scholarly journals Preliminary results on the apparent size of the sources of type III bursts observed at low frequencies

Solar Physics ◽  
1976 ◽  
Vol 46 (2) ◽  
pp. 483-491 ◽  
Author(s):  
Hector Alvarez
Keyword(s):  
Apparent Size ◽  
Low Frequencies ◽  
Preliminary Results ◽  
Type Iii

scholarly journals Blazar monitoring with LOFAR

2014 ◽  
Vol 10 (S313) ◽  
pp. 95-96 ◽  
Author(s):  
Sara Turriziani ◽  
Martin Hardcastle ◽  
James Miller-Jones ◽  
Jess Broderick ◽  
Sera Markoff ◽  
...  
Keyword(s):  
Low Frequencies ◽  
Available Bandwidth ◽  
Preliminary Results ◽  
Flux Variability ◽  
High Band ◽  
Proof Of Principle

AbstractWe have been monitoring some well-known bright blazars with short LOFAR observations since February 2013 with fortnightly cadence using the full available bandwidth of the High Band Antennas (i.e., 48 MHz centred at 226 MHz). The sources were chosen to be bright at low frequencies and to exhibit strong GHz-frequency radio variability on timescales of weeks to years. None of the five objects selected have been monitored previously in the MHz band. Here we report some preliminary results on flux variability obtained so far with LOFAR. These observations are scientifically valuable in their own right and also act as a proof of principle for broader, higher-cadence monitoring of the extragalactic sky with LOFAR and possibly SKA.

Combining high and low frequencies in rTMS antidepressive treatment: preliminary results

2002 ◽  
Vol 17 (7) ◽  
pp. 353-356 ◽  
Author(s):  
Andreas Conca ◽  
Jan Di Pauli ◽  
Wolfgang Beraus ◽  
Armand Hausmann ◽  
William Peschina ◽  
...  
Keyword(s):  
Low Frequencies ◽  
Preliminary Results ◽  
Antidepressive Treatment

Immunocytochemical localization of fibronectin in human fibroblast cultures using a cell surface replica technique.

1983 ◽  
Vol 31 (1) ◽  
pp. 69-77 ◽  
Author(s):  
P S Irish ◽  
D L Hasty
Keyword(s):  
Cultured Cells ◽  
Apparent Size ◽  
Cell Contact ◽  
Immunocytochemical Localization ◽  
Repeat Distance ◽  
Type Iii ◽  
Procollagen Type ◽  
The Matrix ◽  
Surface Replica ◽  
Immunocytochemical Techniques

The pericellular fibronectin-containing matrices of human foreskin fibroblasts cultured in ascorbate-supplemented medium were examined using surface replicas. An extensive filamentous network is present over and between adjacent cells, with a considerable amount at points of cell-to-cell contact. Indirect immunocytochemical localization of the distribution of fibronectin and procollagen type III within the matrix was done using the peroxidase-antiperoxidase (PAP) sandwich technique. The PAP molecule with the surrounding diaminobenzidine reaction product appears as a globular particle of approximately 39 nm in surface replicas. The apparent size of the marker was larger (60-80 nm) when bound to pericellular fibronectin, due presumably to the binding of more than one PAP complex to each fibronectin molecule. The immunocytochemical data suggest that fibronectin is a component of most, if not all, matrix fibrils. Some of the smallest filaments of the matrix (5-10 nm) exhibit a periodic, beaded appearance, with a repeat distance of approximately 70-100 nm. After either anti-fibronectin or anti-procollagen type III labeling, the filaments were decorated at regular 70-100 nm intervals with the globular marker. We suggest that the periodicity may be due to fibronectin molecules bound to collagen microfibrils at regular intervals. Our results demonstrate the usefulness of combined surface replica and immunocytochemical techniques for analysis of matrix components of cultured cells.

scholarly journals The Lockman Hole Project: A Multi-frequency Study of the Faint Radio Population down to LOFAR bands

2013 ◽  
Vol 9 (S304) ◽  
pp. 108-109
Author(s):  
G. Guglielmino ◽  
I. Prandoni ◽  
R. Morganti ◽  
G. Heald ◽  
E. Mahony ◽  
...  
Keyword(s):  
Source Population ◽  
Low Frequencies ◽  
Radio Data ◽  
Preliminary Results ◽  
First Time ◽  
Lockman Hole

AbstractWe are performing a multi-frequency radio analysis of a well-known deep field: the Lockman Hole, which is one of the best studied sky regions in different wavebands. This will provide us with important complementary data (for example redshifts) to the radio data, allowing us to characterize the physical and evolutionary properties of the various classes of sources composing the faint radio population. LOFAR imaging of the Lockman Hole can play an important role in this project, allowing, for the very first time, to observe the sub-mJy source population at very low frequencies (30-200 MHz), where self-absorption phenomena are expected to be very important. Here we present some preliminary results.

Type III solar radio burst storms observed at low frequencies

Solar Physics ◽  
1970 ◽  
Vol 15 (1) ◽  
pp. 222-233 ◽  
Author(s):  
Joseph Fainberg ◽  
R. G. Stone
Keyword(s):  
Radio Burst ◽  
Solar Radio ◽  
Solar Radio Burst ◽  
Low Frequencies ◽  
Type Iii

Type III Radio Bursts and Langmuir Wave Excitation

2020 ◽  
Author(s):  
Gottfried Mann ◽  
Christian Vocks ◽  
Mario Bisi ◽  
Eoin Carley ◽  
Bartosz Dabrowski ◽  
...  
Keyword(s):  
Distribution Function ◽  
Interplanetary Space ◽  
Langmuir Wave ◽  
Velocity Distribution Function ◽  
Radio Bursts ◽  
Radio Waves ◽  
Langmuir Waves ◽  
Low Frequencies ◽  
Energetic Electrons ◽  
Type Iii

<p>Type III radio bursts are a common phenomenon the Sun’s nonthermal radio radiation. They appear as stripes of enhanced radio emission with a rapid drift from high to low frequencies in dynamic radio spectra. They are considered as the radio signatures of beams of energetic electrons travelling along magnetic field lines from the solar corona into the interplanetary space. With the ground based radio interferometer LOFAR and the instrument FIELDS onboard NASA’s “Parker Solar Probe” (PSP) , type III radio bursts can be observed simultaneously from high (10-240 MHz) to low frequencies (0.01-20 MHz) with LOFAR and PSP’s FIELDs, respectively. That allows to track these electron beams from the corona up to the interplanetary space. Assuming that a population of energetic electrons is initially injected, the velocity distribution function of these electrons evolves into a beam like one. Such distribution function leads to the excitation of Langmuir waves which convert into radio waves finally observed as type II radio bursts. Numerical calculations of the electron-beam-plasma interaction reveal that the Langmuir waves are excited by different parts of the energetic electrons at different distances in the corona and interplanetary space. This result is compared with special type III radio bursts observed with LOFAR and PSP’s FIELDS.</p>

Relative Positions of Type I and Type III Solar Metre-Wave Bursts

1981 ◽  
Vol 4 (2) ◽  
pp. 230-235 ◽  
Author(s):  
R. A. Duncan
Keyword(s):  
Type I ◽  
The Sun ◽  
Low Frequencies ◽  
Electron Stream ◽  
High Frequencies ◽  
Type Iii ◽  
Large Loop ◽  
Wide Acceptance ◽  
Field Lines ◽  
Fast Drift

Solar metre-wave noise storms commonly show continuum and short-lived narrow-band bursts (Type I) at high frequencies and fast-drift bursts (Type III) at low frequencies (Malville 1962; Hanasz 1966; Boischot et al. 1970; Moller-Pedersen 1974; see also Figs. 2-3 of this paper). The Type I and Type III emissions have the same sense of polarization (Komesaroff 1958; Suzuki 1978). Impressed by this spectral association, Malville (1962) and Boischot et al. (1970) suggested that the two types of emission might be excited by the same electron stream. However, Type I emission is associated with sunspots and strong photospheric magnetic fields (McCready et al. 1947; Payne-Scott and Little 1951; Le Squeren 1963) and for this reason Kai (1970) suggested that Type I emission arises on strong closed magnetic loops. Type III emission, by contrast, almost certainly arises on open or quasi-open (large-loop) magnetic field lines (Wild et al. 1959, 1963). Thus on these models one would expect Type I and Type III emissions to arise from different magnetic regimes and different areas of the Sun. Kai’s (1970) and Stewart and Labrum’s (1972) Culgoora radioheliograph observations, which suggested that Type I and Type III sources are always separated on the Sun, seemed to clinch the matter. Kai’s model and his statement ‘Type III sources avoid the precise location of Type I storm centres’ gained wide acceptance (e.g. Boischot et al. 1971; Elgaroy 1977; Stewart 1977).

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