1,521 research outputs found
Deconvolution of directly precipitating and trap-precipitating electrons in solar flare hard x-rays. III.Yohkoh hard x-ray telescope data analysis
We analyze the footpoint separation d and flux asymmetry A of magnetically conjugate double footpoint sources in hard X-ray images from the Yohkoh Hard X-Ray Telescope (HXT). The data set of 54 solar flares includes all events simultaneously observed with the Compton Gamma Ray Observatory (CGRO) in high time resolution mode. From the CGRO data we deconvolved the direct-precipitation and trap-precipitation components previously (in Paper II). Using the combined measurements from CGRO and HXT, we develop an asymmetric trap model that allows us to quantify the relative fractions of four different electron components, i.e., the ratios of direct-precipitating (q_P1, q_P2) and trap-precipitating electrons (q_T1, q_T2) at both magnetically conjugate footpoints. We find mean ratios of q_P1=0.14+/-0.06, q_P2=0.26+/-0.10, and q_T=q_T1+q_T2=0.60+/-0.13. We assume an isotropic pitch-angle distribution at the acceleration site and double-sided trap precipitation (q_T2/q_T1=q_P2/q_P1) to determine the conjugate loss-cone angles (alpha_1=42^deg+/-11^deg and alpha_2=52^deg+/-10^deg) and magnetic mirror ratiosat both footpoints (R_1=1.6,...,4.0 and R_2=1.3,...,2.5). From the relative displacement of footpoint sources we also measure altitude differences of hard X-ray emission at different energies, which are found to decrease systematically with higher energies, with a statistical height difference of h_Lo-h_M1=980+/-250 km and h_M1-h_M2=310+/-300 km between the three lower HXT energy channels (Lo, M1, M2
Dark filaments observed at 8.3mm and 3.1mm wavelength
Mapping of the sun was made at 3.1mm (98 GHz) and 8.3mm (36 GHz) wavelengths with a 45m dish radio telescope at the Nobeyama Cosmic Radio Observatory. The depressions associated with large H alpha filaments are derived to be -0.2 at 8.3mm and -0.05 at 3.1mm, which are darker than the values inferred by Raoult et al. (1979
Signatures of current loop coalescence in solar flares
The nonlinear coalescence instability of current carrying solar loops can explain many of the characteristics of the solar flares such as their impulsive nature, heating and high energy particle acceleration, amplitude oscillations of electromagnetic emission as well as the characteristics of 2-D microwave images obtained during a solar flare. The physical characteristics of the explosive coalescence of currents are presented in detail through computer simulation and theory. Canonical characteristics of the explosive coalescence are: (1) a large amount of impulsive increase of kinetic energies of electrons and ions; (2) simultaneous heating and acceleration of electrons and ions in high and low energy spectra; (3) ensuing quasi-periodic amplitude oscillations in fields and particle quantities; and (4) the double peak (or triple peak) structure in these profiles, participate in the coalescence process, yielding varieties of phenomena
Single-crystal growth of underdoped Bi-2223
To investigate the origin of the enhanced Tc ({\approx} 110 K) of the
trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+{\delta} (Bi-2223), its
underdoped single crystals are a critical requirement. Here, we demonstrate the
first successful in-plane resistivity measurements of heavily underdoped
Bi-2223 (zero-resistivity temperatures {\approx} 20~35 K). Detailed crystal
growth methods, the annealing process, as well as X-ray diffraction (XRD) and
magnetic susceptibility measurement results are also reported.Comment: 4 pages, 4 figures, 27th International Symposium on
Superconductivity, ISS 2014, to appear in Physics Procedi
Analysis of IgE turnover in non-sensitized and sensitized rats.
BACKGROUND: Although the levels of immunoglobulin E (IgE) in the circulating blood are often elevated in patients with allergic diseases, such levels cannot always be considered as pathognomonic signs of allergy. The induction of allergic reactions in the tissue was inferred to be related to the amount of IgE passing through the vascular wall. AIMS: We attempted to clarify which compartment, the intravascular or extravascular, plays an important role in the regulation of the turnover of rat IgE. METHODS: The level of DNP-specific rat IgE in the serum was estimated by IgE-capture enzyme-linked immunosorbent assay, and the turnover of IgE was analyzed from its pharmacokinetic parameters. RESULTS: The transfer rate constants from the central to tissue compartment (Kct) were larger than those from the tissue to central compartment (Ktc) irrespective of the sensitized state. The value of the distribution volume of the tissue compartment (Vt) was larger than that of the distribution volume of the central compartment (Vc) irrespective of the sensitized state. CONCLUSIONS: These Findings suggest that the short half-life of rat IgE in the circulation could be attributable to the distribution of IgE from the intravascular to the extravascular compartment
Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare: Implications for Plasma Heating and Electron Acceleration
We present radio and X-ray observations of an impulsive solar flare that was
moderately intense in microwaves, yet showed very meager EUV and X-ray
emission. The flare occurred on 2001 Oct 24 and was well-observed at radio
wavelengths by the Nobeyama Radioheliograph (NoRH), the Nobeyama Radio
Polarimeters (NoRP), and by the Owens Valley Solar Array (OVSA). It was also
observed in EUV and X-ray wavelength bands by the TRACE, GOES, and Yohkoh
satellites. We find that the impulsive onset of the radio emission is
progressively delayed with increasing frequency relative to the onset of hard
X-ray emission. In contrast, the time of flux density maximum is progressively
delayed with decreasing frequency. The decay phase is independent of radio
frequency. The simple source morphology and the excellent spectral coverage at
radio wavelengths allowed us to employ a nonlinear chi-squared minimization
scheme to fit the time series of radio spectra to a source model that accounts
for the observed radio emission in terms of gyrosynchrotron radiation from
MeV-energy electrons in a relatively dense thermal plasma. We discuss plasma
heating and electron acceleration in view of the parametric trends implied by
the model fitting. We suggest that stochastic acceleration likely plays a role
in accelerating the radio-emitting electrons.Comment: 22 pages, 10 figure
An examination for increasing the motor constant of a cylindrical moving magnet-type linear actuator
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.ArticleIEEE TRANSACTIONS ON MAGNETICS. 41(10): 3976-3978 (2005)journal articl
ソーラーフレアーにおける電流ループのコアレッセンス
The nonlinear coalescence instability of current carrying solar loops can explain many of the characteristics of the solar flares such as their impulsive nature, heating and high energy particle acceleration, amplitude oscillations of electromagnetic emission as well as the characteristics of 2-D microwave images obtained during a solar flare. The physical characteristics of the explosive coalescence of currents are presented in detail through computer simulation and theory.Canonical characteristics of the explosive coalescence are: (1) a large amount of impulsive increase of kinetic energies of electrons and ions, (2) simultaneous heating and acceleration of electrons and ions in high and low energy spectra, (3) ensuing quasi-periodic amplitude oscillations in fields and particle quantities, (4) the double peak (or triple peak) structure in these profiles, and (5) characteristic break in energy spectra of electrons and ions. A single pair of currents as well as multiple currents may participate in the coalescence process, yielding varieties of phenomena. These physical properties seem to underlie in some of impulsive solar flares.In particular, double sub-peak structures in the quasi-periodic oscillations found in the time profiles of two solar flares on June 7, 1980 and November 26, 1982 are well explained in terms of the coalescence instability of two current loops. This interpretation is supported by the observations of two microwave sources and their interaction for the November 26, 1982 flare.Some more details as well as a generalization of the present model to solar flares with the coalescence as an elementary process in the flare phenomenon are presented
The Role of Inverse Compton Scattering in Solar Coronal Hard X-ray and Gamma-ray Sources
Coronal hard X-ray (HXR) and continuum gamma-ray sources associated with the
impulsive phase of solar flares have been the subject of renewed interest in
recent years. They have been interpreted in terms of thin-target, nonthermal
bremsstrahlung emission. This interpretation has led to rather extreme physical
requirements in some cases. For example, in one case, essentially all of the
electrons in the source must be accelerated to nonthermal energies to account
for the coronal HXR source. In other cases, the extremely hard photon spectra
of the coronal continuum gamma-ray emission suggest that the low energy cutoff
of the electron energy distribution lies in the MeV energy range. Here we
consider the role of inverse Compton scattering (ICS) as an alternate emission
mechanism in both the ultra- and mildly relativistic regimes. It is known that
relativistic electrons are produced during powerful flares; these are capable
of up-scattering soft photospheric photons to HXR and gamma-ray energies.
Previously overlooked is the fact that mildly relativistic electrons, generally
produced in much greater numbers in flares of all sizes, can up-scatter EUV/SXR
photons to HXR energies. We also explore ICS on anisotropic electron
distributions and show that the resulting emission can be significantly
enhanced over an isotropic electron distribution for favorable viewing
geometries. We briefly review results from bremsstrahlung emission and
reconsider circumstances under which nonthermal bremsstrahlung or ICS would be
favored. Finally, we consider a selection of coronal HXR and gamma-ray events
and find that in some cases the ICS is a viable alternative emission mechanism
- …