3,603 research outputs found
Dynamic Magnetography of Solar Flaring Loops
We develop a practical forward fitting method based on the SIMPLEX algorithm
with shaking, which allows the derivation of the magnetic field and other
parameters along a solar flaring loop using microwave imaging spectroscopy of
gyrosynchrotron emission. We illustrate the method using a model loop with
spatially varying magnetic field, filled with uniform ambient density and an
evenly distributed fast electron population with an isotropic, power-law energy
distribution.Comment: ApJ Letters, in pres
Parasites Recovered From Overwintering Mimosa Webworm, \u3ci\u3eHomadaula Anisocentra\u3c/i\u3e (Lepidoptera: Plutellidae)
The mimosa webworm, Homadaula anisocentra, overwinters in the pupal stage. Two parasites, Parania geniculata and Elasmus albizziae, are associated with overwintering pupae or the immediate prepupal larvae. Combined parasitism during the winters of 1981-82,1982-83, and 1983-84 was 2.1,3.9, and 2.9%, respectively
Spatially and Spectrally Resolved Observations of a Zebra Pattern in Solar Decimetric Radio Burst
We present the first interferometric observation of a zebra-pattern radio
burst with simultaneous high spectral (~ 1 MHz) and high time (20 ms)
resolution. The Frequency-Agile Solar Radiotelescope (FASR) Subsystem Testbed
(FST) and the Owens Valley Solar Array (OVSA) were used in parallel to observe
the X1.5 flare on 14 December 2006. By using OVSA to calibrate the FST the
source position of the zebra pattern can be located on the solar disk. With the
help of multi-wavelength observations and a nonlinear force-free field (NLFFF)
extrapolation, the zebra source is explored in relation to the magnetic field
configuration. New constraints are placed on the source size and position as a
function of frequency and time. We conclude that the zebra burst is consistent
with a double-plasma resonance (DPR) model in which the radio emission occurs
in resonance layers where the upper hybrid frequency is harmonically related to
the electron cyclotron frequency in a coronal magnetic loop.Comment: Accepted for publication in Ap
1971 Farm Business Analysis Report General Crop Summary
Exact date of working paper unknown
The Importance of Screening for Medullary Thyroid Carcinoma in Families of Patients with MEN 2
Family .screening for medullary thyroid cancer (MTC) is important for detecting members of multiple endocrine neoplasia type 2 (MEN 2) families who may be gene carriers but show no clinical evidence of the disease. Most members of our MEN 2 families are screened yearly by measuring basal and pentagastrin-stimulated calcitonin (CT) levels. A 15-year-old first-degree relative of an affected member of the D-kindred showed a normal basal and an elevated stimulated CT level. Clinical examination, ultrasonography, and scintigraphy were normal. Thyroidectomy and bilateral neck dissection revealed a multicentric MTC with no lymph node involvement. In the O-kindred we detected elevated basal and/or stimulated CT levels in three asymptomatic first-degree relatives. At surgery we found a small multicentric MTC in one family member, C-cell hyperplasia in another member, and bilateral lymph node metastases in one member who had been previously thyroidectomized. Basal and stimulated CT estimations in MEN 2 family members provide an effective method for detecting MTC in early, treatable stages
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
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