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Sample records for dvinjaninov otsis aafrikast

  1. Phase Coupling in Langmuir Wave Packets: Evidence for Four Wave Interactions in Solar Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2012-01-01

    The four wave interaction process, known as the oscillating two stream instability (OTSI) is considered as one of the mechanisms responsible for stabilizing the electron beams associated with solar type III radio bursts. It has been reported that (1) an intense localized Langmuir wave packet associated with a type III burst contains the spectral characteristics of the OTSI: (a) a resonant peak at the local electron plasma frequency, f(sub pe), (b) a Stokes peak at a frequency slightly lower than f(sub pe), (c) anti-Stokes peak at a frequency slightly higher than f(sub pe), and (d) a low frequency enhancement below a few hundred Hz, (2) the frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI, and (3) the peak intensity of the wave packet is well above the thresholds for the OTSI as well as spatial collapse of envelope solitons. Here, for the first time, applying the trispectral analysis on this wave packet, we show that the tricoherence, which measures the degree of coherent four-wave coupling amongst the observed spectral components exhibits a peak. This provides an additional evidence for the OTSI and related spatial collapse of Langmuir envelope solitons in type III burst sources.

  2. Occupational therapy using sensory integration to improve participation of a child with autism: a case report.

    PubMed

    Schaaf, Roseann C; Hunt, Joanne; Benevides, Teal

    2012-01-01

    In this case report, we describe the changes in adaptive behaviors and participation of 1 child with autism during a 10-wk program of intensive occupational therapy using a sensory integrative approach (OT-SI) following a manualized protocol. This case is part of a larger study examining the efficacy of the OT-SI approach. We found improvement in sensory processing, as measured by the Sensory Integration and Praxis Tests, as well as enhanced participation in home, school, and family activities, as indicated on parent-rated goal attainment scales.

  3. Oscillating two-stream instability in a magnetized electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Tinakiche, Nouara; Annou, R.

    2015-04-01

    Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters.

  4. Interrater reliability and discriminative validity of the structural elements of the Ayres Sensory Integration Fidelity Measure.

    PubMed

    May-Benson, Teresa A; Roley, Susanne Smith; Mailloux, Zoe; Parham, L Diane; Koomar, Jane; Schaaf, Roseann C; Jaarsveld, Annamarie Van; Cohn, Ellen

    2014-01-01

    This study examined the reliability and validity of the structural section of the Ayres Sensory Integration® Fidelity Measure© (ASIFM), which provides a method for monitoring the extent to which an intervention was implemented as conceptualized in studies of occupational therapy using sensory integration intervention methods (OT-SI). We examined the structural elements of the measure, including content of assessment reports, availability of specific equipment and adequate space, safety monitoring, and integration of communication with parents and other team members, such as collaborative goal setting with parents or family and teacher education, into the intervention program. Analysis of self-report ratings by 259 occupational therapists from 185 different facilities indicated that the structural section of the ASIFM has acceptable interrater reliability (r ≥ .82) and significantly differentiates between settings in which therapists reportedly do and do not practice OT-SI (p < .001).

  5. Oscillating two-stream instability in a magnetized electron-positron-ion plasma

    SciTech Connect

    Tinakiche, Nouara; Annou, R.

    2015-04-15

    Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters.

  6. EVIDENCE FOR THE OSCILLATING TWO STREAM INSTABILITY AND SPATIAL COLLAPSE OF LANGMUIR WAVES IN A SOLAR TYPE III RADIO BURST

    SciTech Connect

    Thejappa, G.; Bergamo, M.; Papadopoulos, K.; MacDowall, R. J. E-mail: mbergamo@umd.edu E-mail: Robert.MacDowall@nasa.gov

    2012-03-15

    We present observational evidence for the oscillating two stream instability (OTSI) and spatial collapse of Langmuir waves in the source region of a solar type III radio burst. High time resolution observations from the STEREO A spacecraft show that Langmuir waves excited by the electron beam occur as isolated field structures with short durations {approx}3.2 ms and with high intensities exceeding the strong turbulence thresholds. These short duration events are identified as the envelope solitons which have collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets contain an intense peak and two sidebands, corresponding to beam-resonant Langmuir waves, and down-shifted and up-shifted daughter Langmuir waves, respectively, and low-frequency enhancements below a few hundred Hz. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI. The observed high intensities, short scale lengths, sideband spectral structures, and low-frequency enhancements strongly suggest that the OTSI and spatial collapse of Langmuir waves probably control the nonlinear beam-plasma interactions in type III radio bursts.

  7. Thermodynamic Modeling and Analysis of Human Stress Response

    NASA Technical Reports Server (NTRS)

    Boregowda, S. C.; Tiwari, S. N.

    1999-01-01

    A novel approach based on the second law of thermodynamics is developed to investigate the psychophysiology and quantify human stress level. Two types of stresses (thermal and mental) are examined. A Unified Stress Response Theory (USRT) is developed under the new proposed field of study called Engineering Psychophysiology. The USRT is used to investigate both thermal and mental stresses from a holistic (human body as a whole) and thermodynamic viewpoint. The original concepts and definitions are established as postulates which form the basis for thermodynamic approach to quantify human stress level. An Objective Thermal Stress Index (OTSI) is developed by applying the second law of thermodynamics to the human thermal system to quantify thermal stress or dis- comfort in the human body. The human thermal model based on finite element method is implemented. It is utilized as a "Computational Environmental Chamber" to conduct series of simulations to examine the human thermal stress responses under different environmental conditions. An innovative hybrid technique is developed to analyze human thermal behavior based on series of human-environment interaction simulations. Continuous monitoring of thermal stress is demonstrated with the help of OTSI. It is well established that the human thermal system obeys the second law of thermodynamics. Further, the OTSI is validated against the experimental data. Regarding mental stress, an Objective Mental Stress Index (OMSI) is developed by applying the Maxwell relations of thermodynamics to the combined thermal and cardiovascular system in the human body. The OMSI is utilized to demonstrate the technique of monitoring mental stress continuously and is validated with the help of series of experimental studies. Although the OMSI indicates the level of mental stress, it provides a strong thermodynamic and mathematical relationship between activities of thermal and cardiovascular systems of the human body.

  8. Bispectral Analysis of a Langmuir Wave Packet Associated with a Solar Type III Radio Burst

    NASA Astrophysics Data System (ADS)

    Golla, T.; MacDowall, R. J.; Bergamo, M.

    2012-12-01

    We present the observations of an intense localized wave packet, obtained by the STEREO spacecraft in the source region of a solar type III radio burst. The FFT spectrum of this wave packet contains a primary peak at the local electron plasma frequency, fpe (Langmuir waves), and two secondary peaks, one at 2fpe (second harmonic) and a second one at 3fpe (third harmonic). The wavelet based time-frequency spectrogram indicates that these spectral peaks are coincident in time. It is found that the bicoherence spectrum, computed using the wavelet based bispectral analysis technique contains two peaks, one at (fpe, fpe) and a second one at (2fpe, fpe). The high values of the bicoherences of these spectral peaks, which quantify the phase coherences amongst the harmonic components provide unambiguous evidence for the three wave interactions L + L' -> T2f{pe}, and L + T2f{pe} -> T3f{pe} in the waveform data, where L and L' are the oppositely propagating Langmuir waves, and T2f{pe} and T3f{pe} are the second and third harmonic electromagnetic waves, respectively. The peak intensity and short duration of this wave packet, which indicate that it is probably a collapsing soliton formed as a result of oscillating two stream instability (OTSI), strongly suggest that the L and L' probably correspond to the OTSI excited oppositely propagating Langmuir waves.

  9. Comment on: 'An intervention for sensory difficulties in children with autism: a randomized trial' by Schaaf et al. (2013).

    PubMed

    Ashburner, Jill K; Rodger, Sylvia A; Ziviani, Jenny M; Hinder, Elizabeth A

    2014-06-01

    The purpose of this letter to the editor is to comment on a recently published paper in the Journal of Autism and Developmental Disorders, 'An Intervention for Sensory Difficulties in Children with Autism: A Randomized Trial' by Schaaf et al. (2013). The authors are commended for undertaking a randomised clinical trial (RCT) examining the efficacy of occupational therapy using sensory integration (OT/SI). The study complies with many of the recommended standards of RCT's including: (a) detailed eligibility criteria, (b) well-matched experimental and control groups, (c) use of gold-standard instruments to measure the symptoms of autism spectrum disorder, (d) the use of functionally relevant outcome measures, (e) fidelity checking, and (f) manualization of the intervention. Additional aspects of rigour that could be considered in subsequent research include: (a) independent blinded measure of observational outcomes, (b) treatment and control interventions of equivalent dose, (c) public access to the manualized treatment guidelines, and (d) the use of a comparison occupational therapy intervention to address the same goals as the OT/SI intervention.

  10. Evidence for Langmuir Envelope Solitons in Solar Type III Burst Source Regions

    NASA Technical Reports Server (NTRS)

    Thejappa, G.; Goldstein, M. L.; MacDowall, R. J.; Papadopoulos, K.; Stone, R. G.

    1998-01-01

    We present observational evidence for the generation of Langmuir envelope solitons in the source regions of solar type III radio bursts. The solitons appear to be formed by electron beams which excite either the modulational instability or oscillating two-stream instability (OTSI). Millisecond data from the Ulysses Unified Radio and Plasma Wave Experiment (URAP) show that Langmuir waves associated with type III bursts occur as broad intense peaks with time scales ranging from 15 to 90 milliseconds (6 - 27 km). These broad field structures have the properties expected of Langmuir envelope solitons, viz.: the normalized peak energy densities, W(sub L)/n(sub e)T(sub e) approximately 10(exp -5), are well above the modulational instability threshold; the spatial scales, L, which range from 1 - 5 Langmuir wavelengths, show a high degree of inverse correlation with (W(sub L)/n(sub e)T(sub e))(sup 1/2); and the observed widths of these broad peaks agree well with the predicted widths of envelope solitons. We show that the orientation of the Langmuir field structures is random with respect to the ambient magnetic field, indicating that they are probably isotropic structures that have evolved from initially pancake-like solitons. These observations suggest that strong turbulence processes, such as the modulational instability or the OTSI, stabilize the electron beams that produce type III bursts.

  11. Isophotes of a field in the Cygnus loop photographed in the (O III) and (N II)+H. cap alpha. lines

    SciTech Connect

    Sitnik, T.G.; Toropova, M.S.

    1982-11-01

    From interference-filter image-tube photographs of a 9' field in the western part of the Cygnus Loop supernova remnant, taken in the lambda5007 (O III) and lambdalambda 6584, 6563 (N II) + H..cap alpha.. lines, sets of isophotes are derived by an equidensitometry technique based on the Sabattier effect. The emission regions in these lines exhibit a relative displacement, interpreted as evidence for radiative cooling of the gas behind the shock generated in the supernova outburst. An explanation is offered for the differing morphology of the nebular filaments in the (O III) and (N II) + H..cap alpha.. lines. The anomalously high I/sub Otsi/II/I/sub H/..beta.. intensity ratio may reflect a spatial separation of the corresponding emission zones.

  12. Nonlinear stability of solar type 3 radio bursts. 1: Theory

    NASA Technical Reports Server (NTRS)

    Smith, R. A.; Goldstein, M. L.; Papadopoulos, K.

    1978-01-01

    A theory of the excitation of solar type 3 bursts is presented. Electrons initially unstable to the linear bump-in-tail instability are shown to rapidly amplify Langmuir waves to energy densities characteristic of strong turbulence. The three-dimensional equations which describe the strong coupling (wave-wave) interactions are derived. For parameters characteristic of the interplanetary medium the equations reduce to one dimension. In this case, the oscillating two stream instability (OTSI) is the dominant nonlinear instability, and is stablized through the production of nonlinear ion density fluctuations that efficiently scatter Langmuir waves out of resonance with the electron beam. An analytical model of the electron distribution function is also developed which is used to estimate the total energy losses suffered by the electron beam as it propagates from the solar corona to 1 A.U. and beyond.

  13. Observational evidence for the collapsing Langmuir wave packet in a solar type III radio burst

    NASA Astrophysics Data System (ADS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2013-07-01

    High time resolution observations from the STEREO spacecraft show that in solar type III radio bursts, Langmuir waves often occur as very intense one-dimensional magnetic field aligned field structures. One of these events represents the most intense Langmuir wave packet with WLneTe~7.2×10-3 ever detected in a type III radio burst until now (WL is the peak energy density, and ne and Te are the electron density and temperature, respectively). The detailed analysis of this wave packet indicates that (1) its peak intensity is well above the threshold for the oscillating two-stream instability (OTSI) and supersonic collapse; (2) its peak intensity and spatial scale satisfy the criterion for it to be a collapsing envelope soliton; (3) its low-frequency components provide evidence for a density cavity, whose depth, width, and temporal coincidence indicate that probably it is the ponderomotive force generated density cavity; and (4) its spectrum contains harmonic peaks at 2fpe and 3fpe (in addition to the main Langmuir wave peak at the electron plasma frequency, fpe), which, as indicated by the bispectral analysis, probably are of the electromagnetic waves generated as a result of coalescence of two oppositely propagating Langmuir waves, and a Langmuir wave and a second harmonic electromagnetic wave, respectively. These characteristics strongly suggest that this wave packet and its associated density cavity represent the collapsing envelope soliton-caviton pair formed as a result of OTSI, and in the present case, the strong turbulence processes probably play key roles in the beam stabilization as well as conversion of Langmuir waves into escaping radiation at 2fpe and 3fpe.