44 research outputs found
Type II Radio Emission and Solar Particle Observations
The 28 October 2003 flare gave us the unique opportunity to compare the
acceleration time of high-energy protons with the escaping time of those
particles which have been measured onboard spacecraft and by neutron monitors
network as GLE event. High-energy emission time scale and shock wave height and
velocity time dependencies were also studied.Comment: International Journal of Modern Physics A, Volume 20, Issue 29, pp.
6705-6707 (2005
The improved ARTEMIS IV multichannel solar radio spectrograph of the University of Athens
We present the improved solar radio spectrograph of the University of Athens
operating at the Thermopylae Satellite Telecommunication Station. Observations
now cover the frequency range from 20 to 650 MHz. The spectrograph has a
7-meter moving parabola fed by a log-periodic antenna for 100 650 MHz and a
stationary inverted V fat dipole antenna for the 20 100 MHz range. Two
receivers are operating in parallel, one swept frequency for the whole range
(10 spectrums/sec, 630 channels/spectrum) and one acousto-optical receiver for
the range 270 to 450 MHz (100 spectrums/sec, 128 channels/spectrum). The data
acquisition system consists of two PCs (equipped with 12 bit, 225 ksamples/sec
ADC, one for each receiver). Sensitivity is about 3 SFU and 30 SFU in the 20
100 MHz and 100 650 MHz range respectively. The daily operation is fully
automated: receiving universal time from a GPS, pointing the antenna to the
sun, system calibration, starting and stopping the observations at preset
times, data acquisition, and archiving on DVD. We can also control the whole
system through modem or Internet. The instrument can be used either by itself
or in conjunction with other instruments to study the onset and evolution of
solar radio bursts and associated interplanetary phenomena.Comment: Experimental Astronomy, Volume 21, Issue 1, pp.41-5
CT-guided iodine-125 seed permanent implantation for recurrent head and neck cancers
<p>Abstract</p> <p>Background</p> <p>To investigate the feasibility, and safety of <sup>125</sup>I seed permanent implantation for recurrent head and neck carcinoma under CT-guidance.</p> <p>Results</p> <p>A retrospective study on 14 patients with recurrent head and neck cancers undergone <sup>125</sup>I seed implantation with different seed activities. The post-plan showed that the actuarial D90 of <sup>125</sup>I seeds ranged from 90 to 218 Gy (median, 157.5 Gy). The follow-up was 3 to 60 months (median, 13 months). The median local control was 18 months (95% CI, 6.1-29.9 months), and the 1-, 2-, 3-, and 5- year local controls were 52%, 39%, 39%, and 39%, respectively. The 1-, 2-, 3-, and 5- survival rates were 65%, 39%, 39% and 39%, respectively, with a median survival time of 20 months (95% CI, 8.7-31.3 months). Of all patients, 28.6% (4/14) died of local recurrence, 7.1% (1/14) died of metastases, one patient died of hepatocirrhosis, and 8 patients are still alive to the date of data analysis.</p> <p>Conclusion</p> <p>CT-guided <sup>125</sup>I seed implantation is feasible and safe as a salvage or palliative treatment for patients with recurrent head and neck cancers.</p
New developments in ARTEMIS IV solar radio spectrograph
We present recent developments of the ARTEMIS IV solar radio spectrograph operating at Thermopylae, central Greece. Observations are obtained daily in total intensity and in the frequency range from 20 to 650 MHz, using two antennas and two receivers. We are now in the process of developing a new system that will record consecutively the intensity of right-hand and left-hand polarized waves using one of the antennas and the same receivers. © Springer Science+Business Media B.V. 2008