial magnetic fluctuations slightly increase again between 12 and 18 kHz but the decrease in the poloidal magnetic fluctuation is maintained. The confinement of fast electrons may be improved in the period of the QSH state although the radial magnetic fluctuation increases between 12 and 18 kHz. It is suggested that the improved confinement of fast electrons may be obtained by the decrease in the fast radial magnetic fluctuation having the frequency higher than 20 kHz in the period of the QSH state. Contrarily, the transition from QSH to MH states occurs with the increase in the slow toroidal magnetic fluctuation having the frequency lower than 10 kHz. The QSH state may bring a good confinement of fast electrons by the reduced high-frequency magnetic fluctuation compared with the MH state.

  16. Measurements of Plasma Potential Distribution in Segmented Electrode Hall Thruster

    Energy Technology Data Exchange (ETDEWEB)

    Y. Raitses; D. Staack; N.J. Fisch

    2001-10-16

    Use of a segmented electrode placed at the Hall thruster exit can substantially reduce the voltage potential drop in the fringing magnetic field outside the thruster channel. In this paper, we investigate the dependence of this effect on thruster operating conditions and segmented electrode configuration. A fast movable emissive probe is used to measure plasma potential in a 1 kW laboratory Hall thruster with semented electrodes made of a graphite material. Relatively small probe-induced perturbations of the thruster discharge in the vicinity of the thruster exit allow a reasonable comparison of the measured results for different thruster configurations. It is shown that the plasma potential distribution is almost not sensitive to changes of the electrode potential, but depends on the magnetic field distribution and the electrode placement.

  17. Two Dimensional LIF Measurements and Potential Structure of Ion Beam Formation in an Argon Helicon Plasma

    Science.gov (United States)

    Aguirre, Evan; Scime, Earl; Good, Timothy

    2016-10-01

    We report 2-dimensional, spatially resolved observations of ion beam formation in an expanding helicon plasma. Previous studies found that a current free double layer (CFDL) spontaneously arises at low pressure, below 1 mT. We use Laser Induced Fluorescence (LIF), a non-perturbative diagnostic to measure the ion velocity distribution functions (IVDFs) of argon ions both parallel and perpendicular to the background magnetic field. We report ion beam formation as a function of the expansion chamber magnetic field (0-108 G). The ion beam appears peaked in the center of the expansion chamber and decays over a few centimeters radially. We also report the potential structure of the plasma obtained with a planar Langmuir probe. To obtain meaningful Langmuir probe measurements, averages of tens of current-voltage are needed to reduce the effects of large electrostatic fluctuations that arise in plasmas that generate ion beams. We report the dependence of density, electron temperature, and floating potential on radial and axial position in the expansion plume. NSF Award PHYS-1360278.

  18. Monte Carlo simulations of ionization potential depression in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stransky, M., E-mail: stransky@fzu.cz [Department of Radiation and Chemical Physics, Institute of Physics ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2016-01-15

    A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model.

  19. Effective potential kinetic theory for strongly coupled plasmas

    Science.gov (United States)

    Baalrud, Scott D.; Daligault, Jérôme

    2016-11-01

    The effective potential theory (EPT) is a recently proposed method for extending traditional plasma kinetic and transport theory into the strongly coupled regime. Validation from experiments and molecular dynamics simulations have shown it to be accurate up to the onset of liquid-like correlation parameters (corresponding to Γ ≃ 10-50 for the one-component plasma, depending on the process of interest). Here, this theory is briefly reviewed along with comparisons between the theory and molecular dynamics simulations for self-diffusivity and viscosity of the one-component plasma. A number of new results are also provided, including calculations of friction coefficients, energy exchange rates, stopping power, and mobility. The theory is also cast in the Landau and Fokker-Planck kinetic forms, which may prove useful for enabling efficient kinetic computations.

  20. A gedankenexperiment for anomalous diffusion in a charge-fluctuating dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Andreas, E-mail: kopp@physik.uni-kiel.de [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24118 Kiel (Germany); Shchekinov, Yuri A., E-mail: yus@sfedu.ru [Department of Physics, Southern Federal University, Rostov on Don 344090 (Russian Federation)

    2014-02-15

    possible prototype of anomalous diffusion. We discuss briefly possible implications to space and astrophysical dusty plasma. In particular, we show that in a plasma with polydisperse dust particles, a superposition of the three regimes of the anomalous diffusion can simultaneously come into play.

  1. Potential Barrier around an Emitting Body an a Plasma

    Science.gov (United States)

    Bruno, Antonio; Luca Delzanno, Gian; Sorasio, Gianfranco; Lapenta, Giovanni

    2005-10-01

    We present a self-consistent, kinetic theory for the charging and shielding of an object at rest in a collisionless plasma [1]. The body is an electron emitter according to thermionic emission, photoemission or secondary emission. The theory is formulated for positively charged bodies, derived under the assumption of spherical symmetry so that conservation of energy and angular momentum can be used to calculate the plasma distribution functions at any given point in phase space. Far away from the body the plasma is assumed unperturbed, described by a Maxwellian distribution function at rest. Thus, the unperturbed plasma acts as a source of particles balancing the absorptions from the body and a steady state is eventually reached. The theory is shown to be in good agreement with PIC simulations [1-2]. Further on, several cases (focusing on parameters typical of laboratory experiments) are presented for the three different emission mechanisms, showing that shielding potentials having an attractive well are possible for all of them.[1] G. L. Delzanno, A. Bruno, G. Sorasio, G. Lapenta, Phys. Plasmas 12, 062102 (2005).[2] G. L. Delzanno, G. Lapenta, M. Rosenberg, Phys. Rev. Lett. 92 (3), 035002 (2004).

  2. Spontaneous emission of Alfvénic fluctuations

    Science.gov (United States)

    Yoon, P. H.; López, R. A.; Vafin, S.; Kim, S.; Schlickeiser, R.

    2017-09-01

    Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvénic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvénic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed.

  3. Reduction in plasma potential by applying negative DC cathode bias in RF magnetron sputtering

    Science.gov (United States)

    Isomura, Masao; Yamada, Toshinori; Osuga, Kosuke; Shindo, Haruo

    2016-11-01

    We applied a negative DC bias voltage to the cathode of an RF magnetron sputtering system and successfully reduced the plasma potential in both argon plasma and hydrogen-diluted argon plasma. The crystallinity of the deposited Ge films is improved by increasing the negative DC bias voltage. It is indicated that the reduction in plasma potential is effective for reducing the plasma damage on deposited materials, caused by the electric potential between the plasma and substrates. In addition, the deposition rate is increased by the increased electric potential between the plasma and the cathode owing to the negative DC bias voltage. The present method successfully gives us higher speed and lower damage sputtering deposition. The increased electric potential between the plasma and the cathode suppresses the evacuation of electrons from the plasma and also enhances the generation of secondary electrons on the cathode. These probably suppress the electron loss from the plasma and result in the reduction in plasma potential.

  4. Investigation of potential fluctuating intra-unit cell magnetic order in cuprates by μ SR

    Science.gov (United States)

    Pal, A.; Akintola, K.; Potma, M.; Ishikado, M.; Eisaki, H.; Hardy, W. N.; Bonn, D. A.; Liang, R.; Sonier, J. E.

    2016-10-01

    We report low temperature muon spin relaxation (μ SR ) measurements of the high-transition-temperature (Tc) cuprate superconductors Bi2 +xSr2 -xCaCu2O8 +δ and YBa2Cu3O6.57 , aimed at detecting the mysterious intra-unit cell (IUC) magnetic order that has been observed by spin-polarized neutron scattering in the pseudogap phase of four different cuprate families. A lack of confirmation by local magnetic probe methods has raised the possibility that the magnetic order fluctuates slowly enough to appear static on the time scale of neutron scattering, but too fast to affect μ SR or nuclear magnetic resonance signals. The IUC magnetic order has been linked to a theoretical model for the cuprates, which predicts a long-range ordered phase of electron-current loop order that terminates at a quantum crictical point (QCP). Our study suggests that lowering the temperature to T ˜25 mK and moving far below the purported QCP does not cause enough of a slowing down of fluctuations for the IUC magnetic order to become detectable on the time scale of μ SR . Our measurements place narrow limits on the fluctuation rate of this unidentified magnetic order.

  5. Diurnal fluctuations of cocaine and potential precursors in leaves of Erythroxylum coca.

    Science.gov (United States)

    Johnson, E L

    1993-01-01

    Cocaine is abundant in leaves of Erythroxylum coca var. coca Lam. Consequently, cocaine and two of its early biosynthetic precursors were monitored for 24 h to determine whether they fluctuated diurnally. E. coca was grown under controlled environmental conditions in a growth chamber in soil at pH 3.5. After 17.5 months of growth, leaves not less than 35 days old were harvested every 2 and 4 h for 24 h for arginine, phenylalanine and cocaine content, respectively. The content of cocaine was determined by GC/MS and amino acid content by HPLC. Diurnal fluctuation of cocaine occurred during the 24 h cycle. Cocaine was highest in leaves of E. coca at 8 and 16 h where its content was 7.67 and 9.45 mg.g-1 dry weight, respectively. Arginine and phenylalanine in leaves of E. coca also displayed diurnal rhythmic patterns of fluctuation. The content of arginine declined from hours 6 to 12 and increased to the highest content at 13 h (21.8 mg.g-1 dry weight). Overall, phenylalanine content was lower than arginine, but had two peak periods of accumulation during the 24 h cycle, occurring at 8 and 14 h. The content of phenylalanine in leaves of E. coca during the peak hours was 6.98 and 6.54 mg.g-1 dry weight, respectively.

  6. Effective polarization interaction potentials of the partially ionized dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T S [IETP, Al Farabi Kazakh National University, Tole Bi 96a, 050012 Almaty (Kazakhstan); Dzhumagulova, K N [IETP, Al Farabi Kazakh National University, Tole Bi 96a, 050012 Almaty (Kazakhstan); Omarbakiyeva, Yu A [IETP, Al Farabi Kazakh National University, Tole Bi 96a, 050012 Almaty (Kazakhstan); Roepke, G [Institute of Physics, University of Rostock, D-18051 Rostock (Germany)

    2006-04-28

    The effective polarization interaction potential between charged and neutral particles is considered for a partially ionized plasma. This pseudopotential is deduced taking into account quantum-mechanical effects at short distances as well as screening effects at large distances. Furthermore, a cutoff radius is obtained using a modified effective-range theory. Explicit results for parameters describing the interaction of the atom with charged particles are given.

  7. Effects of auroral potential drops on plasma sheet dynamics

    Science.gov (United States)

    Xi, Sheng; Lotko, William; Zhang, Binzheng; Wiltberger, Michael; Lyon, John

    2016-11-01

    The reaction of the magnetosphere-ionosphere system to dynamic auroral potential drops is investigated using the Lyon-Fedder-Mobarry global model including, for the first time in a global simulation, the dissipative load of field-aligned potential drops in the low-altitude boundary condition. This extra load reduces the field-aligned current (j||) supplied by nightside reconnection dynamos. The system adapts by forcing the nightside X line closer to Earth, with a corresponding reduction in current lensing (j||/B = constant) at the ionosphere and additional contraction of the plasma sheet during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross polar cap potential and hemispheric field-aligned current are lower by approximately the ratio of the peak field-aligned potential drop to the cross polar cap potential (10-15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area-integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 RE. Effects on the nightside plasma sheet include (1) an average X line 4 RE closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn-dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector.

  8. Spectral fluctuation analysis of ionospheric inhomogeneities over Brazilian territory. Part I: Equatorial F-region plasma bubbles

    Science.gov (United States)

    Fornari, G.; Rosa, R. R.; de Meneses, F. C.; Muralikrishna, P.

    2016-11-01

    In this Part I of a more general paper on the analysis of ionospheric irregularities over Brazilian territory, we apply the Detrended Fluctuation Analysis (DFA) method to evaluate in situ equatorial F-region plasma bubbles events carried out with a sounding rocket over equatorial region in Brazil. The range of scaling exponents derived from the DFA technique are compared to previous results obtained using Power Spectral Density (PSD) technique (which is widely used in this area despite its recognized inaccuracy to analyze short series). The results obtained in this first part of our investigation, using DFA, also show a wide range of spectral index variation with standard deviation of the same order found from the previous application using PSD (σm ≫ 10 %). Therefore, since the dependence of the technique are disregarded, our findings also supports that the observed lack of a universality class characterized by the nonexistence of a single spectral index (with σm ≈ 2 %) may be due to non-homogeneity energy cascades that can appear in the incoherent ionospheric turbulent process.

  9. Space-time Evolution Of Quantum Fluctuations And Creation Of Quark- Gluon Plasma In Ultrarelativistic Nuclear Collisions

    CERN Document Server

    Surdutovich, Y

    1998-01-01

    We study the dynamics of quantum fluctuations which take place during the earliest stage of high-energy collision processes and the conditions under which the data from e– p deep- inelastic scattering(DIS) may serve as a guide for computing the initial data for heavy- ion collisions at high energies. Our method is essentially based on the space-time picture of these seemingly different phenomena. We analyze the inclusive quantum-mechanical measurements, in both cases, and derive the main results relying on causality. The main result is that the transition from the initial- state composite nuclei to the final-state dense system of quark-gluon fields, i.e. quark-gluon plasma, is possible only as a single quantum transition. We prove that the ultra-violet renormalization of virtual loops does not bring any scale into the problem. The scale appears only in connection with real processes of emission of quark and gluon fields and reveals itself through the collinear cut-off in the evolution equations. Thi...

  10. Detection of Plasma Fluctuations in White-light Images of the Outer Solar Corona: Investigation of the Spatial and Temporal Evolution

    Science.gov (United States)

    Telloni, D.; Ventura, R.; Romano, P.; Spadaro, D.; Antonucci, E.

    2013-04-01

    This work focuses on the first results from the identification and characterization of periodic plasma density fluctuations in the outer corona, observed in STEREO-A COR1 white-light image time series. A two-dimensional reconstruction of the spatial distribution and temporal evolution of the coronal fluctuation power has been performed over the whole plane of the sky, from 1.4 to 4.0 R ⊙. The adopted diagnostic tool is based on wavelet transforms. This technique, with respect to the standard Fourier analysis, has the advantage of localizing non-persistent fluctuating features and exploring variations of the relating wavelet power in both space and time. The map of the variance of the coronal brightness clearly outlines intermittent spatially coherent fluctuating features, localized along, or adjacent to, the strongest magnetic field lines. In most cases, they do not correspond to the visible coronal structures in the brightness maps. The results obtained provide a scenario in which the solar corona shows quasi-periodic, non-stationary density variations characterized by a wide range of temporal and spatial scales and strongly confined by the magnetic field topology. In addition, structures fluctuating with larger power are larger in size and evolve more slowly. The characteristic periodicities of the fluctuations are comparable to their lifetimes. This suggests that plasma fluctuations lasting only one or two wave periods and initially characterized by a single dominant periodicity either rapidly decay into a turbulent mixed flow via nonlinear interactions with other plasma modes, or they are damped by thermal conduction. The periodic non-stationary coronal fluctuations outlined by the closed field lines at low and mid latitudes might be associated with the existence of slow standing magneto-acoustic waves excited by the convective supergranular motion. The fluctuating ray-like structures observed along open field lines appear to be linked either to the

  11. Three-dimensional wake potential in a streaming dusty plasma

    Indian Academy of Sciences (India)

    M Salahuddin; M K Islam; A K Banerjee; M Salimullah; S K Ghosh

    2003-09-01

    The oscillatory wake potential for a slowly moving or static test dust particulate in a finite temperature, collisionless and unmagnetized dusty plasma with a continuous flow of ions and dust particles has been studied. The collective resonant interaction of the moving test particle with the low-frequency and low-phase-velocity dust-acoustic mode is the origin of the periodic attractive force between the like polarity particulates along and perpendicular to the streaming ions and dust grains resulting into dust-Coulomb crystal formation. This wake potential can explain the three-dimensional dust-Coulomb crystal formation in the laboratory conditions.

  12. Statically screened ion potential and Bohm potential in a quantum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Moldabekov, Zhandos [Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel (Germany); Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Str., 050040 Almaty (Kazakhstan); Schoof, Tim; Ludwig, Patrick; Bonitz, Michael [Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel (Germany); Ramazanov, Tlekkabul [Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Str., 050040 Almaty (Kazakhstan)

    2015-10-15

    The effective potential Φ of a classical ion in a weakly correlated quantum plasma in thermodynamic equilibrium at finite temperature is well described by the random phase approximation screened Coulomb potential. Additionally, collision effects can be included via a relaxation time ansatz (Mermin dielectric function). These potentials are used to study the quality of various statically screened potentials that were recently proposed by Shukla and Eliasson (SE) [Phys. Rev. Lett. 108, 165007 (2012)], Akbari-Moghanjoughi (AM) [Phys. Plasmas 22, 022103 (2015)], and Stanton and Murillo (SM) [Phys. Rev. E 91, 033104 (2015)] starting from quantum hydrodynamic (QHD) theory. Our analysis reveals that the SE potential is qualitatively different from the full potential, whereas the SM potential (at any temperature) and the AM potential (at zero temperature) are significantly more accurate. This confirms the correctness of the recently derived [Michta et al., Contrib. Plasma Phys. 55, 437 (2015)] pre-factor 1/9 in front of the Bohm term of QHD for fermions.

  13. A linear radio frequency plasma reactor for potential and current mapping in a magnetized plasma.

    Science.gov (United States)

    Faudot, E; Devaux, S; Moritz, J; Heuraux, S; Molina Cabrera, P; Brochard, F

    2015-06-01

    Langmuir probe measurements in front of high power ion cyclotron resonant frequency antennas are not possible or simply too noisy to be analyzed properly. A linear experiment is a radio frequency (RF) magnetized plasma discharge reactor designed to probe the rectified potential in front of such antennas but at low power level (1 kW) to next improve antenna design and mitigate sheath effects. The maximum magnetic field is 0.1 T, and the RF amplifier can work between 10 kHz and 250 MHz allowing ion cyclotron resonances for argon or helium. The first measurements with no magnetic field are presented here, especially 2D potential maps extracted from the RF compensated probe measurements yield ni ≈ 10(15) m(-3) and Te ≈ 2 eV for RF power lower than 100 W. Series resonances in the chamber are highlighted and allow to deduce the plasma parameters from a simple equivalent impedance model of the plasma in helium gas. Next studies will be focused on magnetized plasmas and especially magnetized RF sheaths.

  14. Laser Diagnostic Method for Plasma Sheath Potential Mapping

    Science.gov (United States)

    Walsh, Sean P.

    Electric propulsion systems are gaining popularity in the aerospace field as a viable option for long term positioning and thrusting applications. In particular, Hall thrusters have shown promise as the primary propulsion engine for space probes during interplanetary journeys. However, the interaction between propellant xenon ions and the ceramic channel wall continues to remain a complex issue. The most significant source of power loss in Hall thrusters is due to electron and ion currents through the sheath to the channel wall. A sheath is a region of high electric field that separates a plasma from a wall or surface in contact. Plasma electrons with enough energy to penetrate the sheath may result emission of a secondary electron from the wall. With significant secondary electron emission (SEE), the sheath voltage is reduced and so too is the electron retarding electric field. Therefore, a lower sheath voltage further increases the particle loss to the wall of a Hall thruster and leads to plasma cooling and lower efficiency. To further understand sheath dynamics, laser-induced fluorescence is employed to provide a non-invasive, in situ, and spatially resolved technique for measuring xenon ion velocity. By scanning the laser wavelength over an electronic transition of singly ionized xenon and collecting the resulting fluorescence, one can determine the ion velocity from the Doppler shifted absorption. Knowing the velocity at multiple points in the sheath, it can be converted to a relative electric potential profile which can reveal a lot about the plasma-wall interaction and the severity of SEE. The challenge of adequately measuring sheath potential profiles is optimizing the experiment to maximize the signal-to-noise ratio. A strong signal with low noise, enables high resolution measurements and increases the depth of measurement in the sheath, where the signal strength is lowest. Many improvements were made to reduce the background luminosity, increase the

  15. A stochastic mechanism for signal propagation in the brain: Force of rapid random fluctuations in membrane potentials of individual neurons.

    Science.gov (United States)

    Hong, Dawei; Man, Shushuang; Martin, Joseph V

    2016-01-21

    There are two functionally important factors in signal propagation in a brain structural network: the very first synaptic delay-a time delay about 1ms-from the moment when signals originate to the moment when observation on the signal propagation can begin; and rapid random fluctuations in membrane potentials of every individual neuron in the network at a timescale of microseconds. We provide a stochastic analysis of signal propagation in a general setting. The analysis shows that the two factors together result in a stochastic mechanism for the signal propagation as described below. A brain structural network is not a rigid circuit rather a very flexible framework that guides signals to propagate but does not guarantee success of the signal propagation. In such a framework, with the very first synaptic delay, rapid random fluctuations in every individual neuron in the network cause an "alter-and-concentrate effect" that almost surely forces signals to successfully propagate. By the stochastic mechanism we provide analytic evidence for the existence of a force behind signal propagation in a brain structural network caused by rapid random fluctuations in every individual neuron in the network at a timescale of microseconds with a time delay of 1ms.

  16. Two dimensional density and its fluctuation measurements by using phase imaging method in GAMMA 10

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, M.; Negishi, S.; Shima, Y.; Hojo, H.; Imai, T. [Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Mase, A. [Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Kogi, Y. [Fukuoka Institute of Technology, 3-30-1 Wajiro-higashi, Higashiku, Fukuoka 811-0295 (Japan)

    2010-10-15

    Two dimensional (2D) plasma image analysis is useful to study the improvement of plasma confinement in magnetically confined fusion plasmas. We have constructed a 2D interferometer system with phase imaging method for studying 2D plasma density distribution and its fluctuation measurement in the tandem mirror GAMMA 10. 2D profiles of electron density and its fluctuation have been successfully obtained by using this 2D phase imaging system. We show that 2D plasma density and fluctuation profiles clearly depends on the axial confining potential formation with application of plug electron cyclotron heating in GAMMA 10.

  17. Magnetic fluctuations can contribute to plasma transport, ''self-consistency constraints'' notwithstanding

    Energy Technology Data Exchange (ETDEWEB)

    Krommes, J.A.; Kim, Chang-Bae

    1987-09-01

    The recent conclusion that in a turbulent, collisionless plasma ''magnetic transport including quasilinear magnetic flutter transport ... does not contribute to the relaxation of (f), and thus is not responsible for electron energy or momentum transport'' is shown to be incorrect for a variety of situations of physical interest, including saturation by quasilinear plateau formation, induced scattering, and, most importantly, conventional mode coupling. The well-established theory of the mean infinitesimal response function and the spectral balance equation provides a unifying framework for understanding the above conclusion. In particular, the cancellations which lead to their conclusion are special cases of well-known relationships between the response function, particle propagator, and dielectric function. A more general, concise, and manifestly gauge-invariant algebraic derivation of the cancellations is given. Though the cancellations occur in a certain limit, these conclusions do not follow in general: The picture of steady-state turbulence as consisting of small-scale ''incoherent'' ballistic ''clumps'' shielded by long-wavelength ''coherent'' dielectric response is physically misleading and mathematically incomplete, as it ignores or mistreates the often dominant process of renormalized n-wave coupling. Thus, when ion nonlinearities are considered, formulas for the magnetic contribution to transport emerge which are quite similar to the quasilinear one. Furthermore, limits are possible in which all or part of the noise can be negligible, yet in which the total fluctuation spectrum remains finite. 56 refs.

  18. Plasma-potentiated small molecules—possible alternative to antibiotics?

    Science.gov (United States)

    Bazaka, Kateryna; Bazaka, Olha; Levchenko, Igor; Xu, Shuyan; Ivanova, Elena P.; Keidar, Michael; (Ken Ostrikov, Kostya

    2017-09-01

    The efficacy of the existing arsenal of antibiotics is continuously compromised by their indiscriminative and often excessive use. The antibiotic arsenal can be expanded with agents that have different mechanisms of activity to conventional drugs, such as plant-derived natural antimicrobial small molecules, yet these often lack sufficient activity and selectivity to fulfill the antibiotics requirements and conventional thermochemical methods of their transient activation may not be compatible with biomedical applications. Here, non-equilibrium conditions of atmospheric-pressure plasma are used for rapid, single-step potentiation of activity of select terpenes without the use of chemicals or heating. Substantial potentiation of activity against Staphylococcus aureus cells in planktonic and biofilm states is observed in both inherently antibacterial terpenes, e.g. terpinen-4-ol, and compounds generally considered to have limited effect against S. aureus, e.g. γ-terpinene. The improved biological activity may arise, at least in part, from the changes in the physico–chemical properties of the terpenes induced by plasma-generated chemical species and physical effects, such as electric fields and UV irradiation. This activation approach is generic, and thus can potentially be applied to other molecules and their mixtures in an effort to expand the range of effective antimicrobial agents for deactivation of pathogenic organisms in hygiene, medical and food applications.

  19. Interaction of deep levels and potential fluctuations in scattering and recombination phenomena in semi-insulating GaAs

    Science.gov (United States)

    Kažukauskas, V.; Storasta, J.; Vaitkus, J.-V.

    1996-08-01

    The complex influence of recombination centers and potential fluctuations of the band gap on the scattering and recombination phenomena in n-type semiinsulating liquid- encapsulated-Czochralski-grown GaAs were investigated by using the transient photoconductivity and photo-Hall effects. The inhomogeneities cause a hyperbolic decrease of nonequilibrium carrier concentration and the saturation of Hall mobility, while the exponential parts of the decay appear due to the recharge of deep levels. The mean recombination barrier heights of potential fluctuations were evaluated. We propose a complex ``island'' model of scattering and recombination centers, consisting of defect clusters and their associations around dislocations, surrounded by potential barriers. At low light intensities and at the temperatures below 330 K they are insulating for majority charge carriers, thus reducing an effective crystal volume and causing percolation transport effects. At the temperature higher than 330-360 K the main barrier of the island can be recharged or screened by nonequilibrium carriers and its fine barrier structure appears as an effective scatterer, causing a sharp decrease of the nonequilibrium Hall mobility. It was demonstrated that although doping with Sb reduce dislocation density, it can intensify the effect of smaller defects on transport phenomena.

  20. Scrape-off layer-induced beam density fluctuations and their effect on beam emission spectroscopy

    Science.gov (United States)

    Moulton, D.; Marandet, Y.; Tamain, P.; Dif-Pradalier, G.

    2015-07-01

    A statistical model is presented to calculate the magnitude of beam density fluctuations generated by a turbulent scrape-off layer (SOL). It is shown that the SOL can induce neutral beam density fluctuations of a similar magnitude to the plasma density fluctuations in the core, potentially corrupting beam emission spectroscopy measurements. The degree of corruption is quantified by combining simulations of beam and plasma density fluctuations inside a simulated measurement window. A change in pitch angle from the separatrix to the measurement window is found to reduce the effect of beam fluctuations, whose largest effect is to significantly reduce the measured correlation time.

  1. On the effect of electron temperature fluctuations on turbulent heat transport in the edge plasma of tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Baudoin, C.; Tamain, P.; Ciraolo, G.; Futtersack, R.; Gallo, A.; Ghendrih, P.; Nace, N.; Norscini, C. [CEA, IRFM, Saint-Paul-lez-Durance (France); Marandet, Y. [Aix-Marseille Universite, CNRS, PIIM, UMR 7345, Marseille (France)

    2016-08-15

    In this paper we study the impact of electron temperature fluctuations in a two-dimensional turbulent model. This modification adds a second linear instability, known as sheath-driven conducting-wall instability, with respect to the previous isothermal model only driven by the interchange instability. Non-linear simulations, backed up by the linear analysis, show that the additional mechanism can change drastically the dynamics of turbulence (scales, density-potential correlation, and statistical momentum). Moreover, its importance relatively to the interchange instability should be more significant in the private flux region than in the main scrape of layer. Its effect on heat transport is also investigated for different regimes of parameters, results show that both instabilities are at play in the heat transport. Finally, the sheath negative resistance instability could be responsible for the existence of corrugated heat flux profiles in the scrape-off layer leading to a multiple decay length. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Partial Charges in Periodic Systems: Improving Electrostatic Potential (ESP) Fitting via Total Dipole Fluctuations and Multiframe Approaches.

    Science.gov (United States)

    Gabrieli, Andrea; Sant, Marco; Demontis, Pierfranco; Suffritti, Giuseppe B

    2015-08-11

    Two major improvements to the state-of-the-art Repeating Electrostatic Potential Extracted Atomic (REPEAT) method, for generating accurate partial charges for molecular simulations of periodic structures, are here developed. The first, D-REPEAT, consists in the simultaneous fit of the electrostatic potential (ESP), together with the total dipole fluctuations (TDF) of the framework. The second, M-REPEAT, allows the fit of multiple ESP configurations at once. When both techniques are fused into one, DM-REPEAT method, the resulting charges become remarkably stable over a large set of fitting regions, giving a robust and physically sound solution to the buried atoms problem. The method capabilities are extensively studied in ZIF-8 framework, and subsequently applied to IRMOF-1 and ITQ-29 crystal structures. To our knowledge, this is the first time that this approach is proposed in the context of periodic systems.

  3. Effect of dust size distribution and dust charge fluctuation on dust ion-acoustic shock waves in a multi-ion dusty plasma

    Indian Academy of Sciences (India)

    WANG HONGYAN; ZHANG KAIBIAO

    2016-07-01

    The effects of dust size distribution and dust charge fluctuation of dust grains on the small but finite amplitude nonlinear dust ion-acoustic shock waves, in an unmagnetized multi-ion dusty plasma which contains negative ions, positive ions and electrons, are studied in this paper. A Burgers equation and its stationary solutions are obtained by using the reductive perturbation method. The analytical and numerical results show that the height with polynomial dust size distribution is larger than that of the monosized dusty plasmas with the same dustgrains, but the thickness in the case of different dust grains is smaller than that of the monosized dusty plasmas. Furthermore, the moving speed of the shock waves also depend on different dust size distributions.

  4. Detection of plasma fluctuations in white-light images of the outer solar corona: investigation of the spatial and temporal evolution

    CERN Document Server

    Telloni, D; Romano, P; Spadaro, D; Antonucci, E

    2013-01-01

    This work focus on the first results on the identification and characterization of periodic plasma density fluctuations in the outer corona, observed in STEREO-A COR1 white-light image time series. A 2D reconstruction of the spatial distribution and temporal evolution of the coronal fluctuation power has been performed over the whole plane of the sky, from 1.4 to 4.0 solar radii. The adopted diagnostic tool is based on wavelet transforms. This technique, with respect to the standard Fourier analysis, has the advantage of localizing non-persistent fluctuating features and exploring the variations of the relating wavelet power in both space and time. The map of the variance of the coronal brightness clearly outlines intermittent, spatially coherent fluctuating features, localized along, or adjacent to, the strongest magnetic field lines. In most cases they do not correspond to the coronal structures visible in the brightness maps. The results obtained provide a scenario in which the solar corona shows quasi-per...

  5. An oscillatory component of propagated fluctuation electric potential in lupine shoot

    Directory of Open Access Journals (Sweden)

    Zygmunt Hejnowicz

    2014-01-01

    Full Text Available Application of a drop of auxin solution to a cut surface on the petiole in lupine shoot elicits a travelling pulse of electric potential decrease. This pulse was simultaneously recorded by means of a DC amplifier and band-pass amplifier 0.1-100 Hz, both connected to the same exploring AgCl electrode driven into the stem. The DC record shows a pulse 20-80 mV in height of about 30 s duration at its height with smooth slopes. The band-pass amplifier shows one to a few pairs of spikes (negative and positive whose amplitude is at least of an order lower than that of the DC pulse. These spikes are interpreted as the action potential of certain excitable cells recorded in a "volume conductor". The pulse is interpreted as a wave of cooperative depolarization of excitable and a mass of inexcitable cells.

  6. Correlation between phonon and impurity scatterings, potential fluctuations and leakage conduction of graphene/n-type Si Schottky diodes

    Science.gov (United States)

    Lin, Yow-Jon

    2015-12-01

    A correlation between the temperature-dependent leakage conduction, phonon and impurity scatterings and potential fluctuations of graphene/n-type Si Schottky diodes is identified. For applying a sufficiently high reverse-bias voltage, the significantly increase in the leakage current density with voltage at low temperature is mainly the result of graphene's Fermi-energy shifts. However, the high-field saturating leakage current is observed at high temperature. This is because of the competition among the phonon and impurity scatterings. In the graphene film transferred onto the n-type Si substrate, the Femi energy level is lower and the phonon coupling is stronger, giving a stronger dependence in the carrier velocity with temperature and a weaker dependence in the leakage current density with reserve-bias voltage.

  7. Analysis of density fluctuations in the Tore Supra tokamak. Up-down asymmetries and limiter effect on plasma turbulence; Etude des fluctuations de density dans les plasmas du tokamak Tore Supra. Asymetries haut-bas et effet du limiteur sur la turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Fenzi, Ch

    1999-10-29

    In magnetic fusion devices, the optimisation of the power deposition profile on plasma facing components crucially depends on the heat diffusivity across the magnetic field fines, which is determined by the plasma edge turbulence. In this regard, spatial asymmetries of plasma edge turbulence are of great interest. In this work, we interest in up-down asymmetries of density fluctuations which are usually observed in Tore Supra, using a coherent light scattering experiment. It is shown that these asymmetries are correlated to the plasma edge geometrical configuration (plasma facing components, limiters). In fact, the plasma-limiter interaction induces locally in the plasma edge and the SOL (r/a > 0.9) an additional turbulence with short correlation length along the magnetic field fines, which spreads in the plasma core (0.9 {>=} r/a {>=} 0.5). The resultant up-down asymmetry weakly depends on density, increases with the edge safety factor, and inverts when the plasma current direction is reversed. Such up-down asymmetry observations bring strong impact on edge turbulence and transport models, which usually predict a ballooning of the turbulence in the high-field side but not an up-down asymmetry. A possible model is proposed here, based on the Kelvin Helmholtz instability. (author)

  8. Synaptic inhibition and excitation estimated via the time constant of membrane potential fluctuations

    DEFF Research Database (Denmark)

    Berg, Rune W.; Ditlevsen, Susanne

    2013-01-01

    and excitation and their confidence limits from single sweep trials. The estimates are based on the mean membrane potential, (V) , and the membrane time constant,τ. The time constant provides the total conductance (G = capacitance/τ) and is extracted from the autocorrelation of V. The synaptic conductances can....... The method gives best results if the synaptic input is large compared to other conductances, the intrinsic conductances have little or no time dependence or are comparably small, the ligand gated kinetics is faster than the membrane time constant, and the majority of synaptic contacts are electrotonically...

  9. Synaptic inhibition and excitation estimated via the time constant of membrane potential fluctuations.

    Science.gov (United States)

    Berg, Rune W; Ditlevsen, Susanne

    2013-08-01

    When recording the membrane potential, V, of a neuron it is desirable to be able to extract the synaptic input. Critically, the synaptic input is stochastic and nonreproducible so one is therefore often restricted to single-trial data. Here, we introduce means of estimating the inhibition and excitation and their confidence limits from single sweep trials. The estimates are based on the mean membrane potential, V, and the membrane time constant, τ. The time constant provides the total conductance (G = capacitance/τ) and is extracted from the autocorrelation of V. The synaptic conductances can then be inferred from V when approximating the neuron as a single compartment. We further employ a stochastic model to establish limits of confidence. The method is verified on models and experimental data, where the synaptic input is manipulated pharmacologically or estimated by an alternative method. The method gives best results if the synaptic input is large compared with other conductances, the intrinsic conductances have little or no time dependence or are comparably small, the ligand-gated kinetics is faster than the membrane time constant, and the majority of synaptic contacts are electrotonically close to soma (recording site). Although our data are in current clamp, the method also works in V-clamp recordings, with some minor adaptations. All custom made procedures are provided in Matlab.

  10. Influence of chain topology and bond potential on the glass transition of polymer chains simulated with the bond fluctuation model

    Energy Technology Data Exchange (ETDEWEB)

    Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), Senda del Rey 9, 28040 Madrid (Spain)], E-mail: jfreire@invi.uned.es

    2008-07-16

    The bond fluctuation model with a bond potential has been applied to investigation of the glass transition of linear chains and chains with a regular disposition of small branches. Cooling and subsequent heating curves are obtained for the chain energies and also for the mean acceptance probability of a bead jump. In order to mimic different trends to vitrification, a factor B gauging the strength of the bond potential with respect to the long-range potential (i.e. the intramolecular or intermolecular potential between indirectly bonded beads) has been introduced. (A higher value of B leads to a preference for the highest bond lengths and a higher total energy, implying a greater tendency to vitrify.) Different cases have been considered for linear chains: no long-range potential, no bond potential and several choices for B. Furthermore, two distinct values of B have been considered for alternate bonds in linear chains. In the case of the branched chains, mixed models with different values of B for bonds in the main chain and in the branches have also been investigated. The possible presence of ordering or crystallization has been characterized by calculating the collective light scattering function of the different samples after annealing at a convenient temperature below the onset of the abrupt change in the curves associated with a thermodynamic transition. It is concluded that ordering is inherited more efficiently in the systems with branched chains and also for higher values of B. The branched molecules with the highest B values in the main chain bonds exhibit two distinct transitions in the heating curves, which may be associated with two glass transitions. This behavior has been detected experimentally for chains with relatively long flexible branches.

  11. Plasma YKL-40: a potential new cancer biomarker?

    DEFF Research Database (Denmark)

    Johansen, Julia S; Schultz, Nicolai A; Jensen, Benny V

    2009-01-01

    tissue remodeling. Plasma levels of YKL-40 are elevated in a subgroup of patients with primary or advanced cancer compared with age-matched healthy subjects, but also in patients with many different diseases characterized by inflammation. Elevated plasma YKL-40 levels are an independent prognostic...... by inflammation. Large prospective, longitudinal clinical cancer studies are needed to determine if plasma YKL-40 is a new cancer biomarker, or is mainly a biomarker of inflammation....

  12. Sustained high plasma mannose less sensitive to fluctuating blood glucose in glycogen storage disease type Ia children

    NARCIS (Netherlands)

    Nagasaka, Hironori; Yorifuji, Tohru; Bandsma, Robert H. J.; Takatani, Tomozumi; Asano, Hisaki; Mochizuki, Hiroshi; Takuwa, Mayuko; Tsukahara, Hirokazu; Inui, Ayano; Tsunoda, Tomoyuki; Komatsu, Haruki; Hiejima, Eitaro; Fujisawa, Tomoo; Hirano, Ken-ichi; Miida, Takashi; Ohtake, Akira; Taguchi, Tadao; Miwa, Ichitomo

    2013-01-01

    Plasma mannose is suggested to be largely generated from liver glycogen-oriented glucose-6-phosphate. This study examined plasma mannose in glycogen storage disease type Ia (GSD Ia) lacking conversion of glucose-6-phosphate to glucose in the liver. We initially examined fasting-and postprandial 2 h-

  13. Tokamak Plasmas : Observation of floating potential asymmetry in the edge plasma of the SINP tokamak

    Indian Academy of Sciences (India)

    Krishnendu Bhattacharyya; N R Ray

    2000-11-01

    Edge plasma properties in a tokamak is an interesting subject of study from the view point of confinement and stability of tokamak plasma. The edge plasma of SINP-tokamak has been investigated using specially designed Langmuir probes. We have observed a poloidal asymmetry of floating potentials, particularly the top-bottom floating potential differences are quite noticeable, which in turn produces a vertical electric field (v). This v remains throughout the discharge but changes its direction at certain point of time which seems to depend on applied vertical magnetic field v).

  14. Higher order quark number fluctuations via imaginary chemical potentials in $N_f=2+1$ QCD

    CERN Document Server

    D'Elia, Massimo; Sanfilippo, Francesco

    2016-01-01

    We discuss analytic continuation as a tool to extract the cumulants of the quark number fluctuations in the strongly interacting medium from lattice QCD simulations at imaginary chemical potentials. The method is applied to $N_f = 2+1$ QCD, discretized with stout improved staggered fermions, physical quark masses and the tree level Symanzik gauge action, exploring temperatures ranging from 135 up to 350 MeV and adopting mostly lattices with $N_t = 8$ sites in the temporal direction. The method is based on a global fit of various cumulants as a function of the imaginary chemical potentials. We show that it is particularly convenient to consider cumulants up to order two, and that below $T_c$ the method can be advantageous, with respect to a direct Montecarlo sampling at $\\mu = 0$, for the determination of generalized susceptibilities of order four or higher, and especially for mixed susceptibilities, for which the gain is well above one order of magnitude. We provide cumulants up to order eight, which are then...

  15. Effects of Adiabatic Dust Charge Fluctuation and Particles Collisions on Dust-Acoustic Solitary Waves in Three-Dimensional Magnetized Dusty Plasmas

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-Hong; WEI Nan-Xia

    2009-01-01

    Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust gains and neutral gas particles (dust-neutral collisions), the dust-acoustic solitary waves in three-dimensional uniform dusty plasmas are investigated analytically. By using the reductive perturbation method, the Korteweg-de Vries (KdV) equation governing the dust-acoustic solitary waves is obtained. The present analytical results show that only rarefactive solitary waves exist in this system. It is also found that the effects of the wave vector along the z-direction, dust charge variation, collisional frequency, the plasma density, and temperature ratio can significantly influence the characteristics of low-frequency wave modes. Moreover, for the collisional dusty plasmas, there is a certain critical value μc of the plasma density ratio #, if μ < μc, the width of the waves increases with μ, otherwise the width of waves decreases with μ.

  16. Characteristics and potential applications of an ORNL microwave ECR multicusp plasma ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C.

    1990-01-01

    A new microwave electron cyclotron resonance (ECR) multicusp plasma ion source that has two ECR plasma production regions and uses multicusp plasma confinement has been developed at Oak Ridge National Laboratory. This source has been operated to produce uniform and dense plasma over large areas of 300 to 400 cm{sup 2} and could be scaled up to produce uniform plasma over 700 cm{sup 2} or larger. The plasma source has been operated with continuous argon gas feed and pulsed microwave power. The working gases used were argon, helium, hydrogen, and oxygen. The discharge initiation phenomena and plasma properties have been investigated and studied as functions of the discharge parameters. The discharge characteristics and a hypothetical discharge mechanism for this plasma source are described and discussed. Potential applications, including plasma and ion-beam sources for manufacturing advanced microelectronics, for space electric propulsion, and for fusion research, are discussed. 10 refs., 10 figs.

  17. Dusty plasma as a unique object of plasma physics

    Science.gov (United States)

    Norman, G. E.; Timofeev, A. V.

    2016-11-01

    The self-consistency and basic openness of dusty plasma, charge fluctuations, high dissipation and other features of dusty plasma system lead to the appearance of a number of unusual and unique properties of dusty plasma. “Anomalous” heating of dusty particles, anisotropy of temperatures and other features, parametric resonance, charge fluctuations and interaction potential are among these unique properties. Study is based on analytical approach and numerical simulation. Mechanisms of “anomalous” heating and energy transfer are proposed. Influence of charge fluctuations on the system properties is discussed. The self-consistent, many-particle, fluctuation and anisotropic interparticle interaction potential is studied for a significant range of gas temperature. These properties are interconnected and necessary for a full description of dusty plasmas physics.

  18. Potential applications of a new microwave ECR (electron cyclotron resonance) multicusp plasma ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C.

    1990-01-01

    A new microwave electron cyclotron resonance (ECR) multicusp plasma ion source using two ECR plasma production regions and multicusp plasma confinement has been developed at Oak Ridge National Laboratory. This source has been operated to produce uniform and dense plasmas over large areas of 300 to 400 cm{sup 2}. The plasma source has been operated with continuous argon gas feed and pulsed microwave power. The discharge initiation phenomena and plasma properties have been investigated and studied as functions of discharge parameters. Together with the discharge characteristics observed, a hypothetical discharge mechanism for this plasma source is reported and discussed. Potential applications, including plasma and ion-beam processing for manufacturing advanced microelectronics and for space electric propulsion, are discussed. 7 refs., 6 figs.

  19. Potential applications of a new microwave ECR multicusp plasma ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, C.C. (Fusion Energy Div., Oak Ridge National Lab., TN (USA))

    1991-05-01

    A new microwave electron cyclotron resonance (ECR) multicusp plasma ion source using two ECR plasma production regions and multicusp plasma confinement has been developed at Oak Ridge National Laboratory. This source has been operated to produce uniform and dense plasmas over large areas of 300-400 cm{sup 2}. The plasma source has been operated with continuous argon gas feed and pulsed microwave power. The discharge initiation phenomena and plasma properties have been investigated and studied as functions of discharge parameters. Together with the discharge characteristics observed, a hypothetical discharge mechanism for this plasma source is reported and discussed. Potential applications, including plasma and ion-beam processing for manufacturing advanced microelectronics and for space electric propulsion, are discussed. (orig.).

  20. Interwell Radiative Recombination in the Presence of Random Potential Fluctuations in GaAs/AlGaAs Biased Double Quantum Wells

    DEFF Research Database (Denmark)

    Timofeev, V.B.; Larionov, A.V.; Ioselevich, A.S.;

    1999-01-01

    The interwell luminescence (PL) of spatially separated e-h pairs exhibits systematic narrowing with temperature increase which are explained in terms of lateral thermo-activated tunneling of e-h pairs localized by random potential fluctuations (RPF). At critical temperatures the quasi-equilibrium...

  1. Edge Particle Flux with Temperature Fluctuation in the HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    CHENG Jun; YAN Long-Wen; HONG Wen-Yu; QIAN Jun; ZHAO Kai-Jun

    2007-01-01

    Electron temperature, density, plasma potential and their fluctuation profiles at edge plasmas are measured simultaneously with a reciprocating probe system in HL-2A. The analysis results of four-tip data indicate that the temperature fluctuation has relative amplitude of 10-15%, gives more contribution to particle flux in lower (0- 25 kHz) and higher frequency (50-250 kHz) ranges. The coherence between temperature fluctuation's and density or potential fluctuations implies that their coupling will impact anomalous transport. The measured diffusion coefficient is about three times of the Bohm diffusion coefficient when considering the temperature fluctuation. The particle flux with temperature fluctuation is discussed in HL-2A for the first time.

  2. On Floating Potential of Emissive Probes in a Partially-Magnetized Plasma

    Science.gov (United States)

    Raitses, Yevgeny; Kraus, Brian

    2016-10-01

    We compare measurements of plasma potential in a cross-field Penning discharge from two probes: swept biased Langmuir probe and floating emissive probe. The plasma potential was deduced from the first derivative of the Langmuir probe characteristic. In previous studies, the emissive and swept biased probes were placed at the channel exit of a Hall thruster (HT). Measurements showed that the emissive probe floats below the plasma potential, in agreement with conventional theories. However, recent measurements in the Penning discharge indicate a floating potential of a strongly-emitting hot probe above the plasma potential. In both probe applications, xenon plasmas have magnetized electrons and non-magnetized ions with similar plasma densities (1010 - 1011 cm-3) . Though their electron temperatures differ by an order of magnitude (Penning 5 eV, HT 50 eV), this difference cannot explain the difference in measurement values of the hot floating potential because both temperatures are much higher than the emitting wire. In this work, we investigate how the ion velocity and other plasma parameters affect this discrepancy between probe measurements of the plasma potential. This work was supported by DOE contract DE-AC02-09CH11466.

  3. Multiscale, Intermittent, Turbulent Fluctuations in Space Plasmas and Their Influence on the Interscale Behavior of the Space Environment

    Science.gov (United States)

    2012-06-26

    Belgium Institute of Spatial Aeronomy and Center of Excellence in Solar-Terrestrial Physics, 2010. Invited Lectures: 1. Invited Lecturer, (ROMA...NM 87545, USA 4Belgian Institute for Space Aeronomy , 1180 Brussels, Belgium 5Institute for Space Sciences, 077125 Bucharest, Romania 6Plasma and

  4. Weibel-mediated collisionless shocks in laser-irradiated dense plasmas: Prevailing role of the electrons in generating the field fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Ruyer, C., E-mail: charles.ruyer@polytechnique.edu; Gremillet, L., E-mail: laurent.gremillet@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Bonnaud, G. [CEA, Saclay, INSTN, F-91191 Gif-sur-Yvette (France)

    2015-08-15

    We present a particle-in-cell simulation of the generation of a collisionless strong shock in a dense plasma driven by an ultra-intense, plane-wave laser pulse. A linear theory analysis, based on a multi-waterbag model of the particle distributions, highlights the role of the laser-heated electrons in triggering the Weibel-like instability causing shock formation. It is demonstrated that the return-current electrons play a major role in the instability development as well as in the determination of the saturated magnetic field. By contrast, the ions are found of minor importance in driving the instability and the magnetic field fluctuations responsible for their isotropization. Finally, we show that a Weibel-mediated shock can also be generated by a focused laser pulse of large enough spot size.

  5. Weibel-mediated collisionless shocks in laser-irradiated dense plasmas: Prevailing role of the electrons in generating the field fluctuations

    Science.gov (United States)

    Ruyer, C.; Gremillet, L.; Bonnaud, G.

    2015-08-01

    We present a particle-in-cell simulation of the generation of a collisionless strong shock in a dense plasma driven by an ultra-intense, plane-wave laser pulse. A linear theory analysis, based on a multi-waterbag model of the particle distributions, highlights the role of the laser-heated electrons in triggering the Weibel-like instability causing shock formation. It is demonstrated that the return-current electrons play a major role in the instability development as well as in the determination of the saturated magnetic field. By contrast, the ions are found of minor importance in driving the instability and the magnetic field fluctuations responsible for their isotropization. Finally, we show that a Weibel-mediated shock can also be generated by a focused laser pulse of large enough spot size.

  6. Transport formulas for multi-component plasmas within the effective potential theory framework

    CERN Document Server

    Kagan, Grigory

    2016-01-01

    The recently proposed effective potential theory [Phys. Rev. Lett. 110, 235001 (2013)] allows evaluating transport in coupled plasmas with the well-developed formalisms for systems with binary collisions. To facilitate practical implementation of this concept in fluid models of multi-component plasmas, compact expressions for the transport coefficients in terms the generalized Coulomb logarithms are summarized from existing prescriptions. For weakly coupled plasmas, characterized by Debye-shielded Coulomb interaction potential, expressions become fully analytical. In coupled plasmas the generalized Coulomb logarithms need to be evaluated numerically. Routines implementing the described formalisms are included as supplemental material.

  7. Scattering of electromagnetic waves from a plasma: Enhanced ion acoustic fluctuations due to ion-ion two-stream instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Wahlund, J.E.; Opgenoorth, H.J.; Persson, M.A.L. (Swedish Institute of Space Physics, Uppsala (Sweden)); Mishin, E.V.; Volokitin, A.S. (IZMIRAN, Troitsk, Moscow Region (Russian Federation)); Forme, F.R.E. (CNRS/CRPE (France))

    1992-10-02

    The authors propose an explanation for ion acoustic line spectra which have been observed by the EISCAT and Millstone Hill radars in the topside auroral ionosphere. They show that such lines can be generated in plasmas which are unstable to the ion-ion two-stream instability. This mechanism has the advantage of explaining the observed phenomena, and being consistent with typical conditions in the topside ionosphere.

  8. Membrane potential modulates plasma membrane phospholipid dynamics and K-Ras signaling

    Science.gov (United States)

    Zhou, Yong; Wong, Ching-On; Cho, Kwang-jin; van der Hoeven, Dharini; Liang, Hong; Thakur, Dhananiay P.; Luo, Jialie; Babic, Milos; Zinsmaier, Konrad E.; Zhu, Michael X.; Hu, Hongzhen; Venkatachalam, Kartik; Hancock, John F.

    2015-01-01

    Plasma membrane depolarization can trigger cell proliferation, but how membrane potential influences mitogenic signaling is uncertain. Here, we show that plasma membrane depolarization induces nanoscale reorganization of phosphatidylserine and phosphatidylinositol 4,5-bisphosphate but not other anionic phospholipids. K-Ras, which is targeted to the plasma membrane by electrostatic interactions with phosphatidylserine, in turn undergoes enhanced nanoclustering. Depolarization-induced changes in phosphatidylserine and K-Ras plasma membrane organization occur in fibroblasts, excitable neuroblastoma cells, and Drosophila neurons in vivo and robustly amplify K-Ras–dependent mitogen-activated protein kinase (MAPK) signaling. Conversely, plasma membrane repolarization disrupts K-Ras nanoclustering and inhibits MAPK signaling. By responding to voltage-induced changes in phosphatidylserine spatiotemporal dynamics, K-Ras nanoclusters set up the plasma membrane as a biological field-effect transistor, allowing membrane potential to control the gain in mitogenic signaling circuits. PMID:26293964

  9. Molecular Dynamic Studies of Particle Wake Potentials in Plasmas

    Science.gov (United States)

    Ellis, Ian; Graziani, Frank; Glosli, James; Strozzi, David; Surh, Michael; Richards, David; Decyk, Viktor; Mori, Warren

    2010-11-01

    Fast Ignition studies require a detailed understanding of electron scattering, stopping, and energy deposition in plasmas with variable values for the number of particles within a Debye sphere. Presently there is disagreement in the literature concerning the proper description of these processes. Developing and validating proper descriptions requires studying the processes using first-principle electrostatic simulations and possibly including magnetic fields. We are using the particle-particle particle-mesh (P^3M) code ddcMD to perform these simulations. As a starting point in our study, we examined the wake of a particle passing through a plasma. In this poster, we compare the wake observed in 3D ddcMD simulations with that predicted by Vlasov theory and those observed in the electrostatic PIC code BEPS where the cell size was reduced to .03λD.

  10. Diagnostic potential of plasma carboxymethyllysine and carboxyethyllysine in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Weinstock-Guttmann Bianca

    2010-10-01

    Full Text Available Abstract Background This study compared the level of advanced glycation end products (AGEs, N-(Carboxymethyllysine (CML and N-(Carboxyethyllysine (CEL, in patients with multiple sclerosis (MS and healthy controls (HCs, correlating these markers with clinical indicators of MS disease severity. Methods CML and CEL plasma levels were analyzed in 99 MS patients and 43 HCs by tandem mass spectrometry (LC/MS/MS. Patients were stratified based on drug modifying therapies (DMTs including interferon beta, glatiramer acetate and natalizumab. Results The level of plasma CEL, but not CML, was significantly higher in DMT-naïve MS patients when compared to HCs (P Conclusion Our results suggest that AGEs in general and CEL in particular could be useful biomarkers in MS clinical practice. Longitudinal studies are warranted to determine any causal relationship between changes in plasma level of AGEs and MS disease pathology. These studies will pave the way for use of AGE inhibitors and AGE-breaking agents as new therapeutic modalities in MS.

  11. Nonthermal Argon Plasma Generator and Some Potential Applications

    Directory of Open Access Journals (Sweden)

    Bunoiu M.

    2015-12-01

    Full Text Available A laboratory - made nonthermal plasma generator is presented. It has a diameter of 0.020 m and length of 0.155 m and contains two electrodes. The first electrode is a 2% Th-W alloy, 0.002 m in diameter bar, centred inside the generator’s body by means of a four channel teflon piece; the other three channels, 0.003 m in diameter, are used for Ar supply. The second electrode is a nozzle of 0.002 m - 0.008 m diameter and 0.005m length. A ~500 kV/m electric field is generated between the two electrodes by a high frequency source (13.56 MHz ±5%, equipped with a OT-1000 (Tungsram power triode. For Ar flows ranging from 0.00008 m3/s to 0.00056 m3/s, a plasma jet of length not exceeding 0.015 m and temperature below 315 K is obtained. Anthurium andraeanumis sample , blood matrix, human hair and textile fibers may be introduced in the plasma jet. For time periods of 30 s and 60 s, various effects like, cell detexturization, fast blood coagulation or textile fiber or hair cleaning and smoothing are obtained. These effects are presented and discussed in the paper.

  12. Effective Potential Theory: A Practical Way to Extend Plasma Transport Theory to Strong Coupling

    CERN Document Server

    Baalrud, Scott D; Daligault, Jerome

    2014-01-01

    The effective potential theory is a physically motivated method for extending traditional plasma transport theories to stronger coupling. It is practical in the sense that it is easily incorporated within the framework of the Chapman-Enskog or Grad methods that are commonly applied in plasma physics and it is computationally efficient to evaluate. The extension is to treat binary scatterers as interacting through the potential of mean force, rather than the bare Coulomb or Debye-screened Coulomb potential. This allows for aspects of many-body correlations to be included in the transport coefficients. Recent work has shown that this method accurately extends plasma theory to orders of magnitude stronger coupling when applied to the classical one-component plasma model. The present work shows that similar accuracy is realized for the Yukawa one-component plasma model and it provides a comparison with other approaches.

  13. Direct Measurements of the Spatial and Velocity Dependence of the Ion Density Fluctuation Spectrum of a Laboratory Plasma with Two Independent LIF Schemes

    Science.gov (United States)

    Mattingly, Sean; Berumen, Jorge; Chu, Feng; Hood, Ryan; Skiff, Fred

    2014-10-01

    By using two independently tunable lasers, each with its own collection optics and Ar II LIF transition scheme, we are able to investigate plasma ion density fluctuations as a function of not only spatial scales but also as a function of ion velocities as sampled on different points of a single Doppler-broadened spectral emission line. We do this by measuring the two point correlation C (x , v ,x' ,v' , τ) = t . With the current system, the two carriages determine x and x', while the velocities selected by each laser determine v and v'. Using the two lasers to make two point correlations in phase space demonstrates effects that are not fully understood. In this experiment, we explore the striking difference in correlations when, in the past, the particle orbits overlap in space versus when they do not overlap. This is performed on a small cylindrical laboratory plasma with n ~109 cm-3 , Te ~ 5 eV, Ti ~ 0 . 06 , and a 1 kG axial magnetic field. LIF is performed on ions at two locations aligned with the magnetic field line with a viewing volume comparable to the size of the Larmor radius. Results and interpretations from these experiments are presented and discussed. DOE Grant DE-FG02-99ER54543.

  14. Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade

    DEFF Research Database (Denmark)

    Horacek, J.; Adamek, J.; Müller, H.W.

    2010-01-01

    This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements of plasma density, potential and electron temperature in the edge plasma of tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate the credibility of the ball-pen probe. We demonstrate that floating poten...

  15. Diagnostics for fluctuation measurements

    NARCIS (Netherlands)

    Donne, A. J. H.

    2000-01-01

    Transport of particles and heat in magnetic confinement devices is largely attributed to the presence of microscopic instabilities. To better understand the physical mechanisms underlying plasma transport processes it is necessary to diagnose the fluctuations in the various quantities along with the

  16. A Vlasov equation with Dirac potential used in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bardos, Claude [Universite Paris-Diderot, Laboratoire J.-L. Lions, BP187, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Nouri, Anne [Laboratoire d' Analyse, Topologie et Probabilites (UMR 6632), Aix-Marseille Universite, 39 Rue Joliot-Curie, 13453 Marseille Cedex 13 (France)

    2012-11-15

    Well-posedness of the Cauchy problem is analyzed for a singular Vlasov equation governing the evolution of the ionic distribution function of a quasineutral fusion plasma. The Penrose criterium is adapted to the linearized problem around a time and space homogeneous distribution function showing (due to the singularity) more drastic differences between stable and unstable situations. This pathology appears on the full nonlinear problem, well-posed locally in time with analytic initial data, but generally ill-posed in the Hadamard sense. Eventually with a very different class of solutions, mono-kinetic, which constrains the structure of the density distribution, the problem becomes locally in time well-posed.

  17. Characterization of SOL plasma flows and potentials in ICRF-heated plasmas in Alcator C-mod

    Science.gov (United States)

    Hong, R.; Wukitch, S. J.; Lin, Y.; Terry, J. L.; Cziegler, I.; Reinke, M. L.; Tynan, G. R.

    2017-10-01

    Gas-puff imaging techniques are employed to determine the far SOL region radial electric field and the plasma potential in ICRF heated discharges in the Alcator C-Mod tokamak. The two-dimensional velocity fields of the turbulent structures, which are advected by RF-induced {E}× {B} flows, are obtained via the time-delay estimation (TDE) techniques. Both the magnitude and radial extension of the radial electric field E r are observed to increase with the toroidal magnetic field strength B φ and the ICRF power. In particular, the RF-induced E r extends from the vicinity of the ICRF antenna to the separatrix when {B}\\varphi =7.9 {{T}} and {P}{ICRF}≳ 1 {MW}. In addition, low-Z impurity seeding near the antenna is found to substantially reduce the sheath potential associated with ICRF power. The TDE techniques have also been used to revisit and estimate ICRF-induced potentials in different antenna configurations: (1) conventional toroidally aligned (TA) antenna versus field-aligned (FA) antenna; (2) FA monopole versus FA dipole. It shows that FA and TA antennas produce similar magnitude of plasma potentials, and the FA monopole induced greater potential than the FA dipole phasing. The TDE estimations of RF-induced plasma potentials are consistent with previous results based on the poloidal phase velocity.

  18. Cytotoxic and mutagenic potential of solutions exposed to cold atmospheric plasma.

    Science.gov (United States)

    Boehm, Daniela; Heslin, Caitlin; Cullen, Patrick J; Bourke, Paula

    2016-01-01

    The exposure of aqueous solutions to atmospheric plasmas results in the generation of relatively long-lived secondary products such as hydrogen peroxide which are biologically active and have demonstrated anti-microbial and cytotoxic activity. The use of plasma-activated solutions in applications such as microbial decontamination or anti-cancer treatments requires not only adequate performance on target cells but also a safe operating window regarding the impact on surrounding tissues. Furthermore the generation of plasma-activated fluids needs to be considered as a by-stander effect of subjecting tissue to plasma discharges. Cytotoxicity and mutagenicity assays using mammalian cell lines were used to elucidate the effects of solutions treated with di-electric barrier discharge atmospheric cold plasma. Plasma-treated PBS inhibited cell growth in a treatment time-dependent manner showing a linear correlation to the solutions' peroxide concentration which remained stable over several weeks. Plasma-treated foetal bovine serum (FBS) acting as a model for complex bio-fluids showed not only cytotoxic effects but also exhibited increased mutagenic potential as determined using the mammalian HPRT assay. Further studies are warranted to determine the nature, causes and effects of the cyto- and genotoxic potential of solutions exposed to plasma discharges to ensure long-term safety of novel plasma applications in medicine and healthcare.

  19. Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasma

    CERN Document Server

    Choudhary, Mangilal; Bandyopadhyay, P

    2016-01-01

    A versatile linear dusty (complex) plasma device is designed to study the transport and dynamical behavior of dust particles in a large volume. Diffused inductively coupled plasma is generated in the background of argon gas. A novel technique is used to introduce the dust particles in the main plasma by striking a secondary direct current (DC) glow discharge. These dust particles are found to get trapped in an electrostatic potential well which is formed due to the combination of the ambipolar electric field caused by diffusive plasma and the field produced by the charged glass wall of the vacuum chamber. According to the requirements, the volume of the dust cloud can be controlled very precisely by tuning the plasma and discharge parameters. The present device can be used to address the underlying physics behind the transport of dust particles, self excited dust acoustic waves and instabilities. The detailed design of this device, plasma production and characterization, trapping and transport of the dust par...

  20. Results of direct measurements of the plasma potential using a laser-heated emissive probe

    Energy Technology Data Exchange (ETDEWEB)

    Schrittwieser, R.; Sarma, A.; Amarandei, G.; Ionita, C. [Univ. of Innsbruck (Austria). Inst. for Ion Physics; Klinger, T.; Grulke, O.; Vogelsang, A.; Windisch, T. [Max Planck Inst. for Plasma Physics, Greifswald (Germany)

    2006-04-15

    Reliable diagnostics of the plasma potential is one of the most important challenges in context with the production, control and confinement of a plasma. Emissive probes are readily available as direct diagnostic tools for the plasma potential with a good temporal and spatial resolution in many plasmas, even up to middle-sized fusion experiments. We present the results of investigations on the heating of lanthanum hexaboride and graphite with an infrared diode laser and on the development of a laser-heated emissive probe. Such a probe has a higher electron emission, much longer life time and better time response than a conventional emissive wire probe. We have observed that from both materials electron emission current can be achieved sufficiently strongly even for dense laboratory and experimental fusion plasmas.

  1. Levitation and Oscillation of Dust Grains in Plasma Sheath with Wake Potential

    Institute of Scientific and Technical Information of China (English)

    练海俊; 谢柏松; 周宏余

    2002-01-01

    We investigate the equilibrium and levitation of dust grains in a plasma sheath with various forces, in particular the wake potential force. The vertical oscillation frequency of dust chains is also obtained by including the wake potential term. It is found that the wake potential has a significant role for the levitation and oscillation of dust grains.

  2. Beneficial Effect of Post-Deposition Treatment in High-Efficiency Cu(In,Ga)Se2 Solar Cells through Reduced Potential Fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Soren A.; Glynn, Stephen; Kanevce, Ana; Dippo, Pat; Li, Jian V.; Levi, Dean H.; Kuciauskas, Darius

    2016-08-14

    World-record power conversion efficiencies for Cu(In,Ga)Se2 (CIGS) solar cells have been achieved via a post-deposition treatment with alkaline metals, which increases the open-circuit voltage and fill factor. We explore the role of the potassium fluoride (KF) post-deposition treatment in CIGS by employing energy- and time-resolved photoluminescence spectroscopy and electrical characterization combined with numerical modeling. The bulk carrier lifetime is found to increase with post-deposition treatment from 255 ns to 388 ns, which is the longest charge carrier lifetime reported for CIGS, and within ~40% of the radiative limit. We find evidence that the post-deposition treatment causes a decrease in the electronic potential fluctuations. These potential fluctuations have previously been shown to reduce the open-circuit voltage and the device efficiency in CIGS. Additionally, numerical simulations based on the measured carrier lifetimes and mobilities show a diffusion length of ~10 um, which is ~4 times larger than the film thickness. Thus, carrier collection in the bulk is not a limiting factor for device efficiency. By considering differences in doping, bandgap, and potential fluctuations, we present a possible explanation for the voltage difference between KF-treated and untreated samples.

  3. On the scaling features of magnetic field fluctuations at non-MHD scales in turbulent space plasmas

    Science.gov (United States)

    Consolini, G.; Giannattasio, F.; Yordanova, E.; Vörös, Z.; Marcucci, M. F.; Echim, M.; Chang, T.

    2016-11-01

    In several different contexts space plasmas display intermittent turbulence at magneto-hydro-dynamic (MHD) scales, which manifests in anomalous scaling features of the structure functions of the magnetic field increments. Moving to smaller scales, i.e. below the ion-cyclotron and/or ion inertial length, these scaling features are still observed, even though its is not clear if these scaling features are still anomalous or not. Here, we investigate the nature of scaling properties of magnetic field increments at non-MHD scales for a period of fast solar wind to investigate the occurrence or not of multifractal features and collapsing of probability distribution functions (PDFs) using the novel Rank-Ordered Multifractal Analysis (ROMA) method, which is more sensitive than the traditional structure function approach. We find a strong evidence for the occurrence of a near mono-scaling behavior, which suggests that the observed turbulent regime at non-MHD scales mainly displays a mono-fractal nature of magnetic field increments. The results are discussed in terms of a non-compact fractal structure of the dissipation field.

  4. Luminescence properties of Cu2ZnSn (S,Se ) 4 solar cell absorbers: State filling versus screening of electrostatic potential fluctuations

    Science.gov (United States)

    Lang, Mario; Zimmermann, Christian; Krämmer, Christoph; Renz, Tobias; Huber, Christian; Kalt, Heinz; Hetterich, Michael

    2017-04-01

    The power conversion efficiency of Cu2ZnSn (S,Se ) 4 kesterite thin-film solar cells is mainly limited by a low open-circuit voltage VOC. In the literature, this low VOC has been amongst others attributed to electrostatic potential fluctuations leading to fluctuating band edges. This assignment was mainly based on the observation of a shift of the photoluminescence (PL) maximum to higher photon energies as a function of excitation power, which was interpreted in terms of a screening of the electrostatic potential fluctuations. However, in this paper, we show evidence that the observed shift of the PL maximum is dominantly caused by state filling rather than screening. Our assignment is based on the investigation of the full PL line shape (not only of the PL maximum) and the PL yield as a function of excitation power and temperature. Further support of our interpretation is given by the observation of additional band-tail emission showing up as a second high-energy PL band at the highest excitation powers. The spectral position of this additional band coincides with the absorption-tail deduced from photoluminescence excitation spectroscopy (PLE).

  5. Theory of slightly fluctuating ratchets

    Science.gov (United States)

    Rozenbaum, V. M.; Shapochkina, I. V.; Lin, S. H.; Trakhtenberg, L. I.

    2017-04-01

    We consider a Brownian particle moving in a slightly fluctuating potential. Using the perturbation theory on small potential fluctuations, we derive a general analytical expression for the average particle velocity valid for both flashing and rocking ratchets with arbitrary, stochastic or deterministic, time dependence of potential energy fluctuations. The result is determined by the Green's function for diffusion in the time-independent part of the potential and by the features of correlations in the fluctuating part of the potential. The generality of the result allows describing complex ratchet systems with competing characteristic times; these systems are exemplified by the model of a Brownian photomotor with relaxation processes of finite duration.

  6. Frequency Spectrum of Fluctuations Near a Rational Surface in a Toroidal Heliac

    Science.gov (United States)

    Zama, Tatsuya; Kitajima, Sumio; Takayama, Masakazu; Takeuchi, Nobunao; Watanabe, Hiroshige

    1993-03-01

    Density and space potential fluctuations have been studied in electron cyclotron resonance heating (ECRH) plasma of a helical axis stellarator TU Heliac using Langmuir probe techniques. These fluctuations are coherent and global, which can be explained by a drift instability model in cylindrical geometry. A particular fluctuation mode vanishes inside a rational surface. The ratio of this mode, n/m, corresponds to the rotational transform \\includegraphics{dummy.eps} of this rational surface, (m, n: poloidal, toroidal fluctuation modes, respectively). This phenomenon near the rational surface can also be explained by a drift instability theory.

  7. Estimate of electrical potential difference between plasmas with different degrees of ionization

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-12

    The electrical potential difference has been estimated across the mixing region of two plasmas with different degrees of ionization. The estimation has been carried out in two different contexts of a charge neutral mixing region and a charge non-neutral sheath. Ion energy gained due to the potential difference has also been estimated. In both analyses, ion energy gain is proportional to the degree of ionization, and a fairly large ionization appears to be needed for overcoming the potential energy barrier of strongly coupled plasmas.

  8. Normal chemotaxis in Dictyostelium discoideum cells with a depolarized plasma membrane potential

    NARCIS (Netherlands)

    Duijn, Bert van; Vogelzang, Sake A.; Ypey, Dirk L.; Molen, Loek G. van der; Haastert, Peter J.M. van

    1990-01-01

    We examined a possible role for the plasma membrane potential in signal transduction during cyclic AMP-induced chemotaxis in the cellular slime mold Dictyostelium discoideum. Chemotaxis, cyclic GMP and cyclic AMP responses in cells with a depolarized membrane potential were measured. Cells can be

  9. Internal oscillating current-sustained RF plasmas: Parameters, stability, and potential for surface engineering

    DEFF Research Database (Denmark)

    Ostrikov, K.; Tsakadze, E.L.; Tsakadze, Z.L.;

    2005-01-01

    plasma parameters by the optical and Langmuir probes are presented. It is shown that the spatial profiles of the electron density, the effective electron temperature and plasma potential feature a great deal of the radial and axial uniformity compared with conventional sources of inductively coupled......A new source of low-frequency (0.46 MHz) inductively coupled plasmas sustained by the internal planar "unidirectional" RF current driven through a specially designed internal antenna configuration has been developed. The experimental results of the investigation of the optical and global argon...... applications and surface engineering. (c) 2005 Elsevier B.V. All rights reserved....

  10. Band gaps, ionization potentials, and electron affinities of periodic electron systems via the adiabatic-connection fluctuation-dissipation theorem

    Science.gov (United States)

    Trushin, Egor; Betzinger, Markus; Blügel, Stefan; Görling, Andreas

    2016-08-01

    An approach to calculate fundamental band gaps, ionization energies, and electron affinities of periodic electron systems is explored. Starting from total energies obtained with the help of the adiabatic-connection fluctuation-dissipation (ACFD) theorem, these physical observables are calculated according to their basic definition by differences of the total energies of the N -, (N -1 ) -, and (N +1 ) -electron system. The response functions entering the ACFD theorem are approximated here by the direct random phase approximation (dRPA). For a set of prototypical semiconductors and insulators it is shown that even with this quite drastic approximation the resulting band gaps are very close to experiment and of a similar quality to those from the computationally more involved G W approximation. By going beyond the dRPA in the future the accuracy of the calculated band gaps may be significantly improved further.

  11. Membrane potential governs lateral segregation of plasma membrane proteins and lipids in yeast.

    Science.gov (United States)

    Grossmann, Guido; Opekarová, Miroslava; Malinsky, Jan; Weig-Meckl, Ina; Tanner, Widmar

    2007-01-10

    The plasma membrane potential is mainly considered as the driving force for ion and nutrient translocation. Using the yeast Saccharomyces cerevisiae as a model organism, we have discovered a novel role of the membrane potential in the organization of the plasma membrane. Within the yeast plasma membrane, two non-overlapping sub-compartments can be visualized. The first one, represented by a network-like structure, is occupied by the proton ATPase, Pma1, and the second one, forming 300-nm patches, houses a number of proton symporters (Can1, Fur4, Tat2 and HUP1) and Sur7, a component of the recently described eisosomes. Evidence is presented that sterols, the main lipid constituent of the plasma membrane, also accumulate within the patchy compartment. It is documented that this compartmentation is highly dependent on the energization of the membrane. Plasma membrane depolarization causes reversible dispersion of the H(+)-symporters, not however of the Sur7 protein. Mitochondrial mutants, affected in plasma membrane energization, show a significantly lower degree of membrane protein segregation. In accordance with these observations, depolarized membranes also considerably change their physical properties (detergent sensitivity).

  12. Edge Electrostatic Fluctuation Characteristics in the Sino-United Spherical Tokamak

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-Hao; HE Ye-Xi; GAO Zhe; ZENG Li; ZHANG Guo-Ping; XIE Li-Feng; FENG Chun-Hua; XIAO Qiong; LI Xiao-Yan

    2004-01-01

    @@ Edge plasma parameters, including electron temperature Te, density ne, plasma potential φp, radial electric field Er and the corresponding fluctuations in the Sino- United Spherical Tokamak, have been systematically measured with Langmuir probe arrays. Wavenumber spectrum analyses show that edge fluctuations have a radial propagation character of the drift wave turbulence, with a characteristic radial phase velocity νphr ~ 0.7 km.s-1in the scrape-off layer and vphr ~ 0.9-1.4km's-1 in the plasma edge.

  13. Plasma-modified and polyethylene glycol-grafted polymers for potential tissue engineering applications.

    Science.gov (United States)

    Svorcík, V; Makajová, Z; Kasálková-Slepicková, N; Kolská, Z; Bacáková, L

    2012-08-01

    Modified and grafted polymers may serve as building blocks for creating artificial bioinspired nanostructured surfaces for tissue engineering. Polyethylene (PE) and polystyrene (PS) were modified by Ar plasma and the surface of the plasma activated polymers was grafted with polyethylene glycol (PEG). The changes in the surface wettability (contact angle) of the modified polymers were examined by goniometry. Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology and electrokinetical analysis (Zeta potential) characterized surface chemistry of the modified polymers. Plasma treatment and subsequent PEG grafting lead to dramatic changes in the polymer surface morphology, roughness and wettability. The plasma treated and PEG grafted polymers were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with PEG increases cell proliferation, especially on PS. The cell proliferation was shown to be an increasing function of PEG molecular weight.

  14. Transport generated by dichotomous fluctuations

    Science.gov (United States)

    Kula, J.; Czernik, T.; łuczka, J.

    1996-02-01

    Overdamped motion of Brownian particles in spatially periodic potentials and subjected to fluctuations modeled by asymmetric exponentially correlated two-state noise of zero mean value is considered. The probability current is presented in a closed form and analyzed in asymptotic regimes of very long and very short correlation times of the fluctuations. Explicit results are obtained for a piecewise linear potential. The role of correlations and temporal asymmetry of fluctuations is elucidated.

  15. Potential cellular targets and antibacterial efficacy of atmospheric pressure non-thermal plasma.

    Science.gov (United States)

    Alkawareek, Mahmoud Y; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2014-02-01

    Atmospheric pressure non-thermal plasma (APNTP) has been gaining increasing interest as a new alternative antibacterial approach. Although this approach has demonstrated promising antibacterial activity, its exact mechanism of action remains unclear. Mechanistic elucidation of the antimicrobial activity will facilitate development and rational optimisation of this approach for potential medical applications. In this study, the antibacterial efficacy of an in-house-built APNTP jet was evaluated alongside an investigation of the interactions between APNTP and major cellular components in order to identify the potential cellular targets involved in plasma-mediated bacterial destruction mechanisms. The investigated plasma jet exhibited excellent, rapid antibacterial activity against a selected panel of clinically significant bacterial species including Bacillus cereus, meticillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa, all of which were completely inactivated within 2 min of plasma exposure. Plasma-mediated damaging effects were observed, to varying degrees, on all of the investigated cellular components including DNA, a model protein enzyme, and lipid membrane integrity and permeability. The antibacterial efficacy of APNTP appears to involve a multiple-target mechanism, which potentially reduces the likelihood of emergence of microbial resistance towards this promising antimicrobial approach. However, cellular membrane damage and resulting permeability perturbation was found to be the most likely rate-determining step in this mechanism.

  16. Double Potential Pulse Chronocoulometry for Detection of Plasma Membrane Cholesterol Efflux at Disk Platinum Microelectrodes

    Science.gov (United States)

    West, Richard H.; Lu, Hui; Shaw, Kendrick; Chiel, Hillel J.; Kelley, Thomas J.; Burgess, James D.

    2016-01-01

    A double potential pulse scheme is reported for observation of cholesterol efflux from the plasma membrane of a single neuron cell. Capillary Pt disk microelectrodes having a thin glass insulator allow the 10 μm diameter electrode and cell to be viewed under optical magnification. The electrode, covalently functionalized with cholesterol oxidase, is positioned in contact with the cell surface resulting in enzyme catalyzed cholesterol oxidation and efflux of cholesterol from the plasma membrane at the electrode contact site. Enzymatically generated hydrogen peroxide accumulates at the electrode/cell interface during a 5 s hold-time and is oxidized during application of a potential pulse. A second, replicate potential pulse is applied 0.5 s after the first potential pulse to gauge background charge prior to significant accumulation of hydrogen peroxide. The difference in charge passed between the first and second potential pulse provides a measure of hydrogen peroxide generated by the enzyme and is an indication of the cholesterol efflux. Control experiments for bare Pt microelectrodes in contact with the cell plasma membrane show difference charge signals in the range of about 7–10 pC. Enzyme-modified electrodes in contact with the plasma membrane show signals in the range of 16–26 pC. PMID:27330196

  17. Factors associated with motor fluctuations and dyskinesia in Parkinson Disease: potential role of a new melevodopa plus carbidopa formulation (Sirio).

    Science.gov (United States)

    Stocchi, Fabrizio; Marconi, Stefano

    2010-07-01

    Parkinson disease is a progressive movement disorder caused by loss of dopaminergic neurons in the substantia nigra. Of unknown etiology, Parkinson disease is characterized by 4 cardinal symptoms: tremor at rest, bradykinesia, postural instability, and rigidity. The current criterion-standard drug used in the management of parkinsonian symptoms is levodopa (l-dopa). However, long-term l-dopa therapy is associated with the development of motor complications; approximately 50% to 80% of patients will develop motor complications within 5 to 10 years of l-dopa treatment initiation. Motor complications can be divided into motor fluctuations, caused largely through pulsatile dopamine stimulation and low l-dopa concentrations, and dyskinesia, associated more often with peak l-dopa concentrations. Ultimately, the main goal was to provide steady l-dopa concentrations, without peaks and troughs. Empirical investigations using parenteral infusions of l-dopa and highly soluble l-dopa prodrugs have shown that there is benefit in ameliorating the peaks and troughs associated with traditional oral l-dopa formulations. Recently, the development of highly soluble oral l-dopa prodrugs has facilitated rapid, regular, and reliable l-dopa availability. This review evaluates some of the pharmacologic strategies in the management of motor complications in Parkinson disease and therapy optimization, with a focus on the use of CHF 1512 (Sirio), a combination of melevodopa (l-dopa methylester, a highly soluble prodrug of l-dopa) plus carbidopa in an effervescent tablet formulation.

  18. Formation of Non-Monotonic Potential Structure in the Detached Plasma

    Science.gov (United States)

    Ishiguro, Seiji; Pianpanit, Theerasarn; Hasegawa, Hiroki

    2016-10-01

    Plasma detachment has been investigated by means of PIC simulation which includes plasma-neutral collision and Coulomb collision. In our previous study, we have shown that a strong gradient in temperature appears in front of the target plate in the case that high density and low temperature neutral gas is introduced. It is observed that a potential hill is created in the neutral gas region where ions lose energy due to the elastic and charge exchange collision and, as a result, the ion density increases. This potential structure traps the low energy electrons and may play a role in the development of plasma detachment state. This work is supported by NIFS Collaboration Research Programs NIFS14KNXN279 and NIFS14KNSS059 and the NIFS/NINS project of Formation of International Scientific Base and Network.

  19. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  20. Space charge, plasma potential and electric field distributions in HiPIMS discharges of varying configuration

    Science.gov (United States)

    Liebig, B.; Bradley, J. W.

    2013-08-01

    An electron-emitting (emissive) probe has been used to study the temporal and spatial distribution of the plasma potential during high-power impulse magnetron sputtering (HiPIMS) discharges with various substrate and magnetic field configurations. The average power was 700 W, with a repetition frequency of 100 Hz and pulse duration of 100 µs. Strongly negative plasma potentials exceeding -300 V and electric fields up to 10 kV m-1, caused by strong separation of charges with net charge carrier densities Δn of about 1014 m-3, were observed during the ignition of the discharge. The spatial distribution of the plasma potential in the stable stage of the discharge showed values consistently 5 V more negative for a floating substrate compared with a grounded one, so enhancing electron transport around the insulated substrate to grounded walls. However, this change in the electrical configuration of the plasma does not alter significantly the fraction of ionized sputtered particles (of about 30%) that can potentially reach the substrate. By changing the degree of unbalance of the sputtering source, we find a strong correlation between the electric field strength in the magnetic trap (created through charge separation) and the absolute value (and shape) of the magnetic field. For the more unbalanced magnetron, a flattening of the plasma potential structure (decrease in the axial electric field) was observed close to the target. Our findings show in principle that manipulation of the potential barrier close to the target through changing the magnetic field can regulate the proportion of sputtered and ionized species reaching the substrate.

  1. Contribution of Ca2+-dependent conductances to membrane potential fluctuations of medullary respiratory neurons of newborn rats in vitro.

    Science.gov (United States)

    Onimaru, Hiroshi; Ballanyi, Klaus; Homma, Ikuo

    2003-11-01

    Ca2+-dependent conductances were studied in respiratory interneurons in the brainstem-spinal cord preparation of newborn rats. omega-Conotoxin-GVIA attenuated evoked postsynaptic potentials, spontaneous or evoked inspiratory spinal nerve activity and blocked spike afterhyperpolarization. Furthermore, omega-conotoxin-GVIA augmented rhythmic drive potentials of pre-inspiratory and inspiratory neurons and increased respiratory-related spike frequency of pre-inspiratory cells with no effect on inspiratory hyperpolarization. In contrast, omega-agatoxin-IVA depressed drive potentials of pre-inspiratory and inspiratory neurons and attenuated inspiratory hyperpolarization and spike frequency of pre-inspiratory cells. It did not affect spike shape and exerted only minor, non-significant, attenuating effects on spontaneous or evoked nerve bursts or evoked postsynaptic potentials. Nifedipine diminished drive potentials and spike frequency of pre-inspiratory neurons and shortened drive potentials in some cells. omega-Conotoxin-MVIIC attenuated drive potentials and intraburst firing rate of pre-inspiratory neurons and decreased substantially respiratory frequency. Respiratory rhythm disappeared following combined application of omega-conotoxin-GVIA, omega-conotoxin-MVIIC, omega-agatoxin-IVA and nifedipine. Apamin potentiated drive potentials and abolished spike afterhyperpolarization, whereas charybdotoxin and tetraethylammonium prolonged spike duration without effect on shape of drive potentials. The results show that specific sets of voltage-activated L-, N- and P/Q-type Ca2+ channels determine the activity of particular subclasses of neonatal respiratory neurons, whereas SK- and BK-type K+ channels attenuate drive potentials and shorten spikes, respectively, independent of cell type. We hypothesize that modulation of spontaneous activity of pre-inspiratory neurons via N-, L- and P/Q-type Ca2+ channels is important for respiratory rhythm or pattern generation.

  2. Plasma soluble prion protein, a potential biomarker for sport-related concussions: a pilot study.

    Directory of Open Access Journals (Sweden)

    Nam Pham

    Full Text Available Sport-related mild traumatic brain injury (mTBI or concussion is a significant health concern to athletes with potential long-term consequences. The diagnosis of sport concussion and return to sport decision making is one of the greatest challenges facing health care clinicians working in sports. Blood biomarkers have recently demonstrated their potential in assisting the detection of brain injury particularly, in those cases with no obvious physical injury. We have recently discovered plasma soluble cellular prion protein (PrP(C as a potential reliable biomarker for blast induced TBI (bTBI in a rodent animal model. In order to explore the application of this novel TBI biomarker to sport-related concussion, we conducted a pilot study at the University of Saskatchewan (U of S by recruiting athlete and non-athlete 18 to 30 year-old students. Using a modified quantitative ELISA method, we first established normal values for the plasma soluble PrP(C in male and female students. The measured plasma soluble PrP(C in confirmed concussion cases demonstrated a significant elevation of this analyte in post-concussion samples. Data collected from our pilot study indicates that the plasma soluble PrP(C is a potential biomarker for sport-related concussion, which may be further developed into a clinical diagnostic tool to assist clinicians in the assessment of sport concussion and return-to-play decision making.

  3. Plasma soluble prion protein, a potential biomarker for sport-related concussions: a pilot study.

    Science.gov (United States)

    Pham, Nam; Akonasu, Hungbo; Shishkin, Rhonda; Taghibiglou, Changiz

    2015-01-01

    Sport-related mild traumatic brain injury (mTBI) or concussion is a significant health concern to athletes with potential long-term consequences. The diagnosis of sport concussion and return to sport decision making is one of the greatest challenges facing health care clinicians working in sports. Blood biomarkers have recently demonstrated their potential in assisting the detection of brain injury particularly, in those cases with no obvious physical injury. We have recently discovered plasma soluble cellular prion protein (PrP(C)) as a potential reliable biomarker for blast induced TBI (bTBI) in a rodent animal model. In order to explore the application of this novel TBI biomarker to sport-related concussion, we conducted a pilot study at the University of Saskatchewan (U of S) by recruiting athlete and non-athlete 18 to 30 year-old students. Using a modified quantitative ELISA method, we first established normal values for the plasma soluble PrP(C) in male and female students. The measured plasma soluble PrP(C) in confirmed concussion cases demonstrated a significant elevation of this analyte in post-concussion samples. Data collected from our pilot study indicates that the plasma soluble PrP(C) is a potential biomarker for sport-related concussion, which may be further developed into a clinical diagnostic tool to assist clinicians in the assessment of sport concussion and return-to-play decision making.

  4. Equation of state of a quark-gluon plasma using the Cornell potential

    Science.gov (United States)

    Udayanandan, K. M.; Sethumadhavan, P.; Bannur, V. M.

    2007-10-01

    The equation of state (EOS) of quark-gluon plasma (QGP) using the Cornell potential based on Mayer's cluster expansion is presented. The string constant and the strong coupling constant for QGP are calculated. The EOS developed could describe the lattice EOS for pure gauge, two-flavor and three-flavor QGP qualitatively.

  5. Dynamic interaction potential and the scattering cross sections of the semiclassical plasma particles

    Energy Technology Data Exchange (ETDEWEB)

    Dzhumagulova, K. N.; Shalenov, E. O.; Gabdullina, G. L. [IETP, Al Farabi Kazakh National University, 71al Farabi Street, Almaty 050040 (Kazakhstan)

    2013-04-15

    The dynamic model of the charged particles interaction in non-ideal semiclassical plasma is presented. This model takes into account the quantum mechanical diffraction effect and the dynamic screening effect. On the basis of the dynamic interaction potential, the electron scattering cross sections are investigated. Comparison with the results obtained on the basis of other models and conclusions were made.

  6. Cross-field flow and electric potential in a plasma slab

    Directory of Open Access Journals (Sweden)

    J. De Keyser

    2013-08-01

    Full Text Available We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.

  7. Quantification of plasma exosome is a potential prognostic marker for esophageal squamous cell carcinoma.

    Science.gov (United States)

    Matsumoto, Yasunori; Kano, Masayuki; Akutsu, Yasunori; Hanari, Naoyuki; Hoshino, Isamu; Murakami, Kentaro; Usui, Akihiro; Suito, Hiroshi; Takahashi, Masahiko; Otsuka, Ryota; Xin, Hu; Komatsu, Aki; Iida, Keiko; Matsubara, Hisahiro

    2016-11-01

    Exosomes play important roles in cancer progression. Although its contents (e.g., proteins and microRNAs) have been focused on in cancer research, particularly as potential diagnostic markers, the exosome behavior and methods for exosome quantification remain unclear. In the present study, we analyzed the tumor-derived exosome behavior and assessed the quantification of exosomes in patient plasma as a biomarker for esophageal squamous cell carcinoma (ESCC). A CD63-GFP expressing human ESCC cell line (TE2-CD63-GFP) was made by transfection, and mouse subcutaneous tumor models were established. Fluorescence imaging was performed on tumors and plasma exosomes harvested from mice. GFP-positive small vesicles were confirmed in the plasma obtained from TE2-CD63-GFP tumor-bearing mice. Patient plasma was collected in Chiba University Hospital (n=86). Exosomes were extracted from 100 µl of the plasma and quantified by acetylcholinesterase (AChE) activity. The relationship between exosome quantification and the patient clinical characteristics was assessed. The quantification of exosomes isolated from the patient plasma revealed that esophageal cancer patients (n=66) expressed higher exosome levels than non-malignant patients (n=20) (P=0.0002). Although there was no correlation between the tumor progression and the exosome levels, exosome number was the independent prognostic marker and low levels of exosome predicted a poor prognosis (P=0.03). In conclusion, exosome levels may be useful as an independent prognostic factor for ESCC patients.

  8. Quantification of plasma exosome is a potential prognostic marker for esophageal squamous cell carcinoma

    Science.gov (United States)

    Matsumoto, Yasunori; Kano, Masayuki; Akutsu, Yasunori; Hanari, Naoyuki; Hoshino, Isamu; Murakami, Kentaro; Usui, Akihiro; Suito, Hiroshi; Takahashi, Masahiko; Otsuka, Ryota; Xin, Hu; Komatsu, Aki; Iida, Keiko; Matsubara, Hisahiro

    2016-01-01

    Exosomes play important roles in cancer progression. Although its contents (e.g., proteins and microRNAs) have been focused on in cancer research, particularly as potential diagnostic markers, the exosome behavior and methods for exosome quantification remain unclear. In the present study, we analyzed the tumor-derived exosome behavior and assessed the quantification of exosomes in patient plasma as a biomarker for esophageal squamous cell carcinoma (ESCC). A CD63-GFP expressing human ESCC cell line (TE2-CD63-GFP) was made by transfection, and mouse subcutaneous tumor models were established. Fluorescence imaging was performed on tumors and plasma exosomes harvested from mice. GFP-positive small vesicles were confirmed in the plasma obtained from TE2-CD63-GFP tumor-bearing mice. Patient plasma was collected in Chiba University Hospital (n=86). Exosomes were extracted from 100 µl of the plasma and quantified by acetylcholinesterase (AChE) activity. The relationship between exosome quantification and the patient clinical characteristics was assessed. The quantification of exosomes isolated from the patient plasma revealed that esophageal cancer patients (n=66) expressed higher exosome levels than non-malignant patients (n=20) (P=0.0002). Although there was no correlation between the tumor progression and the exosome levels, exosome number was the independent prognostic marker and low levels of exosome predicted a poor prognosis (P=0.03). In conclusion, exosome levels may be useful as an independent prognostic factor for ESCC patients. PMID:27599779

  9. Drag force of Anisotropic plasma at finite U(1) chemical potential

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Long; Ge, Xian-Hui [Shanghai University, Department of Physics, Shanghai (China); Wu, Shang-Yu [National Chiao Tung University, Department of Electrophysics, Yau Shing Tung Center, Hsinchu (China); National Center for Theoretical Science, Hsinchu (China)

    2016-05-15

    We perform the calculation of the drag force acting on a massive quark moving through an anisotropic N = 4 SU(N) Super Yang-Mills plasma in the presence of a U(1) chemical potential. We present the numerical results for any value of the anisotropy and arbitrary direction of the quark velocity with respect to the direction of the anisotropy. We find the effect of the chemical potential or charge density will enhance the drag force for our charged solution. (orig.)

  10. Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics and Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588, South Korea and Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States)

    2016-09-15

    The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order. It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.

  11. Bifurcation of space-charge wave in a plasma waveguide including the wake potential effect

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-09-01

    The wake potential effects on the propagation of the space-charge dust ion-acoustic wave are investigated in a cylindrically bounded dusty plasma with the ion flow. The results show that the wake potential would generate the double frequency modes in a cylindrically bounded dusty plasma. It is found that the upper mode of the wave frequency with the root of higher-order is smaller than that with the root of lower-order in intermediate wave number domains. However, the lower mode of the scaled wave frequency with the root of higher-order is found to be greater than that with the root of lower-order. It is found that the influence in the order of the root of the Bessel function on the wave frequency of the space-charge dust-ion-acoustic wave in a cylindrically confined dusty plasma decreases with an increase in the propagation wave number. It is also found that the double frequency modes increase with increasing Mach number due to the ion flow in a cylindrical dusty plasma. In addition, it is found that the upper mode of the group velocity decreases with an increase in the scaled radius of the plasma cylinder. However, it is shown that the lower mode of the scaled group velocity of the space-charge dust ion acoustic wave increases with an increase in the radius of the plasma cylinder. The variation of the space-charge dust-ion-acoustic wave due to the wake potential and geometric effects is also discussed.

  12. Direct Measurements of the Ionization Potential Depression in a Dense Plasma

    Science.gov (United States)

    Ciricosta, O.; Vinko, S. M.; Chung, H.-K.; Cho, B.-I.; Brown, C. R. D.; Burian, T.; Chalupský, J.; Engelhorn, K.; Falcone, R. W.; Graves, C.; Hájková, V.; Higginbotham, A.; Juha, L.; Krzywinski, J.; Lee, H. J.; Messerschmidt, M.; Murphy, C. D.; Ping, Y.; Rackstraw, D. S.; Scherz, A.; Schlotter, W.; Toleikis, S.; Turner, J. J.; Vysin, L.; Wang, T.; Wu, B.; Zastrau, U.; Zhu, D.; Lee, R. W.; Heimann, P.; Nagler, B.; Wark, J. S.

    2012-08-01

    We have used the Linac Coherent Light Source to generate solid-density aluminum plasmas at temperatures of up to 180 eV. By varying the photon energy of the x rays that both create and probe the plasma, and observing the K-α fluorescence, we can directly measure the position of the K edge of the highly charged ions within the system. The results are found to disagree with the predictions of the extensively used Stewart-Pyatt model, but are consistent with the earlier model of Ecker and Kröll, which predicts significantly greater depression of the ionization potential.

  13. Enzymatic Modification of Plasma Low Density Lipoproteins in Rabbits: A Potential Treatment for Hypercholesterolemia

    Science.gov (United States)

    Labeque, Regine; Mullon, Claudy J. P.; Ferreira, Joao Paulo M.; Lees, Robert S.; Langer, Robert

    1993-04-01

    Phospholipase A_2 (EC 3.1.1.4) hydrolyzes certain phospholipids of low density lipoprotein (LDL). Plasma clearance of phospholipase A_2-modified human LDL is up to 17 times faster than that of native human LDL in hypercholesterolemic rabbits. Modification of blood lipoproteins of hypercholesterolemic rabbits was performed by using an extracorporeal circuit containing immobilized phospholipase A_2. After 90-min treatments, nearly 30% decreases in plasma cholesterol concentrations were observed. Erythrocyte, leukocyte, and platelet counts showed no net change after treatment. This technique does not require any fluid replacement or sorbent regeneration and offers a potential approach for lowering serum cholesterol and LDL levels.

  14. Jump Conditions of a Non-Neutral Plasma Shock with Current and Potential Difference

    Institute of Scientific and Technical Information of China (English)

    胡希伟

    2002-01-01

    Jump conditions about the total momentum flux and energy flux in a non-neutral plasma shock with electric current and field are given, which are derived from the double fluid equations and the Poisson equation for electron and ion fluids. Furthermore, we derive the relations between the upstream and downstream velocities and temperatures, and the minimum upstream Mach number for the plasma shock existence M1min, which depend on the current through the shock front J0, the electric potential difference between the upstream and downstream of shock △φ, and the ion charge Z.

  15. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-02-01

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained.

  16. Differential proteomics of human seminal plasma: A potential target for searching male infertility marker proteins.

    Science.gov (United States)

    Tomar, Anil Kumar; Sooch, Balwinder Singh; Singh, Sarman; Yadav, Savita

    2012-04-01

    The clinical fertility tests, available in the market, fail to define the exact cause of male infertility in almost half of the cases and point toward a crucial need of developing better ways of infertility investigations. The protein biomarkers may help us toward better understanding of unknown cases of male infertility that, in turn, can guide us to find better therapeutic solutions. Many clinical attempts have been made to identify biomarkers of male infertility in sperm proteome but only few studies have targeted seminal plasma. Human seminal plasma is a rich source of proteins that are essentially required for development of sperm and successful fertilization. This viewpoint article highlights the importance of human seminal plasma proteome in reproductive physiology and suggests that differential proteomics integrated with functional analysis may help us in searching potential biomarkers of male infertility.

  17. Plasma DNA integrity index as a potential molecular diagnostic marker for breast cancer.

    Science.gov (United States)

    Kamel, Azza M; Teama, Salwa; Fawzy, Amal; El Deftar, Mervat

    2016-06-01

    Plasma DNA integrity index is increased in various malignancies including breast cancer, the most common cancer in women worldwide; early detection is crucial for successful treatment. Current screening methods fail to detect many cases of breast cancer at an early stage. In this study, we evaluated the level of plasma DNA integrity index in 260 females (95 with breast cancer, 95 with benign breast lesions, and 70 healthy controls) to verify its potential value in discriminating malignant from benign breast lesions. The criteria of the American Joint Committee on Cancer were used for staging of breast cancer patients. DNA integrity index was measured by real-time PCR. DNA integrity index was significantly higher in breast cancer than in benign breast patients and healthy subjects (P = cancer group was 85.3 % at 0.55 DNA integrity index cutoff. In conclusion, the plasma DNA integrity index may be a promising molecular diagnostic marker of malignancy in breast lesions.

  18. Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas

    CERN Document Server

    Kim, Jaewook; Lampert, M; Ghim, Y -c

    2016-01-01

    A statistical method for the estimation of spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, sizes of averaging time windows and ratios of the distance between the two measurement points to the true correlation length, the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.

  19. Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas

    Science.gov (United States)

    Kim, Jaewook; Nam, Y. U.; Lampert, M.; Ghim, Y.-C.

    2016-10-01

    A statistical method for the estimation of the spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, the sizes of averaging time windows and the ratios of the distance between the two measurement points to the true correlation length, and the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.

  20. Measurements of Electric Field Fluctuations Using a Capacitive Probe on the MST Reversed Field Pinch

    Science.gov (United States)

    Tan, Mingsheng; Almagri, A. F.; Sarff, J. S.; McCollam, K. J.; Triana, J. C.; Li, H.; Ding, W. X.; Liu, W.

    2015-11-01

    Experimental measurements and extended MHD computation reveal that both flow and current density fluctuations are important for the magnetic relaxation of RFP plasmas via tearing fluctuations. Motivated by these results, we have developed a multi-electrode capacitive probe for radial profile measurements of the electrostatic potential deep in the plasma. The capacitive probe measures the ac plasma potential via electrodes insulated from the plasma using an annular boron nitride dielectric (also the particle shield), provided the secondary emission is sufficiently large (Te>20 eV). The probe has ten sets of four capacitors with 1.5 cm radial separation. At each radius, four capacitors are arranged on a 1.3 cm square grid. This probe has been inserted up to 15 cm from the wall in 200 kA deuterium plasmas. The fluctuation amplitudes increase during the sawtooth crash and the power spectrum broadens (similar to the behavior of magnetic field fluctuations). The frequency bandwidth allows measurements of the radial coherence and phase of the fluctuations associated with rotating tearing modes up to the Alfvénic range. A next-step goal is measurement of the total dynamo emf, ~ /B0 , to complement ongoing measurements of the Hall dynamo emf, / ne , using a deep-insertion magnetic probe. M. Tan is supported by ITER-China Program. Work is supported by US DOE.

  1. Molecular characterization of the cold- and heat-induced Arabidopsis PXL1 gene and its potential role in transduction pathways under temperature fluctuations.

    Science.gov (United States)

    Jung, Chang Gyo; Hwang, Sun-Goo; Park, Yong Chan; Park, Hyeon Mi; Kim, Dong Sub; Park, Duck Hwan; Jang, Cheol Seong

    2015-03-15

    LRR-RLK (Leucine-Rich Repeat Receptor-Like Kinase) proteins are believed to play essential roles in cell-to-cell communication during various cellular processes including development, hormone perception, and abiotic stress responses. We isolated an LRR-RLK gene previously named Arabidopsis PHLOEM INTERCALATED WITH XYLEM-LIKE 1 (AtPXL1) and examined its expression patterns. AtPXL1 was highly induced by cold and heat stress, but not by drought. The fluorescence signal of 35S::AtPXL1-EGFP was closely localized to the plasma membrane. A yeast two-hybrid and bimolecular fluorescence complementation assay exhibited that AtPXL1 interacts with both proteins, A. thaliana histidine-rich dehydrin1 (AtHIRD1) and A. thaliana light-harvesting protein complex I (AtLHCA1). We found that AtPXL1 possesses autophosphorylation activity and phosphorylates AtHIRD1 and AtLHCA1 in an in vitro assay. Subsequently, we found that the knockout line (atpxl1) showed hypersensitive phenotypes when subjected to cold and heat during the germination stage, while the AtPXL1 overexpressing line as well as wild type plants showed high germination rates compared to the knockout plants. These results provide an insight into the molecular function of AtPXL1 in the regulation of signal transduction pathways under temperature fluctuations.

  2. Surface Potential of Dust Grains at the Sheath Edge of Electronegative Dusty Plasmas

    Institute of Scientific and Technical Information of China (English)

    段萍; 王正汹; 王文春; 刘金远; 刘悦; 王晓钢

    2004-01-01

    In this paper we investigate the dust surface potential at the sheath edge of electronegative dusty plasmas theoretically, using the standard fluid model for the sheath and treating electrons and negative ions as Boltzmann particles but positive ions and dust grains as cold fluids.The dust charging model is self-consistently coupled with the sheath formation criterion by the dust surface potential and the ion Mach number, moreover the dust density variation is taken into account. The numerical results reveal that the dust number density and negative ion number density as well as its temperature can significantly affect the dust surface potential at the sheath edge.

  3. High-field plasma acceleration in a high-ionization-potential gas.

    Science.gov (United States)

    Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clausse, B; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m(-1), over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources.

  4. Magnetically insulated baffled probe for real-time monitoring of equilibrium and fluctuating values of space potentials, electron and ion temperatures, and densities.

    Science.gov (United States)

    Demidov, V I; Koepke, M E; Raitses, Y

    2010-10-01

    By restricting the electron-collection area of a cold Langmuir probe compared to the ion-collection area, the probe floating potential can become equal to the space potential, and thus conveniently monitored, rather than to a value shifted from the space potential by an electron-temperature-dependent offset, i.e., the case with an equal-collection-area probe. This design goal is achieved by combining an ambient magnetic field in the plasma with baffles, or shields, on the probe, resulting in species-selective magnetic insulation of the probe collection area. This permits the elimination of electron current to the probe by further adjustment of magnetic insulation which results in an ion-temperature-dependent offset when the probe is electrically floating. Subtracting the floating potential of two magnetically insulated baffled probes, each with a different degree of magnetic insulation, enables the electron or ion temperature to be measured in real time.

  5. Accuracy of the coherent potential approximation for a one-dimensional Frenkel exciton system with a Gaussian distribution of fluctuations in the optical transition frequency

    Science.gov (United States)

    Avgin, I.; Boukahil, A.; Huber, D. L.

    2010-07-01

    We investigate the accuracy of the coherent potential approximation (CPA) for a one-dimensional Frenkel exciton system with nearest-neighbor interactions and a Gaussian distribution of fluctuations in the optical transition frequency. The CPA values of the integrated density of states and the inverse localization length are shown to be in excellent agreement with the results of mode-counting studies carried out on arrays of 10 7-10 8 sites. We also consider the asymptotic behavior of the inverse localization length and show that it can be approximated by the reciprocal of the decay length of an eigenstate localized about a single, strongly perturbed site in an otherwise perfect lattice.

  6. Comparison of fluctuating potentials and donor-acceptor pair transitions in a Cu-poor Cu{sub 2}ZnSnS{sub 4} based solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, J. P.; Sousa, R. A.; Sousa, M. G.; Cunha, A. F. da; Leitão, J. P., E-mail: joaquim.leitao@ua.pt [Departamento de Física and I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Fernandes, P. A. [Departamento de Física and I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Departamento de Física, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida, 431, 4200-072 Porto (Portugal); Salomé, P. M. P. [INL - International Iberian Nanotechnology Laboratory, Laboratory for Nanostructured Solar Cells (LaNaSC), Av. Mestre José Veiga, 4715-330 Braga (Portugal); González, J. C. [Departamento de Física, Universidade Federal de Minas Gerais, 30123-970 Belo Horizonte, Minas Gerais (Brazil)

    2014-10-20

    The structure of the electronic energy levels of a single phase Cu{sub 2}ZnSnS{sub 4} film, as confirmed by Raman Scattering and x-ray diffraction, is investigated through a dependence on the excitation power of the photoluminescence (PL). The behavior of the observed asymmetric band, with a peak energy at ∼1.22 eV, is compared with two theoretical models: (i) fluctuating potentials and (ii) donor-acceptor pair transitions. It is shown that the radiative recombination channels in the Cu-poor film are strongly influenced by tail states in the bandgap as a consequence of a heavy doping and compensation levels. The contribution of the PL for the evaluation of secondary phases is also highlighted.

  7. InfiniCharges: A tool for generating partial charges via the simultaneous fit of multiframe electrostatic potential (ESP) and total dipole fluctuations (TDF)

    Science.gov (United States)

    Sant, Marco; Gabrieli, Andrea; Demontis, Pierfranco; Suffritti, Giuseppe B.

    2016-03-01

    The InfiniCharges computer program, for generating reliable partial charges for molecular simulations in periodic systems, is here presented. This tool is an efficient implementation of the recently developed DM-REPEAT method, where the stability of the resulting charges, over a large set of fitting regions, is obtained through the simultaneous fit of multiple electrostatic potential (ESP) configurations together with the total dipole fluctuations (TDF). Besides DM-REPEAT, the program can also perform standard REPEAT fit and its multiframe extension (M-REPEAT), with the possibility to restrain the charges to an arbitrary value. Finally, the code is employed to generate partial charges for ZIF-90, a microporous material of the metal organic frameworks (MOFs) family, and an extensive analysis of the results is carried out.

  8. Characterization of plasma thiol redox potential in a common marmoset model of aging

    Directory of Open Access Journals (Sweden)

    James R. Roede

    2013-01-01

    Full Text Available Due to its short lifespan, ease of use and age-related pathologies that mirror those observed in humans, the common marmoset (Callithrix jacchus is poised to become a standard nonhuman primate model of aging. Blood and extracellular fluid possess two major thiol-dependent redox nodes involving cysteine (Cys, cystine (CySS, glutathione (GSH and glutathione disulfide (GSSG. Alteration in these plasma redox nodes significantly affects cellular physiology, and oxidation of the plasma Cys/CySS redox potential (EhCySS is associated with aging and disease risk in humans. The purpose of this study was to determine age-related changes in plasma redox metabolites and corresponding redox potentials (Eh to further validate the marmoset as a nonhuman primate model of aging. We measured plasma thiol redox states in marmosets and used existing human data with multivariate adaptive regression splines (MARS to model the relationships between age and redox metabolites. A classification accuracy of 70.2% and an AUC of 0.703 were achieved using the MARS model built from the marmoset redox data to classify the human samples as young or old. These results show that common marmosets provide a useful model for thiol redox biology of aging.

  9. A comparison of inflection point and floating point emissive probe techniques for electric potential measurements in a Hall thruster plasma

    Science.gov (United States)

    Sheehan, J. P.; Raitses, Yevgeny; Hershkowitz, Noah; Fisch, Nathaniel

    2010-11-01

    Theory suggests that when increasing the electron emission of an emissive probe the floating potential will saturate ˜Te/e below the plasma potential. This can introduce significant errors in plasma potential measurements in Hall thrusters where Te> 10 eV. The method of determining the plasma potential from the inflection point of emissive IV traces in the limit of zero emission may give a more accurate measurement of the plasma potential. The two methods are compared in a Hall thruster where ne˜10^11 cm-3, Te˜20 eV, and ion flows are significant. The results can be generalized to other types of plasmas.

  10. Modified Jeans instability in Lorentzian dusty self-gravitating plasmas with Lennard-Jones potential

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Y. Z., E-mail: qyzbird@live.com; Chen, H., E-mail: hchen61@ncu.edu.cn; Liu, S. Q., E-mail: sqlgroup@ncu.edu.cn [Department of Physics, Nanchang University, Nanchang 330047 (China)

    2014-11-15

    The Jeans instability in self-gravitating plasma with Kappa distributed dust grains is investigated basing on assumption that the mutual interaction among dust grains is governed by Lennard-Jones potential. It is shown that the presence of additional suprathermal particles has significant effects on the range of unstable modes and growth rate of Jeans instability. Compared with Maxwellian scenario, suprathermality stabilized the Jeans instability.

  11. Plasma-Assisted Combustion Studies at AFRL

    Science.gov (United States)

    2009-11-04

    important for lean, gas-turbine ( powerplant ) operation Might one also mitigate/influence acoustic fluctuations? Potential for uniform performance with...Thermometry with pulsed -W Source No -W Pulsed -W Direct coupled plasma torch: flame OH vs. - wave power: Plasma-assisted Ignition Cathey, Gundersen, Wang...Determine physical mechanism, primarily for transient plasma ignition  What is role of humidity: XH2O affects detonation wave speed in PDE but not

  12. 2D DIGE analysis of maternal plasma for potential biomarkers of Down Syndrome

    Directory of Open Access Journals (Sweden)

    Hogg Julie

    2011-09-01

    Full Text Available Abstract Background Prenatal screening for Down Syndrome (DS would benefit from an increased number of biomarkers to improve sensitivity and specificity. Improving sensitivity and specificity would decrease the need for potentially risky invasive diagnostic procedures. Results We have performed an in depth two-dimensional difference gel electrophoresis (2D DIGE study to identify potential biomarkers. We have used maternal plasma samples obtained from first and second trimesters from mothers carrying DS affected fetuses compared with mothers carrying normal fetuses. Plasma samples were albumin/IgG depleted and expanded pH ranges of pH 4.5 - 5.5, pH 5.3 - 6.5 and pH 6 - 9 were used for two-dimensional gel electrophoresis (2DE. We found no differentially expressed proteins in the first trimester between the two groups. Significant up-regulation of ceruloplasmin, inter-alpha-trypsin inhibitor heavy chain H4, complement proteins C1s subcomponent, C4-A, C5, and C9 and kininogen 1 were detected in the second trimester in maternal plasma samples where a DS affected fetus was being carried. However, ceruloplasmin could not be confirmed as being consistently up-regulated in DS affected pregnancies by Western blotting. Conclusions Despite the in depth 2DE approach used in this study the results underline the deficiencies of gel-based proteomics for detection of plasma biomarkers. Gel-free approaches may be more productive to increase the number of plasma biomarkers for DS for non-invasive prenatal screening and diagnosis.

  13. FCCP depolarizes plasma membrane potential by activating proton and Na+ currents in bovine aortic endothelial cells.

    Science.gov (United States)

    Park, Kyu-Sang; Jo, Inho; Pak, Kim; Bae, Sung-Won; Rhim, Hyewhon; Suh, Suk-Hyo; Park, Jin; Zhu, Hong; So, Insuk; Kim, Ki Whan

    2002-01-01

    We investigated the effects of carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP), a protonophore and uncoupler of mitochondrial oxidative phosphorylation in mitochondria, on plasma membrane potential and ionic currents in bovine aortic endothelial cells (BAECs). The membrane potential and ionic currents of BAECs were recorded using the patch-clamp technique in current-clamp and voltage-clamp modes, respectively. FCCP activated ionic currents and depolarized the plasma membrane potential in a dose-dependent manner. Neither the removal of extracellular Ca2+ nor pretreatment with BAPTA/AM affected the FCCP-induced currents, implying that the currents are not associated with the FCCP-induced intracellular [Ca2+]i increase. FCCP-induced currents were significantly influenced by the changes in extracellular or intracellular pH; the increased proton gradient produced by lowering the extracellular pH or intracellular alkalinization augmented the changes in membrane potential and ionic currents caused by FCCP. FCCP-induced currents were significantly reduced under extracellular Na+-free conditions. The reversal potentials of FCCP-induced currents under Na+-free conditions were well fitted to the calculated equilibrium potential for protons. Interestingly, FCCP-induced Na+ transport (subtracted currents, I(control)- I(Na+-free) was closely dependent on extracellular pH, whereas FCCP-induced H+transport was not significantly affected by the absence of Na+. These results suggest that the FCCP-induced ionic currents and depolarization, which are strongly dependent on the plasmalemmal proton gradient, are likely to be mediated by both H+ and Na+ currents across the plasma membrane. The relationship between H+ and Na+ transport still needs to be determined.

  14. Different stimulation frequencies alter synchronous fluctuations in motor evoked potential amplitude of intrinsic hand muscles – a TMS study.

    Directory of Open Access Journals (Sweden)

    Martin Victor Sale

    2016-03-01

    Full Text Available The amplitude of motor-evoked potentials (MEPs elicited with transcranial magnetic stimulation (TMS varies from trial-to-trial. Synchronous oscillations in cortical neuronal excitability contribute to this variability, however it is not known how different frequencies of stimulation influence MEP variability, and whether these oscillations are rhythmic or aperiodic. We stimulated the motor cortex with TMS at different regular (i.e., rhythmic rates, and compared this with pseudo-random (aperiodic timing. In 18 subjects, TMS was applied at three regular frequencies (0.05 Hz, 0.2 Hz, 1 Hz and one aperiodic frequency (mean 0.2 Hz. MEPs (n = 50 were recorded from three intrinsic hand muscles of the left hand with different functional and anatomical relations. MEP amplitude correlation was highest for the functionally related muscle pair, less for the anatomically related muscle pair and least for the functionally- and anatomically-unrelated muscle pair. MEP correlations were greatest with 1 Hz, and least for stimulation at 0.05 Hz. Corticospinal neuron synchrony is higher with shorter TMS intervals. Further, corticospinal neuron synchrony is similar irrespective of whether the stimulation is periodic or aperiodic. These findings suggest TMS frequency is a crucial consideration for studies using TMS to probe correlated activity between muscle pairs.

  15. Different Stimulation Frequencies Alter Synchronous Fluctuations in Motor Evoked Potential Amplitude of Intrinsic Hand Muscles-a TMS Study.

    Science.gov (United States)

    Sale, Martin V; Rogasch, Nigel C; Nordstrom, Michael A

    2016-01-01

    The amplitude of motor-evoked potentials (MEPs) elicited with transcranial magnetic stimulation (TMS) varies from trial-to-trial. Synchronous oscillations in cortical neuronal excitability contribute to this variability, however it is not known how different frequencies of stimulation influence MEP variability, and whether these oscillations are rhythmic or aperiodic. We stimulated the motor cortex with TMS at different regular (i.e., rhythmic) rates, and compared this with pseudo-random (aperiodic) timing. In 18 subjects, TMS was applied at three regular frequencies (0.05 Hz, 0.2 Hz, 1 Hz) and one aperiodic frequency (mean 0.2 Hz). MEPs (n = 50) were recorded from three intrinsic hand muscles of the left hand with different functional and anatomical relations. MEP amplitude correlation was highest for the functionally related muscle pair, less for the anatomically related muscle pair and least for the functionally- and anatomically-unrelated muscle pair. MEP correlations were greatest with 1 Hz, and least for stimulation at 0.05 Hz. Corticospinal neuron synchrony is higher with shorter TMS intervals. Further, corticospinal neuron synchrony is similar irrespective of whether the stimulation is periodic or aperiodic. These findings suggest TMS frequency is a crucial consideration for studies using TMS to probe correlated activity between muscle pairs.

  16. Conditional Eddies in Plasma Turbulence

    DEFF Research Database (Denmark)

    Johnsen, Helene; Pécseli, Hans; Trulsen, J.

    1986-01-01

    Conditional structures, or eddies, in turbulent flows are discussed with special attention to electrostatic turbulence in plasmas. The potential variation of these eddies is obtained by sampling the fluctuations only when a certain condition is satisfied in a reference point. The resulting...

  17. Nucleation rate of the quark-gluon plasma droplet at finite quark chemical potential

    Indian Academy of Sciences (India)

    D S Gosain; S Somorendro Singh; Agam K Jha

    2012-05-01

    The nucleation rate of quark-gluon plasma (QGP) droplet is computed at finite quark chemical potential. In the course of computing the nucleation rate, the finite size effects of the QGP droplet are taken into account. We consider the phenomenological flow parameter of quarks and gluons, which is dependent on quark chemical potential and we calculate the nucleation rate of the QGP droplet with this parameter. While calculating the nucleation rate, we find that for low values of quark phenomenological parameter $ q$, nucleation rate is negligible and when increases, nucleation rate increases significantly.

  18. Potential Distribution of Podocnemis lewyana (Reptilia:Podocnemididae and Its Possible Fluctuation Under Different Global Climate Change Scenarios

    Directory of Open Access Journals (Sweden)

    Carlos Ortiz-Yusty

    2014-06-01

    Full Text Available We implemented a species distribution modelling approach to establish the potential distribution of Podocnemis lewyana, to explore the climatic factors that may influence the species’ distribution and to evaluate possible changes in distribution under future climate scenarios. The distribution models predicted a continuous distribution from south to north along the Magdalena River, from Rivera and Palermo in the department of Huila to the departments of Atlántico and Magdalena in the north. Temperature was the variable most influential in the distribution of P. lewyana; this species tends to be present in warm regions with low temperature variability. The distribution model predicted an increase in the geographic range of P. lewyana under climate change scenarios. However, taking into account the habitat preferences of this species and its strong association with water, this result should be treated with caution since the model considered only terrestrial climatic variables. Given the life history characteristics of this species (temperature-dependent sex determination, high pivotal temperature and a very narrow transition range and the negative effect of changes in hydrological regimes on embryo survival, expansion of the potential distribution of P. lewyana in the future does not mean that the species will not be affected by global climate change.DISTRIBUCIÓN POTENCIAL DE (Podocnemis lewyana, REPTILIA: Podocnemididae Y SU POSIBLE FLUCTUACIÓN BAJO ESCENARIOS DE CAMBIO CLIMÁTICO GLOBALEn este estudio se implementó el modelaje de distribución de especies para establecer el rango de distribución potencial de Podocnemis lewyana, explorar los componentes del clima que pueden influenciar dicha distribución y evaluar posibles fluctuaciones de su distribución bajo escenarios de clima futuro. Los modelos obtenidos predicen una distribución continua de sur a norte por todo el río Magdalena, desde los municipios de Rivera y Palermo en el

  19. Quantum-mechanical calculation of ionization potential lowering in dense plasmas

    CERN Document Server

    Son, Sang-Kil; Jurek, Zoltan; Ziaja, Beata; Santra, Robin

    2014-01-01

    The charged environment within a dense plasma leads to the phenomenon of ionization potential depression (IPD) for ions embedded in the plasma. Accurate predictions of the IPD effect are of crucial importance for modeling atomic processes occurring within dense plasmas. Several theoretical models have been developed to describe the IPD effect, with frequently discrepant predictions. Only recently, first experiments on IPD in Al plasma have been performed with an x-ray free-electron laser (XFEL), where their results were found to be in disagreement with the widely-used IPD model by Stewart and Pyatt. Another experiment on Al, at the Orion laser, showed disagreement with the model by Ecker and Kr\\"oll. This controversy shows a strong need for a rigorous and consistent theoretical approach to calculate the IPD effect. Here we propose such an approach: a two-step Hartree-Fock-Slater model. With this parameter-free model we can accurately and efficiently describe the experimental Al data and validate the accuracy ...

  20. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics, Hanyang University, Seoul 04763 (Korea, Republic of); Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

    2017-02-12

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained. - Highlights: • High frequency electrostatic wave propagation is investigated in a dense semi-bounded quantum plasma. • The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. • The quantum effect enhances the frequency of the wave especially in the high wave number regime. • The frequency of surface wave is found to be always lower than that of the bulk wave. • The group velocity of the surface wave for various quantum wave number is also obtained.

  1. Electron cooling and finite potential drop in a magnetized plasma expansion

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Sanchez, M. [Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Navarro-Cavallé, J. [Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio, Universidad Politécnica de Madrid, Plaza Cardenal Cisneros 3, Madrid 28040 (Spain); Ahedo, E. [Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Avda. Universidad 30, Leganés 28911, Madrid (Spain)

    2015-05-15

    The steady, collisionless, slender flow of a magnetized plasma into a surrounding vacuum is considered. The ion component is modeled as mono-energetic, while electrons are assumed Maxwellian upstream. The magnetic field has a convergent-divergent geometry, and attention is restricted to its paraxial region, so that 2D and drift effects are ignored. By using the conservation of energy and magnetic moment of particles and the quasi-neutrality condition, the ambipolar electric field and the distribution functions of both species are calculated self-consistently, paying attention to the existence of effective potential barriers associated to magnetic mirroring. The solution is used to find the total potential drop for a set of upstream conditions, plus the axial evolution of various moments of interest (density, temperatures, and heat fluxes). The results illuminate the behavior of magnetic nozzles, plasma jets, and other configurations of interest, showing, in particular, in the divergent plasma the collisionless cooling of electrons, and the generation of collisionless electron heat fluxes.

  2. Potential biomarkers of fatigue identified by plasma metabolome analysis in rats.

    Directory of Open Access Journals (Sweden)

    Satoshi Kume

    Full Text Available In the present study, prior to the establishment of a method for the clinical diagnosis of chronic fatigue in humans, we validated the utility of plasma metabolomic analysis in a rat model of fatigue using capillary electrophoresis-mass spectrometry (CE-MS. In order to obtain a fatigued animal group, rats were placed in a cage filled with water to a height of 2.2 cm for 5 days. A food-restricted group, in which rats were limited to 10 g/d of food (around 50% of the control group, was also assessed. The food-restricted group exhibited weight reduction similar to that of the fatigued group. CE-MS measurements were performed to evaluate the profile of food intake-dependent metabolic changes, as well as the profile in fatigue loading, resulting in the identification of 48 metabolites in plasma. Multivariate analyses using hierarchical clustering and principal component analysis revealed that the plasma metabolome in the fatigued group showed clear differences from those in the control and food-restricted groups. In the fatigued group, we found distinctive changes in metabolites related to branched-chain amino acid metabolism, urea cycle, and proline metabolism. Specifically, the fatigued group exhibited significant increases in valine, leucine, isoleucine, and 2-oxoisopentanoate, and significant decreases in citrulline and hydroxyproline compared with the control and food-restricted groups. Plasma levels of total nitric oxide were increased in the fatigued group, indicating systemic oxidative stress. Further, plasma metabolites involved in the citrate cycle, such as cis-aconitate and isocitrate, were reduced in the fatigued group. The levels of ATP were significantly decreased in the liver and skeletal muscle, indicative of a deterioration in energy metabolism in these organs. Thus, this comprehensive metabolic analysis furthered our understanding of the pathophysiology of fatigue, and identified potential diagnostic biomarkers based on fatigue

  3. Potential biomarkers of fatigue identified by plasma metabolome analysis in rats.

    Science.gov (United States)

    Kume, Satoshi; Yamato, Masanori; Tamura, Yasuhisa; Jin, Guanghua; Nakano, Masayuki; Miyashige, Yukiharu; Eguchi, Asami; Ogata, Yoshiyuki; Goda, Nobuhito; Iwai, Kazuhiro; Yamano, Emi; Watanabe, Yasuyoshi; Soga, Tomoyoshi; Kataoka, Yosky

    2015-01-01

    In the present study, prior to the establishment of a method for the clinical diagnosis of chronic fatigue in humans, we validated the utility of plasma metabolomic analysis in a rat model of fatigue using capillary electrophoresis-mass spectrometry (CE-MS). In order to obtain a fatigued animal group, rats were placed in a cage filled with water to a height of 2.2 cm for 5 days. A food-restricted group, in which rats were limited to 10 g/d of food (around 50% of the control group), was also assessed. The food-restricted group exhibited weight reduction similar to that of the fatigued group. CE-MS measurements were performed to evaluate the profile of food intake-dependent metabolic changes, as well as the profile in fatigue loading, resulting in the identification of 48 metabolites in plasma. Multivariate analyses using hierarchical clustering and principal component analysis revealed that the plasma metabolome in the fatigued group showed clear differences from those in the control and food-restricted groups. In the fatigued group, we found distinctive changes in metabolites related to branched-chain amino acid metabolism, urea cycle, and proline metabolism. Specifically, the fatigued group exhibited significant increases in valine, leucine, isoleucine, and 2-oxoisopentanoate, and significant decreases in citrulline and hydroxyproline compared with the control and food-restricted groups. Plasma levels of total nitric oxide were increased in the fatigued group, indicating systemic oxidative stress. Further, plasma metabolites involved in the citrate cycle, such as cis-aconitate and isocitrate, were reduced in the fatigued group. The levels of ATP were significantly decreased in the liver and skeletal muscle, indicative of a deterioration in energy metabolism in these organs. Thus, this comprehensive metabolic analysis furthered our understanding of the pathophysiology of fatigue, and identified potential diagnostic biomarkers based on fatigue pathophysiology.

  4. Holographic dual of a boost-invariant plasma with chemical potential

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, Tigran; Kirsch, Ingo

    2010-12-15

    We construct a gravity dual of a boost-invariant flow of an N=4 SU(N) supersymmetric Yang-Mills gauge theory plasma with chemical potential. We present both a first-order corrected late-time solution in Eddington-Finkelstein coordinates and a zeroth-order solution in parametric form in Fefferman-Graham coordinates. The resulting background takes the form of a time-dependent AdS Reissner-Nordstroem-type black hole whose horizons move into the bulk of the AdS space. The solution correctly reproduces the energy and charge density as well as the viscosity of the plasma previously computed in the literature. (orig.)

  5. A potential tool for diagnosis of male infertility: Plasma metabolomics based on GC-MS.

    Science.gov (United States)

    Zhou, Xinyi; Wang, Yang; Yun, Yonghuan; Xia, Zian; Lu, Hongmei; Luo, Jiekun; Liang, Yizeng

    2016-01-15

    Male infertility has become an important public health problem worldwide. Nowadays the diagnosis of male infertility frequently depends on the results of semen quality or requires more invasive surgical intervention. Therefore, it is necessary to develop a novel approach for early diagnosis of male infertility. According to the presence or absence of normal sexual function, the male infertility is classified into two phenotypes, erectile dysfunction (ED) and semen abnormalities (SA). The aim of this study was to investigate the GC-MS plasma profiles of infertile male having erectile dysfunction (ED) and having semen abnormalities (SA) and discover the potential biomarkers. The plasma samples from healthy controls (HC) (n=61) and infertility patients with ED (n=26) or with SA (n=44) were analyzed by gas chromatography-mass spectrometry (GC-MS) for discrimination and screening potential biomarkers. The partial least squares-discriminant analysis (PLS-DA) was performed on GC-MS dataset. The results showed that HC could be discriminated from infertile cases having SA (AUC=86.96%, sensitivity=78.69%, specificity=84.09%, accuracy=80.95%) and infertile cases having ED (AUC=94.33%, sensitivity=80.33%, specificity=100%, accuracy=87.36%). Some potential biomarkers were successfully discovered by two commonly used variable selection methods, variable importance on projection (VIP) and original coefficients of PLS-DA (β). 1,5-Anhydro-sorbitol and α-hydroxyisovaleric acid were identified as the potential biomarkers for distinguishing HC from the male infertility patients. Meanwhile, lactate, glutamate and cholesterol were the found to be the important variables to distinguish between patients with erectile dysfunction from those with semen abnormalities. The plasma metabolomics may be developed as a novel approach for fast, noninvasive, and acceptable diagnosis and characterization of male infertility.

  6. Net baryon fluctuations from a crossover equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Kapusta, J.; Albright, M. [University of Minnesota, School of Physics and Astronomy, Minneapolis, MN (United States); Young, C. [Michigan State University, National Superconducting Cyclotron Laboratory, East Lansing, MI (United States)

    2016-08-15

    We have constructed an equation of state which smoothly interpolates between an excluded-volume hadron resonance gas at low energy density to a plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with lattice calculations at both zero and nonzero baryon chemical potential. We use it to compute the variance, skewness, and kurtosis of fluctuations of baryon number, and compare to measurements of proton number fluctuations in central Au-Au collisions as measured by the STAR Collaboration in a beam energy scan at the Relativistic Heavy-Ion Collider. The crossover equation of state can reproduce the data if the fluctuations are frozen out at temperatures well below than the average chemical freeze-out. (orig.)

  7. Net Baryon Fluctuations from a Crossover Equation of State

    CERN Document Server

    Kapusta, J; Young, C

    2016-01-01

    We have constructed an equation of state which smoothly interpolates between an excluded volume hadron resonance gas at low energy density to a plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with lattice calculations at both zero and nonzero baryon chemical potential. We use it to compute the variance, skewness, and kurtosis of fluctuations of baryon number, and compare to measurements of proton number fluctuations in central Au-Au collisions as measured by the STAR collaboration in a beam energy scan at the Relativistic Heavy Ion Collider. The crossover equation of state can reproduce the data if the fluctuations are frozen out at temperatures well below than the average chemical freeze-out.

  8. Near Discharge Cathode Assembly Plasma Potential Measurements in a 30-cm NSTAR Type Ion Engine During Beam Extraction

    Science.gov (United States)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Floating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8 and TH 12 consequently they are of specific interest in investigating discharge keeper erosion phenomena. The data do not validate the presence of a potential hill plasma structure downstream of the DCA, which has been proposed as a possible erosion mechanism. The data are comparable in magnitude to data taken by other researchers in ring-cusp electron-bombardment ion thrusters. The plasma potential structures are insensitive to thruster throttling level with a minimum as low as 14 V measured at the DCA exit plane and increasing gradually in the axial direction. A sharp increase in plasma potential to the bulk discharge value of 26 to 28 volts, roughly 10 mm radially from DCA centerline, was observed. Plasma potential measurements indicate a low-potential plume structure that is roughly 20 mm in diameter emanating from the discharge cathode that may be attributed to a free-standing plasma double layer.

  9. Inverse scattering problem in turbulent magnetic fluctuations

    CERN Document Server

    Treumann, R A; Narita, Y

    2016-01-01

    We apply a particular form of the inverse scattering theory to turbulent magnetic fluctuations in a plasma. In the present note we develop the theory, formulate the magnetic fluctuation problem in terms of its electrodynamic turbulent response function, and reduce it to the solution of a special form of the famous Gel$'$fand-Levitan-Marchenko equation of quantum mechanical scattering theory.

  10. Wave Beam Propagation Through Density Fluctuations

    NARCIS (Netherlands)

    Balakin, A. A.; Bertelli, N.; Westerhof, E.

    2011-01-01

    Perturbations induced by edge density fluctuations on electron cyclotron wave beams propagating in fusion plasmas are studied by means of a quasi-optical code. The effects of such fluctuations are illustrated here by showing the beam propagation in the case of single harmonic perturbations to the wa

  11. Scintillations of cosmic radio sources in the decametre waveband. I - Spectra of scintillations due to ionospheric and interplanetary plasma fluctuations and the possibility of their separation. remnants of the Crab Nebula and Cassiopeia A

    Science.gov (United States)

    Bovkun, V. P.; Zhuk, I. N.

    1981-09-01

    The effect of fluctuations of the interplanetary plasma and the ionosphere upon the scintillation spectra of radio sources at decametre waves is considered with due regard for the finite antenna aperture, fluctuation anisotropy, and the direction of their drift in space. It has been shown that scintillation due to interplanetary plasma (IPP), can be reliably separated from the ionospheric scintillation background at decametre wavelengths. For elongations between 90° to 150°, the IPP scintillation power spectrum observed in the 12.6-25 MHz waveband is of a power law form with the index 3.1 ± 0.6, which is in close agreement with the values known for smaller elongations. The solar wind velocity projection orthogonal to the line of sight is estimated for elongations about 1 10~ and has been found to be 300 ± 80 km s~1. As in the case of smaller elongations, the velocity dispersion is significant. At night, wideband spectra of ionospheric scintillations are observed in the decametre band, with the breaking point at approximately 0.01 Hz in the 12 m band, and narrow-band spectra whose cut-off frequency is below 0.01 Hz. The power spectrum of ionospheric scintillations is of a power-law form with the index 3.4 ± 0.5. In some cases steeper spectra are observed

  12. Plasma potential of a moving ionization zone in DC magnetron sputtering

    Science.gov (United States)

    Panjan, Matjaž; Anders, André

    2017-02-01

    Using movable emissive and floating probes, we determined the plasma and floating potentials of an ionization zone (spoke) in a direct current magnetron sputtering discharge. Measurements were recorded in a space and time resolved manner, which allowed us to make a three-dimensional representation of the plasma potential. From this information we could derive the related electric field, space charge, and the related spatial distribution of electron heating. The data reveal the existence of strong electric fields parallel and perpendicular to the target surface. The largest E-fields result from a double layer structure at the leading edge of the ionization zone. We suggest that the double layer plays a crucial role in the energization of electrons since electrons can gain several 10 eV of energy when crossing the double layer. We find sustained coupling between the potential structure, electron heating, and excitation and ionization processes as electrons drift over the magnetron target. The brightest region of an ionization zone is present right after the potential jump, where drifting electrons arrive and where most local electron heating occurs. The ionization zone intensity decays as electrons continue to drift in the Ez × B direction, losing energy by inelastic collisions; electrons become energized again as they cross the potential jump. This results in the elongated, arrowhead-like shape of the ionization zone. The ionization zone moves in the -Ez × B direction from which the to-be-heated electrons arrive and into which the heating region expands; the zone motion is dictated by the force of the local electric field on the ions at the leading edge of the ionization zone. We hypothesize that electron heating caused by the potential jump and physical processes associated with the double layer also apply to magnetrons at higher discharge power, including high power impulse magnetron sputtering.

  13. Synchronous plasma membrane electrochemical potential oscillations during yeast colony development and aging.

    Science.gov (United States)

    Palková, Zdena; Váchová, Libuse; Gásková, Dana; Kucerová, Helena

    2009-05-01

    Microorganisms that survive in natural environments form organized multicellular communities, biofilms and colonies with specific properties. During stress and nutrient limitation, slow growing and senescent cells in such communities retain vital processes by maintaining plasma membrane integrity and retaining the ability to generate transmembrane electrochemical gradients. We report the use of a Saccharomyces cerevisiae colonial model to show that population growth in a multicellular community depends on nutrient diffusion and that resting cells start to accumulate from the beginning of the second acidic phase of colony development. Despite differentiation of colony members, synchronous transmembrane potential oscillation was detected in the organized colony. The electrochemical membrane potential periodically oscillated at frequencies between those for circadian to infradian rhythms during colony aging and transiently decreased at time points previously linked with rebuilding of yeast metabolism. Despite extensive decreases in the intracellular ATP concentration and in the amount and activity of the plasma membrane proton pump during nutrient limited growth and colony aging, the transmembrane electrochemical potential appeared to be maintained above a level critical for population survival.

  14. A plasma source driven predator-prey like mechanism as a potential cause of spiraling intermittencies in linear plasma devices

    Energy Technology Data Exchange (ETDEWEB)

    Reiser, D. [Research Center Jülich GmbH, Institute for Energy and Climate Research—Plasma Physics, D-52425 Jülich (Germany); Ohno, N. [Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Tanaka, H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Vela, L. [Physics Department, Universidad Carlos III de Madrid, Avda de la Universidad 30, 28911-Leganés, Madrid (Spain)

    2014-03-15

    Three-dimensional global drift fluid simulations are carried out to analyze coherent plasma structures appearing in the NAGDIS-II linear device (nagoya divertor plasma Simulator-II). The numerical simulations reproduce several features of the intermittent spiraling structures observed, for instance, statistical properties, rotation frequency, and the frequency of plasma expulsion. The detailed inspection of the three-dimensional plasma dynamics allows to identify the key mechanism behind the formation of these intermittent events. The resistive coupling between electron pressure and parallel electric field in the plasma source region gives rise to a quasilinear predator-prey like dynamics where the axisymmetric mode represents the prey and the spiraling structure with low azimuthal mode number represents the predator. This interpretation is confirmed by a reduced one-dimensional quasilinear model derived on the basis of the findings in the full three-dimensional simulations. The dominant dynamics reveals certain similarities to the classical Lotka-Volterra cycle.

  15. A plasma source driven predator-prey like mechanism as a potential cause of spiraling intermittencies in linear plasma devices

    Science.gov (United States)

    Reiser, D.; Ohno, N.; Tanaka, H.; Vela, L.

    2014-03-01

    Three-dimensional global drift fluid simulations are carried out to analyze coherent plasma structures appearing in the NAGDIS-II linear device (nagoya divertor plasma Simulator-II). The numerical simulations reproduce several features of the intermittent spiraling structures observed, for instance, statistical properties, rotation frequency, and the frequency of plasma expulsion. The detailed inspection of the three-dimensional plasma dynamics allows to identify the key mechanism behind the formation of these intermittent events. The resistive coupling between electron pressure and parallel electric field in the plasma source region gives rise to a quasilinear predator-prey like dynamics where the axisymmetric mode represents the prey and the spiraling structure with low azimuthal mode number represents the predator. This interpretation is confirmed by a reduced one-dimensional quasilinear model derived on the basis of the findings in the full three-dimensional simulations. The dominant dynamics reveals certain similarities to the classical Lotka-Volterra cycle.

  16. The potential of rapid cooling spark plasma sintering for metallic materials

    Directory of Open Access Journals (Sweden)

    Faming Zhang

    2013-05-01

    Full Text Available Spark plasma sintering (SPS is a remarkable technique for consolidating a large variety of advanced materials with rapid heating rates. However, adjusting the cooling rates has so far faced limitations. This communication discusses the potentials of SPS integrated with a novel gas quenching system that can allow metallic materials to be sintered and rapidly quenched directly after the sintering step, saving energy and costs. Results on numerical simulations of rapid cooling-SPS and the mechanical properties and microstructures of Ti6Al4V alloy are discussed; exhibiting the feasibility of this rapid cooling SPS technique and the major implications for the field of SPS and metallic powder consolidation.

  17. The potential role of curcumin (diferuloylmethane in plasma cell dyscrasias/paraproteinemia

    Directory of Open Access Journals (Sweden)

    Terry Golombick

    2008-03-01

    Full Text Available Terry Golombick, Terry DiamondDepartment of Endocrinology, St George Hospital, Kogarah, AustraliaAbstract: Plasma cell dyscrasias, most commonly associated with paraproteinemia, are a diverse group of diseases. Monoclonal gammopathy of undefined significance (MGUS can precede multiple myeloma, a progressive neoplastic disease. MGUS occurs in association with a variety of other diseases and currently no treatment is recommended but rather “watchful waiting”. Given that the size of the M-protein is a risk factor for disease progression, early intervention with the aim of reducing the paraprotein load would provide an innovative therapeutic tool. Preliminary results from our pilot study show a drop of between 5% and 30% serum paraprotein in patients taking curcumin compared with patients on placebo. Curcumin is a diferuloylmethane present in extracts of the rhizome of the Curcuma longa plant. As a natural product, this has exciting potential in the treatment of plasma cell dyscrasias.Keywords: plasma cell dyscrasias, MGUS, myeloma, curcumin, paraproteinemia

  18. Potential applications of nonthermal plasmas against biofilm-associated micro-organisms in vitro.

    Science.gov (United States)

    Puligundla, P; Mok, C

    2017-01-20

    Biofilms as complex microbial communities attached to surfaces pose several challenges in different sectors, ranging from food and healthcare to desalination and power generation. The biofilm mode of growth allows microorganisms to survive in hostile environments and biofilm cells exhibit distinct physiology and behaviour in comparison with their planktonic counterparts. They are ubiquitous, resilient and difficult to eradicate due to their resistant phenotype. Several chemical-based cleaning and disinfection regimens are conventionally used against biofilm-dwelling micro-organisms in vitro. Although such approaches are generally considered to be effective, they may contribute to the dissemination of antimicrobial resistance and environmental pollution. Consequently, advanced green technologies for biofilm control are constantly emerging. Disinfection using nonthermal plasmas (NTPs) is one of the novel strategies having a great potential for control of biofilms of a broad spectrum of micro-organisms. This review discusses several aspects related to the inactivation of biofilm-associated bacteria and fungi by different types of NTPs under in vitro conditions. A brief introduction summarizes prevailing methods in biofilm inactivation, followed by introduction to gas discharge plasmas, active plasma species and their inactivating mechanism. Subsequently, significance and aspects of NTP inactivation of biofilm-associated bacteria, especially those of medical importance, including opportunistic pathogens, oral pathogenic bacteria, foodborne pathogens and implant bacteria, are discussed. The remainder of the review discusses majorly about the synergistic effect of NTPs and their activity against biofilm-associated fungi, especially Candida species.

  19. MicroRNAs in plasma and cerebrospinal fluid as potential markers for Alzheimer's disease.

    Science.gov (United States)

    Kiko, Takehiro; Nakagawa, Kiyotaka; Tsuduki, Tsuyoshi; Furukawa, Katsutoshi; Arai, Hiroyuki; Miyazawa, Teruo

    2014-01-01

    The development of Alzheimer's disease (AD) biomarkers remains an unmet challenge, and new approaches that can improve current AD biomarker strategies are needed. Recent reports suggested that microRNA (miRNA) profiling of biological fluids has emerged as a diagnostic tool for several pathologic conditions. In this study, we measured six candidate miRNAs (miR-9, miR-29a, miR-29b, miR-34a, miR-125b, and miR-146a) in plasma and cerebrospinal fluid (CSF) of AD and normal subjects by using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) to evaluate their potential usability as AD biomarkers. The qRT-PCR results showed that plasma miR-34a and miR-146a levels, and CSF miR-34a, miR-125b, and miR-146a levels in AD patients were significantly lower than in control subjects. On the other hand, CSF miR-29a and miR-29b levels were significantly higher than in control subjects. Our results provide a possibility that miRNAs detected in plasma and CSF can serve as biomarkers for AD.

  20. Heavy ion beam probing—diagnostics to study potential and turbulence in toroidal plasmas

    Science.gov (United States)

    Melnikov, A. V.; Krupnik, L. I.; Eliseev, L. G.; Barcala, J. M.; Bravo, A.; Chmyga, A. A.; Deshko, G. N.; Drabinskij, M. A.; Hidalgo, C.; Khabanov, P. O.; Khrebtov, S. M.; Kharchev, N. K.; Komarov, A. D.; Kozachek, A. S.; Lopez, J.; Lysenko, S. E.; Martin, G.; Molinero, A.; de Pablos, J. L.; Soleto, A.; Ufimtsev, M. V.; Zenin, V. N.; Zhezhera, A. I.; T-10 Team; TJ-II Team

    2017-07-01

    Heavy ion beam probing (HIBP) is a unique diagnostics to study the core plasma potential and turbulence. Advanced HIBPs operate in the T-10 tokamak and TJ-II flexible heliac with fine focused (magnetic configurations with ECR and neutral beam injection (NBI) heating at TJ-II. Time evolution of the radial profiles and/or local values of plasma parameters from high field side (HFS) to low field side (LFS), -1  magnetic field B pol (by the beam toroidal shift), poloidal electric filed E pol that allows one to derive the electrostatic turbulent particle flux ΓE×B. The cross-phase of density oscillations produces the phase velocity of their poloidal propagation or rotation; also it gives the poloidal mode number. Dual HIBP, consisting of two identical HIBPs located ¼ torus apart provide the long-range correlations of core plasma parameters. Low-noise high-gain electronics allows us to study broadband turbulence and quasi-coherent modes like geodesic acoustic modes and Alfvén eigenmodes.

  1. Effect of Bohm quantum potential in the propagation of ion-acoustic waves in degenerate plasmas

    Science.gov (United States)

    Hasan, M. M.; Hossen, M. A.; Rafat, A.; Mamun, A. A.

    2016-10-01

    A theoretical investigation has been carried out on the propagation of the ion-acoustic (IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries (K-dV), modified K-dV (mK-dV), and mixed mK-dV (mmK-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features (phase speed, amplitude, width, etc.) of the IA solitary waves (SWs), the SWs solutions of the K-dV, mK-dV, and mmK-dV are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects (arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g., white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser-solid matter interaction experiments, etc., are mentioned.

  2. The transport of phosphate between the plasma and dialysate compartments in peritoneal dialysis is influenced by an electric potential difference

    DEFF Research Database (Denmark)

    Graff, J; Fugleberg, S; Brahm, J

    1996-01-01

    was not identifiable. Furthermore, it was demonstrated that the electrochemical gradient between plasma water and dialysate favours the diffusive phosphate transport, and both electric and chemical potentials must be taken into account in calculations of the transperitoneal phosphate transport....

  3. Polarization-mediated Debye-screening of surface potential fluctuations in dual-channel AlN/GaN high electron mobility transistors

    Science.gov (United States)

    Deen, David A.; Miller, Ross A.; Osinsky, Andrei V.; Downey, Brian P.; Storm, David F.; Meyer, David J.; Scott Katzer, D.; Nepal, Neeraj

    2016-12-01

    A dual-channel AlN/GaN/AlN/GaN high electron mobility transistor (HEMT) architecture is proposed, simulated, and demonstrated that suppresses gate lag due to surface-originated trapped charge. Dual two-dimensional electron gas (2DEG) channels are utilized such that the top 2DEG serves as an equipotential that screens potential fluctuations resulting from surface trapped charge. The bottom channel serves as the transistor's modulated channel. Two device modeling approaches have been performed as a means to guide the device design and to elucidate the relationship between the design and performance metrics. The modeling efforts include a self-consistent Poisson-Schrodinger solution for electrostatic simulation as well as hydrodynamic three-dimensional device modeling for three-dimensional electrostatics, steady-state, and transient simulations. Experimental results validated the HEMT design whereby homo-epitaxial growth on free-standing GaN substrates and fabrication of the same-wafer dual-channel and recessed-gate AlN/GaN HEMTs have been demonstrated. Notable pulsed-gate performance has been achieved by the fabricated HEMTs through a gate lag ratio of 0.86 with minimal drain current collapse while maintaining high levels of dc and rf performance.

  4. Derivation and Testing of Computer Algorithms for Automatic Real-Time Determination of Space Vehicle Potentials in Various Plasma Environments

    Science.gov (United States)

    1988-05-31

    COMPUTER ALGORITHMS FOR AUTOMATIC REAL-TIME DETERMINATION OF SPACE VEHICLE POTENTIALS IN VARIOUS PLASMA ENVIRONMENTS May 31, 1988 Stanley L. Spiegel...crrnaion DiviSiofl 838 12 2 DERIVATION AND TESTING OF COMPUTER ALGORITHMS FOR AUTOMATIC REAL-TIME DETERMINATION OF SPACE VEHICLE POTENTIALS IN VARIOUS...S.L., "Derivation and testing of computer algorithms for automatic real time determination of space vehicle poteuatials in various plasma

  5. Terrestrial Gravity Fluctuations

    Science.gov (United States)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10-23 Hz-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  6. Terrestrial Gravity Fluctuations.

    Science.gov (United States)

    Harms, Jan

    2015-01-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10(-23) Hz(-1/2) above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  7. Terrestrial Gravity Fluctuations

    Directory of Open Access Journals (Sweden)

    Jan Harms

    2015-12-01

    Full Text Available Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our

  8. Chromium(VI)-induced Production of Reactive Oxygen Species, Change of Plasma Membrane Potential and Dissipation of Mitochondria Membrane Potential in Chinese Hamster Lung Cell Cultures

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective To examine whether Reactive Oxygen Species (ROS) is generated, and whether plasma membrane potential and mitochondrial membrane potential are depolarized in Chinese Hamster Lung (CHL) cell lines exposed to Cr (VI). Methods CHL cells were incubated with Cr(VI) at 10 μmol/L, 2.5 μmol/L, 0.65 μmol/L for 3 and 6 hours, respectively. The production of ROS was performed by using 2,7_dichlorofluorescin diacetate; The changes in plasma membrane potential were estimated using fluorescent cationic dye DiBAC4; And the changes in mitochondria membrane potential were estimated using fluorescent dye Rhodamine 123. Results The ROS levels in CHL cells increased in all treated groups compared with the control group (P<0.01); The plasma membrane potential and mitochondrial membrane potential in CHL cells dissipated after incubated with Cr(VI) at 10 μmol/L for 3 hours and 6 hours (P<0.01), at 2.5 μmol/L for 6 hours (P<0.01 or 0.05). Conclusion Cr(VI) causes the dissipation of plasma membrane potential and mitochondrial membrane potential in CHL cell cultures, and Cr(VI)_induced ROS may play a role in the injuries.

  9. Note on one-fluid modeling of low-frequency Alfvénic fluctuations in a solar wind plasma with multi-ion components

    Energy Technology Data Exchange (ETDEWEB)

    Nariyuki, Y. [Faculty of Human Development, University of Toyama, 3190, Toyama City, Toyama 930-8555 (Japan); Umeda, T. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Suzuki, T. K. [Department of Physics, Nagoya University, Furo-cho, Nagoya, Aichi 464-8602 (Japan); Hada, T. [Department of Earth System Science and Technology, Kyushu University, 6-1, Kasuga City, Fukuoka 816-8580 (Japan)

    2015-12-15

    A simple point of view that non-zero Alfvén ratio (residual energy) appears as a consequence of one-fluid modeling of uni-directional Alfvén waves in a solar wind plasma is presented. Since relative speeds among ions are incorporated into the one-fluid model as a pressure anisotropy, the Alfvén ratio can be finite due to the decrease in the phase velocity. It is shown that a proton beam component typically found in the solar wind plasma can contribute to generating non-zero Alfvén ratio observed in the solar wind plasma. Local equilibrium velocity distribution functions of each ion component are also discussed by using maximum entropy principle.

  10. Solar wind thermally induced magnetic fluctuations.

    Science.gov (United States)

    Navarro, R E; Moya, P S; Muñoz, V; Araneda, J A; F-Viñas, A; Valdivia, J A

    2014-06-20

    A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

  11. Microscopic potential fluctuations in Si-doped AlGaN epitaxial layers with various AlN molar fractions and Si concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kurai, Satoshi, E-mail: kurai@yamaguchi-u.ac.jp; Yamada, Yoichi [Department of Material Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611 (Japan); Miyake, Hideto; Hiramatsu, Kazumasa [Department of Electrical and Electronic Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507 (Japan)

    2016-01-14

    Nanoscopic potential fluctuations of Si-doped AlGaN epitaxial layers with the AlN molar fraction varying from 0.42 to 0.95 and Si-doped Al{sub 0.61}Ga{sub 0.39}N epitaxial layers with Si concentrations of 3.0–37 × 10{sup 17 }cm{sup −3} were investigated by cathodoluminescence (CL) imaging combined with scanning electron microscopy. The spot CL linewidths of AlGaN epitaxial layers broadened as the AlN molar fraction was increased to 0.7, and then narrowed at higher AlN molar fractions. The experimental linewidths were compared with the theoretical prediction from the alloy broadening model. The trends displayed by our spot CL linewidths were consistent with calculated results at AlN molar fractions of less than about 0.60, but the spot CL linewidths were markedly broader than the calculated linewidths at higher AlN molar fractions. The dependence of the difference between the spot CL linewidth and calculated line broadening on AlN molar fraction was found to be similar to the dependence of reported S values, indicating that the vacancy clusters acted as the origin of additional line broadening at high AlN molar fractions. The spot CL linewidths of Al{sub 0.61}Ga{sub 0.39}N epitaxial layers with the same Al concentration and different Si concentrations were nearly constant in the entire Si concentration range tested. From the comparison of reported S values, the increase of V{sub Al} did not contribute to the linewidth broadening, unlike the case of the V{sub Al} clusters.

  12. Plasma membranes modified by plasma treatment or deposition as solid electrolytes for potential application in solid alkaline fuel cells.

    Science.gov (United States)

    Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

    2012-07-30

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

  13. Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells

    Directory of Open Access Journals (Sweden)

    Christophe Coutanceau

    2012-07-01

    Full Text Available In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

  14. Operation circuits of emissive probes for determination of potentials in discharge plasmas; Circuitos de operacao de sondas emissivas para a determinacao de potenciais em plasmas de descargas eletricas

    Energy Technology Data Exchange (ETDEWEB)

    Petraconi, G.; Maciel, H.S.; Borges, C. [Centro Tecnico Aeroespacial, Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica. Lab. de Plasmas e Processos

    1999-12-01

    In this paper two circuits for plasma potential measurement are presented. The first one is an emissive probe control circuit for fast probe characteristics reading. The second one is a differential emissive probe control circuit that adjusts the bias voltage automatically and allows a direct potential measurement. These circuits present inconveniences if the characteristic of the probe does not exhibit an ideal saturation of the current as show the results obtained in continuous current discharge and RF discharge. (author)

  15. Hepatitis B virus (HBV) variants fluctuate in paired plasma and peripheral blood mononuclear cells among patient cohorts during different chronic hepatitis B (CHB) disease phases.

    Science.gov (United States)

    Coffin, C S; Osiowy, C; Gao, S; Nishikawa, S; van der Meer, F; van Marle, G

    2015-04-01

    Hepatitis B virus is classically considered a hepatotropic virus but also infects peripheral blood mononuclear cells. Chronic hepatitis B has different disease phases modulated by host immunity. We compared HBV variability, drug resistance and immune escape mutations in the overlapping HBV polymerase/surface gene in plasma and peripheral blood mononuclear cells in different disease phases. Plasma and peripheral blood mononuclear cells were isolated from 22 treatment naïve patient cohorts (five inactive, six immune-active, nine HBeAg negative and two immune-tolerant). HBV was genotyped via line probe assay, hepatitis B surface antigen titres were determined by an in-house immunoassay, and HBV DNA was quantified by kinetic PCR. The HBV polymerase/surface region, including full genome in some, was PCR-amplified and cloned, and ~20 clones/sample were sequenced. The sequences were subjected to various mutational and phylogenetic analyses. Clonal sequencing showed that only three of 22 patients had identical HBV genotype profiles in both sites. In immune-active chronic hepatitis B, viral diversity in plasma was higher compared with peripheral blood mononuclear cells. Mutations at residues, in a minority of clones, associated with drug resistance, and/or immune escape were found in both compartments but were more common in plasma. Immune escape mutations were more often observed in the peripheral blood mononuclear cells of immune-active CHB carriers, compared with other disease phases. During all CHB disease phases, differences exist between HBV variants found in peripheral blood mononuclear cells and plasma. Moreover, these data indicate that HBV evolution occurs in a compartment and disease phase-specific fashion.

  16. Vaccine potential of plasma bead-based dual antigen delivery system against experimental murine candidiasis.

    Science.gov (United States)

    Ahmad, Ejaj; Zia, Qamar; Fatima, Munazza Tamkeen; Owais, Mohammad; Saleemuddin, Mohammed

    2015-11-01

    The development of prophylactic anti-candidal vaccine comprising the Candida albicans cytosolic proteins (Cp) as antigen and plasma beads (PB) prepared from plasma as sustained delivery system, is described. The immune-prophylactic potential of various PBs-based dual antigen delivery systems, co-entrapping Cp pre-entrapped in PLGA microspheres were tested in the murine model. Induction of cell mediated immunity was measured by assaying DTH and NO production as well as in vitro proliferation of lymphocytes derived from the immunized animals. Expression of surface markers on APCs (CD80, CD86) and T-cells (CD4+, CD8+) was also evaluated. Humoral immune response was studied by measuring circulating anti-Cp antibodies and their subclasses. When the prophylactic efficacy of the vaccines was tested in mice challenged with virulent C. albicans, the PB-based formulation (PB-PLGA-Cp vaccine) was found to be most effective in the generation of desirable immune response, in terms of suppression of fungal load and facilitating the survival of the immunized animals.

  17. Altered Daytime Fluctuation Pattern of Plasminogen Activator Inhibitor 1 in Type 2 Diabetes Patients with Coronary Artery Disease: A Strong Association with Persistently Elevated Plasma Insulin, Increased Insulin Resistance, and Abdominal Obesity

    Directory of Open Access Journals (Sweden)

    Katarina Lalić

    2015-01-01

    Full Text Available This study was aimed at investigating daily fluctuation of PAI-1 levels in relation to insulin resistance (IR and daily profile of plasma insulin and glucose levels in 26 type 2 diabetic (T2D patients with coronary artery disease (CAD (group A, 10 T2D patients without CAD (group B, 12 nondiabetics with CAD (group C, and 12 healthy controls (group D. The percentage of PAI-1 decrease was lower in group A versus group B (4.4 ± 2.7 versus 35.0 ± 5.4%; P<0.05 and in C versus D (14.0 ± 5.8 versus 44.7 ± 3.1%; P<0.001. HOMA-IR was higher in group A versus group B (P<0.05 and in C versus D (P<0.01. Simultaneously, AUCs of PAI-1 and insulin were higher in group A versus group B (P<0.05 and in C versus D (P<0.01, while AUC of glucose did not differ between groups. In multiple regression analysis waist-to-hip ratio and AUC of insulin were independent determinants of decrease in PAI-1. The altered diurnal fluctuation of PAI-1, especially in T2D with CAD, might be strongly influenced by a prolonged exposure to hyperinsulinemia in the settings of increased IR and abdominal obesity, facilitating altogether an accelerated atherosclerosis.

  18. Controlling VUV photon fluxes in pulsed inductively coupled Ar/Cl2 plasmas and potential applications in plasma etching

    Science.gov (United States)

    Tian, Peng; Kushner, Mark J.

    2017-02-01

    UV/VUV photon fluxes in plasma materials processing have a variety of effects ranging from producing damage to stimulating synergistic reactions. Although in plasma etching processes, the rate and quality of the feature are typically controlled by the characteristics of the ion flux, to truly optimize these ion and photon driven processes, it is desirable to control the relative fluxes of ions and photons to the wafer. In prior works, it was determined that the ratio of VUV photon to ion fluxes to the substrate in low pressure inductively coupled plasmas (ICPs) sustained in rare gases can be controlled by combinations of pressure and pulse power, while the spectrum of these VUV photons can be tuned by adding additional rare gases to the plasma. In this work, VUV photon and ion fluxes are computationally investigated for Ar/Cl2 ICPs as used in etching of silicon. We found that while the overall ratio of VUV photon flux to ion flux are controlled by pressure and pulse power, by varying the fraction of Cl2 in the mixture, both the ratio of VUV to ion fluxes and the spectrum of VUV photons can be tuned. It was also found that the intensity of VUV emission from Cl(3p 44s) can be independently tuned by controlling wall surface conditions. With this ability to control ratios of ion to photon fluxes, photon stimulated processes, as observed in halogen etching of Si, can be tuned to optimize the shape of the etched features.

  19. Equation of state for hot quark-gluon plasma transitions to hadrons with full QCD potential

    Science.gov (United States)

    Sheikholeslami-Sabzevari, Bijan

    2002-05-01

    A practical method based on Mayer's cluster expansion to calculate critical values for a quark-gluon plasma (QGP) phase transition to hadrons is represented. It can be applied to a high-temperature QGP for clustering of quarks to mesons and baryons. The potential used is the Cornell potential, i.e., a potential containing both confining and gluon exchange terms. Debye screening effects are included. An equation of state (EOS) for hadron production is found by analytical methods, which is valid near the critical point. The example of the formation of J/ψ and Υ is recalculated. It is shown that in the range of temperatures available by today's accelerators, the latter particles are suppressed. This is further confirmation for heavy quarkonia suppression and, hence, for a signature of a QGP. The EOS presented here also shows that in future colliders there will be no heavy quarkonia production by the mechanism of phase transition. Hence, if there will be heavy quarkonia production, it must be based on some other mechanisms, perhaps on the basis of some recently suggested possibilities.

  20. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch

    Science.gov (United States)

    Tan, Mingsheng; Stone, Douglas R.; Triana, Joseph C.; Almagri, Abdulgader F.; Fiksel, Gennady; Ding, Weixing; Sarff, John S.; McCollam, Karsten J.; Li, Hong; Liu, Wandong

    2017-02-01

    A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. The capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit, sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.

  1. Examining the Potential of Plasma-Assisted Pretreated Wheat Straw for Enzyme Production by Trichoderma reesei

    DEFF Research Database (Denmark)

    Rodríguez Gómez, Divanery; Lehmann, Linda Olkjær; Schultz-Jensen, Nadja

    2012-01-01

    Plasma-assisted pretreated wheat straw was investigated for cellulase and xylanase production by Trichoderma reesei fermentation. Fermentations were conducted with media containing washed and unwashed plasma-assisted pretreated wheat straw as carbon source which was sterilized by autoclavation...

  2. Effect of Ambipolar Potential on the Propulsive Performance of the GDM Plasma Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The gasdynamic mirror (GDM) plasma thruster has the ability to confine high-density plasma for the length of time required to heat it to the temperatures...

  3. Electrostatic Noise in the Plasma Environment Around the Shuttle

    Science.gov (United States)

    Vayner, Boris V.; Ferguson, Dale C.

    1995-01-01

    The Langmuir probe flown as part of the Solar Array Module Plasma Interactions Experiment (SAMPIE) package aboard the space shuttle flight STS-62 was used to determine plasma potential fluctuations in the vicinity of the shuttle. The broadband noise was observed at frequencies 250 - 20,000 Hz. Measurements were performed in ram conditions; thus, it seems reasonable to believe that the influence of spacecraft operations on plasma parameters was absolutely negligible. The average spectrum of fluctuations is in agreement with theoretical predictions. The influence on the observed spectra of arcing generated by high negative bias voltages applied to solar cell samples is briefly discussed.

  4. Enhancement of residual stress by electromagnetic fluctuations: A quasi-linear study

    Science.gov (United States)

    Kaang, Helen H.; Jhang, Hogun; Singh, R.; Kim, Juhyung; Kim, S. S.

    2016-05-01

    A study is conducted on the impact of electromagnetic (EM) fluctuations on residual Reynolds stress in the context of the quasi-linear theory. We employ a fluid formulation describing EM ion temperature gradient turbulence. Analyses show that finite plasma β (=plasma thermal energy/magnetic energy) significantly increases the residual stress, potentially leading to the strong enhancement of flow generation in high β plasmas. We identify that this strong increase of residual stress originates from the reinforcement of radial ⟨ k ∥ ⟩ (=spectrally averaged parallel wavenumber) asymmetry due to the deformation of eigenfunctions near a rational surface.

  5. Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells

    OpenAIRE

    Christophe Coutanceau; Marc Reinholdt; Jean Durand; Valérie Flaud; Serguei Martemianov; Alina Ilie; Eric Beche; Stéphanie Roualdès; Mauricio Schieda; Jérémy Frugier

    2012-01-01

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, com...

  6. Parameterizing the Morse potential for coarse-grained modeling of blood plasma

    Science.gov (United States)

    Zhang, Na; Zhang, Peng; Kang, Wei; Bluestein, Danny; Deng, Yuefan

    2014-01-01

    Multiscale simulations of fluids such as blood represent a major computational challenge of coupling the disparate spatiotemporal scales between molecular and macroscopic transport phenomena characterizing such complex fluids. In this paper, a coarse-grained (CG) particle model is developed for simulating blood flow by modifying the Morse potential, traditionally used in Molecular Dynamics for modeling vibrating structures. The modified Morse potential is parameterized with effective mass scales for reproducing blood viscous flow properties, including density, pressure, viscosity, compressibility and characteristic flow dynamics of human blood plasma fluid. The parameterization follows a standard inverse-problem approach in which the optimal micro parameters are systematically searched, by gradually decoupling loosely correlated parameter spaces, to match the macro physical quantities of viscous blood flow. The predictions of this particle based multiscale model compare favorably to classic viscous flow solutions such as Counter-Poiseuille and Couette flows. It demonstrates that such coarse grained particle model can be applied to replicate the dynamics of viscous blood flow, with the advantage of bridging the gap between macroscopic flow scales and the cellular scales characterizing blood flow that continuum based models fail to handle adequately.

  7. Parameterizing the Morse potential for coarse-grained modeling of blood plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Na [Department of Applied Mathematics and Statistics, Stony Brook University, NY 11794 (United States); Zhang, Peng [Department of Biomedical Engineering, Stony Brook University, NY 11790 (United States); Kang, Wei [Center for Applied Physics and Technology, College of Engineering, Peking University, Beijing 100871 (China); Bluestein, Danny [Department of Biomedical Engineering, Stony Brook University, NY 11790 (United States); Deng, Yuefan, E-mail: Yuefan.Deng@StonyBrook.edu [Department of Applied Mathematics and Statistics, Stony Brook University, NY 11794 (United States)

    2014-01-15

    Multiscale simulations of fluids such as blood represent a major computational challenge of coupling the disparate spatiotemporal scales between molecular and macroscopic transport phenomena characterizing such complex fluids. In this paper, a coarse-grained (CG) particle model is developed for simulating blood flow by modifying the Morse potential, traditionally used in Molecular Dynamics for modeling vibrating structures. The modified Morse potential is parameterized with effective mass scales for reproducing blood viscous flow properties, including density, pressure, viscosity, compressibility and characteristic flow dynamics of human blood plasma fluid. The parameterization follows a standard inverse-problem approach in which the optimal micro parameters are systematically searched, by gradually decoupling loosely correlated parameter spaces, to match the macro physical quantities of viscous blood flow. The predictions of this particle based multiscale model compare favorably to classic viscous flow solutions such as Counter-Poiseuille and Couette flows. It demonstrates that such coarse grained particle model can be applied to replicate the dynamics of viscous blood flow, with the advantage of bridging the gap between macroscopic flow scales and the cellular scales characterizing blood flow that continuum based models fail to handle adequately.

  8. Performance and plasma urea nitrogen of immunocastrated males pigs of medium genetic potential

    Directory of Open Access Journals (Sweden)

    Fabiana R Caldara

    2015-05-01

    Full Text Available ABSTRACT Objective. A study was carried out to evaluate the performance and the plasma urea nitrogen (PUN of male pigs of medium genetic potential for lean meat deposition in carcass, which underwent immunocastration. Materials and methods. Forty-five seventy-days old Large White x Landrace crossbred were used. The pigs were distributed in a randomized design in three treatments: castrated males, females and immunocastrated males. Each treatment group was replicated three times with five pigs per replicate. The trial period was of 70 days, divided into phases of growing (70 to 110 days old and finishing (111 to 140 days old. The pigs were weighed four times: at the beginning of the trial, at the first immunocastration vaccine dose (80 days old, at the second immunocastration vaccine dose (110 days old and just before slaughter (140 days old. Blood samples were taken on the same day that the animals were weighed. Results. Between 80 and 110 days old, there was an increase in PUN value, only for castrated males and females. No differences were found in weight gain between the studied groups within the periods. Immunocastrated males had lower feed intake than females and these had a lower feed intake than castrated males. To 110 days old, immunocastrated animals showed feed conversion ratio similar to females and better than castrated males. However, after the second dose of the vaccine, feed conversion was similar between groups. Conclusions. The benefits of immunocastration are prominent in animals with low to medium genetic potential.

  9. Potential plasma markers of type 1 and type 2 leprosy reactions: a preliminary report

    Directory of Open Access Journals (Sweden)

    Oliveira Maria

    2009-05-01

    Full Text Available Abstract Background The clinical management of leprosy Type 1 (T1R and Type 2 (T2R reactions pose challenges mainly because they can cause severe nerve injury and disability. No laboratory test or marker is available for the diagnosis or prognosis of leprosy reactions. This study simultaneously screened plasma factors to identify circulating biomarkers associated with leprosy T1R and T2R among patients recruited in Goiania, Central Brazil. Methods A nested case-control study evaluated T1R (n = 10 and TR2 (n = 10 compared to leprosy patients without reactions (n = 29, matched by sex and age-group (+/- 5 years and histopathological classification. Multiplex bead based technique provided profiles of 27 plasma factors including 16 pro inflammatory cytokines: tumor necrosis factor-α (TNF-α, Interferon-γ (IFN-γ, interleukin (IL- IL12p70, IL2, IL17, IL1 β, IL6, IL15, IL5, IL8, macrophage inflammatory protein (MIP-1 alpha (MIP1α, 1 beta (MIP1β, regulated upon activation normal T-cell expressed and secreted (RANTES, monocyte chemoattractrant protein 1 (MCP1, CC-chemokine 11 (CCL11/Eotaxin, CXC-chemokine 10 (CXCL10/IP10; 4 anti inflammatory interleukins: IL4, IL10, IL13, IL1Rα and 7 growth factors: IL7, IL9, granulocyte-colony stimulating factor (G-CSF, granulocyte macrophage-colony stimulating factor (GM-CSF, platelet-derived growth factor BB (PDGF BB, basic fibroblast growth factor (bFGF, vascular endothelial growth factor (VEGF. Results Elevations of plasma CXCL10 (P = 0.004 and IL6 (p = 0.013 were observed in T1R patients compared to controls without reaction. IL6 (p = 0.05, IL7 (p = 0.039, and PDGF-BB (p = 0.041 were elevated in T2R. RANTES and GMCSF were excluded due to values above and below detection limit respectively in all samples. Conclusion Potential biomarkers of T1R identified were CXCL10 and IL6 whereas IL7, PDGF-BB and IL6, may be laboratory markers of TR2. Additional studies on these biomarkers may help understand the

  10. NITROGEN POTENTIAL DURING ION NITRIDING PROCESS IN GLOW-DISCHARGE PLASMA

    Directory of Open Access Journals (Sweden)

    A. A. Kozlov

    2015-01-01

    Full Text Available The paper considers problems on regulation of phase composition of a nitrided layer during gas and ion nitriding process in a glow-discharge. It has been established that  available models for control of nitrided layer structure with the help of nitriding index (nitrogen potential can not be applied for nitriding process in the glow-discharge. Principal difference of the ion nitriding from the gas one is in the fact that chemically active nitrogen is formed in the discharge zone (cathode layer and its mass-transfer is carried out in the form of an active particle flow (ions, atoms, molecules which directed to the metal surface.Interrelation of chemical discharge activity with such characteristics of nitriding steel as nitrogen solubility in  α-solid solution and  coefficient diffusion during ion nitriding in low-discharge plasma. It has been shown that regulation of the nitride layer structure during ion nitriding is reached due to changes in nitrogen flow density in plasma. While supporting the flow at the level of nitrogen solubility in  one phase or another (α, γ′  it is possible to obtain the nitrided layer consisting only of α-solid solution or γ′-nitride layer and diffusion sub-layer. Moreover a specific range of nitrogen flow density values exists for every steel grade where it is possible to ensure a limiting nitrogen concentration in α-solid solution and the γ′-layer characterized by low diffusion  mobility is not formed on the surface.

  11. Effects of exercise intensity on plasma concentrations of appetite-regulating hormones: Potential mechanisms.

    Science.gov (United States)

    Hazell, Tom J; Islam, Hashim; Townsend, Logan K; Schmale, Matt S; Copeland, Jennifer L

    2016-03-01

    The physiological control of appetite regulation involves circulating hormones with orexigenic (appetite-stimulating) and anorexigenic (appetite-inhibiting) properties that induce alterations in energy intake via perceptions of hunger and satiety. As the effectiveness of exercise to induce weight loss is a controversial topic, there is considerable interest in the effect of exercise on the appetite-regulating hormones such as acylated ghrelin, peptide YY (PYY), glucagon-like peptide-1 (GLP-1), and pancreatic polypeptide (PP). Research to date suggests short-term appetite regulation following a single exercise session is likely affected by decreases in acylated ghrelin and increases in PYY, GLP-1, and PP. Further, this exercise-induced response may be intensity-dependent. In an effort to guide future research, it is important to consider how exercise alters the circulating concentrations of these appetite-regulating hormones. Potential mechanisms include blood redistribution, sympathetic nervous system activity, gastrointestinal motility, cytokine release, free fatty acid concentrations, lactate production, and changes in plasma glucose and insulin concentrations. This review of relevant research suggests blood redistribution during exercise may be important for suppressing ghrelin, while other mechanisms involving cytokine release, changes in plasma glucose and insulin concentrations, SNS activity, and muscle metabolism likely mediate changes in the anorexigenic signals PYY and GLP-1. Overall, changes in appetite-regulating hormones following acute exercise appear to be intensity-dependent, with increasing intensity leading to a greater suppression of orexigenic signals and greater stimulation of anorexigenic signals. However, there is less research on how exercise-induced responses in appetite-regulating hormones differ between sexes or different age groups. A better understanding of how exercise intensity and workload affect appetite across the sexes and life

  12. Levels of plasma circulating cell free nuclear and mitochondrial DNA as potential biomarkers for breast tumors

    Directory of Open Access Journals (Sweden)

    Diesch Claude

    2009-11-01

    Full Text Available Abstract Background With the aim to simplify cancer management, cancer research lately dedicated itself more and more to discover and develop non-invasive biomarkers. In this connection, circulating cell-free DNA (ccf DNA seems to be a promising candidate. Altered levels of ccf nuclear DNA (nDNA and mitochondrial DNA (mtDNA have been found in several cancer types and might have a diagnostic value. Methods Using multiplex real-time PCR we investigated the levels of ccf nDNA and mtDNA in plasma samples from patients with malignant and benign breast tumors, and from healthy controls. To evaluate the applicability of plasma ccf nDNA and mtDNA as a biomarker for distinguishing between the three study-groups we performed ROC (Receiver Operating Characteristic curve analysis. We also compared the levels of both species in the cancer group with clinicopathological parameters. Results While the levels of ccf nDNA in the cancer group were significantly higher in comparison with the benign tumor group (P P P P = 0.022. The level of ccf nDNA was also associated with tumor-size (2 cmP = 0.034. Using ROC curve analysis, we were able to distinguish between the breast cancer cases and the healthy controls using ccf nDNA as marker (cut-off: 1866 GE/ml; sensitivity: 81%; specificity: 69%; P P Conclusion Our data suggests that nuclear and mitochondrial ccf DNA have potential as biomarkers in breast tumor management. However, ccf nDNA shows greater promise regarding sensitivity and specificity.

  13. Plasma-grafted alkaline anion-exchange membranes based on polyvinyl chloride for potential application in direct alcohol fuel cell

    Science.gov (United States)

    Hu, Jue; Zhang, Chengxu; Cong, Jie; Toyoda, Hirotaka; Nagatsu, Masaaki; Meng, Yuedong

    2011-05-01

    Plasma grafting is employed to prepare alkaline anion-exchange membranes in this study. The attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis demonstrate that the benzyltrimethylammonium cationic groups are successfully introduced into the polyvinyl chloride matrix via plasma grafting, quaternization and alkalization. The plasma-grafted alkaline anion-exchange membrane exhibits a satisfactory ionic exchange capacity (1.01 mmol g-1), thermal stability, mechanical property, ionic conductivity (0.0145 S cm-1) and methanol permeability (9.59 × 10-12 m2 s-1), suggesting a great potential for application in direct alcohol fuel cells. The open circuit voltage of air-breathing ADAFC using plasma-grafted alkaline anion-exchange membrane is 0.796 V with 1 M EtOH solution at ambient temperature.

  14. Effective potentials for charge-helium and charge-singly-ionized helium interactions in a dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T.S.; Amirov, S.M.; Moldabekov, Zh.A. [Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, Almaty (Kazakhstan)

    2016-06-15

    The effective electron (proton)-He and electron (proton)-He{sup +} screened pair interaction potentials arising as a result of partial screening of the helium nucleus field by bound electrons, taking into account both screening by free charged particles and quantum diffraction effect in dense plasmas were derived. The impact of quantum effects on screening was analyzed. It was shown that plasma polarization around the atom leads to the additional repulsion (attraction) between the electron (proton) and the helium atom. The method of constructing the full electron (proton)-He and electron (proton)-He{sup +} screened pair interaction potentials as the sum of the derived potentials with the polarization potential and exchange potential is discussed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Analysis of confinement potential fluctuation and band-gap renormalization effects on excitonic transition in GaAs/AlGaAs multiquantum wells grown on (1 0 0) and (3 1 1)A GaAs surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, S.A., E-mail: sidneylourenco@utfpr.edu.br [Engenharia de Materiais, Universidade Tecnologica Federal do Parana, Londrina, PR 86036-370 (Brazil); Teodoro, M.D. [Departamento de Fisica, Universidade Estadual de Londrina, Londrina, PR 86051-970 (Brazil); Gonzalez-Borrero, P.P. [Departamento de Fisica, Universidade Estadual do Centro-Oeste, Guarapuava, PR 85040-080 (Brazil); Dias, I.F.L.; Duarte, J.L. [Departamento de Fisica, Universidade Estadual de Londrina, Londrina, PR 86051-970 (Brazil); Marega, E. [Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP 13560-970 (Brazil); Salamo, G.J. [Arkansas Institute for Nanoscale Materials Science and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States)

    2012-06-15

    The competition between confinement potential fluctuations and band-gap renormalization (BGR) in GaAs/Al{sub x}Ga{sub 1-x}As quantum wells grown on [1 0 0] and [3 1 1]A GaAs substrates is evaluated. The results clearly demonstrate the coexistence of the band-tail states filling related to potential fluctuations and the band-gap renormalization caused by an increase in the density of photogenerated carriers during the photoluminescence (PL) experiments. Both phenomena have strong influence on temperature dependence of the PL-peak energy (E{sub PL}(T)). As the photon density increases, the E{sub PL} can shift to either higher or lower energies, depending on the sample temperature. The temperature at which the displacement changes from a blueshift to a redshift is governed by the magnitude of the potential fluctuations and by the variation of BGR with excitation density. A simple band-tail model with a Gaussian-like distribution of the density of state was used to describe the competition between the band-tail filling and the BGR effects on E{sub PL}(T).

  16. Plasma miR-216a as a potential marker of pancreatic injury in a rat model of acute pancreatitis

    Science.gov (United States)

    Kong, Xiang-Yu; Du, Yi-Qi; Li, Lei; Liu, Jian-Qiang; Wang, Guo-Kun; Zhu, Jia-Qi; Man, Xiao-Hua; Gong, Yan-Fang; Xiao, Li-Ning; Zheng, Yong-Zhi; Deng, Shang-Xin; Gu, Jun-Jun; Li, Zhao-Shen

    2010-01-01

    AIM: To study the potential value and specificity of plasma miR-216a as a marker for pancreatic injury. METHODS: Two rat models were applied in this article: L-arginine-induced acute pancreatitis was used as one model to explore the potential value of plasma miR-216a for detection of pancreatic injury; nonlethal sepsis induced in rats by single puncture cecal ligation and puncture (CLP) was used as the other model to evaluate the specificity of plasma miR-216a compared with two commonly used markers (amylase and lipase) for acute pancreatitis. Plasmas were sampled from rats at indicated time points and total RNA was isolated. Real-Time Quantitative reverse transcriptase-polymerase chain reaction was used to quantify miR-216a in plasmas. RESULTS: In the acute pancreatitis model, among five time points at which plasmas were sampled, miR-216a concentrations were significantly elevated 24 h after arginine administration and remained significantly increased until 48 h after operation (compared with 0 h time point, P < 0.01, Kruskal-Wallis Test). In the CLP model, plasma amylase and lipase, two commonly used biomarkers for acute pancreatitis, were significantly elevated 24 h after operation (compared with 0 h time point, P < 0.01 and 0.05 respectively, Pairwise Bonferroni corrected t-tests), while miR-216a remained undetectable among four tested time points. CONCLUSION: Our article showed for the first time that plasma miR-216a might serve as a candidate marker of pancreatic injury with novel specificity. PMID:20857533

  17. Edge resonant fluctuations and particle transport in a reversed-field pinch

    Science.gov (United States)

    Möller, A.

    1998-12-01

    Electrostatic fluctuations are measured in the Extrap T2 reversed-field pinch [J. R. Drake et al., in Plasma Physics and Controlled Nuclear Fusion Research 1996 (International Atomic Energy Agency, Vienna, 1997), Vol. 2, pp. 193-199] using a Langmuir probe array. The electrostatic fluctuation, driven particle transport ΓnΦ is derived and found to constitute a large fraction of the total particle transport. The spectral density of all measured quantities exhibits a peak in the frequency range 100-250 kHz, which originates from fluctuations that are resonant close to the edge [n=-(40-80)]. This peak contains only about 10-20% of the total fluctuation power, but is shown to dominate ΓnΦ. The main reason for this is the high toroidal mode number as compared with internally resonant magnetohydrodynamic fluctuations. The edge resonant fluctuations also features a higher coherence (γ=0.5) and close to 90° phase shift between density and potential fluctuations.

  18. Effective momentum-dependent potentials for atomic bound states and scattering in strongly coupled plasmas

    Science.gov (United States)

    Christlieb, A.; Dharuman, G.; Verboncoeur, J.; Murillo, M. S.

    2016-10-01

    Modeling high energy-density experiments requires simulations spanning large length and time scales. These non-equilibrium experiments have time evolving ionization and partial degeneracy, obviating the direct use of the time-dependent Schrodinger equation. Therefore, efficient approximate methods are greatly needed. We have examined the accuracy of one such method based on an effective classical-dynamics approach employing effective momentum dependent potentials (MDPs) within a Hamiltonian framework that enables large-scale simulations. We have found that a commonly used formulation, based on Kirschbaum-Wilets MDPs leads to very accurate ground state energies and good first/second-ionization energies. The continuum scattering properties of free electrons were examined by comparing the momentum-transfer cross section (MTCS) predicted by KW MDP to a semi-classical phase-shift calculation. Optimizing the KW MDP parameters for the scattering process yielded poor MTCSs, suggesting a limitation of the use of KW MDP for plasmas. However, our new MDP yields MTCS values in much better agreement than KW MDP.

  19. Plasma levels of the tissue inhibitor matrix metalloproteinase-3 as a potential biomarker in oral cancer progression

    Science.gov (United States)

    Su, Chun-Wen; Su, Bo-Feng; Chiang, Whei-Ling; Yang, Shun-Fa; Chen, Mu-Kuan; Lin, Chiao-Wen

    2017-01-01

    Oral cancer is the most common malignancy with poor prognosis and is the fourth most common cancer in men in Taiwan. The tissue inhibitor of metalloproteinase-3 (TIMP3) acts as a tumor suppressor gene by inhibiting the growth, angiogenesis, migration, and invasion of cancer cells. However, few studies have examined the association of plasma TIMP3 levels with oral squamous cell carcinoma (OSCC), and the role of plasma TIMP3 levels in OSCC progression is still unclear. We measured the plasma TIMP3 levels of 450 OSCC patients and 64 healthy controls by using a commercial enzyme-linked immunosorbent assay. We also analyzed TIMP3 mRNA levels of 328 OSCC patients and 32 normal tissues from The Cancer Genome Atlas (TCGA) dataset. Our results revealed that plasma TIMP3 levels were significantly lower in patients with OSCC than in healthy controls (p < 0.001). Moreover, plasma TIMP3 levels in patients with OSCC were significantly associated with the tumor stage and tumor status but not with the lymph node status, metastasis, and cell differentiation. To verify our findings, we also examined TCGA bioinformatics database and discovered similar results for the association with the pathological stage of OSCC. In conclusion, our results suggest that plasma TIMP3 is a potential biomarker for predicting the tumor stage and T status in patients with OSCC. PMID:28138307

  20. Potential application of X-ray communication through a plasma sheath encountered during spacecraft reentry into earth's atmosphere

    Science.gov (United States)

    Li, Huan; Tang, Xiaobin; Hang, Shuang; Liu, Yunpeng; Chen, Da

    2017-03-01

    Rapid progress in exploiting X-ray science has fueled its potential application in communication networks as a carrier wave for transmitting information through a plasma sheath during spacecraft reentry into earth's atmosphere. In this study, we addressed the physical transmission process of X-rays in the reentry plasma sheath and near-earth space theoretically. The interactions between the X-rays and reentry plasma sheath were investigated through the theoretical Wentzel-Kramers-Brillouin method, and the Monte Carlo simulation was employed to explore the transmission properties of X-rays in the near-earth space. The simulation results indicated that X-ray transmission was not influenced by the reentry plasma sheath compared with regular RF signals, and adopting various X-ray energies according to different spacecraft reentry altitudes is imperative when using X-ray uplink communication especially in the near-earth space. Additionally, the performance of the X-ray communication system was evaluated by applying the additive white Gaussian noise, Rayleigh fading channel, and plasma sheath channel. The Doppler shift, as a result of spacecraft velocity changes, was also calculated through the Matlab Simulink simulation, and various plasma sheath environments have no significant influence on X-ray communication owing to its exceedingly high carrier frequency.

  1. Chiral Charge Erasure via Thermal Fluctuations of Magnetic Helicity

    CERN Document Server

    Long, Andrew J

    2016-01-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, $\\lambda \\gtrsim 1/(\\alpha \\mu_5)$, the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential $\\mu_{5}$ parametrizes the chiral asymmetry and $\\alpha$ is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale $\\lambda$, finding $\\delta \\mathcal{H} \\sim \\lambda T$ and $\\tau \\sim \\alpha \\lambda^3 T^2$ for a relativistic plasma at temperature $T$. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively fo...

  2. A Method for Measuring Fast Time Evolutions of the Plasma Potential by Means of a Simple Emissive Probe

    DEFF Research Database (Denmark)

    Iizuka, S.; Michelsen, Poul; Juul Rasmussen, Jens;

    1981-01-01

    A method is presented for obtaining the temporal evolution of the plasma potential, which is assumed to be given by the floating potential of a simple emissive probe. The construction of the probe is also described. The method avoids the slow time response of the usual technique where the floating...... potential is measured across a high resistance. During each sweep of the probe voltage, the changing of the sign of the probe current, which is sampled at a specific time, gives rise to a negative pulse, driving the pen-lift of an X-Y recorder. Since the real floating potential is measured where the probe...

  3. Plasma Amino Acids Profiles in Children with Autism: Potential Risk of Nutritional Deficiencies.

    Science.gov (United States)

    Arnold, Georgianne L.; Hyman, Susan L.; Mooney, Robert A.; Kirby, Russell S.

    2003-01-01

    The plasma amino acid profiles of 10 children with autism on gluten and casein restricted diets and 26 on unrestricted diets were reviewed. There was a trend for the children on restricted diets to have an increased prevalence of essential amino acid deficiencies and lower plasma levels of essential acids. (Contains references.) (Author/CR)

  4. Plasma Amino Acids Profiles in Children with Autism: Potential Risk of Nutritional Deficiencies.

    Science.gov (United States)

    Arnold, Georgianne L.; Hyman, Susan L.; Mooney, Robert A.; Kirby, Russell S.

    2003-01-01

    The plasma amino acid profiles of 10 children with autism on gluten and casein restricted diets and 26 on unrestricted diets were reviewed. There was a trend for the children on restricted diets to have an increased prevalence of essential amino acid deficiencies and lower plasma levels of essential acids. (Contains references.) (Author/CR)

  5. Instabilities in a capacitively coupled oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Küllig, C., E-mail: kuellig@physik.uni-greifswald.de; Wegner, Th., E-mail: physics@thwegner.com; Meichsner, J., E-mail: meichsner@physik.uni-greifswald.de [Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  6. Cold Atmospheric Plasma Generated in Water and its Potential Use in Cancer Therapy

    CERN Document Server

    Chen, Zhitong; Lin, Li; Keidar, Michael

    2016-01-01

    Cold atmospheric plasma (CAP) has been emerged as a novel technology for cancer treatment. CAP can directly treat cells and tissue but such direct application is limited to skin or can be invoked as a supplement during open surgery. In this letter we report indirect plasma treatment using CAP produced in a water using three gases as carrier (argon, helium and nitrogen). Plasma stimulated water was applied to human breast cancer cell line (MDA-MB-231). MTT assays tests showed that using argon plasma had the strongest effect on inducing apoptosis in cultured human breast cancer cells. This result is attributed to the elevated production of the reactive oxygen species and reactive nitrogen species in water in the case of argon plasma.

  7. Plasma cadmium and zinc and their interrelationship in adult Nigerians: potential health implications

    Directory of Open Access Journals (Sweden)

    Ugwuja Emmanuel Ike

    2015-06-01

    Full Text Available Zinc (an essential trace element and cadmium (a ubiquitous environmental pollutant with acclaimed toxicity have been found to occur together in nature, with reported antagonism between the two elements. The present study aimed at determination of plasma levels of zinc (Zn and cadmium (Cd and their interrelationship in adult Nigerians. The series comprised adults (n=443 aged ≥18 yrs (mean ± SD 38.4±13.7 yrs, consisting of 117 males, 184 non-pregnant and 140 pregnant females. Sociodemographic data were collected by questionnaire while anthropometrics were determined using standard methods. Plasma Cd and Zn were determined by using an atomic absorption spectrophotometer. The mean plasma zinc and cadmium were 94.7±18.1 μg/dl and 0.150±0.548 μg/dl, respectively. Age, sex, pregnancy, and parity had no effect on either plasma Zn or Cd. Although educational level had no effect on plasma Zn, it had a significant effect on Cd; subjects possessing either secondary or tertiary education had significantly lower plasma Cd than subjects without formal education. Moreover, there seemed to be an inverse relationship between Cd and Zn, but this was not statistically significant (r=–0.089; p=0.061. Although plasma Zn was not related to BMI (r=0.037; p=0.432, Cd was significantly negatively correlated with BMI (r=–0.124; p=0.009. It may be concluded that adult Nigerians in Ebonyi State have elevated plasma levels of Cd, with apparent impact on the levels of plasma Zn. This has important public health implications considering the essential roles of Zn in the protection of Cd mediated adverse health effects. While food diversification is recommended to improve plasma Zn, efforts should be made to reduce exposure to Cd to mitigate partially its possible adverse effects.

  8. Pseudo-Potentials in Dense and He-like Hot temperature Plasmas

    Science.gov (United States)

    Deutsch, Claude; Rahal, Hamid

    2012-10-01

    Extending our former derivations in dense and high temperature plasmas of hydrogenic effective interactions mimiking the Heisenberg uncertainty principle [1,2], we worked out in a canonical ensemble, effective interactions in He-like plasmas where an orbital 1s electron remains strongly tighted to the He-like ions. The plasma electrons are then taken into account through appropriate Slater sums obtained in the most economical hydrogenic extension of the He-like bound and scattered states with angular orbital momentum lClementi and C. Roetti, Atomic Data and Nucl. Data Tables, 14,177(1974)

  9. Osteogenic potential of platelet-rich plasma in dental stem-cell cultures.

    Science.gov (United States)

    Otero, L; Carrillo, N; Calvo-Guirado, J L; Villamil, J; Delgado-Ruíz, R A

    2017-09-01

    The purpose of this study was to analyse the potential of platelet-rich plasma (PRP) culture media to induce osteogenic differentiation of periodontal ligament stem cells and dental pulp stem cells compared with four other methods of culture. Both types of cell were collected from 35 healthy patients and cultured in five different media (Dulbecco's modified eagle's medium (DMEM); DMEM and melatonin; DMEM and PRP; DMEM and ascorbic acid 200μmol; DMEM and l-ascorbate 2-phosphate 50μmol). Cells were characterised by flow cytometry. Alizarin Red stain, alkaline phosphatase stain, and the expression of collagen type 1 (Col-1), runt-related transcription factor (RUNX2), osteoprotegerin, and osteopontin (quantified by qRT-PCR) were used to detect the osteogenic profile in each culture. Flow cytometry showed that both types of stem cell were a homogeneous mixture of CD90(+), CD105(+), STRO-1(+), CD34 (-), and CD45 (-) cells. Dental pulp stem cells that were cultured with PRP showed the best osteogenic profile (RUNX2 p=0.0002; osteoprotegerin p=0.001). The group of these stem cells that showed the best osteogenic profile was also cultured with PRP (osteoprotegerin p=0.001). Medium five (with l-ascorbate 2-phosphate 50μmol added) showed an increase in all osteogenic markers for periodontal ligament stem cells after PRP, while the best culture conditions for osteogenic expression of dental pulp stem cells after PRP was in medium four (ascorbic acid 200μmol added). These results suggested that culture in PRP induces osteogenic differentiation of both types of stem cell, modulating molecular pathways to promote bony formation. Copyright © 2017 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  10. Cold atmospheric plasma discharged in water and its potential use in cancer therapy

    Science.gov (United States)

    Chen, Zhitong; Cheng, Xiaoqian; Lin, Li; Keidar, Michael

    2017-01-01

    Cold atmospheric plasma (CAP) has emerged as a novel technology for cancer treatment. CAP can directly treat cells and tissue but such direct application is limited to skin or can be invoked as a supplement during open surgery. In this study we report indirect plasma treatment using CAP discharged in deionized (DI) water using three gases as carriers (argon (Ar), helium (He), and nitrogen (N2)). Plasma stimulated water was applied to the human breast cancer cell line (MDA-MB-231). MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay tests showed that using Ar plasma had the strongest effect on inducing apoptosis in cultured human breast cancer cells. This result is attributed to the elevated production of reactive oxygen species and reactive nitrogen species in water.

  11. Effect of Ambipolar Potential on the Propulsive Performance of the GDM Plasma Thruster Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Gasdynamic Mirror (GDM) thruster is an electric propulsion device, without electrodes, that will magnetically confine a plasma with such density and temperature...

  12. A sustained decrease in plasma fibrinolytic potential following partial liver resection or pancreas resection

    NARCIS (Netherlands)

    Kleiss, Simone F.; Adelmeijer, Jelle; Meijers, Joost C. M.; Porte, Robert J.; Lisman, Ton

    Background: Patients undergoing partial hepatectomy have a substantial risk for postoperative venous thrombosis even in the presence of optimal thromboprophylaxis. Recently we demonstrated a hypercoagulable state following a partial hepatectomy which was related to decreased plasma levels of natural

  13. Potential role of plasma myeloperoxidase level in predicting long-term outcome of acute myocardial infarction.

    Science.gov (United States)

    Kaya, Mehmet Gungor; Yalcin, Ridvan; Okyay, Kaan; Poyraz, Fatih; Bayraktar, Nilufer; Pasaoglu, Hatice; Boyaci, Bulent; Cengel, Atiye

    2012-01-01

    We investigated the prognostic importance of plasma myeloperoxidase levels in patients with ST-elevation myocardial infarction (STEMI) at long-term follow-up, and we analyzed the correlations between plasma myeloperoxidase levels and other biochemical values. We evaluated 73 consecutive patients (56 men; mean age, 56 ± 11 yr) diagnosed with acute STEMI and 46 age- and sex-matched healthy control participants. Patients were divided into 2 groups according to the median myeloperoxidase level (Group 1: plasma myeloperoxidase ≤ 68 ng/mL; and Group 2: plasma myeloperoxidase > 68 ng/mL). Patients were monitored for the occurrence of major adverse cardiovascular events (MACE), which were defined as cardiac death; reinfarction; new hospital admission for angina; heart failure; and revascularization procedures. The mean follow-up period was 25 ± 16 months. Plasma myeloperoxidase levels were higher in STEMI patients than in control participants (82 ± 34 vs 20 ± 12 ng/mL; P = 0.001). Composite MACE occurred in 12 patients with high myeloperoxidase levels (33%) and in 4 patients with low myeloperoxidase levels (11%) (P = 0.02). The incidences of nonfatal recurrent myocardial infarction and verified cardiac death were higher in the high-myeloperoxidase group. In multivariate analysis, high plasma myeloperoxidase levels were independent predictors of MACE (odds ratio = 3.843; <95% confidence interval, 1.625-6.563; P = 0.003). High plasma myeloperoxidase levels identify patients with a worse prognosis after acute STEMI at 2-year follow-up. Evaluation of plasma myeloperoxidase levels might be useful in determining patients at high risk of death and MACE who can benefit from further aggressive treatment and closer follow-up.

  14. Dynamic Electric Potential Redistribution And Its Influence On The Development Of A Dielectric Barrier Plasma Jet

    Science.gov (United States)

    2012-05-01

    dielectric barrier discharge (DBD) devices. The dielectric barrier plasma jet represents a hybrid between streamer corona and conventional DBD sources...capillary tip and beyond indicating a transition away from a DBD to what was essentially a classical streamer corona discharge drawing current directly...plasma jet generated in a single-electrode dielectric barrier configuration at atmospheric pressure. The influence of dielectric boundary conditions

  15. Kaon fluctuations from lattice QCD

    CERN Document Server

    Noronha-Hostler, Jacquelyn; Gunther, Jana; Parotto, Paolo; Pasztor, Attila; Vazquez, Israel Portillo; Ratti, Claudia

    2016-01-01

    We show that it is possible to isolate a set of kaon fluctuations in lattice QCD. By means of the Hadron Resonance Gas (HRG) model, we calculate the actual kaon second-to-first fluctuation ratio, which receives contribution from primordial kaons and resonance decays, and show that it is very close to the one obtained for primordial kaons in the Boltzmann approximation. The latter only involves the strangeness and electric charge chemical potentials, which are functions of $T$ and $\\mu_B$ due to the experimental constraint on strangeness and electric charge, and can therefore be calculated on the lattice. This provides an unambiguous method to extract the kaon freeze-out temperature, by comparing the lattice results to the experimental values for the corresponding fluctuations.

  16. Fluctuating brane in a dilatonic bulk

    CERN Document Server

    Brax, P; Rodríguez-Martinez, M; Brax, Philippe; Langlois, David; Rodriguez-Martinez, Maria

    2003-01-01

    We consider a cosmological brane moving in a static five-dimensional bulk spacetime endowed with a scalar field whose potential is exponential. After studying various cosmological behaviours for the homogeneous background, we investigate the fluctuations of the brane that leave spacetime unaffected. A single mode embodies these fluctuations and obeys a wave equation which we study for bouncing and ever-expanding branes.

  17. Potential of electric discharge plasma methods in abatement of volatile organic compounds originating from the food industry.

    Science.gov (United States)

    Preis, S; Klauson, D; Gregor, A

    2013-01-15

    Increased volatile organic compounds emissions and commensurate tightening of applicable legislation mean that the development and application of effective, cost-efficient abatement methods are areas of growing concern. This paper reviews the last two decades' publications on organic vapour emissions from food processing, their sources, impacts and treatment methods. An overview of the latest developments in conventional air treatment methods is presented, followed by the main focus of the paper, non-thermal plasma technology. The results of the review suggest that non-thermal plasma technology, in its pulsed corona discharge configuration, is an emerging treatment method with potential for low-cost, effective abatement of a wide spectrum of organic air pollutants. It is found that the combination of plasma treatment with catalysis is a development trend that demonstrates considerable potential. The as yet relatively small number of plasma treatment applications is considered to be due to the novelty of pulsed electric discharge techniques and a lack of reliable pulse generators and reactors. Other issues acting as barriers to widespread adoption of the technique include the possible formation of stable oxidation by-products, residual ozone and nitrogen oxides, and sensitivity towards air humidity.

  18. Spatial distribution of the electrical potential and ion concentration in the downstream area of atmospheric pressure remote plasma

    Directory of Open Access Journals (Sweden)

    M. V. Mishin

    2014-10-01

    Full Text Available This paper presents the results from an experimental study of the ion flux characteristics behind the remote plasma zone in a vertical tube reaction chamber for atmospheric pressure plasma enhanced chemical vapor deposition. Capacitively coupled radio frequency plasma was generated in pure He and gas mixtures: He–Ar, He–O2, He–TEOS. We previously used the reaction system He–TEOS for the synthesis of self-assembled structures of silicon dioxide nanoparticles. It is likely that the electrical parameters of the area, where nanoparticles have been transported from the synthesis zone to the substrate, play a significant role in the self-organization processes both in the vapor phase and on the substrate surface. The results from the spatial distribution of the electrical potential and ion concentration in the discharge downstream area measured by means of the external probe of original design and the special data processing method are demonstrated in this work. Positive and negatives ions with maximum concentrations of 106–107 cm−3 have been found at 10–80 mm distance behind the plasma zone. On the basis of the revealed distributions for different gas mixtures, the physical model of the observed phenomena is proposed. The model illustrates the capability of the virtual ion emitter formation behind the discharge gap and the presence of an extremum of the electrical potential at the distance of approximately 10−2–10−1 mm from the grounded electrode.

  19. Correlation length of magnetosheath fluctuations: Cluster statistics

    Directory of Open Access Journals (Sweden)

    O. Gutynska

    2008-09-01

    Full Text Available Magnetosheath parameters are usually described by gasdynamic or magnetohydrodynamic (MHD models but these models cannot account for one of the most important sources of magnetosheath fluctuations – the foreshock. Earlier statistical processing of a large amount of magnetosheath observations has shown that the magnetosheath magnetic field and plasma flow fluctuations downstream of the quasiparallel shock are much larger than those at the opposite flank. These studies were based on the observations of a single spacecraft and thus they could not provide full information on propagation of the fluctuations through the magnetosheath.

    We present the results of a statistical survey of the magnetosheath magnetic field fluctuations using two years of Cluster observations. We discuss the dependence of the cross-correlation coefficients between different spacecraft pairs on the orientation of the separation vector with respect to the average magnetic field and plasma flow vectors and other parameters. We have found that the correlation length does not exceed ~1 RE in the analyzed frequency range (0.001–0.125 Hz and does not depend significantly on the magnetic field or plasma flow direction. A close connection of cross-correlation coefficients computed in the magnetosheath with the cross-correlation coefficients between a solar wind monitor and a magnetosheath spacecraft suggests that solar wind structures persist on the background of magnetosheath fluctuations.

  20. Evaluation of the potentials of humic acid removal in water by gas phase surface discharge plasma.

    Science.gov (United States)

    Wang, Tiecheng; Qu, Guangzhou; Ren, Jingyu; Yan, Qiuhe; Sun, Qiuhong; Liang, Dongli; Hu, Shibin

    2016-02-01

    Degradation of humic acid (HA), a predominant type of natural organic matter in ground water and surface waters, was conducted using a gas phase surface discharge plasma system. HA standard and two surface waters (Wetland, and Weihe River) were selected as the targets. The experimental results showed that about 90.9% of standard HA was smoothly removed within 40 min's discharge plasma treatment at discharge voltage 23.0 kV, and the removal process fitted the first-order kinetic model. Roles of some active species in HA removal were studied by evaluating the effects of solution pH and OH radical scavenger; and the results presented that O3 and OH radical played significant roles in HA removal. Scanning electron microscope (SEM) and FTIR analysis showed that HA surface topography and molecular structure were changed during discharge plasma process. The mineralization of HA was analyzed by UV-Vis spectrum, dissolved organic carbon (DOC), specific UV absorbance (SUVA), UV absorption ratios, and excitation-emission matrix (EEM) fluorescence. The formation of disinfection by-products during HA sample chlorination was also identified, and CHCl3 was detected as the main disinfection by-product, but discharge plasma treatment could suppress its formation to a certain extent. In addition, approximately 82.3% and 67.9% of UV254 were removed for the Weihe River water and the Wetland water after 40 min of discharge plasma treatment.

  1. Dilepton production as a useful probe of quark gluon plasma with temperature dependent chemical potential quark mass

    Science.gov (United States)

    Kumar, Yogesh; Singh, S. Somorendro

    2016-07-01

    We extend the previous study of dilepton production using [S. Somorendro Singh and Y. Kumar, Can. J. Phys. 92 (2014) 31] based on a simple quasiparticle model of quark-gluon plasma (QGP). In this model, finite value of quark mass uses temperature dependent chemical potential the so-called Temperature Dependent Chemical Potential Quark Mass (TDCPQM). We calculate dilepton production in the relevant range of mass region. It is observed that the production rate is marginally enhanced from the earlier work. This is due to the effect of TDCPQM and its effect is highly significant in the production of dilepton.

  2. Fluctuation relations for spintronics.

    Science.gov (United States)

    López, Rosa; Lim, Jong Soo; Sánchez, David

    2012-06-15

    Fluctuation relations are derived in systems where the spin degree of freedom and magnetic interactions play a crucial role. The form of the nonequilibrium fluctuation theorems relies on the assumption of a local balance condition. We demonstrate that in some cases the presence of magnetic interactions violates this condition. Nevertheless, fluctuation relations can be obtained from the microreversibility principle sustained only at equilibrium as a symmetry of the cumulant generating function for spin currents. We illustrate the spintronic fluctuation relations for a quantum dot coupled to partially polarized helical edge states.

  3. Survival of Bc mesons in a hot plasma within a potential model

    CERN Document Server

    Alberico, W M; Czerski, P; De Pace, A; Nardi, M; Ratti, C

    2013-01-01

    We extend a previous work on the study of heavy charmonia and bottomonia in a deconfined quark-gluon plasma by considering the Bc family of mesons. With the introduction of this bound state of a charm and a beauty quark, we investigate at finite temperature the behavior of the quarkonium, in an energy region between the {\\psi} and the {\\Upsilon} states.

  4. THE POTENTIAL VALUE OF PHOTOTHERMAL IMAGING FOR THE TESTING OF PLASMA SPRAYED COATINGS

    OpenAIRE

    Almond, D.; Patel, P; Reiter, H.

    1983-01-01

    Measurements are presented which show that the photothermal technique may be used to evaluate plasma sprayed coatings. A photothermal image of a coating adhesion defect is shown and changes in photothermal signal with coating thickness are demonstrated. These measurements are compared directly with ultrasonic measurements of the same sample.

  5. A note on the Weibel instability and thermal fluctuations

    CERN Document Server

    Treumann, R A

    2012-01-01

    The thermal fluctuation level of the Weibel instability is recalculated. It is shown that the divergence of the fluctuations at long wavelengths, i.e. the Weibel infrared catastrophe, never occurs. At large wavelengths the thermal fluctuation level is terminated by the presence of even the smallest available stable thermal anisotropy. Weibel fields penetrate only one skin depth into the plasma. When excited inside, they cause layers of antiparallel fields of skin depth width and vortices which may be subject to reconnection.

  6. Resistin in dairy cows: plasma concentrations during early lactation, expression and potential role in adipose tissue.

    Directory of Open Access Journals (Sweden)

    Maxime Reverchon

    Full Text Available Resistin is an adipokine that has been implicated in energy metabolism regulation in rodents but has been little studied in dairy cows. We determined plasma resistin concentrations in early lactation in dairy cows and investigated the levels of resistin mRNA and protein in adipose tissue and the phosphorylation of several components of insulin signaling pathways one week post partum (1 WPP and at five months of gestation (5 MG. We detected resistin in mature bovine adipocytes and investigated the effect of recombinant bovine resistin on lipolysis in bovine adipose tissue explants. ELISA showed that plasma resistin concentration was low before calving, subsequently increasing and reaching a peak at 1 WPP, decreasing steadily thereafter to reach pre-calving levels at 6 WPP. Plasma resistin concentration was significantly positively correlated with plasma non esterified fatty acid (NEFA levels and negatively with milk yield, dry matter intake and energy balance between WPP1 to WPP22. We showed, by quantitative RT-PCR and western blotting, that resistin mRNA and protein levels in adipose tissue were higher at WPP1 than at 5 MG. The level of phosphorylation of several early and downstream insulin signaling components (IRβ, IRS-1, IRS-2, Akt, MAPK ERK1/2, P70S6K and S6 in adipose tissue was also lower at 1 WPP than at 5 MG. Finally, we showed that recombinant bovine resistin increased the release of glycerol and mRNA levels for ATGL (adipose triglyceride lipase and HSL (hormone-sensitive lipase in adipose tissue explants. Overall, resistin levels were high in the plasma and adipose tissue and were positively correlated with NEFA levels after calving. Resistin is expressed in bovine mature adipocytes and promotes lipid mobilization in adipose explants in vitro.

  7. MicroRNA-134 as a potential plasma biomarker for the diagnosis of acute pulmonary embolism

    Directory of Open Access Journals (Sweden)

    Liu Yi

    2011-09-01

    Full Text Available Abstract Background Acute pulmonary embolism (APE remains a diagnostic challenge due to a variable clinical presentation and the lack of a reliable screening tool. MicroRNAs (miRNAs regulate gene expression in a wide range of pathophysiologic processes. Circulating miRNAs are emerging biomarkers in heart failure, type 2 diabetes and other disease states; however, using plasma miRNAs as biomarkers for the diagnosis of APE is still unknown. Methods Thirty-two APE patients, 32 healthy controls, and 22 non-APE patients (reported dyspnea, chest pain, or cough were enrolled in this study. The TaqMan miRNA microarray was used to identify dysregulated miRNAs in the plasma of APE patients. The TaqMan-based miRNA quantitative real-time reverse transcription polymerase chain reactions were used to validate the dysregulated miRNAs. The receiver-operator characteristic (ROC curve analysis was conducted to evaluate the diagnostic accuracy of the miRNA identified as the candidate biomarker. Results Plasma miRNA-134 (miR-134 level was significantly higher in the APE patients than in the healthy controls or non-APE patients. The ROC curve showed that plasma miR-134 was a specific diagnostic predictor of APE with an area under the curve of 0.833 (95% confidence interval, 0.737 to 0.929; P Conclusions Our findings indicated that plasma miR-134 could be an important biomarker for the diagnosis of APE. Because of this finding, large-scale investigations are urgently needed to pave the way from basic research to clinical utilization.

  8. Metric fluctuations and its evolution during inflation

    CERN Document Server

    Anabitarte, M; Anabitarte, Mariano; Bellini, Mauricio

    2003-01-01

    W discuss the evolution of the fluctuations in a symmetric $\\phi_c$-exponential potential which provides a power-law expansion during inflation using both, the gauge invariant field $\\Phi$ and the Sasaki-Mukhanov field.

  9. Plasma HSPA12B is a potential predictor for poor outcome in severe sepsis.

    Directory of Open Access Journals (Sweden)

    Ran Zhang

    Full Text Available INTRODUCTION: Endothelium-derived molecules may be predictive to organ injury. Heat shock protein (HSP A12B is mainly located in endothelial cells, which can be detected in the plasma of septic patients. Whether it is correlated with prognosis of sepsis remains unclear. METHODS: Extracellular HSPA12B (eHSPA12B was determined in plasma of septic mice at 6 h, 12 h, 24 h and 48 h after cecal ligation and puncture (CLP. It was also detected in plasma of patients with severe sepsis, sepsis, systemic inflammatory response syndrome and healthy volunteers. The predictive value for prognosis of severe sepsis was assessed by receiver operating curve (ROC and Cox regression analyses. RESULTS: eHSPA12B was elevated in plasma of CLP mice at 6 h and peaked at 24 h after surgery. A total of 118 subjects were included in the clinical section, including 66 patients with severe sepsis, 21 patients with sepsis, 16 patients with SIRS and 15 volunteers. Plasma eHSPA12B was significantly higher in patients with severe sepsis than in patients with sepsis, SIRS and volunteers. The level of eHSPA12B was also higher in non-survivals than survivals with severe sepsis. The area under the curve (AUC of eHSPA12B in predicting death among patients with severe sepsis was 0.782 (0.654-0.909 in ROC analysis, much higher than that of IL-6 and IL-10. Cox regression analysis showed that cardiovascular diseases, IL-6 and eHSPA12B were risk factors for mortality in patients with severe sepsis. Survival curve demonstrated a strikingly significant difference between 28-day survival rates of patients with an eHSPA12B lower or not lower than 1.466 ng/ml. CONCLUSIONS: Plasma eHSPA12B is elevated in both septic mice and patients. It may be a good predictor for poor outcome in patients with severe sepsis.

  10. Electromagnetic effects on rippling instability and tokamak edge fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Sadayoshi; Saleem, Hamid [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1998-07-01

    Electromagnetic effects on rippling mode are investigated as a cause of low frequency electromagnetic fluctuations in tokamak edge region. It is shown that, in a current-carrying resistive plasma, the purely growing electrostatic rippling mode can turn out to be an electromagnetic oscillatory instability. The resistivity fluctuation and temperature gradient are the main sources of this instability, which requires both parallel and perpendicular wave vectors. The Alfven waves in a coupled dispersion relation are found heavily damped in such dissipative plasmas. (author)

  11. Concentrations of thiocyanate and goitrin in human plasma, their precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism.

    Science.gov (United States)

    Felker, Peter; Bunch, Ronald; Leung, Angela M

    2016-04-01

    Brassica vegetables are common components of the diet and have beneficial as well as potentially adverse health effects. Following enzymatic breakdown, some glucosinolates in brassica vegetables produce sulforaphane, phenethyl, and indolylic isothiocyanates that possess anticarcinogenic activity. In contrast, progoitrin and indolylic glucosinolates degrade to goitrin and thiocyanate, respectively, and may decrease thyroid hormone production. Radioiodine uptake to the thyroid is inhibited by 194 μmol of goitrin, but not by 77 μmol of goitrin. Collards, Brussels sprouts, and some Russian kale (Brassica napus) contain sufficient goitrin to potentially decrease iodine uptake by the thyroid. However, turnip tops, commercial broccoli, broccoli rabe, and kale belonging to Brassica oleracae contain less than 10 μmol of goitrin per 100-g serving and can be considered of minimal risk. Using sulforaphane plasma levels following glucoraphanin ingestion as a surrogate for thiocyanate plasma concentrations after indole glucosinolate ingestion, the maximum thiocyanate contribution from indole glucosinolate degradation is estimated to be 10 μM, which is significantly lower than background plasma thiocyanate concentrations (40-69 μM). Thiocyanate generated from consumption of indole glucosinolate can be assumed to have minimal adverse risks for thyroid health.

  12. Chromium(VI)—induces Production of Reactive Oxygen Species,Change of Plasma Membrane Potential and Dissipation of Mitochondria Membrane otential in Chinese Hamster Lung Cell Cultures

    Institute of Scientific and Technical Information of China (English)

    XIEYI; ZHUANGZHI-XIONG

    2001-01-01

    Objective:To examine whether Reactive Oxygen Species(ROS) is generated,and whether plasma membrane potential and mitochnodrial membrane potential are depolarized in Chinese Hamster Lung(CHL)cell lines exposed to Cr(VI),Methods:CHL Cells were incubated with Cr(VI) at 10 umol/L,2.5umol/L,0.65umol/L for 3 and 6 hours,respectively.The rpoduction of ROS was performed by using 2,7-dichlorofluorescin discetate;The changes in plasma membrane potential were performed by using 2,7-dichlorofluorescin discetate;The changes in plasma membrane potential were performed by using 2,7-dichlorofluorescin diacetate;The changes in plasma membrane potential were estimated using fluorescent cationic dye DiBAC4;And the changes in mitochondria membrane potential were estimated using fluorescent dye Rhodamine 123,Results:The ROS levels in CHL cells increased in all treated groups compared with the control group(P<0.01);The plasma membrane potential and mitochondrial membrane potential in CHL cells dissipated after incubated with Cr(VI) at 10umol/L for 3 hours and 6 hours(P<0.01),at 2.5umol/L for 6 hours(P<0.01 or 0.05),Conclusion:Cr(VI) causes the dissipation of plasma membrane potential and mitochnodrial membrane otential in CHL cell cultrues,and Cr(VI)-induced ROS may play a role in the injuries.

  13. Charge Fluctuation of Dust Grain and Its Impact on Dusty-Acoustic Wave Damping

    CERN Document Server

    Atamaniuk, B

    2007-01-01

    We consider the influence of dust charge fluctuations on damping of the dust-ion-acoustic waves. It is assumed that all grains have equal masses but charges are not constant in time - they may fluctuate in time. The dust charges are not really independent of the variations in the plasma potentials. All modes will influence the charging mechanism, and feedback will lead to several new interesting and unexpected phenomena. The charging of the grains depends on local plasma characteristics. If the waves disturb these characteristic, then charging of the grains is affected and the grain charge is modified, with a resulting feedback on the wave mode. In the case considered here, when the temperature of electrons is much greater than the temperature of the ions and the temperature of electrons is not great enough for further ionization of the ions, we show that attenuation of the acoustic wave depends only on one phenomenological coefficient

  14. Plasma lysosphingomyelin demonstrates great potential as a diagnostic biomarker for Niemann-Pick disease type C in a retrospective study.

    Directory of Open Access Journals (Sweden)

    Richard W D Welford

    Full Text Available Niemann-Pick disease type C (NP-C is a devastating, neurovisceral lysosomal storage disorder which is characterised by variable manifestation of visceral signs, progressive neuropsychiatric deterioration and premature death, caused by mutations in the NPC1 and NPC2 genes. Due to the complexity of diagnosis and the availability of an approved therapy in the EU, improved detection of NP-C may have a huge impact on future disease management. At the cellular level dysfunction or deficiency of either the NPC1 or NPC2 protein leads to a complex intracellular endosomal/lysosomal trafficking defect, and organ specific patterns of sphingolipid accumulation. Lysosphingolipids have been shown to be excellent biomarkers of sphingolipidosis in several enzyme deficient lysosomal storage disorders. Additionally, in a recent study the lysosphingolipids, lysosphingomyelin (SPC and glucosylsphingosine (GlcSph, appeared to be elevated in the plasma of three adult NP-C patients. In order to investigate the clinical utility of SPC and GlcSph as diagnostic markers, an in-depth fit for purpose biomarker assay validation for measurement of these biomarkers in plasma by liquid chromatography-tandem mass spectrometry was performed. Plasma SPC and GlcSph are stable and can be measured accurately, precisely and reproducibly. In a retrospective analysis of 57 NP-C patients and 70 control subjects, median plasma SPC and GlcSph were significantly elevated in NP-C by 2.8-fold and 1.4-fold respectively. For miglustat-naïve NP-C patients, aged 2-50 years, the area under the ROC curve was 0.999 for SPC and 0.776 for GlcSph. Plasma GlcSph did not correlate with SPC levels in NP-C patients. The data indicate excellent potential for the use of lysosphingomyelin in NP-C diagnosis, where it could be used to identify NP-C patients for confirmatory genetic testing.

  15. A method to measure deferasirox in plasma using HPLC coupled with MS/MS detection and its potential application.

    Science.gov (United States)

    Chauzit, Emmanuelle; Bouchet, Stéphane; Micheau, Marguerite; Mahon, François Xavier; Moore, Nicholas; Titier, Karine; Molimard, Mathieu

    2010-08-01

    Iron overload resulting from transfusion dependency in some patients with chronic anaemia can be prevented by chelation. Deferasirox is an oral alternative to the well studied but inconvenient deferroxamine therapy. The pharmacokinetic parameters of this new drug suggest potential interindividual variability and patients might benefit from pharmacologic drug monitoring. We developed an liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS) method to quantify deferasirox in plasma. After protein precipitation, samples were injected onto an XTerra RP18 column with a gradient of acetonitrile and formiate buffer (4 mM, pH 3.0) with 5% methanol. Detection by electrospray ionization mass-spectrometry was performed using the multiple reaction monitoring mode. Sixty-three samples from patients treated with deferasirox were then analyzed to evaluate pharmacokinetic/pharmacodynamic relationships. Calibration curves were linear from 0.5 to 40 microg/mL. Interday and intraday precision were lower than 8.9% and 7.3%, respectively. Bias did not exceed 12.7%. Plasma iron overload did not interfere with analysis. Plasma drug concentrations of patients treated by deferasirox were compared with plasma ferritin, considered as a marker of treatment efficacy. No statistically significant correlation was observed, though higher ferritin concentrations (>1000 microg/L, n = 30) were observed in patients with lower mean deferasirox concentration (9.5 +/- 9.1 microg/mL). This simple method is suitable for routine monitoring of deferasirox concentrations in plasma as it requires very few steps and has a short runtime. It allows evaluation of patient compliance, drug-drug interactions, and further investigations of pharmacokinetic/pharmacodynamic relationships.

  16. Cell-Free Fetal DNA in Plasma of Pregnant Women: Clinical Potential and Origin

    Directory of Open Access Journals (Sweden)

    Akihiko Sekizawa

    2005-06-01

    Full Text Available Circulating fetal DNA in maternal plasma can be used for both fetal genetic testing and evaluation of complications of pregnancy. As a prenatal genetic test, the greatest advantage of using circulating fetal DNA is the lack of risk. This approach has been applied to the diagnosis of fetal gender, fetal Rhesus D (RhD blood type, and fetal single-gene disorders. However, it only allows examination of disorders where the gene of interest is present in the fetal genome but absent from maternal DNA. Since most fetal DNA probably originates from villous trophoblasts, concentrations can be used to evaluate damage to trophoblasts, particularly in pathologic complications of pregnancy such as pre-eclampsia, invasive placenta, hyperemesis gravidarum, and trisomy 21. Fetal DNA in the plasma of pregnant women thus offers a new source of data that can be used in various clinical settings.

  17. Plasma YKL-40: a new potential marker of fibrosis in patients with alcoholic cirrhosis?

    DEFF Research Database (Denmark)

    Johansen, J S; Møller, S; Price, P A

    1997-01-01

    YKL-40 is released or extracted in the hepatosplanchnic system and to localize YKL-40 in liver tissue. METHODS: Plasma YKL-40 was determined by radioimmunoassay in 25 patients with liver diseases (alcoholic cirrhosis (n = 20), chronic active hepatitis (n = 2), cirrhosis of unknown aetiology (n = 2......), and fatty liver (n = 1) and in 18 subjects with normal liver function during a haemodynamic investigation with catheterization of liver vein and the femoral artery. Immunohistochemical studies of the localization of YKL-40 in cryostal liver biopsy specimens were obtained from eight other patients...... with alcoholic liver disease. RESULTS: Plasma YKL-40 was significantly increased in patients with alcoholic cirrhosis (median, 523 micrograms/l; P

  18. Plasma microRNA might as a potential biomarker for hepatocellular carcinoma and chronic liver disease screening.

    Science.gov (United States)

    Jiang, Li; Li, Xue; Cheng, Qi; Zhang, Bin-Hao

    2015-09-01

    Our study aims to investigate the expression signature of plasma microRNA-106b (miRNA-106b, miR-106b) in hepatocellular carcinoma (HCC) patients and chronic liver disease (CLD) patients compared with healthy controls and further evaluate the potential clinical value of miR-106b as biomarker in HCC detection. In addition, a meta-analysis was conducted to assess the diagnostic performance of miR-106a/b as a biochemical marker for cancer screening. This study was divided into two phases. In the first phase, the expression levels of plasma miR-106b obtained from 108 subjects (47 HCC patients, 25 CLD patients, and 36 healthy controls) were measured by using qRT-PCR. Areas under receiver operating characteristic (ROC) curves (AUCs) were used to evaluate the diagnostic accuracy of plasma miR-106. In the second phase, a meta-analysis based on 11 previous researches as well as our current study was conducted to assess the potential clinical value of miR-106 in cancer detection. Plasma levels of miR-106b in HCC patients were significantly higher compared with CLD patients and healthy individuals. ROC curves suggested that plasma miR-106b yielded relative high sensitivities and specificities in differentiating HCC patients from CLD patients or healthy controls with corresponding AUC values of 0.726 and 0.879, respectively. In addition, miR-106b showed a relatively high accuracy in distinguishing CLD patients from healthy controls with its AUC value of 0.703. Furthermore, the meta-analysis for diagnostic performance of miR-106a/b showed a pooled sensitivity of 0.74, specificity of 0.75, and an AUC of 0.81. Subgroup analysis based on samples types revealed a higher diagnostic performance of miR-106 for cancer detection by using non-blood samples. Similarly, miR-106 as biomarker showed a higher diagnostic accuracy for gastric cancer detection. We found that plasma miR-106b has clinical value in the detection of HCC from healthy people and CLD patients. Further large-scale study

  19. Assessment of the toxic potential of engineered metal oxide nanomaterials using an acellular model: citrated rat blood plasma.

    Science.gov (United States)

    Gormley, Patrick Thomas; Callaghan, Neal Ingraham; MacCormack, Tyson James; Dieni, Christopher Anthony

    2016-10-01

    Citrated Sprague-Dawley rat blood plasma was used as a biologically relevant exposure medium to assess the acellular toxic potential of two metal oxide engineered nanomaterials (ENMs), zinc oxide (nZnO), and cerium oxide (nCeO2). Plasma was incubated at 37 °C for up to 48 h with ENM concentrations ranging between 0 and 200 mg/L. The degree of ENM-induced oxidation was assessed by assaying for reactive oxygen species (ROS) levels using dichlorofluorescein (DCF), pH, ferric reducing ability of plasma (FRAP), lipase activity, malondialdehyde (MDA), and protein carbonyls (PC). Whereas previous in vitro studies showed linear-positive correlations between ENM concentration and oxidative damage, our results suggested that low concentrations were generally pro-oxidant and higher concentrations appeared antioxidant or protective, as indicated by DCF fluorescence trends. nZnO and nCeO2 also affected pH in a manner dependent on concentration and elemental composition; higher nZnO concentrations maintained a more alkaline pH, while nCeO2 tended to decrease pH. No other biomarkers of oxidative damage (FRAP, MDA, PC, lipase activity) showed changes at any ENM concentration or time-point tested. Differential dissolution of the two ENMs was also observed, where as much as ∼31.3% of nZnO was instantaneously dissolved to Zn(2+ )and only negligible nCeO2 was degraded. The results suggest that the direct oxidative potential of nZnO and nCeO2 in citrated rat blood plasma is low, and that a physiological or immune response is needed to generate appreciable damage biomarkers. The data also highlight the need for careful consideration when selecting a model for assessing ENM toxicity.

  20. Fluctuation dynamics in reconnecting current sheets

    Science.gov (United States)

    von Stechow, Adrian; Grulke, Olaf; Ji, Hantao; Yamada, Masaaki; Klinger, Thomas

    2015-11-01

    During magnetic reconnection, a highly localized current sheet forms at the boundary between opposed magnetic fields. Its steep perpendicular gradients and fast parallel drifts can give rise to a range of instabilities which can contribute to the overall reconnection dynamics. In two complementary laboratory reconnection experiments, MRX (PPPL, Princeton) and VINETA.II (IPP, Greifswald, Germany), magnetic fluctuations are observed within the current sheet. Despite the large differences in geometries (toroidal vs. linear), plasma parameters (high vs. low beta) and magnetic configuration (low vs. high magnetic guide field), similar broadband fluctuation characteristics are observed in both experiments. These are identified as Whistler-like fluctuations in the lower hybrid frequency range that propagate along the current sheet in the electron drift direction. They are intrinsic to the localized current sheet and largely independent of the slower reconnection dynamics. This contribution characterizes these magnetic fluctuations within the wide parameter range accessible by both experiments. Specifically, the fluctuation spectra and wave dispersion are characterized with respect to the magnetic topology and plasma parameters of the reconnecting current sheet.

  1. Spacetime Conformal Fluctuations and Quantum Dephasing

    CERN Document Server

    Bonifacio, Paolo M

    Any quantum system interacting with a complex environment undergoes decoherence. Empty space is filled with vacuum energy due to matter fields in their ground state and represents an underlying environment that any quantum particle has to cope with. In particular quantum gravity vacuum fluctuations should represent a universal source of decoherence. To study this problem we employ a stochastic approach that models spacetime fluctuations close to the Planck scale by means of a classical, randomly fluctuating metric (random gravity framework). We enrich the classical scheme for metric perturbations over a curved background by also including matter fields and metric conformal fluctuations. We show in general that a conformally modulated metric induces dephasing as a result of an effective nonlinear newtonian potential obtained in the appropriate nonrelativistic limit of a minimally coupled Klein-Gordon field. The special case of vacuum fluctuations is considered and a quantitative estimate of the expected effect...

  2. Fluctuation theorem for constrained equilibrium systems

    Science.gov (United States)

    Gilbert, Thomas; Dorfman, J. Robert

    2006-02-01

    We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as isokinetic and Nosé-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless, finite-time averages of the phase-space contraction rate have nontrivial fluctuations which we show satisfy a simple version of the Gallavotti-Cohen fluctuation theorem, complementary to the usual fluctuation theorem for nonequilibrium stationary states and appropriate to constrained equilibrium states. Moreover, we show that these fluctuations are distributed according to a Gaussian curve for long enough times. Three different systems are considered here: namely, (i) a fluid composed of particles interacting with Lennard-Jones potentials, (ii) a harmonic oscillator with Nosé-Hoover thermostatting, and (iii) a simple hyperbolic two-dimensional map.

  3. Dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Fortov, Vladimir E; Khrapak, Aleksei G; Molotkov, Vladimir I; Petrov, Oleg F [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Khrapak, Sergei A [Max-Planck-Institut fur Extraterrestrische Physik, Garching (Germany)

    2004-05-31

    The properties of dusty plasmas - low-temperature plasmas containing charged macroparticles - are considered. The most important elementary processes in dusty plasmas and the forces acting on dust particles are investigated. The results of experimental and theoretical investigations of different states of strongly nonideal dusty plasmas - crystal-like, liquid-like, gas-like - are summarized. Waves and oscillations in dusty plasmas, as well as their damping and instability mechanisms, are studied. Some results on dusty plasma investigated under microgravity conditions are presented. New directions of experimental research and potential applications of dusty plasmas are discussed. (reviews of topical problems)

  4. The Apolipoprotein B/Apolipoprotein A-I Ratio as a Potential Marker of Plasma Atherogenicity

    Directory of Open Access Journals (Sweden)

    Anastasiya M. Kaneva

    2015-01-01

    Full Text Available Background. The apolipoprotein (apo B/apoA-I ratio represents the balance between apoB-rich atherogenic particles and apoA-I-rich antiatherogenic particles, and this ratio is considered to be a marker of cardiovascular risk. Although many studies have demonstrated the importance of the apoB/apoA-I ratio in predicting the presence or absence of cardiovascular disease, less is known about apoB/apoA-I ratio as a marker of plasma atherogenicity. Methods. A total of 157 normolipidemic men aged 20–59 years were included in the study. The plasma levels of total cholesterol (TC, triglycerides (TG, high-density lipoprotein cholesterol (HDL-C, apoA-I, apoB, and apoE were determined after a 12 h fasting period. Results. The median of the apoB/apoA-I ratio in the studied normolipidemic subjects was 0.52, with values ranging from 0.19 to 2.60. The percentage of subjects with the apoB/apoA-I ratio exceeding 0.9 (the accepted risk value of cardiovascular disease was 19.1%. The subjects with apoB/apoA-I>0.9 were characterized by higher TG levels and atherogenic index of plasma (AIP and lower values of ratio of low-density lipoprotein cholesterol (LDL-C to apoB (LDL-C/apoB and apoE levels compared with men with apoB/apoA-I<0.9. Conclusion. Despite normolipidemia, the subjects with the unfavorable apoB/apoA-I ratio had more atherogenic lipid profile.

  5. Fluctuations near the deconfinement phase transition boundary

    CERN Document Server

    Mishustin, I N

    2005-01-01

    In this talk I discuss how a first order phase transition may proceed in rapidly expanding partonic matter produced in a relativistic heavy-ion collision. The resulting picture is that a strong collective flow of matter will lead to the fragmentation of a metastable phase into droplets. If the transition from quark-gluon plasma to hadron gas is of the first order, it will manifest itself by strong nonstatistical fluctuations in observable hadron distributions. I discuss shortly existing experimental data on the multiplicity fluctuations.

  6. Plasma Potential and Langmuir Probe Measurements in the Near-field Plume of the NASA-457Mv2 Hall Thruster

    Science.gov (United States)

    Shastry, Rohit; Huang, Wensheng; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

    2012-01-01

    In order to further the design of future high-power Hall thrusters and provide experimental validation for ongoing modeling efforts, plasma potential and Langmuir probe measurements were performed on the 50-kW NASA-457Mv2. An electrostatic probe array comprised of a near-field Faraday probe, single Langmuir probe, and emissive probe was used to interrogate the near-field plume from approximately 0.1 - 2.0 mean thruster diameters downstream of the thruster exit plane at the following operating conditions: 300 V, 400 V and 500 V at 30 kW and 500 V at 50 kW. Results have shown that the acceleration zone is limited to within 0.4 mean thruster diameters of the exit plane while the high-temperature region is limited to 0.25 mean thruster diameters from the exit plane at all four operating conditions. Maximum plasma potentials in the near-field at 300 and 400 V were approximately 50 V with respect to cathode potential, while maximum electron temperatures varied from 24 - 32 eV, depending on operating condition. Isothermal lines at all operating conditions were found to strongly resemble the magnetic field topology in the high-temperature regions. This distribution was found to create regions of high temperature and low density near the magnetic poles, indicating strong, thick sheath formation along these surfaces. The data taken from this study are considered valuable for future design as well as modeling validation.

  7. Approximate, semi-implicit calculation of 3D electrostatic potential in a self-consistent plasma simulation

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, E.R.; Kushner, M.J. [Univ. of Illinois, Urbana, IL (United States). Dept. of Electrical and Computer Engineering

    1997-12-31

    Numerical Modeling of low pressure plasma reactors is subject to numerous time step constraints, and among the most restrictive of these is the dielectric relaxation time. In recent years, semi-implicit flux-correction techniques have allowed plasma modelers to loosen the dielectric relaxation time step restriction. However, since these simulations do solve a form of Poisson`s equation, they still have a restriction on time step based on a modified, albeit less restrictive, dielectric relaxation time. For some parameter spaces this is acceptable, but for very large scale simulations (for example in three dimensions) and for simulations of systems having long time scales, obtaining a longer time step is crucial. Using a generalization of a technique already presented, the authors present a method for obtaining an approximate electrostatic potential which has no dielectric relaxation time restriction. Implementation is of comparable difficulty to that of a conventional Poisson`s equation, and is no more computationally intensive. The module is implemented within a large, self-consistent hybrid plasma equipment model (HPEM). A rearranged continuity equation is solved, and charge neutrality is assumed. A comparison to the HPEM running with Poisson`s equation is presented, for both two and three dimensions, and for electropositive and electronegative gases.

  8. Platelet-rich plasma gel composited with nondegradable porous polyurethane scaffolds as a potential auricular cartilage alternative.

    Science.gov (United States)

    Wang, Zhongshan; Qin, Haiyan; Feng, Zhihong; Zhao, Yimin

    2016-02-01

    Total auricular reconstruction is still a challenge, and autologous cartilage transplant is the main therapy so far. Tissue engineering provides a promising method for auricular cartilage reconstruction. However, although degradable framework demonstrated excellent initial cosmetic details, it is difficult to maintain the auricular contour over time and the metabolites tended to be harmful to human body. In this study, biocompatible and safe nondegradable elastic polyurethane was used to make porous scaffold in specific details by rapid prototyping technology. Platelet-rich plasma contains fibrin and abundant autologous growth factors, which was used as cell carriers for in vitro expanded cells. When crosslinking polyurethane framework, platelet-rich plasma and cells together, we successfully made polyurethane/platelet-rich plasma/cell composites, and implanted them into dorsal subcutaneous space of nude mice. The results showed that this method resulted in more even cell distribution and higher cell density, promoted chondrocyte proliferation, induced higher level expressions of aggrecan and type II collagen gene, increased content of newly developed glycosaminoglycans, and produced high-quality cartilaginous tissue. This kind of cartilage tissue engineering approach may be a potential promising alternative for external ear reconstruction.

  9. Hadronic Correlations and Fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Volker

    2008-10-09

    We will provide a review of some of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. We will discuss Lattice QCD results on fluctuations and correlations and will put them into context with observables which have been measured in heavy-ion collisions. Special attention will be given to the QCD critical point and the first order co-existence region, and we will discuss how the measurement of fluctuations and correlations can help in an experimental search for non-trivial structures in the QCD phase diagram.

  10. Continuous information flow fluctuations

    Science.gov (United States)

    Rosinberg, Martin Luc; Horowitz, Jordan M.

    2016-10-01

    Information plays a pivotal role in the thermodynamics of nonequilibrium processes with feedback. However, much remains to be learned about the nature of information fluctuations in small-scale devices and their relation with fluctuations in other thermodynamics quantities, like heat and work. Here we derive a series of fluctuation theorems for information flow and partial entropy production in a Brownian particle model of feedback cooling and extend them to arbitrary driven diffusion processes. We then analyze the long-time behavior of the feedback-cooling model in detail. Our results provide insights into the structure and origin of large deviations of information and thermodynamic quantities in autonomous Maxwell's demons.

  11. Quantum Fractal Fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Benenti, Giuliano; Casati, Giulio; Guarneri, Italo; Terraneo, Marcello

    2001-07-02

    We numerically analyze quantum survival probability fluctuations in an open, classically chaotic system. In a quasiclassical regime and in the presence of classical mixed phase space, such fluctuations are believed to exhibit a fractal pattern, on the grounds of semiclassical arguments. In contrast, we work in a classical regime of complete chaoticity and in a deep quantum regime of strong localization. We provide evidence that fluctuations are still fractal, due to the slow, purely quantum algebraic decay in time produced by dynamical localization. Such findings considerably enlarge the scope of the existing theory.

  12. Spatial fluctuation theorem

    Science.gov (United States)

    Pérez-Espigares, Carlos; Redig, Frank; Giardinà, Cristian

    2015-08-01

    For non-equilibrium systems of interacting particles and for interacting diffusions in d-dimensions, a novel fluctuation relation is derived. The theorem establishes a quantitative relation between the probabilities of observing two current values in different spatial directions. The result is a consequence of spatial symmetries of the microscopic dynamics, generalizing in this way the Gallavotti-Cohen fluctuation theorem related to the time-reversal symmetry. This new perspective opens up the possibility of direct experimental measurements of fluctuation relations of vectorial observables.

  13. Physics and potentials of fissioning plasmas for space power and propulsion

    Science.gov (United States)

    Thom, K.; Schwenk, F. C.; Schneider, R. T.

    1976-01-01

    Fissioning uranium plasmas are the nuclear fuel in conceptual high-temperature gaseous-core reactors for advanced rocket propulsion in space. A gaseous-core nuclear rocket would be a thermal reactor in which an enriched uranium plasma at about 10,000 K is confined in a reflector-moderator cavity where it is nuclear critical and transfers its fission power to a confining propellant flow for the production of thrust at a specific impulse up to 5000 sec. With a thrust-to-engine weight ratio approaching unity, the gaseous-core nuclear rocket could provide for propulsion capabilities needed for manned missions to the nearby planets and for economical cislunar ferry services. Fueled with enriched uranium hexafluoride and operated at temperatures lower than needed for propulsion, the gaseous-core reactor scheme also offers significant benefits in applications for space and terrestrial power. They include high-efficiency power generation at low specific mass, the burnup of certain fission products and actinides, the breeding of U-233 from thorium with short doubling times, and improved convenience of fuel handling and processing in the gaseous phase.

  14. Hundred joules plasma focus device as a potential pulsed source for in vitro cancer cell irradiation

    Science.gov (United States)

    Jain, J.; Moreno, J.; Andaur, R.; Armisen, R.; Morales, D.; Marcelain, K.; Avaria, G.; Bora, B.; Davis, S.; Pavez, C.; Soto, L.

    2017-08-01

    Plasma focus devices may arise as useful source to perform experiments aimed to study the effects of pulsed radiation on human cells in vitro. In the present work, a table top hundred joules plasma focus device, namely "PF-400J", was adapted to irradiate colorectal cancer cell line, DLD-1. For pulsed x-rays, the doses (energy absorbed per unit mass, measured in Gy) were measured using thermoluminescence detectors (TLD-100 dosimeters). The neutron fluence and the average energy were used to estimate the pulsed neutron doses. Fifty pulses of x-rays (0.12 Gy) and fifty pulses of neutrons (3.5 μGy) were used to irradiate the cancer cells. Irradiation-induced DNA damage and cell death were assessed at different time points after irradiation. Cell death was observed using pulsed neutron irradiation, at ultralow doses. Our results indicate that the PF-400J can be used for in vitro assessment of the effect of pulsed radiation in cancer cell research.

  15. Potential for osseous regeneration of platelet rich plasma: a comparitive study in mandibular third molar sockets.

    Science.gov (United States)

    Vivek, G K; Sripathi Rao, B H

    2009-12-01

    To evaluate the efficacy of autologous platelet-rich plasma in soft tissue healing & bone regeneration in mandibular third molar extraction socket. The study was conducted in 10 patients visiting the outpatient Department of Oral & Maxillofacial Surgery, requiring extraction of bilateral mandibular third molars. Following extraction, autologous Platelet Rich Plasma (PRP) was placed in one extraction socket, the other socket was studied as the control site with no PRP. The patients were assessed for postoperative pain, soft tissue healing, bone blending and trabecular formation. Radiological assessment of the extraction site was done for a period of 4 months to evaluate the change in bone density. Pain was less in the study site compared to control site, soft tissue healing was better in study site. Evaluation for bone blending and trabecular bone formation started earlier in PRP site compared to control, non PRP site. The evaluation of bone density by radiological assessment showed the grey level values calculated after 4 months at the PRP site were comparatively higher than the average baseline value of bone density at extraction site in control site. The study showed that autologous PRP is biocompatible and has significantly improved soft tissue healing, bone regeneration and increase in bone density in extraction sockets. However a more elaborate study with a larger number of clinical cases is essential to be more conclusive regarding its efficacy.

  16. Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker?

    Directory of Open Access Journals (Sweden)

    Elena Matteucci

    2007-01-01

    Full Text Available Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na+/H+ exchange and HC3 -/Cl- anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore damaged proteins, it is equipped with high activity of protective enzymes. Redox changes in the cell initiate various signalling pathways. Plasma membrane oxido-reductases (PMORs are transmembrane electron transport systems that have been found in the membranes of all cells and have been extensively characterized in the human erythrocyte. Erythrocyte PMORs transfer reducing equivalents from intracellular reductants to extracellular oxidants, thus their most important role seems to be to enable the cell respond to changes in intra- and extra-cellular redox environments.So far the activity of erythrocyte PMORs in disease states has not been systematically investigated. This review summarizes present knowledge on erythrocyte electron transfer activity in humans (health, type 1 diabetes, diabetic nephropathy, and chronic uremia and hypothesizes an integrated model of the functional organization of erythrocyte plasma membrane where electron pathways work in parallel with transport metabolons to maintain redox homeostasis.

  17. Electron Pathways through Erythrocyte Plasma Membrane in Human Physiology and Pathology: Potential Redox Biomarker?

    Science.gov (United States)

    Matteucci, Elena; Giampietro, Ottavio

    2007-09-17

    Erythrocytes are involved in the transport of oxygen and carbon dioxide in the body. Since pH is the influential factor in the Bohr-Haldane effect, pHi is actively maintained via secondary active transports Na(+)/H(+) exchange and HC(3) (-)/Cl(-) anion exchanger. Because of the redox properties of the iron, hemoglobin generates reactive oxygen species and thus, the human erythrocyte is constantly exposed to oxidative damage. Although the adult erythrocyte lacks protein synthesis and cannot restore damaged proteins, it is equipped with high activity of protective enzymes. Redox changes in the cell initiate various signalling pathways. Plasma membrane oxido-reductases (PMORs) are transmembrane electron transport systems that have been found in the membranes of all cells and have been extensively characterized in the human erythrocyte. Erythrocyte PMORs transfer reducing equivalents from intracellular reductants to extracellular oxidants, thus their most important role seems to be to enable the cell respond to changes in intra- and extra-cellular redox environments.So far the activity of erythrocyte PMORs in disease states has not been systematically investigated. This review summarizes present knowledge on erythrocyte electron transfer activity in humans (health, type 1 diabetes, diabetic nephropathy, and chronic uremia) and hypothesizes an integrated model of the functional organization of erythrocyte plasma membrane where electron pathways work in parallel with transport metabolons to maintain redox homeostasis.

  18. Investigation of toroidal acceleration and potential acceleration forces in EAST and J-TEXT plasmas

    CERN Document Server

    Wang, Fudi; Pan, Xiayun; Cheng, Zhifeng; Chen, Jun; Cao, Guangming; Wang, Yuming; Han, Xiang; Li, Hao; Wu, Bin; Chen, Zhongyong; Bitter, Manfred; Hill, Kenneth; Rice, John; Morita, Shigeru; Li, Yadong; Zhuang, Ge; Ye, Minyou; Wan, Baonian; Shi, Yuejiang

    2014-01-01

    In order to produce intrinsic rotation, bulk plasmas must be collectively accelerated by the net force exerted on them, which results from both driving and damping forces. So, to study the possible mechanisms of intrinsic rotation generation, it is only needed to understand characteristics of driving and damping terms because the toroidal driving and damping forces induce net acceleration which generates intrinsic rotation. Experiments were performed on EAST and J-TEXT for ohmic plasmas with net counter- and co-current toroidal acceleration generated by density ramping up and ramping down. Additionally on EAST, net co-current toroidal acceleration was also formed by LHCD or ICRF. For the current experimental results, toroidal acceleration was between - 50 km/s^2 in counter-current direction and 70 km/s^2 in co-current direction. According to toroidal momentum equation, toroidal electric field (E\\-(\\g(f))), electron-ion toroidal friction, and toroidal viscous force etc. may play roles in the evolution of toroi...

  19. Potential biomarkers for Turner in maternal plasma: possibility for noninvasive prenatal diagnosis.

    Science.gov (United States)

    Kolialexi, Aggeliki; Anagnostopoulos, Athanasios K; Papantoniou, Nikos; Vougas, Konstantinos; Antsaklis, Aris; Fountoulakis, Michael; Mavrou, Ariadni; Tsangaris, George Th

    2010-10-01

    Turner syndrome (TS) is the most common sex chromosome abnormality in females, caused by the complete or partial absence of one X chromosome. To identify biomarkers for TS, we compared the protein composition of maternal plasma samples from pregnant women with normal and TS fetuses, using a proteomic approach consisting of 2D-E separation and MS analysis for the identification of the differentially expressed proteins. Samples were routinely obtained in the second trimester of pregnancy, stored, and used after prenatal determination of the fetal karyotype. Nine proteins (C1S, CO3, CLUS, AFAM, HABP2, IGHA1, HPT, SHBG, and CD5L) were significantly increased in the plasma of women carrying TS fetuses, whereas KNG1, IGJ, and TTHY were decreased. Identified proteins were further evaluated by immunoblot analysis while functional network association was carried out to asses significance. The identification of specific biomarkers may facilitate the development of noninvasive prenatal diagnosis and improve our understanding of the pathology of TS. Nevertheless, testing a larger cohort of pregnant women is necessary to evaluate the relevance of the reported findings.

  20. Application of microwave imaging system for density fluctuation measurements on Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Pavlichenko, R.; Nagayama, Y.; Kawahata, K. [National Institute for Fusion Science (NIFS), Toki (Japan); Ignatenko, M.; Kogi, Y.; Mase, A. [Kyushu Univ., KASTEC, Kasuga (Japan)

    2004-07-01

    This short paper describes the microwave imaging reflectometry system that has been installed on the Large Helical Device as a plasma diagnostic system for spatially resolved plasma density fluctuations.

  1. Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

    Science.gov (United States)

    Trushnikov, D. N.; Mladenov, G. M.; Belenkiy, V. Ya.; Koleva, E. G.; Varushkin, S. V.

    2014-04-01

    Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 1016 m-3, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A.m-2, i.e. 8 mA for a 3-10 cm2 collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

  2. Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane.

    Science.gov (United States)

    Ji, Hongtao; Dong, Hansong

    2015-09-01

    Many plant- and animal-pathogenic Gram-negative bacteria employ the type III secretion system (T3SS) to translocate effector proteins from bacterial cells into the cytosol of eukaryotic host cells. The effector translocation occurs through an integral component of T3SS, the channel-like translocon, assembled by hydrophilic and hydrophobic proteinaceous translocators in a two-step process. In the first, hydrophilic translocators localize to the tip of a proteinaceous needle in animal pathogens, or a proteinaceous pilus in plant pathogens, and associate with hydrophobic translocators, which insert into host plasma membranes in the second step. However, the pilus needs to penetrate plant cell walls in advance. All hydrophilic translocators so far identified in plant pathogens are characteristic of harpins: T3SS accessory proteins containing a unitary hydrophilic domain or an additional enzymatic domain. Two-domain harpins carrying a pectate lyase domain potentially target plant cell walls and facilitate the penetration of the pectin-rich middle lamella by the bacterial pilus. One-domain harpins target plant plasma membranes and may play a crucial role in translocon assembly, which may also involve contrapuntal associations of hydrophobic translocators. In all cases, sensory components in the target plasma membrane are indispensable for the membrane recognition of translocators and the functionality of the translocon. The conjectural sensors point to membrane lipids and proteins, and a phosphatidic acid and an aquaporin are able to interact with selected harpin-type translocators. Interactions between translocators and their sensors at the target plasma membrane are assumed to be critical for translocon assembly.

  3. Turbulent magnetic fluctuations in laboratory reconnection

    Science.gov (United States)

    Von Stechow, Adrian; Grulke, Olaf; Klinger, Thomas

    2016-07-01

    The role of fluctuations and turbulence is an important question in astrophysics. While direct observations in space are rare and difficult dedicated laboratory experiments provide a versatile environment for the investigation of magnetic reconnection due to their good diagnostic access and wide range of accessible plasma parameters. As such, they also provide an ideal chance for the validation of space plasma reconnection theories and numerical simulation results. In particular, we studied magnetic fluctuations within reconnecting current sheets for various reconnection parameters such as the reconnection rate, guide field, as well as plasma density and temperature. These fluctuations have been previously interpreted as signatures of current sheet plasma instabilities in space and laboratory systems. Especially in low collisionality plasmas these may provide a source of anomalous resistivity and thereby contribute a significant fraction of the reconnection rate. We present fluctuation measurements from two complementary reconnection experiments and compare them to numerical simulation results. VINETA.II (Greifswald, Germany) is a cylindrical, high guide field reconnection experiment with an open field line geometry. The reconnecting current sheet has a three-dimensional structure that is predominantly set by the magnetic pitch angle which results from the superposition of the guide field and the in-plane reconnecting field. Within this current sheet, high frequency magnetic fluctuations are observed that correlate well with the local current density and show a power law spectrum with a spectral break at the lower hybrid frequency. Their correlation lengths are found to be extremely short, but propagation is nonetheless observed with high phase velocities that match the Whistler dispersion. To date, the experiment has been run with an external driving field at frequencies higher than the ion cyclotron frequency f_{ci}, which implies that the EMHD framework applies

  4. Dynamical properties of non-ideal plasma on the basis of effective potentials

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T. S.; Kodanova, S. K.; Moldabekov, Zh. A.; Issanova, M. K. [IETP, Al-Farabi Kazakh National University, 71 Al-Farabi str., Almaty 050040 (Kazakhstan)

    2013-11-15

    In this work, stopping power has been calculated on the basis of the Coulomb logarithm using the effective potentials. Calculations of the Coulomb logarithm and stopping power for different interaction potentials and degrees of ionization are compared. The comparison with the data of other theoretical and experimental works was carried out.

  5. A potential role for plasma uric acid in the endothelial pathology of Plasmodium falciparum malaria.

    Directory of Open Access Journals (Sweden)

    Neida K Mita-Mendoza

    Full Text Available BACKGROUND: Inflammatory cytokinemia and systemic activation of the microvascular endothelium are central to the pathogenesis of Plasmodium falciparum malaria. Recently, 'parasite-derived' uric acid (UA was shown to activate human immune cells in vitro, and plasma UA levels were associated with inflammatory cytokine levels and disease severity in Malian children with malaria. Since UA is associated with endothelial inflammation in non-malaria diseases, we hypothesized that elevated UA levels contribute to the endothelial pathology of P. falciparum malaria. METHODOLOGY/PRINCIPAL FINDINGS: We measured levels of UA and soluble forms of intercellular adhesion molecule-1 (sICAM-1, vascular cell adhesion molecule-1 (sVCAM-1, E-selectin (sE-Selectin, thrombomodulin (sTM, tissue factor (sTF and vascular endothelial growth factor (VEGF in the plasma of Malian children aged 0.5-17 years with uncomplicated malaria (UM, n = 487 and non-cerebral severe malaria (NCSM, n = 68. In 69 of these children, we measured these same factors once when they experienced a malaria episode and twice when they were healthy (i.e., before and after the malaria transmission season. We found that levels of UA, sICAM-1, sVCAM-1, sE-Selectin and sTM increase during a malaria episode and return to basal levels at the end of the transmission season (p<0.0001. Plasma levels of UA and these four endothelial biomarkers correlate with parasite density and disease severity. In children with UM, UA levels correlate with parasite density (r = 0.092, p = 0.043, sICAM-1 (r = 0.255, p<0.0001 and sTM (r = 0.175, p = 0.0001 levels. After adjusting for parasite density, UA levels predict sTM levels. CONCLUSIONS/SIGNIFICANCE: Elevated UA levels may contribute to malaria pathogenesis by damaging endothelium and promoting a procoagulant state. The correlation between UA levels and parasite densities suggests that parasitized erythrocytes are one possible source of excess UA. UA-induced shedding of

  6. A potential role for plasma uric acid in the endothelial pathology of Plasmodium falciparum malaria.

    Science.gov (United States)

    Mita-Mendoza, Neida K; van de Hoef, Diana L; Lopera-Mesa, Tatiana M; Doumbia, Saibou; Konate, Drissa; Doumbouya, Mory; Gu, Wenjuan; Anderson, Jennifer M; Santos-Argumedo, Leopoldo; Rodriguez, Ana; Fay, Michael P; Diakite, Mahamadou; Long, Carole A; Fairhurst, Rick M

    2013-01-01

    Inflammatory cytokinemia and systemic activation of the microvascular endothelium are central to the pathogenesis of Plasmodium falciparum malaria. Recently, 'parasite-derived' uric acid (UA) was shown to activate human immune cells in vitro, and plasma UA levels were associated with inflammatory cytokine levels and disease severity in Malian children with malaria. Since UA is associated with endothelial inflammation in non-malaria diseases, we hypothesized that elevated UA levels contribute to the endothelial pathology of P. falciparum malaria. We measured levels of UA and soluble forms of intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-Selectin), thrombomodulin (sTM), tissue factor (sTF) and vascular endothelial growth factor (VEGF) in the plasma of Malian children aged 0.5-17 years with uncomplicated malaria (UM, n = 487) and non-cerebral severe malaria (NCSM, n = 68). In 69 of these children, we measured these same factors once when they experienced a malaria episode and twice when they were healthy (i.e., before and after the malaria transmission season). We found that levels of UA, sICAM-1, sVCAM-1, sE-Selectin and sTM increase during a malaria episode and return to basal levels at the end of the transmission season (p<0.0001). Plasma levels of UA and these four endothelial biomarkers correlate with parasite density and disease severity. In children with UM, UA levels correlate with parasite density (r = 0.092, p = 0.043), sICAM-1 (r = 0.255, p<0.0001) and sTM (r = 0.175, p = 0.0001) levels. After adjusting for parasite density, UA levels predict sTM levels. Elevated UA levels may contribute to malaria pathogenesis by damaging endothelium and promoting a procoagulant state. The correlation between UA levels and parasite densities suggests that parasitized erythrocytes are one possible source of excess UA. UA-induced shedding of endothelial TM may represent a novel mechanism of malaria pathogenesis, in

  7. Thermal fluctuations in loop cosmology

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Singh, Parampreet

    2007-01-01

    Quantum gravitational effects in loop quantum cosmology lead to a resolution of the initial singularity and have the potential to solve the horizon problem and generate a quasi scale-invariant spectrum of density fluctuations. We consider loop modifications to the behavior of the inverse scale factor below a critical scale in closed models and assume a purely thermal origin for the fluctuations. We show that the no-go results for scale invariance in classical thermal models can be evaded even if we just consider modifications to the background (zeroth order) gravitational dynamics. Since a complete and systematic treatment of the perturbed Einstein equations in loop cosmology is still lacking, we simply parameterize their expected modifications. These change quantitatively, but not qualitatively, our conclusions. We thus urge the community to more fully work out this complex aspect of loop cosmology, since the full picture would not only fix the free parameters of the theory, but also provide a model for a no...

  8. Fluctuations of fragment observables

    CERN Document Server

    Gulminelli, F

    2006-01-01

    This contribution presents a review of our present theoretical as well as experimental knowledge of different fluctuation observables relevant to nuclear multifragmentation. The possible connection between the presence of a fluctuation peak and the occurrence of a phase transition or a critical phenomenon is critically analyzed. Many different phenomena can lead both to the creation and to the suppression of a fluctuation peak. In particular, the role of constraints due to conservation laws and to data sorting is shown to be essential. From the experimental point of view, a comparison of the available fragmentation data reveals that there is a good agreement between different data sets of basic fluctuation observables, if the fragmenting source is of comparable size. This compatibility suggests that the fragmentation process is largely independent of the reaction mechanism (central versus peripheral collisions, symmetric versus asymmetric systems, light ions versus heavy ion induced reactions). Configurationa...

  9. Vacuum Radiation Pressure Fluctuations and Barrier Penetration

    CERN Document Server

    Huang, Haiyan

    2016-01-01

    We apply recent results on the probability distribution for quantum stress tensor fluctuations to the problem of barrier penetration by quantum particles. The probability for large stress tensor fluctuations decreases relatively slowly with increasing magnitude of the fluctuation, especially when the quantum stress tensor operator has been averaged over a finite time interval. This can lead to large vacuum radiation pressure fluctuations on charged or polarizable particles, which can in turn push the particle over a potential barrier. The rate for this effect depends sensitively upon the details of the time averaging of the stress tensor operator, which might be determined by factors such as the shape of the potential. We make some estimates for the rate of barrier penetration by this mechanism and argue that in some cases this rate can exceed the rate for quantum tunneling through the barrier. The possibility of observation of this effect is discussed.

  10. Potential role of kinetic Alfvén waves and whistler waves in solar wind plasmas

    Science.gov (United States)

    Nandal, P.; Yadav, N.; Sharma, R. P.; Goldstein, M. L.

    2016-07-01

    Spacecraft observations indicate the signatures of highly oblique kinetic Alfvén waves (KAWs) and whistler waves in the solar wind plasma. In the present work, we explore the possible role of KAWs and whistler waves in the observed solar wind magnetic turbulent spectrum. The nonlinear spatial evolution of KAW is studied including the effects of the ponderomotive force which results in intense localized structures due to the background density modification. Weak quasi-transverse whistler wave propagating through these localized structures also gets localized in the form of small-scale localized structures. We present numerically calculated magnetic power spectra for both KAW as well as for whistler wave. Our obtained results demonstrate the important role that KAWs and whistler waves play in the energy cascading from larger to smaller scales. The relevance of these results to recent spacecraft observations is also pointed out.

  11. Dependence of intermittent density fluctuations on collisionality in TJ-K

    Energy Technology Data Exchange (ETDEWEB)

    Reuther, Kyle; Garland, Stephen; Ramisch, Mirko [Institut fuer Grenzflaechenverfahrenstechnikund Plasmatechnologie, Universitaet Stuttgart (Germany); Manz, Peter [Physik-Department E28, Technische Universitaet Muenchen, Garching (Germany)

    2016-07-01

    Particle and heat transport losses due to edge turbulence are well known phenomena commonly seen in toroidal magnetic confinement devices. Furthermore in the scrape-off layer (SOL), turbulent density fluctuations are often observed to be intermittent and dominate particle transport to the vessel walls. In the adiabatic limit (small collisionality), of the two-field Hasegawa-Wakatani model, simulated turbulent density fluctuations are observed to couple to potential fluctuations and exhibit Gaussian behavior. However, in the hydrodynamic limit (large collisionality) the density and potential decouple. As a result, the density becomes passively advected, evolves towards the vorticity, and exhibits intermittent behavior. The relationship between collisionality and intermittency is investigated experimentally at the stellarator TJ-K. To vary the plasma collisionality, which is related to electron density and temperature, parameters such as gas type, neutral gas pressure, magnetic field, and heating power are varied. Radial profiles of plasma density, temperature, floating potential, and vorticity are recorded via a scanning 7-tip Langmuir probe array. First results are presented.

  12. Langmuir Probe Distortions and Probe Compensation in an Inductively Coupled Plasma

    Science.gov (United States)

    Ji, J. S.; Cappelli, M. A.; Kim, J. S.; Rao, M. V. V. S.; Sharma, S. P.

    1999-01-01

    In many RF discharges, Langmuir probe measurements are usually made against a background of sinusoidal (and not so sinusoidal) fluctuations in the plasma parameters such as the plasma potential (Vp), the electron number density (ne), and the electron temperature (Te). The compensation of sinusoidal fluctuations in Vp has been extensively studied and is relatively well understood. Less attention has been paid to the possible distortions introduced by small fluctuations in plasma density and/or plasma temperature, which may arise in the sheath and pre-sheath regions of RF discharges. Here, we present the results of a model simulation of probe characteristics subject to fluctuations in both Vp and ne. The modeling of probe distortion due to possible fluctuations in Te is less straightforward. A comparison is presented of calculations with experimental measurements using a compensated and uncompensated Langmuir probe in an inductively coupled GEC reference cell plasma, operating on Ar and Ar/CF4 mixtures. The plasma parameters determined from the compensated probe characteristics are compared to previous measurements of others made in similar discharges, and to our own measurements of the average electron density derived from electrical impedance measurements.

  13. Plasma viscosity: a potential predictor of both medical treatment response and clinical stage of ulcerative colitis.

    Science.gov (United States)

    Tolga, Yakar; Mansur, Cosar Arif; Savas, Gokturk Hu Seyin; Gulhan, Unler Kanat Ayse; Alper, Parlakgumus; Ilknur, Kozanoglu; Ender, Serin

    2016-01-01

    La colite ulcerosa (UC) è una delle maggiori forme di colonpatia infiammatoria cronica recidivante. La capacità di identificare tipo, gravità e sensibilità alla terapia su parametri di laboratorio è da tempo oggetto di ricerca degli studi clinici. Lo scopo di questo studio è quello di accertare la relazione tra la viscosità del plasma (PV), l’attività della malattia e la risposta al trattamento medico. Lo studio si è svolto su 105 pazienti con UC e 42 volontari sani. I prelievi di sangue sono stati utilizzati per valutare la viscosità del plasma (PV), la velocità di eritrosedimentazione (ESR), la proteina C-reattiva ultrasensibile (hs-CRP), il D-dimero e il fibrinogeno. I pazienti con UC sono stati raggruppati in relazione al grado di attività flogistica (cioè 59 attivi e 46 in remissione). La PV è risultata più elevata in quelli con UC attiva rispetto a quella dei soggetti in remissione o nei soggetti sani. È risultata significativamente più elevata sia nei casi di UC refrattaria al trattamento steroideo rispetto a quelli sensibili (p< 0.001), e nelle UC rafrattarie alla ciclosrporina rispetto a quelli sensibili (p= 0.003). Con l’aumento della PV nei pazienti affetti da UC sono risultati significativamente associati il punteggio del SCCAI (Increased Simple Clinical Colitis Activity Index), dell’EGS (Endoscopic Grading Scale) e del HAD (Histological Disease Activity (HAD). Si conclude che la PV è un marker utile per la previsione di sensibilità al trattamento sterorideo e con ciclosporina nei pazienti con UC attiva. Potrebbe essere rimpiazzata dalla ESR e dalla hs-CRP come misura della risposta in fase acuta in quanto sufficientemente sensibile. Questi risultati possono essere utili per l’identificazione dei pazienti con UC attiva da destinare alla colectomia.

  14. Experimental investigation of quasiperiodic-chaotic-quasiperiodic-chaotic transition in a direct current magnetron sputtering plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sabavath, Gopi Kishan; Banerjee, I.; Mahapatra, S. K., E-mail: skmahapatra@bitmesra.ac.in [Plasma Laboratory, Department of Physics, Birla Institute of Technology-Mesra, Ranchi 835215 (India); Shaw, Pankaj Kumar; Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India)

    2015-08-15

    Floating potential fluctuations from a direct current magnetron sputtering plasma have been analysed using time series analysis techniques like phase space plots, power spectra, frequency bifurcation plot, etc. The system exhibits quasiperiodic-chaotic-quasiperiodic-chaotic transitions as the discharge voltage was increased. The transitions of the fluctuations, quantified using the largest Lyapunov exponent, have been corroborated by Hurst exponent and the Shannon entropy. The Shannon entropy is high for quasiperiodic and low for chaotic oscillations.

  15. Chiral charge erasure via thermal fluctuations of magnetic helicity

    Energy Technology Data Exchange (ETDEWEB)

    Long, Andrew J. [Kavli Institute for Cosmological Physics, University of Chicago,Chicago, Illinois 60637 (United States); Sabancilar, Eray [Institut de Théorie des Phénoménes Physiques, Ecole Polytechnique Fédérale de Lausanne,CH-1015 Lausanne (Switzerland)

    2016-05-11

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ≳1/(αμ{sub 5}), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ{sub 5} parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δ H∼λT and τ∼αλ{sup 3}T{sup 2} for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t∼T{sup 3}/(α{sup 5}μ{sub 5}{sup 4}) until it reaches an equilibrium value H∼μ{sub 5}T{sup 2}/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ{sub 5}

  16. Chiral charge erasure via thermal fluctuations of magnetic helicity

    Science.gov (United States)

    Long, Andrew J.; Sabancilar, Eray

    2016-05-01

    We consider a relativistic plasma of fermions coupled to an Abelian gauge field and carrying a chiral charge asymmetry, which might arise in the early Universe through baryogenesis. It is known that on large length scales, λ gtrsim 1/(αμ5), the chiral anomaly opens an instability toward the erasure of chiral charge and growth of magnetic helicity. Here the chemical potential μ5 parametrizes the chiral asymmetry and α is the fine-structure constant. We study the process of chiral charge erasure through the thermal fluctuations of magnetic helicity and contrast with the well-studied phenomenon of Chern-Simons number diffusion. Through the fluctuation-dissipation theorem we estimate the amplitude and time scale of helicity fluctuations on the length scale λ, finding δScript H ~ λT and τ ~ αλ3T2 for a relativistic plasma at temperature T. We argue that the presence of a chiral asymmetry allows the helicity to grow diffusively for a time t ~ T3/(α5μ54) until it reaches an equilibrium value Script H ~ μ5T2/α, and the chiral asymmetry is partially erased. If the chiral asymmetry is small, μ5 < T/α, this avenue for chiral charge erasure is found to be slower than the chiral magnetic effect for which t ~ T/(α3μ52). This mechanism for chiral charge erasure can be important for the hypercharge sector of the Standard Model as well as extensions including U(1) gauge interactions, such as asymmetric dark matter models.

  17. Thermodynamics of the quark-gluon plasma at finite chemical potential: color path integral Monte Carlo results

    Energy Technology Data Exchange (ETDEWEB)

    Filinov, V.S.; Fortov, V.E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13, bd. 2, 125412 Moscow (Russian Federation); Bonitz, M. [Institute for Theoretical Physics and Astrophysics, Christian Albrechts University Kiel, Leibnizstrasse 15, D-24098 Kiel (Germany); Ivanov, Y.B. [National Research Center ' ' Kurchatov Institute' ' , Kurchatov Sq. 1, 123182 Moscow, Russia, National Research Nuclear University ' ' MEPhI' ' , Kashirskoe sh. 31, 115409 Moscow (Russian Federation); Ilgenfritz, E.M. [Joint Institute for Nuclear Reseach, Joliot-Curie str. 6, Dubna, 141980, Moscow Region (Russian Federation)

    2015-02-01

    Based on the constituent quasiparticle model of the quark-gluon plasma (QGP), color quantum path-integral Monte-Carlo (PIMC) calculations of the thermodynamic properties of the QGP are performed. We extend our previous zero chemical potential simulations to the QGP at finite baryon chemical potential. The results indicate that color PIMC can be applied not only above the QCD critical temperature T{sub c} but also below T{sub c}. Besides reproducing the lattice equation of state our approach yields also valuable additional insight into the internal structure of the QGP, via the pair distribution functions of the various quasiparticles. In particular, the pair distribution function of gluons reflects the existence of gluon-gluon bound states at low temperatures and μ = 175 MeV, i.e. glueballs, while meson-like bound states are not found. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Plasma Potential and Langmuir Probe Measurements in the Near-field Plume of the NASA 300M Hall Thruster

    Science.gov (United States)

    Herman, Daniel A; Shastry, Rohit; Huang, Wensheng; Soulas, George C.; KamHawi, Hani

    2012-01-01

    In order to aid in the design of high-power Hall thrusters and provide experimental validation for existing modeling efforts, plasma potential and Langmuir probe measurements were performed in the near-field plume of the NASA 300M Hall thruster. A probe array consisting of a Faraday probe, Langmuir probe, and emissive probe was used to interrogate the plume from approximately 0.1 - 2.0 DT,m downstream of the thruster exit plane at four operating conditions: 300 V, 400 V, and 500 V at 20 kW as well as 300 V at 10 kW. Results show that the acceleration zone and high-temperature region were contained within 0.3 DT,m from the exit plane at all operating conditions. Isothermal lines were shown to strongly follow magnetic field lines in the nearfield, with maximum temperatures ranging from 19 - 27 eV. The electron temperature spatial distribution created large drops in measured floating potentials in front of the magnetic pole surfaces where the plasma density was small, which suggests strong sheaths at these surfaces. The data taken have provided valuable information for future design and modeling validation, and complements ongoing internal measurement efforts on the NASA 300 M.

  19. Plasma Potential and Langmuir Probe Measurements in the Near-field Plume of the NASA-300M Hall Thruster

    Science.gov (United States)

    Herman, Daniel A.; Shastry, Rohit; Huang, Wensheng; Soulas, George C.; Kamhawi, Hani

    2012-01-01

    In order to aid in the design of high-power Hall thrusters and provide experimental validation for existing modeling efforts, plasma potential and Langmuir probe measurements were performed in the near-field plume of the NASA-300M Hall thruster. A probe array consisting of a Faraday probe, Langmuir probe, and emissive probe was used to interrogate the plume from approximately 0.1 - 2.0 mean thruster diameters downstream of the thruster exit plane at four operating conditions: 300 V, 400 V, and 500 V at 20 kW as well as 300 V at 10 kW. Results show that the acceleration zone and high-temperature region were contained within 0.3 mean thruster diameters from the exit plane at all operating conditions. Isothermal lines were shown to strongly follow magnetic field lines in the near-field, with maximum temperatures ranging from 19 - 27 eV. The electron temperature spatial distribution created large drops in measured floating potentials in front of the magnetic pole surfaces where the plasma density was low, which suggests strong sheaths at these surfaces. The data taken have provided valuable information for future design and modeling validation, and complements ongoing internal measurement efforts on the NASA-300M.

  20. Turbulence measurements in fusion plasmas

    Science.gov (United States)

    Conway, G. D.

    2008-12-01

    Turbulence measurements in magnetically confined toroidal plasmas have a long history and relevance due to the detrimental role of turbulence induced transport on particle, energy, impurity and momentum confinement. The turbulence—the microscopic random fluctuations in particle density, temperature, potential and magnetic field—is generally driven by radial gradients in the plasma density and temperature. The correlation between the turbulence properties and global confinement, via enhanced diffusion, convection and direct conduction, is now well documented. Theory, together with recent measurements, also indicates that non-linear interactions within the turbulence generate large scale zonal flows and geodesic oscillations, which can feed back onto the turbulence and equilibrium profiles creating a complex interdependence. An overview of the current status and understanding of plasma turbulence measurements in the closed flux surface region of magnetic confinement fusion devices is presented, highlighting some recent developments and outstanding problems.

  1. Statistics of fluctuation induced transport in the scrape-off layer of Alcator C-Mod

    Science.gov (United States)

    Kube, Ralph; Garcia, Odd Erik; Theodorsen, Audun; Labombard, Brian; Terry, James

    2016-10-01

    The fluctuation induced transport in the scrape-off layer of Alcator C-Mod is investigated in an ohmically heated lower single-null discharge using Mirror Langmuir Probes. The probes are connected to a horizontal scanning probe which dwells at the outboard mid plane limiter radius and to electrodes in the outer divertor baffle. At the limiter radius the electron density, electron temperature and plasma potential are correlated with linear correlation coefficients r of approximately r=0.8. The bursts show a steep rise and a decay on a time scales of approximately 5 and 10 microseconds respectively. Amplitudes of bursts in the density, temperature, and plasma potential time series are correlated with r approximately 0.7-0.8. Conditionally averaged bursts in the radial particle and heat flux time series are less coherent and less reproducible, their amplitudes are correlated to the amplitude of bursts in the density time series with r=0.4. Statistics of the fluctuating plasma parameters at the outer divertor baffle are qualitatively similar to those at outboard midplane. Histograms, as well as statistics for level crossings and excess times spent above a given threshold for the time series compare favorably to a stochastic model for time series of scrape-off layer plasmas.

  2. Charge fluctuations in a final state with QGP

    OpenAIRE

    Fialkowski, K.; Wit, R. de

    2001-01-01

    Charge fluctuations as a possible signal of quark - gluon plasma (QGP) were recently suggested. A short summary of comments presented on this subject is given and supplemented by a discussion of the coexistence of pions produced "directly" and through a QGP phase. Such a coexistence may obscure the expected plasma signal similarly to the effects considered in the comments mentioned above.

  3. ECE imaging of electron temperature and electron temperature fluctuations (invited)

    NARCIS (Netherlands)

    Deng, B.H.; Domier, C.W.; N C Luhmann Jr.,; Brower, D.L.; Cima, G.; Donne, A. J. H.; Oyevaar, T.; van de Pol, M.J.

    2001-01-01

    Electron cyclotron emission imaging (ECE imaging or ECEI) is a novel plasma diagnostic technique for the study of electron temperature profiles and fluctuations in magnetic fusion plasma devices. Instead of a single receiver located in the tokamak midplane as in conventional ECE radiometers, ECEI sy

  4. Density fluctuations associated with the internal disruption

    Energy Technology Data Exchange (ETDEWEB)

    Gervais, F.; Gresillon, D.; Hennequin, P.; Quemeneur, A.; Truc, A. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises; Devynck, P.; Garbet, X.; Laviron, C.; Payan, J.; Pecquet, A.L. [Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France)

    1993-12-31

    Fluctuations specially related to the sawtooth relaxations have been recorded in TORE SUPRA ohmic plasmas with the CO{sub 2} scattering experiment ALTAIR. The temperature and density evolutions are simultaneously analysed to observe the sawtooth behaviour on a fast time scale. These observed fluctuations are perfectly connected with two characteristic phases of the sawtooth crash, lasting about 60 and 100 {mu}s respectively, as it can be seen on the soft X-ray signals or ECE temperature measurements. Frequency, wave number spectra and level of these fluctuations are analyzed for the two different sawtooth phases. Some specific turbulence correlated with the sawtooth crash has been previously reported. Theoretical models have suggested that enhanced turbulence could account for the rapid crash time and fast heat propagation observed on most tokamaks. The aim of this study is to check the validity of these models with a better knowledge of the characteristics of the observed turbulence. (author) 9 refs., 5 figs.

  5. Venus Express observations of magnetic field fluctuations in the magnetosheath

    Science.gov (United States)

    Du, J.; Wang, C.; Zhang, T. L.; Volwerk, M.; Delva, M.; Baumjohann, W.

    2008-12-01

    Magnetic field fluctuations within a planetary magnetosheath play an important role in the solar wind interaction with the planet, since they can reconfigure the plasma flow and the magnetic field and transfer energy from the bow shock to the lower boundary. Many studies have been presented on the fluctuations in the terrestrial magnetosheath; however, hardly any studies have so far been carried out for Venusian magnetosheath fluctuations, except for Luhmann et al. [1983] and Vörös et al. [2008] who performed some case studies on the magnetosheath fluctuations at Venus. It was shown that the fluctuations are probably convected from the vicinity of the quasi-parallel bow shock along the streamlines. Based on the Venus Express observations in 2006 and 2007, we investigate the spatial distributions of magnetic field fluctuations in the Venus magnetosheath statistically.

  6. Fusion plasma physics

    CERN Document Server

    Stacey, Weston M

    2012-01-01

    This revised and enlarged second edition of the popular textbook and reference contains comprehensive treatments of both the established foundations of magnetic fusion plasma physics and of the newly developing areas of active research. It concludes with a look ahead to fusion power reactors of the future. The well-established topics of fusion plasma physics -- basic plasma phenomena, Coulomb scattering, drifts of charged particles in magnetic and electric fields, plasma confinement by magnetic fields, kinetic and fluid collective plasma theories, plasma equilibria and flux surface geometry, plasma waves and instabilities, classical and neoclassical transport, plasma-materials interactions, radiation, etc. -- are fully developed from first principles through to the computational models employed in modern plasma physics. The new and emerging topics of fusion plasma physics research -- fluctuation-driven plasma transport and gyrokinetic/gyrofluid computational methodology, the physics of the divertor, neutral ...

  7. Deoxycytidine in human plasma: potential for protecting leukemic cells during chemotherapy.

    Science.gov (United States)

    Cohen, J D; Strock, D J; Teik, J E; Katz, T B; Marcel, P D

    1997-06-24

    Degradation of DNA produces deoxycytidine. Metabolism of deoxycytidine to dCTP inhibits phosphorylation of cytosine arabinoside (araC), fludarabine (FaraA) and 2-chlorodeoxyadenosine (CdA) by deoxycytidine kinase. This study measured plasma deoxycytidine in healthy adults and two leukemia patients and then determined how clinically relevant deoxycytidine levels would affect drug toxicity in human leukemia and lymphoma cells. Deoxycytidine was well below 0.05 microM in ten healthy persons. In the leukemia patients it was <0.05 and 0.44 microM before chemotherapy, rising to 10.3 and 5.5 microM during treatment. A broad range of clinically relevant deoxycytidine levels were high enough to profoundly decrease araC, FaraA and CdA toxicity in MOLT3, CA46 and HL60 leukemia/lymphoma cells and to change dCTP, DNA synthesis and drug incorporation into DNA in a manner consistent with prior mechanistic studies. Varying deoxycytidine levels could be an important factor influencing leukemia therapy.

  8. Hot QCD equation of state and quark-gluon plasma-- finite quark chemical potential

    CERN Document Server

    Chandra, Vinod

    2008-01-01

    We explore the relevance of a hot QCD equation of state of $O[g^6\\ln(1/g)]$, which has been obtained\\cite{avrn} for non-vanishing quark-chemical potentials to heavy ion collisions. Employing a method proposed in a recent paper \\cite{chandra1}, we use the EOS to determine a host of thermodynamic quantities, the energy density, specific heat, entropy dnesity, and the temperature dependence of screening lengths, with the behaviour of QGP at RHIC and LHC in mind. We also investigate the sensitivity of these observables to the quark chemical potential.

  9. Modification of Boundary Fluctuations by LHCD in the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    宋梅; 万宝年; 徐国盛; 凌必利

    2003-01-01

    Measurements of boundary fluctuations and fluctuation driven electron fluxes have been performed in ohmic and lower hybrid current drive enhanced confinement plasma using a graphite Langmuir probe array on HT-7tokamak. The fluctuations are significantly suppressed and the turbulent fluxes are remarkably depressed in the enhanced plasma. We characterized the statistical properties of fluctuations and the particle flux and found a non-Gaussian character in the whole scrape-off layer with minimum deviations from Gaussian in the proximity of the velocity shear layer in ohmic plasma. In the enhanced plasma the deviations in the boundary region are all reduces obviously. The fluctuations and induced electron fluxes show sporadic bursts asymmetric in time and the asymmetry is remarkably weakened in the lower hybrid current driving (LHCD) phase. The results suggest a coupling between the statistical behaviour of fluctuations and the turbulent flow.

  10. Identification of plasma microRNAs as new potential biomarkers with high diagnostic power in human cutaneous melanoma.

    Science.gov (United States)

    Fogli, Stefano; Polini, Beatrice; Carpi, Sara; Pardini, Barbara; Naccarati, Alessio; Dubbini, Nevio; Lanza, Maria; Breschi, Maria Cristina; Romanini, Antonella; Nieri, Paola

    2017-05-01

    Melanoma is a devastating disease with few therapeutic options in the advanced stage and with the urgent need of reliable biomarkers for early detection. In this context, circulating microRNAs are raising great interest as diagnostic biomarkers. We analyzed the expression profiles of 21 selected microRNAs in plasma samples from melanoma patients and healthy donors to identify potential diagnostic biomarkers. Data analysis was performed using global mean normalization and NormFinder algorithm. Linear regression followed by receiver operating characteristic analyses was carried out to evaluate whether selected plasma miRNAs were able to discriminate between cases and controls. We found five microRNAs that were differently expressed among cases and controls after Bonferroni correction for multiple testing. Specifically, miR-15b-5p, miR-149-3p, and miR-150-5p were up-regulated in plasma of melanoma patients compared with healthy controls, while miR-193a-3p and miR-524-5p were down-regulated. Receiver operating characteristic analyses of these selected microRNAs provided area under the receiver operating characteristic curve values ranging from 0.80 to 0.95. Diagnostic value of microRNAs is improved when considering the combination of miR-149-3p, miR-150-5p, and miR-193a-3p. The triple classifier had a high capacity to discriminate between melanoma patients and healthy controls, making it suitable to be used in early melanoma diagnosis.

  11. Identification of a DNA methylome profile of esophageal squamous cell carcinoma and potential plasma epigenetic biomarkers for early diagnosis.

    Directory of Open Access Journals (Sweden)

    Xufeng Li

    Full Text Available DNA methylation is a critical epigenetic mechanism involved in key cellular processes. Its deregulation has been linked to many human cancers including esophageal squamous cell carcinoma (ESCC. This study was designed to explore the whole methylation status of ESCC and to identify potential plasma biomarkers for early diagnosis. We used Infinium Methylation 450k array to analyze ESCC tissues (n = 4, paired normal surrounding tissues (n = 4 and normal mucosa from healthy individuals (n = 4, and combined these with gene expression data from the GEO database. One hundred and sixty eight genes had differentially methylated CpG sites in their promoter region and a gene expression pattern inverse to the direction of change in DNA methylation. These genes were involved in several cancer-related pathways. Three genes were validated in additional 42 ESCC tissues and paired normal surrounding tissues. The methylation frequency of EPB41L3, GPX3, and COL14A1 were higher in tumor tissues than in normal surrounding tissues (P < 0.017. The higher methylation frequency of EPB41l3 was correlated with large tumor size (P = 0.044 and advanced pT tumor stage (P = 0.001. The higher methylation frequency of GPX3 and COL14A1 were correlated with advanced pN tumor stage (P = 0.001 and P < 0.001. The methylation of EPB41L3, GPX3, and COL14A1 genes were only found in ESCC patients' plasma, but not in normal individuals upon testing 42 ESCC patients and 50 healthy individuals. Diagnostic sensitivity was increased when methylation of any of the 3 genes were counted (64.3% sensitivity and 100% specificity. These differentially methylated genes in plasma may be used as biomarkers for early diagnosis of ESCC.

  12. Intracellular protein transport to the thyrocyte plasma membrane: potential implications for thyroid physiology.

    Science.gov (United States)

    Arvan, P; Kim, P S; Kuliawat, R; Prabakaran, D; Muresan, Z; Yoo, S E; Abu Hossain, S

    1997-02-01

    We present a snapshot of developments in epithelial biology that may prove helpful in understanding cellular aspects of the machinery designed for the synthesis of thyroid hormones on the thyroglobulin precursor. The functional unit of the thyroid gland is the follicle, delimited by a monolayer of thyrocytes. Like the cells of most simple epithelia, thyrocytes exhibit specialization of the cell surface that confronts two different extracellular environments-apical and basolateral, which are separated by tight junctions. Specifically, the basolateral domain faces the interstitium/bloodstream, while the apical domain is in contact with the lumen that is the primary target for newly synthesized thyroglobulin secretion and also serves as a storage depot for previously secreted protein. Thyrocytes use their polarity in several important ways, such as for maintaining basolaterally located iodide uptake and T4 deiodination, as well apically located iodide efflux and iodination machinery. The mechanisms by which this organization is established, fall in large part under the more general cell biological problem of intracellular sorting and trafficking of different proteins en route to the cell surface. Nearly all exportable proteins begin their biological life after synthesis in an intracellular compartment known as the endoplasmic reticulum (ER), upon which different degrees of difficulty may be encountered during nascent polypeptide folding and initial export to the Golgi complex. In these initial stages, ER molecular chaperones can assist in monitoring protein folding and export while themselves remaining as resident proteins of the thyroid ER. After export from the ER, most subsequent sorting for protein delivery to apical or basolateral surfaces of thyrocytes occurs within another specialized intracellular compartment known as the trans-Golgi network. Targeting information encoded in secretory proteins and plasma membrane proteins can be exposed or buried at different

  13. Potential plasma biomarkers for progression of knee osteoarthritis using glycoproteomic analysis coupled with a 2D-LC-MALDI system

    Directory of Open Access Journals (Sweden)

    Fukuda Isao

    2012-06-01

    Full Text Available Abstract Background Although osteoarthritis (OA is a highly prevalent joint disease, to date, no reliable biomarkers have been found for the disease. In this study, we attempted to identify factors the amounts of which significantly change in association with the progression of knee OA. Methods A total of 68 subjects with primary knee OA were enrolled in the study. These subjects were followed up over an 18-month period, and plasma and serum samples were obtained together with knee radiographs every 6 months, i.e., 0, 6, 12 and 18 months after the enrollment. Progressors and non-progressors were determined from the changes on radiographs, and plasma samples from those subjects were subjected to N-glycoproteomic 2D-LC-MALDI analysis. MS peaks were identified, and intensities for respective peaks were compared between the progressors and non-progressors to find the peak intensities of which differed significantly between the two groups of subjects. Proteins represented by the chosen peaks were identified by MS/MS analysis. Expression of the identified proteins was evaluated in synovial tissues from 10 OA knee joints by in situ hybridization, western blotting analysis and ELISA. Results Among the subjects involved in the study, 3 subjects were determined to be progressors, and 6 plasma and serum samples from these subjects were subjected to the analysis together with another 6 samples from the non-progressors. More than 3000 MS peaks were identified by N-glycoproteomic 2D-LC-MALDI analysis. Among them, 4 peaks were found to have significantly different peak intensities between the progressors and non-progressors. MS/MS analysis revealed that these peaks represented clusterin, hemopexin, alpha-1 acid glycoprotein-2, and macrophage stimulating protein, respectively. The expression of these genes in OA synovium was confirmed by in situ hybridization, and for clusterin and hemopexin, by western blotting analysis and ELISA as well. Conclusions In this

  14. Fluctuation Measurements at New Spatial Scales

    Science.gov (United States)

    Hood, Ryan; Mattingly, Sean; Berumen, Jorge; Drake, Dereth; Skiff, Fred

    2013-10-01

    We present preliminary measurements from a laser induced fluorescence detection system used to resolve ion density fluctuations on spatial scales approaching the ion Debye length ~0.5 mm. The detection system consists of a pair of moveable periscopes which collimate light collected from a small measurement region (~0.1 cm3) along the axis of a magnetized singly ionized Argon plasma column. The light is imaged onto a pair of 16-channel linear photomultiplier arrays with digitized photon counting on all 32 channels at 1 MHz or on 8 channels at 4 MHz. The viewing regions may be resolved spatially either along or radial to the magnetic field axis depending on the orientation of the entrance slit. Plasma fluctuations resolved in ion velocity have never been observed at this scale. Measurements may provide insight into transport phenomena, which are fundamentally linked to plasma fluctuations. This work is supported by U.S. DOE Grant No. DE-FG02-99ER54543.

  15. Biological Effects of Pulsed Electric Field Based on Potential Fluctuations in Maize Seedlings%基于玉米幼苗电位波动的脉冲电场生物学效应

    Institute of Scientific and Technical Information of China (English)

    习岗; 刘锴; 杨运经; 高宇

    2013-01-01

    为了获取显著的电场生物学效应,通过小波降噪和功率谱分析研究了玉米幼苗本征电位波动的基本特征.研究发现,玉米幼苗本征电位波动的功率谱主要分布在1 Hz以内,重心频率为0.2 Hz.采用电场强度为100kV/m、频率为0.2 Hz的极低频脉冲电场处理萌发玉米种子,在萌发第5d时玉米种子的质量、芽长和根长分别比对照组增加17.55%、60.13%和28.50%.分析萌发种子超弱发光的变化时发现,在萌发第5d时,处理组玉米种子的自发发光和延迟发光积分强度分别比对照组增加了68.84%和33.93%,表明0.2 Hz脉冲电场加速了玉米萌发过程中DNA合成反应和细胞代谢.脉冲电场与植物电位的耦合共振可能是极低频脉冲电场具有显著生物学效应的原因.%In order to obtain remarkable electric field biological effect on crop seeds, the basic characteristics of natural potential fluctuations in maize seedlings were studied by analyzing the wavelet de-noising and power spectrum. The results showed that the power spectrum of natural potential fluctuations in maize seedlings was mainly distributed in 0~1 Hz with a gravity frequency of 0. 2 Hz. Based on the potential fluctuation characteristics, extremely low frequency pulsed electric field of 100 kV/m and 0. 2 Hz was used to treat germinating maize seeds. It was found that the seed germination process was significantly promoted: on the 5th day of germination, the fresh mass, shoot length and root length of germinating maize seed respectively increased by 17.55%, 60.13% and 28. 50% compared with those of the control group. Analysis results of ultraweak luminescence(UL) changes in the geminating seeds showed that the ultraweak luminescence was promoted by the pulsed electric field: the spontaneous luminescence and the integrated intensity of delayed luminescence of the germinating maize seed respectively increased by 68. 84% and 33. 93% compared with those of the control

  16. Drift waves and chaos in a LAPTAG plasma physics experiment

    Science.gov (United States)

    Gekelman, Walter; Pribyl, Patrick; Birge-Lee, Henry; Wise, Joe; Katz, Cami; Wolman, Ben; Baker, Bob; Marmie, Ken; Patankar, Vedang; Bridges, Gabriel; Buckley-Bonanno, Samuel; Buckley, Susan; Ge, Andrew; Thomas, Sam

    2016-02-01

    In a project involving an alliance between universities and high schools, a magnetized plasma column with a steep pressure gradient was established in an experimental device. A two-dimensional probe measured fluctuations in the plasma column in a plane transverse to the background magnetic field. Correlation techniques determined that the fluctuations were that of electrostatic drift waves. The time series data were used to generate the Bandt-Pompe entropy and Jensen-Shannon complexity for the data. These quantities, when plotted against one another, revealed that a combination of drift waves and other background fluctuations were a deterministically chaotic system. Our analysis can be used to tell the difference between deterministic chaos and random noise, making it a potentially useful technique in nonlinear dynamics.

  17. Plasma miR-126 Is a Potential Biomarker for Early Prediction of Type 2 Diabetes Mellitus in Susceptible Individuals

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2013-01-01

    Full Text Available Type 2 diabetes mellitus (T2DM is a major public health problem in China. Diagnostic markers are urgently needed to identify individuals at risk of developing T2DM and encourage them to adapt to a healthier life style. Circulating miRNAs present important sources of noninvasive biomarkers of various diseases. Recently, a novel plasma microRNA signature was identified in T2DM. Here, we evaluated the T2DM-related miRNA signature in plasma of three study groups: normal (fasting glucose (FG, 4.8–5.2 mmol/L, T2DM-susceptible (FG, 6.1–6.9 mmol/L, and T2DM individuals (FG, ≥7.0 mmol/L and tested the feasibility of using circulating miRNAs to identify individuals at risk of developing T2DM. Among the 5 miRNAs included in the signature, miR-29b and miR-28-3p are not detectable. miR-15a and miR-223 have comparable expression levels among three groups. Notably, miR-126 is the only miRNA that showed significantly reduced expression in susceptible individuals and T2DM patients compared to normal individuals, suggesting that miR-126 in circulation may serve as a potential biomarker for early identification of susceptible individuals to T2DM.

  18. Spin fluctuations and the

    Directory of Open Access Journals (Sweden)

    V.M. Loktev

    2008-09-01

    Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

  19. Generalized fluctuation theorems for classical systems

    CERN Document Server

    Agarwal, G S

    2015-01-01

    Fluctuation theorems have a very special place in the study of non equilibrium dynamics of physical systems. The form in which it is used most extensively is the Gallavoti-Cohen Fluctuation Theorem which is in terms of the distribution of the work $p(W)/p(-W)=\\exp(\\alpha W)$. We derive the general form of the fluctuation theorems for an arbitrary Gaussian Markov process and find conditions when the parameter $\\alpha$ becomes a universal parameter $1/kT$. As an application we consider fluctuation theorems for classical cyclotron motion of an electron in a parabolic potential. The motion of the electron is described by four coupled Langevin equations and thus is non-trivial. The generalized theorems are equally valid for non-equilibrium steady states.

  20. Riemannian geometry of fluctuation theory: An introduction

    Science.gov (United States)

    Velazquez, Luisberis

    2016-05-01

    Fluctuation geometry was recently proposed as a counterpart approach of Riemannian geometry of inference theory (information geometry), which describes the geometric features of the statistical manifold M of random events that are described by a family of continuous distributions dpξ(x|θ). This theory states a connection among geometry notions and statistical properties: separation distance as a measure of relative probabilities, curvature as a measure about the existence of irreducible statistical correlations, among others. In statistical mechanics, fluctuation geometry arises as the mathematical apparatus of a Riemannian extension of Einstein fluctuation theory, which is also closely related to Ruppeiner geometry of thermodynamics. Moreover, the curvature tensor allows to express some asymptotic formulae that account for the system fluctuating behavior beyond the gaussian approximation, while curvature scalar appears as a second-order correction of Legendre transformation between thermodynamic potentials.

  1. A new Differential Equation for Anomalous Diffusion with Potential Applications to Nonlinear Space Plasmas

    Science.gov (United States)

    Watkins, N. W.; Credgington, D.; Sanchez, R.; Chapman, S. C.

    2007-12-01

    Since the 1960s Mandelbrot has advocated the use of fractals for the description of the non-Euclidean geometry of many aspects of nature. In particular he proposed two kinds of model to capture persistence in time (his Joseph effect, common in hydrology and with fractional Brownian motion as the prototpe) and/or prone to heavy tailed jumps (the Noah effect, typical of economic indices, for which he proposed Lévy flights as an exemplar). Both effects are now well demonstrated in space plasmas, notably in indices quantifying Earth's auroral currents and in the turbulent solar wind. Models have, however, typically emphasised one of the Noah and Joseph parameters (the Lévy exponent μ and the temporal exponent β) at the other's expense. I will describe recent work [1] in which we studied a simple self-affine stable model-linear fractional stable motion, LFSM, which unifies both effects. I will discuss how this resolves some contradictions seen in earlier work. Such Noah-Joseph hybrid ("ambivalent" [2]) behaviour is highly topical in physics but is typically studied in the paradigm of the continuous time random walk (CTRW) [2,3] rather than LFSM. I will clarify the physical differences between these two pictures and present a recently-derived diffusion equation for LFSM. This replaces the second order spatial derivative in the equation of fBm [4] with a fractional derivative of order μ, but retains a diffusion coefficient with a power law time dependence rather than a fractional derivative in time (c.f. [2,3]). Intriguingly the self-similarity exponent extracted from the CTRW differs from that seen in LFSM. In the CTRW it is the ratio of μ to a temporal exponent, in LFSM it is an additive function of them. I will also show work in progress using an LFSM model and simple analytic scaling arguments to study the problem of the area between an LFSM curve and a threshold-related to the burst size measure introduced by Takalo and Consolini into solar- terrestrial physics

  2. Neutralization potential of the plasma of HIV-1 infected Indian patients in the context of anti-V3 antibody content and antiretroviral therapy. [corrected].

    Science.gov (United States)

    Choudhary, Alok Kumar; Andrabi, Raiees; Prakash, Somi Sankaran; Kumar, Rajesh; Choudhury, Shubhasree Dutta; Wig, Naveet; Biswas, Ashutosh; Hazarika, Anjali; Luthra, Kalpana

    2012-02-01

    We assessed the anti-V3 antibody content and viral neutralization potential of the plasma of 63 HIV-1-infected patients (antiretroviral naïve=39, treated=24) against four primary isolates (PIs) of clade C and a tier 1 clade B isolate SF162. Depletion and inhibition of anti-V3 antibodies in the plasma of five patients with high titers of anti-V3 antibodies led to modest change in the neutralization percentage against two PIs (range 0-21%). The plasma of antiretroviral-treated patients exhibited higher neutralization potential than that of the drug-naïve plasmas against the four PIs tested which was further evidenced by a follow-up study.

  3. The fluctuating gap model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiaobin

    2011-01-15

    The quasi-one-dimensional systems exhibit some unusual phenomenon, such as the Peierls instability, the pseudogap phenomena and the absence of a Fermi-Dirac distribution function line shape in the photoemission spectroscopy. Ever since the discovery of materials with highly anisotropic properties, it has been recognized that fluctuations play an important role above the three-dimensional phase transition. This regime where the precursor fluctuations are presented can be described by the so called fluctuating gap model (FGM) which was derived from the Froehlich Hamiltonian to study the low energy physics of the one-dimensional electron-phonon system. Not only is the FGM of great interest in the context of quasi-one-dimensional materials, liquid metal and spin waves above T{sub c} in ferromagnets, but also in the semiclassical approximation of superconductivity, it is possible to replace the original three-dimensional problem by a directional average over effectively one-dimensional problem which in the weak coupling limit is described by the FGM. In this work, we investigate the FGM in a wide temperature range with different statistics of the order parameter fluctuations. We derive a formally exact solution to this problem and calculate the density of states, the spectral function and the optical conductivity. In our calculation, we show that a Dyson singularity appears in the low energy density of states for Gaussian fluctuations in the commensurate case. In the incommensurate case, there is no such kind of singularity, and the zero frequency density of states varies differently as a function of the correlation lengths for different statistics of the order parameter fluctuations. Using the density of states we calculated with non-Gaussian order parameter fluctuations, we are able to calculate the static spin susceptibility which agrees with the experimental data very well. In the calculation of the spectral functions, we show that as the correlation increases, the

  4. Potential long-term effects of previous schistosome infection may reduce the atherogenic index of plasma in Chinese men.

    Science.gov (United States)

    Shen, Shi-Wei; Lu, Yun; Li, Feng; Shen, Zhen-Hai; Xu, Ming; Yao, Wei-Feng; Feng, Yin-Bo; Yun, Jing-Ting; Wang, Ya-Ping; Ling, Wang; Qi, Hua-Jin; Tong, Da-Xin

    2015-04-01

    The major purpose of this study was to assess the association between the potential long-term effects of previous schistosome infection and atherogenic dyslipidemia. Among 1597 men aged ⩾45 years who received health examinations and lived in previous schistosomiasis-endemic regions of China, 465 patients with previous schistosome infection were selected as study subjects, and 1132 subjects formed the control group. The risk factors for cardiovascular disease were measured and compared between the previous schistosome infection and control groups. The Atherogenic Index of Plasma, triglycerides, waist circumference and body mass index were significantly lower in the previous schistosome infection group than in the control group (all P values immune response against schistosome infections. The development of a schistosomiasis vaccine may effectively prevent the development and progression of atherosclerosis.

  5. The diagnostic potential of maternal plasma in detecting fetal diseases by DNA test

    Directory of Open Access Journals (Sweden)

    Saha Biswajit

    2004-01-01

    Full Text Available Conventionally, DNA based investigations for fetal diseases are done by chorionic villous sampling and amniocentesis. Both are invasive techniques. Recently, molecular diagnosis has also been made possible in early pregnancy from maternal blood which is noninvasive and advantageous. Most of the researches have tried to identify the Y chromosome marker(s to detect a male fetus and paternally inherited allele. This is currently helpful to detect a very few genetic disorders including Rh D status in Rh negative women in early pregnancy and preeclampsia a few weeks preceding the clinical onset. This is a potential area for prenatal diagnosis in future.

  6. Event-by-Event Fluctuations

    OpenAIRE

    2003-01-01

    In this review, we systematically examine the principles and the practices of fluctuations such as the momentum and the charge fluctuations as applied to the heavy ion collisions. Main emphases are: (i) Fluctuations as signals of phase transition (ii) Relationship between correlation functions and fluctuations (iii) Qualitative difference between fluctuations in small systems and large systems. Whenever available, theoretical results are compared with data from RHIC and SPS.

  7. Mixing in plasma and low density jets

    Science.gov (United States)

    Russ, S.; Strykowski, P. J.; Pfender, E.

    1994-04-01

    This study was undertaken to examine the mechanisms which produce the large entrainment measured near the exit of thermal plasma torches. A research facility was constructed to examine low density jet behavior under similar dimensionless conditions as those produced by thermal plasma spray torches; the Reynolds number based on jet diameter and average properties was 1000, and the ratio of jet to ambient density was 0.07. This very low density jet produced organized vortex structures which were partially responsible for the rapid entrainment of external air. The formation of these organized structures could be disrupted by introducing turbulence, but the rapid entrainment process was not significantly affected. The structure of the jet produced by a commercial plasma torch was examined and compared to the low density research jet. At low gas flow rates the plasma jet also displayed the formation of coherent vortex structures, the passage frequency of which compared favorably with that measured in the low density research jet. At higher gas flow rates the shear layer of the plasma jet rapidly broke down producing relatively small scale turbulence. Visualizations of the hot plasma core were compared against measurements of the torch voltage fluctuations caused by arc instabilities. At low flow rates the arc voltage fluctuations were quite low and the plume was very steady. At higher flow rates the arc voltage fluctuations increased and produced “surging” and “whipping” in the hot potential core. It is believed that this low frequency unsteadiness is partially responsible for the rapid entrainment measured in plasma torches.

  8. Causality detection and turbulence in fusion plasmas

    CERN Document Server

    van Milligen, B Ph; Ramisch, M; Estrada, T; Hidalgo, C; Alonso, A

    2013-01-01

    This work explores the potential of an information-theoretical causality detection method for unraveling the relation between fluctuating variables in complex nonlinear systems. The method is tested on some simple though nonlinear models, and guidelines for the choice of analysis parameters are established. Then, measurements from magnetically confined fusion plasmas are analyzed. The selected data bear relevance to the all-important spontaneous confinement transitions often observed in fusion plasmas, fundamental for the design of an economically attractive fusion reactor. It is shown how the present method is capable of clarifying the interaction between fluctuating quantities such as the turbulence amplitude, turbulent flux, and Zonal Flow amplitude, and uncovers several interactions that were missed by traditional methods.

  9. Inverse scattering problem in turbulent magnetic fluctuations

    Science.gov (United States)

    Treumann, Rudolf A.; Baumjohann, Wolfgang; Narita, Yasuhito

    2016-08-01

    We apply a particular form of the inverse scattering theory to turbulent magnetic fluctuations in a plasma. In the present note we develop the theory, formulate the magnetic fluctuation problem in terms of its electrodynamic turbulent response function, and reduce it to the solution of a special form of the famous Gelfand-Levitan-Marchenko equation of quantum mechanical scattering theory. The last of these applies to transmission and reflection in an active medium. The theory of turbulent magnetic fluctuations does not refer to such quantities. It requires a somewhat different formulation. We reduce the theory to the measurement of the low-frequency electromagnetic fluctuation spectrum, which is not the turbulent spectral energy density. The inverse theory in this form enables obtaining information about the turbulent response function of the medium. The dynamic causes of the electromagnetic fluctuations are implicit to it. Thus, it is of vital interest in low-frequency magnetic turbulence. The theory is developed until presentation of the equations in applicable form to observations of turbulent electromagnetic fluctuations as input from measurements. Solution of the final integral equation should be done by standard numerical methods based on iteration. We point to the possibility of treating power law fluctuation spectra as an example. Formulation of the problem to include observations of spectral power densities in turbulence is not attempted. This leads to severe mathematical problems and requires a reformulation of inverse scattering theory. One particular aspect of the present inverse theory of turbulent fluctuations is that its structure naturally leads to spatial information which is obtained from the temporal information that is inherent to the observation of time series. The Taylor assumption is not needed here. This is a consequence of Maxwell's equations, which couple space and time evolution. The inversion procedure takes advantage of a particular

  10. Static quark-antiquark potential in the quark-gluon plasma from lattice QCD.

    Science.gov (United States)

    Burnier, Yannis; Kaczmarek, Olaf; Rothkopf, Alexander

    2015-02-27

    We present a state-of-the-art determination of the complex valued static quark-antiquark potential at phenomenologically relevant temperatures around the deconfinement phase transition. Its values are obtained from nonperturbative lattice QCD simulations using spectral functions extracted via a novel Bayesian inference prescription. We find that the real part, both in a gluonic medium, as well as in realistic QCD with light u, d, and s quarks, lies close to the color singlet free energies in Coulomb gauge and shows Debye screening above the (pseudo)critical temperature T_{c}. The imaginary part is estimated in the gluonic medium, where we find that it is of the same order of magnitude as in hard-thermal loop resummed perturbation theory in the deconfined phase.

  11. Fluctuating Asymmetry and Intelligence

    Science.gov (United States)

    Bates, Timothy C.

    2007-01-01

    The general factor of mental ability ("g") may reflect general biological fitness. If so, "g"-loaded measures such as Raven's progressive matrices should be related to morphological measures of fitness such as fluctuating asymmetry (FA: left-right asymmetry of a set of typically left-right symmetrical body traits such as finger…

  12. Nonequilibrium mesoscopic conductance fluctuations

    Science.gov (United States)

    Ludwig, T.; Blanter, Ya. M.; Mirlin, A. D.

    2004-12-01

    We investigate the amplitude of mesoscopic fluctuations of the differential conductance of a metallic wire at arbitrary bias voltage V . For noninteracting electrons, the variance ⟨δg2⟩ increases with V . The asymptotic large- V behavior is ⟨δg2⟩˜V/Vc (where eVc=D/L2 is the Thouless energy), in agreement with the earlier prediction by Larkin and Khmelnitskii. We find, however, that this asymptotics has a very small numerical prefactor and sets in at very large V/Vc only, which strongly complicates its experimental observation. This high-voltage behavior is preceded by a crossover regime, V/Vc≲30 , where the conductance variance increases by a factor ˜3 as compared to its value in the regime of universal conductance fluctuations (i.e., at V→0 ). We further analyze the effect of dephasing due to the electron-electron scattering on ⟨δg2⟩ at high voltages. With the Coulomb interaction taken into account, the amplitude of conductance fluctuations becomes a nonmonotonic function of V . Specifically, ⟨δg2⟩ drops as 1/V for voltages V≫gVc , where g is the dimensionless conductance. In this regime, the conductance fluctuations are dominated by quantum-coherent regions of the wire adjacent to the reservoirs.

  13. Suppressed ion-scale turbulence in a hot high-β plasma

    Science.gov (United States)

    Schmitz, L.; Fulton, D. P.; Ruskov, E.; Lau, C.; Deng, B. H.; Tajima, T.; Binderbauer, M. W.; Holod, I.; Lin, Z.; Gota, H.; Tuszewski, M.; Dettrick, S. A.; Steinhauer, L. C.

    2016-12-01

    An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements.

  14. Plasma variables, meat quality, and glycolytic potential in broilers stunned with different carbon dioxide concentrations.

    Science.gov (United States)

    Xu, L; Ji, F; Yue, H Y; Wu, S G; Zhang, H J; Zhang, L; Qi, G H

    2011-08-01

    This study aimed to investigate the effects of different CO(2) concentrations on blood variables, glycolytic potential (GP), and meat quality of hot-boned muscles in broilers. Thirty broilers were exposed to one of the following 5 gas mixtures for 90 s: 40% CO(2) + 30% O(2) + N(2) (control), 30% CO(2) + 21% O(2) + N(2) (G30%), 40% CO(2) + 21% O(2) + N(2) (G40%), 50% CO(2) + 21% O(2) + N(2) (G50%), and 60% CO(2) + 21% O(2) + N(2) (G60%). Samples were taken from the pectoralis major (PM), musculus iliofibularis (MI), and tibialis anterior muscles 45 min postmortem. The ultimate pH in both the PM (vs. G30% and G40%) and MI (vs. G40%) was decreased with G60% (P 0.05). In conclusion, stunning broilers with low CO(2) levels (30 and 40%) improved meat quality but had no advantage in animal welfare compared with high CO(2) levels (50 and 60%).

  15. SOL width and intermittent fluctuations in KSTAR

    CERN Document Server

    Garcia, O E; Theodorsen, A; Bak, J -G; Hong, S -H; Kim, H -S; Pitts, R A

    2016-01-01

    Radial profiles of the ion saturation current and its fluctuation statistics are presented from probe measurements in L-mode, neutral beam heated plasmas at the outboard mid-plane region of KSTAR. The familiar two-layer structure, seen elsewhere in tokamak L-mode discharges, with a steep near-SOL profile and a broad far-SOL profile, is observed. The profile scale length in the far-SOL increases drastically with line-averaged density, thereby enhancing plasma interactions with the main chamber walls. Time series from the far-SOL region are characterised by large-amplitude bursts attributed to the radial motion of blob-like plasma filaments. Analysis of a data time series of several seconds duration under stationary plasma conditions reveals the statistical properties of these fluctuations, including the rate of level crossings and the average duration of periods spent above a given threshold level. This is shown to be in excellent agreement with predictions of a stochastic model, giving novel predictions of pl...

  16. The electrostatic ion-cyclotron instability-a two-dimensional potential relaxation instability

    DEFF Research Database (Denmark)

    Popa, G.; Schrittwieser, R.; Juul Rasmussen, Jens;

    1985-01-01

    An experimental investigation shows that the electrostatic ion-cyclotron instability, driven by an electron current to a positively biased collector, is accompanied by strong coherent two-dimensional fluctuations of the plasma potential in front of the collector. These results suggest that this i......An experimental investigation shows that the electrostatic ion-cyclotron instability, driven by an electron current to a positively biased collector, is accompanied by strong coherent two-dimensional fluctuations of the plasma potential in front of the collector. These results suggest...

  17. Origin of density fluctuations in extended inflation

    Science.gov (United States)

    Kolb, Edward W.; Salopek, David S.; Turner, Michael S.

    1990-01-01

    The density fluctuations (both curvature and isocurvature) that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory are calculated. Curvature fluctuations arise due to quantum fluctuations in the Brans-Dicke field, in general have a nonscale-invariant spectrum, and can have an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The density perturbations that arise due to the inflation field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential and the usual formula for the amplitude of curvature perturbations applies.

  18. Acceleration of small astrophysical grains due to charge fluctuations

    CERN Document Server

    Ivlev, A V; Tsytovich, V N; de Angelis, U; Hoang, Thiem; Morfill, G E

    2010-01-01

    We discuss a novel mechanism of dust acceleration which dominates for particles smaller than $\\sim0.1 \\mu$m. The acceleration is caused by charge fluctuations occurring on grains during their mutual Coulomb collisions. The energy source for the acceleration are the irreversible plasma fluxes continuously absorbed by grains. In particular, this mechanism of charge-fluctuation-induced acceleration affects the rate of grain coagulation and shattering of the population of small grains.

  19. QGP Flow Fluctuations and Characteristics of Higher Moments

    Institute of Scientific and Technical Information of China (English)

    WANG; Du-juan; L.P.Csernai; D.Strottman; C.Anderlik; CHENG; Yun; ZHOU; Dai-mei; YAN; Yu-liang; CAI; Xu; SA; Ben-hao

    2012-01-01

    <正>The dynamical development of expanding quark-gluon plasma (QGP) flow is studied in a 3+1D fluid dynamical model with a globally symmetric, initial condition. We minimize fluctuations arising from complex dynamical processes at finite impact parameters and from fluctuating random initial conditions to have a conservative fluid dynamical background estimate for the statistical distributions of the thermo-dynamical parameters. We also avoid a phase transition in the equation of state, and we let the

  20. Local fluctuation control of papain by changing a highly fluctuating residue

    Science.gov (United States)

    Nishiyama, Katsuhiko

    2013-01-01

    To control the local fluctuation of the amino acid residues of papain, ARG59, a highly fluctuating residue in papain, has been changed to GLY. We investigated the binding properties of 2-10GLY (peptides with between 2 and 10 glycine residues) to the modified papain structure via molecular dynamics and docking simulations. The change of the ARG59 residue to GLY alters the binding sites for some peptides, and changed its substrate specificity. Furthermore, the modification alters the binding stability of some peptides. Thus, control of the local fluctuations of residues in proteins has the potential to alter the protein's function.

  1. Evaluation and Optimization of Paper-Based SERS Substrate for Potential Label-Free Raman Analysis of Seminal Plasma

    Directory of Open Access Journals (Sweden)

    Zufang Huang

    2017-01-01

    Full Text Available Characterization and optimization of paper SERS substrate were performed in detail, in which morphologies and distribution of silver nanoparticles (AgNPs on the paper substrate pretreated with different concentrations of NaCl and the subsequent soaking with colloidal AgNPs for different period of time were evaluated. Our results show that both NaCl concentration and soaking time with AgNPs have a significant influence on SERS enhancement, showing that an optimal EF of 2.27 × 107 was achieved when the paper substrate was treated with 20 mM NaCl and one-hour soak with AgNPs. Moreover, seminal plasma (SP was specifically selected to evaluate the performance of paper-based SERS substrate for potential clinical detection and diagnosis. The optimization of the paper SERS substrate demonstrates potential applications in reliable on-site detection of SP and clinical diagnosis of fertility-related diseases as well.

  2. Spacetime Conformal Fluctuations and Quantum Dephasing

    Science.gov (United States)

    Bonifacio, Paolo M.

    2009-06-01

    Any quantum system interacting with a complex environment undergoes decoherence. Empty space is filled with vacuum energy due to matter fields in their ground state and represents an underlying environment that any quantum particle has to cope with. In particular quantum gravity vacuum fluctuations should represent a universal source of decoherence. To study this problem we employ a stochastic approach that models spacetime fluctuations close to the Planck scale by means of a classical, randomly fluctuating metric (random gravity framework). We enrich the classical scheme for metric perturbations over a curved background by also including matter fields and metric conformal fluctuations. We show in general that a conformally modulated metric induces dephasing as a result of an effective nonlinear newtonian potential obtained in the appropriate nonrelativistic limit of a minimally coupled Klein-Gordon field. The special case of vacuum fluctuations is considered and a quantitative estimate of the expected effect deduced. Secondly we address the question of how conformal fluctuations could physically arise. By applying the random gravity framework we first show that standard GR seems to forbid spontaneous conformal metric modulations. Finally we argue that a different result follows within scalar-tensor theories of gravity such as e.g. Brans-Dicke theory. In this case a conformal modulation of the metric arises naturally as a result of the fluctuations in the Brans-Dicke field and quantum dephasing of a test particle is expected to occur. For large negative values of the coupling parameter the conformal fluctuations may also contribute to alleviate the well known problem of the large zero point energy due to quantum matter fields.

  3. Assessment of the coherent potential approximation for the absorption spectra of a one-dimensional Frenkel exciton system with a Gaussian distribution of fluctuations in the optical transition frequency

    Science.gov (United States)

    Boukahil, A.; Avgin, I.; Huber, D. L.

    2015-01-01

    We investigate the accuracy of the coherent potential approximation (CPA) for the optical absorption spectra of a one-dimensional Frenkel exciton system with nearest-neighbor interactions and a Gaussian distribution of fluctuations in the optical transition frequency (diagonal Gaussian disorder). Our earlier studies have established that the CPA gives highly accurate results for the integral of the density of states of this system. In this paper we compare the CPA results for the normalized optical absorption with the finite-array calculations of Schreiber and Toyozawa and Schreiber for the same model. It is found that the CPA results for the absorption are in good agreement with their findings. It is pointed out that an expansion of the density of states in terms of the eigenstates of the ideal (no disorder) array contains a term proportional to the normalized absorption. Since the density of states is accurately approximated by the CPA, the presence of this term explains the success of the CPA in reproducing the absorption spectra. Our findings support the use of the Gaussian disorder model to interpret the absorption spectra of one and quasi-one dimensional exciton systems.

  4. Effect of density fluctuations on ECCD in ITER and TCV

    Directory of Open Access Journals (Sweden)

    Coda S.

    2012-09-01

    Full Text Available Density fluctuations near the edge of tokamak plasmas can affect the propagation of electron cyclotron (EC waves. In the present paper, the EC wave propagation in a fluctuating equilibrium is determined using the ray-tracing code C3PO. The evolution of the electron distribution function is calculated self-consistently with the EC wave damping using the 3-D Fokker-Planck solver LUKE. The cumulative effect of fluctuations results in a significant broadening of the current profile combined with a fluctuating power deposition profile. This mechanism improves the simulation of fully non-inductive EC discharges in the TCV tokamaks. Predictive simulations for ITER show that density fluctuations could make the stabilization of NTMs in ITER more challenging.

  5. A note on the Weibel instability and thermal fluctuations

    Directory of Open Access Journals (Sweden)

    R. A. Treumann

    2012-02-01

    Full Text Available The thermal fluctuation level of the Weibel instability is recalculated. It is shown that the divergence of the fluctuations at long wavelengths, i.e. the Weibel infrared catastrophe, never occurs. At large wavelengths the thermal fluctuation level is terminated by the presence of even the smallest available stable thermal anisotropy. Weibel fields penetrate only one skin depth into the plasma. When excited inside, they cause layers of antiparallel fields of skin depth width and vortices which may be subject to reconnection.

  6. Fluctuations in quantum devices

    Directory of Open Access Journals (Sweden)

    H.Haken

    2004-01-01

    Full Text Available Logical gates can be formalized by Boolean algebra whose elementary operations can be realized by devices that employ the interactions of macroscopic numbers of elementary excitations such as electrons, holes, photons etc. With increasing miniaturization to the nano scale and below, quantum fluctuations become important and can no longer be ignored. Based on Heisenberg equations of motion for the creation and annihilation operators of elementary excitations, I determine the noise sources of composite quantum systems.

  7. Terrestrial Gravity Fluctuations

    CERN Document Server

    Harms, Jan

    2015-01-01

    The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

  8. Magnetic reconnection associated fluctuations in the deep magnetotail: ARTEMIS results

    Directory of Open Access Journals (Sweden)

    Z. Vörös

    2011-11-01

    Full Text Available On the basis of ARTEMIS two-probe mission magnetic reconnection (MR outflow associated magnetic fluctuations and turbulence are analyzed on 19 February 2011. In the deep-tail, at distances between X = 45 – 51 RE, evidence for reconnection associated plasma sheet thinning was found, accompanied by heating of the plasma sheet. Correlated flow and field reversals and the large-scale Hall-effect signatures indicated the presence of the reconnection X-line. Within fast reconnection plasma outflows, magnetic fluctuations exhibit the same spectral scaling features and kinked spectra as magnetic fluctuations in the solar wind or in various parts of geospace. It was shown that the proton scale magnetic fluctuations are constrained by oblique firehose, proton cyclotron and mirror instability thresholds. For parallel plasma β|| > 1, where the thresholds converge, perpendicular magnetic fluctuations are enhanced. Magnetic compressibility decreases with the distance to the neutral sheet, however, near the instability thresholds it is comparable to the values obtained in the solar wind.

  9. Mechanical energy fluctuations in granular chains: the possibility of rogue fluctuations or waves.

    Science.gov (United States)

    Han, Ding; Westley, Matthew; Sen, Surajit

    2014-09-01

    The existence of rogue or freak waves in the ocean has been known for some time. They have been reported in the context of optical lattices and the financial market. We ask whether such waves are generic to late time behavior in nonlinear systems. In that vein, we examine the dynamics of an alignment of spherical elastic beads held within fixed, rigid walls at zero precompression when they are subjected to sufficiently rich initial conditions. Here we define such waves generically as unusually large energy fluctuations that sustain for short periods of time. Our simulations suggest that such unusually large fluctuations ("hot spots") and occasional series of such fluctuations through space and time ("rogue fluctuations") are likely to exist in the late time dynamics of the granular chain system at zero dissipation. We show that while hot spots are common in late time evolution, rogue fluctuations are seen in purely nonlinear systems (i.e., no precompression) at late enough times. We next show that the number of such fluctuations grows exponentially with increasing nonlinearity whereas rogue fluctuations decrease superexponentially with increasing precompression. Dissipation-free granular alignment systems may be possible to realize as integrated circuits and hence our observations may potentially be testable in the laboratory.

  10. Density Fluctuation Measurements Using FIR Interferometer on HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yan; PENG Bei-Bin; YANG Qing-wei; DUAN Xu-Ru; DING Xuan-Tong; LI Lian-Cai; LI Yong-Gao; JIAO Yi-Ming; DENG Zhong-Chao; YI Jiang; LIU Yi; ZHAO Kai-Jun; JI Xiao-Quan

    2008-01-01

    Denity fluctuations were first measured in the core region of HL-2A tokamak plasma using a newly developed multi-channel FIR interferometer system. In divertor ohmic discharges, we measured the radial density fluctuation levels of 5%, which increase to 10-20% during the appearance of MHD activity. Most of the power density in the density fluctuation spectrum is directly associated with m=2 tearing modes. The fluctuation levels reduce to 1/3 and plasma confinement is improved during off-axis electron-cyclotron-resonance heating (ECRH).Supported by the National Natural Science Foundation of China under Grant Nos 10575030 and 10675043.

  11. A Model for Lightcone Fluctuations due to Stress Tensor Fluctuations

    CERN Document Server

    Bessa, C H G; Ford, L H; Ribeiro, C C H

    2016-01-01

    We study a model for quantum lightcone fluctuations in which vacuum fluctuations of the electric field and of the squared electric field in a nonlinear dielectric material produce variations in the flight times of probe pulses. When this material has a non-zero third order polarizability, the flight time variations arise from squared electric field fluctuations, and are analogous to effects expected when the stress tensor of a quantized field drives passive spacetime geometry fluctuations. We also discuss the dependence of the squared electric field fluctuations upon the geometry of the material, which in turn determines a sampling function for averaging the squared electric field along the path of the pulse. This allows us to estimate the probability of especially large fluctuations, which is a measure of the probability distribution for quantum stress tensor fluctuations.

  12. Hydrodynamic Fluctuations in Laminar Fluid Flow. II. Fluctuating Squire Equation

    Science.gov (United States)

    Ortiz de Zárate, José M.; Sengers, Jan V.

    2013-02-01

    We use fluctuating hydrodynamics to evaluate the enhancement of thermally excited fluctuations in laminar fluid flow using plane Couette flow as a representative example. In a previous publication (J. Stat. Phys. 144:774, 2011) we derived the energy amplification arising from thermally excited wall-normal fluctuations by solving a fluctuating Orr-Sommerfeld equation. In the present paper we derive the energy amplification arising from wall-normal vorticity fluctuation by solving a fluctuating Squire equation. The thermally excited wall-normal vorticity fluctuations turn out to yield the dominant contribution to the energy amplification. In addition, we show that thermally excited streaks, even in the absence of any externally imposed perturbations, are present in laminar fluid flow.

  13. Dynamical Fluctuations in Baryon--Meson Ratios

    CERN Document Server

    Tawfik, A

    2010-01-01

    The event-by-event dynamical fluctuations in kaon-to-proton and proton-to-pion ratios have been studied in dependence on center--of--mass energies of nucleon--nucleon collisions $\\sqrt{s}$. Based on changing phase space volume which apparently is the consequence of phase transition from hadrons to quark--gluon plasma at large $\\sqrt{s}$, the single--particle distribution function $f$ is assumed to be rather modified. Varying $f$ and phase space volume are implemented in the grand--canonical partition function, especially at $\\sqrt{s}>17$ GeV, so that hadron resonance gas model, when taking into account the experimental acceptance ${\\cal A}$ and quark phase space occupation factor $\\gamma$, turns to be able to reproduce the dynamical fluctuations in $(K^++K^-)/(p+\\overline{p})$ and $(p+\\overline{p})/(\\pi^++\\pi^-)$ ratios over the entire range of $\\sqrt{s}$.

  14. Thermal Fluctuation and Meson Melting: Holographic Approach

    CERN Document Server

    Ali-Akbari, M; Vahedi, A

    2014-01-01

    We use gauge/gravity duality to investigate the effect of thermal fluctuations on the dissociation of the quarkonium meson in strongly coupled $(3+1)$-dimensional gauge theories. This is done by studying the instability and probable first order phase transition of a probe D7-brane in the dual gravity theory. We explicitly show that for the Minkowski embeddings with their tips close to the horizon in the background, the long wavelength thermal fluctuations lead to an imaginary term in their action signaling an instability in the system. Due to this instability, a phase transition is expected. On the gauge theory side, it indicates that the quarkonium mesons are not stable and dissociate in the plasma. Identifying the imaginary part of the probe barne action with the thermal width of the mesons, we observe that the thermal width increases as one decreases the mass of the quarks. Also keeping the mass fixed, thermal width increases by temperature as expected.

  15. Hydrodynamics of charge fluctuations and balance functions

    CERN Document Server

    Ling, B; Stephanov, M

    2013-01-01

    We apply stochastic hydrodynamics to the study of charge density fluctuations in QCD matter undergoing Bjorken expansion. We find that the charge density correlations are given by a time integral over the history of the system, with the dominant contribution coming from the QCD crossover region where the change of susceptibility per entropy, chi T/s, is most significant. We study the rapidity and azimuthal angle dependence of the resulting charge balance function using a simple analytic model of heavy-ion collision evolution. Our results are in agreement with experimental measurements, indicating that hydrodynamic fluctuations contribute significantly to the measured charge correlations in high energy heavy-ion collisions. The sensitivity of the balance function to the value of the charge diffusion coefficient D allows us to estimate the typical value of this coefficient in the crossover region to be rather small, of the order of 1/(2pi T), characteristic of a strongly coupled plasma.

  16. Trapped Electron Precession Shear Induced Fluctuation Decorrelation

    Energy Technology Data Exchange (ETDEWEB)

    T.S. Hahm; P.H. Diamond; E.-J. Kim

    2002-07-29

    We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

  17. Exploring the potential of remote plasma sputtering for the production of L10 ordered FePt thin films

    Science.gov (United States)

    Zygridou, S.; Barton, C. W.; Nutter, P. W.; Thomson, T.

    2017-07-01

    Lowering the temperature at which the desirable L10 phase forms in FePt thin films is a key requirement in the development of next generation high-density data storage media and spintronic devices. Remote plasma sputtering offers a higher degree of control over the sputtering parameters, allowing the properties of films to be tailored, and potentially can affect the ordering kinetics of the L10 phase of FePt. Here, we report a comprehensive study of FePt thin films deposited under a range of temperatures and sputtering conditions. X-ray diffraction and magnetometry investigations show that whilst FePt thin films ordered in the L10 phase with high perpendicular anisotropy can be produced using this technique, there is no significant reduction in the required ordering temperature compared with films produced using conventional DC sputtering. Optimally ordered L10 FePt films were fabricated when the film was deposited at a substrate temperature of 200 °C, followed by post annealing at 750 °C.

  18. Osteoconductive Potential of Barrier NanoSiO2 PLGA Membranes Functionalized by Plasma Enhanced Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Antonia Terriza

    2014-01-01

    Full Text Available The possibility of tailoring membrane surfaces with osteoconductive potential, in particular in biodegradable devices, to create modified biomaterials that stimulate osteoblast response should make them more suitable for clinical use, hopefully enhancing bone regeneration. Bioactive inorganic materials, such as silica, have been suggested to improve the bioactivity of synthetic biopolymers. An in vitro study on HOB human osteoblasts was performed to assess biocompatibility and bioactivity of SiO2 functionalized poly(lactide-co-glycolide (PLGA membranes, prior to clinical use. A 15 nm SiO2 layer was deposited by plasma enhanced chemical vapour deposition (PECVD, onto a resorbable PLGA membrane. Samples were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and infrared spectroscopy (FT-IR. HOB cells were seeded on sterilized test surfaces where cell morphology, spreading, actin cytoskeletal organization, and focal adhesion expression were assessed. As proved by the FT-IR analysis of samples, the deposition by PECVD of the SiO2 onto the PLGA membrane did not alter the composition and other characteristics of the organic membrane. A temporal and spatial reorganization of cytoskeleton and focal adhesions and morphological changes in response to SiO2 nanolayer were identified in our model. The novedous SiO2 deposition method is compatible with the standard sterilization protocols and reveals as a valuable tool to increase bioactivity of resorbable PLGA membranes.

  19. Osteoconductive Potential of Barrier NanoSiO2 PLGA Membranes Functionalized by Plasma Enhanced Chemical Vapour Deposition

    Science.gov (United States)

    Terriza, Antonia; Vilches-Pérez, Jose I.; de la Orden, Emilio; Yubero, Francisco; Gonzalez-Caballero, Juan L.; González-Elipe, Agustin R.; Vilches, José; Salido, Mercedes

    2014-01-01

    The possibility of tailoring membrane surfaces with osteoconductive potential, in particular in biodegradable devices, to create modified biomaterials that stimulate osteoblast response should make them more suitable for clinical use, hopefully enhancing bone regeneration. Bioactive inorganic materials, such as silica, have been suggested to improve the bioactivity of synthetic biopolymers. An in vitro study on HOB human osteoblasts was performed to assess biocompatibility and bioactivity of SiO2 functionalized poly(lactide-co-glycolide) (PLGA) membranes, prior to clinical use. A 15 nm SiO2 layer was deposited by plasma enhanced chemical vapour deposition (PECVD), onto a resorbable PLGA membrane. Samples were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and infrared spectroscopy (FT-IR). HOB cells were seeded on sterilized test surfaces where cell morphology, spreading, actin cytoskeletal organization, and focal adhesion expression were assessed. As proved by the FT-IR analysis of samples, the deposition by PECVD of the SiO2 onto the PLGA membrane did not alter the composition and other characteristics of the organic membrane. A temporal and spatial reorganization of cytoskeleton and focal adhesions and morphological changes in response to SiO2 nanolayer were identified in our model. The novedous SiO2 deposition method is compatible with the standard sterilization protocols and reveals as a valuable tool to increase bioactivity of resorbable PLGA membranes. PMID:24883304

  20. Evaluation of osteoinductive and endothelial differentiation potential of Platelet-Rich Plasma incorporated Gelatin-Nanohydroxyapatite Fibrous Matrix.

    Science.gov (United States)

    J, Anjana; Kuttappan, Shruthy; Keyan, Kripa S; Nair, Manitha B

    2016-05-01

    In this study, platelet-rich plasma (PRP) was incorporated into gelatin-nanohydroxyapatite fibrous scaffold in two forms (PRP gel as coating on the scaffold [PCSC] and PRP powder within the scaffold [PCSL] and investigated for (a) growth factor release; (b) stability of scaffold at different temperature; (c) stability of scaffold before and after ETO sterilization; and (d) osteogenic and endothelial differentiation potential using mesenchymal stem cells (MSCs). PCSC demonstrated a high and burst growth factor release initially followed by a gradual reduction in its concentration, while PCSL showed a steady state release pattern for 30 days. The stability of growth factors released from PCSL was not altered either through ETO sterilization or through its storage at different temperature. PRP-loaded scaffolds induced the differentiation of MSCs into osteogenic and endothelial lineage without providing any induction factors in the cell culture medium and the differentiation rate was significantly higher when compared to the scaffolds devoid of PRP. PCSC performed better than PCSL. In general, PRP in combination with composite fibrous scaffold could be a promising candidate for bone tissue engineering applications.

  1. Potential of Solid Sampling Electrothermal Vaporization for solving spectral interference in Inductively Coupled Plasma Optical Emission Spectrometry

    Science.gov (United States)

    Asfaw, Alemayehu; Wibetoe, Grethe

    2009-05-01

    Spectral interference is one of the main causes of erroneous results in Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). This paper describes some cases of spectral interferences with conventional nebulization ICP-OES and the potential of solving them utilizing electrothermal vaporization for volatility-based separation. The cases studied were, the well-known spectral overlap between the As and Cd lines at 228.8 nm that are only 10 pm apart, and the interference of Fe on the main emission lines of As, Cd and Pb. The spectral interferences were studied by monitoring the typical signals of solutions that contain the analytes and the potential interferent, by studying the spectra and calculating Background Equivalent Concentration (BEC)-values. A three step temperature program was developed to be used for direct analysis of solid soil samples by Electrothermal Vaporization (ETV)-ICP-OES: step 1 (760 °C, 40 s), step 2 (1620 °C, 20 s) and a cleaning step (2250 °C, 10 s) where Cd vaporizes in step 1, As, Pb and part of Fe in step 2 and the major part of Fe in the cleaning step. Because As and Cd were time-separated using this program, their prominent lines at 228.8 nm, could be used for determination of each element by ETV-ICP-OES, in spite of the serious wavelength overlap. Selective vaporization was also shown to reduce or eliminate the Fe background emission on As, Cd and Pb lines. To confirm the applicability of the method, a solid soil certified reference materials was analyzed directly without any sample treatment. Good or reasonable accuracy was obtained for the three elements.

  2. Plasma Epstein–Barr virus and Hepatitis B virus in non-Hodgkin lymphomas: Two lymphotropic, potentially oncogenic, latently occurring DNA viruses

    Directory of Open Access Journals (Sweden)

    Mahua Sinha

    2016-01-01

    Full Text Available Context: There is a need to study potential infective etiologies in lymphomas. Lymphocyte-transforming viruses can directly infect lymphocytes, disrupt normal cell functions, and promote cell division. Epstein–Barr virus (EBV is known to be associated with several lymphomas, especially Hodgkin lymphomas (HLs. And recently, the lymphocyte-transforming role of hepatitis B virus (HBV has been emphasized. Aims: The aim of this study was to elucidate the association of two potentially oncogenic, widely prevalent latent DNA viruses, EBV and HBV, in non-HL (NHL. Settings and Design: In this prospective study, we estimated plasma EBV and HBV DNA in NHL patients. Materials and Methods: Peripheral blood was obtained from newly diagnosed, treatment na ïve, histologically confirmed NHL patients. Plasma EBV DNA was quantified by real-time polymerase chain reaction (PCR targeting Epstein–Barr Nucleic acid 1 while the plasma HBV DNA was detected using nested PCR targeting HBX gene. In a small subset of patients, follow-up plasma samples post-anticancer chemotherapy were available and retested for viral DNA. Results: Of the 110 NHL patients, ~79% were B-cell NHL and ~21% were T-cell NHL. Plasma EBV-DNA was detected in 10% NHLs with a higher EBV association in Burkitt lymphoma (33.3% than other subtypes. Pretherapy HBV DNA was detected in 21% NHLs; most of them being diffuse large B-cell lymphoma (DLBCL. Moreover, 42% of DLBCL patients had HBV DNA in plasma. Since all patients were HBV surface antigen seronegative at diagnosis, baseline plasma HBV-DNAemia before chemotherapy was indicative of occult hepatitis B infection. Conclusions: Our findings indicate a significant association of HBV with newly diagnosed DLBCL.

  3. A potential kidney-bone axis involved in the rapid minute-to-minute regulation of plasma Ca2+

    DEFF Research Database (Denmark)

    Nordholm, Anders; Mace, Maria L; Gravesen, Eva;

    2015-01-01

    of plasma-Ca(2+) (p-Ca(2+)) takes place via an exchange mechanism of Ca(2+) between plasma and bone. A labile Ca storage pool exists on bone surfaces storing excess or supplying Ca when blood Ca is lowered. Aim was to examine minute-to-minute regulation of p-Ca(2+) in the very early phase of acute uremia...

  4. Potentials of plasma NGAL and MIC-1 as biomarker(s in the diagnosis of lethal pancreatic cancer.

    Directory of Open Access Journals (Sweden)

    Sukhwinder Kaur

    Full Text Available Pancreatic cancer (PC is lethal malignancy with very high mortality rate. Absence of sensitive and specific marker(s is one of the major factors for poor prognosis of PC patients. In pilot studies using small set of patients, secreted acute phase proteins neutrophil gelatinase associated lipocalin (NGAL and TGF-β family member macrophage inhibitory cytokine-1 (MIC-1 are proposed as most potential biomarkers specifically elevated in the blood of PC patients. However, their performance as diagnostic markers for PC, particularly in pre-treatment patients, remains unknown. In order to evaluate the diagnostic efficacy of NGAL and MIC-1, their levels were measured in plasma samples from patients with pre-treatment PC patients (n = 91 and compared it with those in healthy control (HC individuals (n = 24 and patients with chronic pancreatitis (CP, n = 23. The diagnostic performance of these two proteins was further compared with that of CA19-9, a tumor marker commonly used to follow PC progression. The levels of all three biomarkers were significantly higher in PC compared to HCs. The mean (± standard deviation, SD plasma NGAL, CA19-9 and MIC-1 levels in PC patients was 111.1 ng/mL (2.2, 219.2 U/mL (7.8 and 4.5 ng/mL (4.1, respectively. In comparing resectable PC to healthy patients, all three biomarkers were found to have comparable sensitivities (between 64%-81% but CA19-9 and NGAL had a higher specificity (92% and 88%, respectively. For distinguishing resectable PC from CP patients, CA19-9 and MIC-1 were most specific (74% and 78% respectively. CA19-9 at an optimal cut-off of 54.1 U/ml is highly specific in differentiating resectable (stage 1/2 pancreatic cancer patients from controls in comparison to its clinical cut-off (37.1 U/ml. Notably, the addition of MIC-1 to CA19-9 significantly improved the ability to distinguish resectable PC cases from CP (p = 0.029. Overall, MIC-1 in combination with CA19-9 improved the diagnostic

  5. Lensing Reconstruction using redshifted 21cm Fluctuations

    CERN Document Server

    Zahn, O; Zahn, Oliver; Zaldarriaga, Matias

    2005-01-01

    We investigate the potential of second generation measurements of redshifted 21 cm radiation from the epoch of reionization (EOR) to reconstruct the matter density fluctuations along the line of sight. To do so we generalize the quadratic methods developed for the Cosmic Microwave Background (CMB) to 21cm fluctuations. The three dimensional signal can be analyzed into a finite number of line of sight Fourier modes that contribute to the lensing reconstruction. In comparison with reconstruction using the CMB, 21cm fluctuations have a disadvantage of relative featurelessness, which can be compensated for by the fact that there are multiple uncorrelated backgrounds. The multiple redshift information allows to reconstruct relatively small scales even if one is limited by angular resolution. We estimate that a square kilometer of collecting area is needed with a maximal baseline of 3 km to achieve lensing reconstruction noise levels an order of magnitude below CMB quadratic estimator constraints at $l=1000$, and c...

  6. Thermal conduction in a mirror-unstable plasma

    Science.gov (United States)

    Komarov, S. V.; Churazov, E. M.; Kunz, M. W.; Schekochihin, A. A.

    2016-07-01

    The plasma of galaxy clusters is subject to firehose and mirror instabilities at scales of order the ion Larmor radius. The mirror instability generates fluctuations of magnetic-field strength δB/B ˜ 1. These fluctuations act as magnetic traps for the heat-conducting electrons, suppressing their transport. We calculate the effective parallel thermal conductivity in the ICM in the presence of the mirror fluctuations for different stages of the evolution of the instability. The mirror fluctuations are limited in amplitude by the maximum and minimum values of the field strength, with no large deviations from the mean value. This key property leads to a finite suppression of thermal conduction at large scales. We find suppression down to ≈0.2 of the Spitzer value for the secular phase of the perturbations' growth, and ≈0.3 for their saturated phase. The effect operates in addition to other suppression mechanisms and independently of them. Globally, fluctuations δB/B ˜ 1 can be present on much larger scales, of the order of the scale of turbulent motions. However, we do not expect large suppression of thermal conduction by these, because their scale is considerably larger than the collisional mean free path of the ICM electrons. The obtained suppression of thermal conduction by a factor of ˜5 appears to be characteristic and potentially universal for a weakly collisional mirror-unstable plasma.

  7. Fluctuation dynamo based on magnetic reconnections

    OpenAIRE

    Baggaley, Andrew W.; Barenghi, Carlo F.; Shukurov, Anvar; Subramanian, Kandaswamy

    2009-01-01

    We develop a new model of the fluctuation dynamo in which the magnetic field is confined to thin flux ropes advected by a multi-scale flow which models turbulence. Magnetic dissipation occurs only via reconnections of flux ropes. The model is particularly suitable for rarefied plasma, such as the Solar corona or galactic halos. We investigate the kinetic energy release into heat, mediated by dynamo action, both in our model and by solving the induction equation with the same flow. We find tha...

  8. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Castracane, J.

    2001-01-04

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies.

  9. PIC code modeling of spacecraft charging potential during electron beam injection into a background of neutral gas and plasma, part 1

    Science.gov (United States)

    Koga, J. K.; Lin, C. S.; Winglee, R. M.

    1989-01-01

    Injections of nonrelativistic electron beams from an isolated equipotential conductor into a uniform background of plasma and neutral gas were simulated using a 2-D electrostatic particle code. The ionization effects on spacecraft charging are examined by including interactions of electrons with neutral gas. The simulations show that the conductor charging potential decreases with increasing neutral background density due to the production of secondary electrons near the conductor surface. In the spacecraft wake, the background electrons accelerated towards the charged spacecraft produce an enhancement of secondary electrons and ions. Simulations run for longer times indicate that the spacecraft potential is further reduced and short wavelength beam-plasma oscillations appear. The results are applied to explain the spacecraft charging potential measured during the SEPAC experiments from Spacelab 1.

  10. Toxic metals signature in the human seminal plasma of Pakistani population and their potential role in male infertility.

    Science.gov (United States)

    Zafar, Ambreen; Eqani, Syed Ali Musstjab Akber Shah; Bostan, Nazish; Cincinelli, Alessandra; Tahir, Faheem; Shah, Syed Tahir Abbas; Hussain, Alamdar; Alamdar, Ambreen; Huang, Qingyu; Peng, Siyuan; Shen, Heqing

    2015-06-01

    Aims of this study were to provide firsthand data on the incidence of trace metals in human seminal plasma and find possible correlations between levels of toxic metals and semen quality of Pakistani population. Human semen samples were collected from male partners of couples undergoing infertility assessment at the National Institute of Health Islamabad (Pakistan). We investigated seventy-five seminal plasma samples, which were further categorized into three groups (normozoospermia, oligozoospermia and azoospermia) according to WHO guidelines. The concentration of 17 different toxic metals in human seminal plasma was determined simultaneously by using Inductively coupled plasma mass spectrometry (ICP-MS). Out of 17 trace metals, Cd and Ni showed significant difference (p metals were lower and/or comparable to that found in populations of other countries. The results show the first evidence of the effect of toxic metals on semen quality and male infertility in Pakistan.

  11. Determining potential adverse effects in marine fish exposed to pharmaceuticals and personal care products with the fish plasma model and whole-body tissue concentrations.

    Science.gov (United States)

    Meador, James P; Yeh, Andrew; Gallagher, Evan P

    2017-07-26

    The Fish Plasma Model (FPM) was applied to water exposure and tissue concentrations in fish collected from two wastewater treatment plant impacted estuarine sites. In this study we compared predicted fish plasma concentrations to Cmax values for humans, which represents the maximum plasma concentration for the minimum therapeutic dose. The results of this study show that predictions of plasma concentrations for a variety of pharmaceutical and personal care products (PPCPs) from effluent concentrations resulted in 37 compounds (54%) exceeding the response ratio (RR = Fish [Plasma]/1%Cmaxtotal) of 1 compared to 3 compounds (14%) detected with values generated with estuarine receiving water concentrations. When plasma concentrations were modeled from observed whole-body tissue residues, 16 compounds out of 24 detected for Chinook (67%) and 7 of 14 (50%) for sculpin resulted in an RRtissue value greater than 1, which highlights the importance of this dose metric over that using estuarine water. Because the tissue residue approach resulted in a high percentage of compounds with calculated response ratios exceeding a value of unity, we believe this is a more accurate representation for exposure in the field. Predicting plasma concentrations from tissue residues improves our ability to assess the potential for adverse effects in fish because exposure from all sources is captured. Tissue residues are also more likely to represent steady-state conditions compared to those from water exposure because of the inherent reduction in variability usually observed for field data and the time course for bioaccumulation. We also examined the RR in a toxic unit approach to highlight the importance of considering multiple compounds exhibiting a similar mechanism of action. Published by Elsevier Ltd.

  12. Quantifying economic fluctuations

    Science.gov (United States)

    Stanley, H. Eugene; Nunes Amaral, Luis A.; Gabaix, Xavier; Gopikrishnan, Parameswaran; Plerou, Vasiliki

    2001-12-01

    This manuscript is a brief summary of a talk designed to address the question of whether two of the pillars of the field of phase transitions and critical phenomena-scale invariance and universality-can be useful in guiding research on interpreting empirical data on economic fluctuations. Using this conceptual framework as a guide, we empirically quantify the relation between trading activity-measured by the number of transactions N-and the price change G( t) for a given stock, over a time interval [ t, t+Δ t]. We relate the time-dependent standard deviation of price changes-volatility-to two microscopic quantities: the number of transactions N( t) in Δ t and the variance W2( t) of the price changes for all transactions in Δ t. We find that the long-ranged volatility correlations are largely due to those of N. We then argue that the tail-exponent of the distribution of N is insufficient to account for the tail-exponent of P{ G> x}. Since N and W display only weak inter-dependency, our results show that the fat tails of the distribution P{ G> x} arises from W. Finally, we review recent work on quantifying collective behavior among stocks by applying the conceptual framework of random matrix theory (RMT). RMT makes predictions for “universal” properties that do not depend on the interactions between the elements comprising the system, and deviations from RMT provide clues regarding system-specific properties. We compare the statistics of the cross-correlation matrix C-whose elements Cij are the correlation coefficients of price fluctuations of stock i and j-against a random matrix having the same symmetry properties. It is found that RMT methods can distinguish random and non-random parts of C. The non-random part of C which deviates from RMT results, provides information regarding genuine collective behavior among stocks. We also discuss results that are reminiscent of phase transitions in spin systems, where the divergent behavior of the response function at

  13. Quantifying mitochondrial and plasma membrane potentials in intact pulmonary arterial endothelial cells based on extracellular disposition of rhodamine dyes.

    Science.gov (United States)

    Gan, Zhuohui; Audi, Said H; Bongard, Robert D; Gauthier, Kathryn M; Merker, Marilyn P

    2011-05-01

    Our goal was to quantify mitochondrial and plasma potential (Δψ(m) and Δψ(p)) based on the disposition of rhodamine 123 (R123) or tetramethylrhodamine ethyl ester (TMRE) in the medium surrounding pulmonary endothelial cells. Dyes were added to the medium, and their concentrations in extracellular medium ([R(e)]) were measured over time. R123 [R(e)] fell from 10 nM to 6.6 ± 0.1 (SE) nM over 120 min. TMRE [R(e)] fell from 20 nM to a steady state of 4.9 ± 0.4 nM after ∼30 min. Protonophore or high K(+) concentration ([K(+)]), used to manipulate contributions of membrane potentials, attenuated decreases in [R(e)], and P-glycoprotein (Pgp) inhibition had the opposite effect, demonstrating the qualitative impact of these processes on [R(e)]. A kinetic model incorporating a modified Goldman-Hodgkin-Katz model was fit to [R(e)] vs. time data for R123 and TMRE, respectively, under various conditions to obtain (means ± 95% confidence intervals) Δψ(m) (-130 ± 7 and -133 ± 4 mV), Δψ(p) (-36 ± 4 and -49 ± 4 mV), and a Pgp activity parameter (K(Pgp), 25 ± 5 and 51 ± 11 μl/min). The higher membrane permeability of TMRE also allowed application of steady-state analysis to obtain Δψ(m) (-124 ± 6 mV). The consistency of kinetic parameter values obtained from R123 and TMRE data demonstrates the utility of this experimental and theoretical approach for quantifying intact cell Δψ(m) and Δψ(p.) Finally, steady-state analysis revealed that although room air- and hyperoxia-exposed (95% O(2) for 48 h) cells have equivalent resting Δψ(m), hyperoxic cell Δψ(m) was more sensitive to depolarization with protonophore, consistent with previous observations of pulmonary endothelial hyperoxia-induced mitochondrial dysfunction.

  14. Quantifying mitochondrial and plasma membrane potentials in intact pulmonary arterial endothelial cells based on extracellular disposition of rhodamine dyes

    Science.gov (United States)

    Gan, Zhuohui; Audi, Said H.; Bongard, Robert D.; Gauthier, Kathryn M.

    2011-01-01

    Our goal was to quantify mitochondrial and plasma potential (Δψm and Δψp) based on the disposition of rhodamine 123 (R123) or tetramethylrhodamine ethyl ester (TMRE) in the medium surrounding pulmonary endothelial cells. Dyes were added to the medium, and their concentrations in extracellular medium ([Re]) were measured over time. R123 [Re] fell from 10 nM to 6.6 ± 0.1 (SE) nM over 120 min. TMRE [Re] fell from 20 nM to a steady state of 4.9 ± 0.4 nM after ∼30 min. Protonophore or high K+ concentration ([K+]), used to manipulate contributions of membrane potentials, attenuated decreases in [Re], and P-glycoprotein (Pgp) inhibition had the opposite effect, demonstrating the qualitative impact of these processes on [Re]. A kinetic model incorporating a modified Goldman-Hodgkin-Katz model was fit to [Re] vs. time data for R123 and TMRE, respectively, under various conditions to obtain (means ± 95% confidence intervals) Δψm (−130 ± 7 and −133 ± 4 mV), Δψp (−36 ± 4 and −49 ± 4 mV), and a Pgp activity parameter (KPgp, 25 ± 5 and 51 ± 11 μl/min). The higher membrane permeability of TMRE also allowed application of steady-state analysis to obtain Δψm (−124 ± 6 mV). The consistency of kinetic parameter values obtained from R123 and TMRE data demonstrates the utility of this experimental and theoretical approach for quantifying intact cell Δψm and Δψp. Finally, steady-state analysis revealed that although room air- and hyperoxia-exposed (95% O2 for 48 h) cells have equivalent resting Δψm, hyperoxic cell Δψm was more sensitive to depolarization with protonophore, consistent with previous observations of pulmonary endothelial hyperoxia-induced mitochondrial dysfunction. PMID:21239539

  15. Critical fluctuations and anomalous transport in soft Yukawa-Langevin systems.

    Science.gov (United States)

    Ratynskaia, S; Regnoli, G; Rypdal, K; Klumov, B; Morfill, G

    2009-10-01

    Simulation of a Langevin-dynamics model demonstrates emergence of critical fluctuations and anomalous grain transport which have been observed in experiments on "soft" quasi-two-dimensional dusty plasma clusters. Our model does not contain external drive or plasma interactions that serve to drive the system away from thermodynamic equilibrium. The grains are confined by an external potential, interact via static Yukawa forces, and are subject to stochastic heating and dissipation from neutrals. One remarkable feature is emergence of leptokurtic probability distributions of grain displacements xi(tau) on time scales tau tau(Delta). The latter is a signature of intermittency, here interpreted as a transition from bursty transport associated with hopping on intermediate time scales to vortical flows on longer time scales. These intermittency features are quantitatively modeled by a single-particle Itô-Langevin stochastic equation with a nonlinear drift term.

  16. Potential utility of soluble p3-alcadein α plasma levels as a biomarker for sporadic Alzheimer's disease.

    Science.gov (United States)

    Kamogawa, Kenji; Kohara, Katsuhiko; Tabara, Yasuharu; Takita, Rie; Miki, Tetsuro; Konno, Tomoko; Hata, Saori; Suzuki, Toshiharu

    2012-01-01

    Alcadeins (Alcs) constitute a family of neuronal type I membrane proteins (α, β, γ) that share identical localization and function to the amyloid-β protein precursor (AβPP) in the brain. Alcs are proteolyzed in neurons through successive cleavages via secretases, resulting in non-aggregative p3-Alc, where p3 corresponds to the AβPP-fragment. We found p3-Alcα detected in human plasma reflected the pathological process of amyloid-β accumulation in Alzheimer's disease (AD) patients and therefore investigated the utility of p3-Alcα as a plasma biomarker in AD. We measured p3-Alcα plasma levels in 83 sporadic-AD, 18 mild cognitive impaired (MCI), and 24 control subjects using the sandwich-ELISA system. Pooled samples with previously published data (171 AD and 45 controls) were also analyzed. The plasma p3-Alcα concentrations in patients with AD and MCI were significantly higher compared with control subjects (224.7 ± 40.4, 223.3 ± 53.9, and 189.1 ± 32.9 pg/ml, respectively; p = 0.0012). In AD patients, the plasma p3-Alcα concentration significantly correlated with age (r = 0.23, p = 0.037) and serum creatinine levels (r = 0.23, p = 0.0012). Even after adjusting for confounding factors of age, gender, renal function, and ApoE-ε4, high plasma p3-Alcα levels were correlated with significant AD risk, with an odds ratio 1.47 (95% confidence interval: 1.18-1.93, p = 0.0019) for every 10 pg/ml increase. Pooled analysis further confirmed these findings. Increased plasma p3-Alcα, evident in the early stages of cognitive impairment, suggests that Alc metabolites are useful plasma biomarkers of AD.

  17. Simultaneous profiling of eicosanoid metabolome in plasma by UPLC-MS/MS method: Application to identify potential makers for rheumatoid arthritis.

    Science.gov (United States)

    Wang, Nannan; Dai, Ronghua; Wang, Weihui; Peng, Yan; Zhao, Xiaoning; Bi, Kaishun

    2016-12-01

    To evaluate the potential relationship between rheumatoid arthritis and arachidonic acid (AA) metabonomics via cyclooxygenase (COX) and lipoxygenase (LOX) pathways, a UPLC-MS/MS method has been developed and validated for simultaneous and quantitative profiling of eicosanoid metabolome in rat plasma. The analytes were extracted from plasma samples by protein precipitation procedure, and then separated on a Shim-pack XR-ODS column with mobile phase A (0.05% formic acid in water, pH=3.3 adjusted with dilute ammonium hydroxide) and mobile phase B [methanol: acetonitrile (20:80, v/v)]. The detection was performed on UPLC-MS/MS system with an electro spray ion source in the negative ion and multiple reaction-monitoring modes. The developed method was optimized to completely separate all twenty-three analytes and three internal standards in 12min. All standard calibration curves were linear and the calibration regression coefficients were ranged from 0.9903 to 0.9992 for all analytes. The recoveries of analytes were all more than 60%. By means of the method developed, the plasma samples from model rats and normal rats had been successfully determined. Results showed that AA and fifteen kinds of metabolites by LOX and COX pathways in model rat plasma were significant higher than those in normal ones(Peicosanoid metabolome occurring in plasma from rat subjects with rheumatoid arthritis. It could be a powerful manner to diagnostic and/or prognostic values for rheumatoid arthritis.

  18. A Colored Particle Acceleration by Fluctuations in QGP

    OpenAIRE

    Xiaoping, Zheng; Jiarong, Li

    1997-01-01

    We discuss the energy variation of a parton passing through a quark-gluon plasma(QGP) taking into account nonlinear polarization effect. We find the parton can be accelerated by fluctuations in QGP, which gives us a new physical insight about the response of QGP to such external the current.

  19. Primordial Fluctuations within Teleparallelism

    CERN Document Server

    Wu, Yi-Peng

    2011-01-01

    To study the primordial fluctuations for gravity within teleparallelism, we perform a 3+1 decomposition of the vierbein field which makes the metric tensor identical to the ADM formulation. The torsion scalar is differ by a total divergence from the Ricci scalar under this representation as a consistent result. Using the unitary gauge of the scalar field, we obtain the same quadratic actions for both scalar and tensor perturbations as the standard ones in the minimal torsion scalar coupling. When the same scenario is applied to the higher-order action, $f(T)$ gravity, we find that the scalar-tensor coupling in the Einstein frame becomes a total divergence. Consequently, the cosmological perturbations are the same for $f(T)$ and $f(R)$ gravity theories in the earlier universe although the behaviors of the late time cosmic acceleration are apparently different.

  20. Collisionality dependent transport in TCV SOL plasmas

    DEFF Research Database (Denmark)

    Garcia, Odd Erik; Pitts, R.A.; Horacek, J.

    2007-01-01

    Results are presented from probe measurements in the low field side scrape-off layer (SOL) region of TCV during plasma current scan experiments. It is shown that with decreasing plasma current the radial particle density profile becomes broader and the fluctuation levels and turbulence driven...... radial particle flux increase. In the far SOL the fluctuations exhibit a high degree of statistical similarity and the particle density and flux at the wall radius scale inversely with the plasma current. Together with previous TCV density scan experiments, this indicates that plasma fluctuations...