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

Radio Observations of the January 20, 2005 X-Class Event

We present a multi-frequency and multi-instrument study of the 20 January 2005 event. We focus mainly on the complex radio signatures and their association with the active phenomena taking place: flares, CMEs, particle acceleration and magnetic restructuring. As a variety of energetic particle accelerators and sources of radio bursts are present, in the flare-ejecta combination, we investigate their relative importance in the progress of this event. The dynamic spectra of {Artemis-IV-Wind/Waves-Hiras with 2000 MHz-20 kHz frequency coverage, were used to track the evolution of the event from the low corona to the interplanetary space; these were supplemented with SXR, HXR and gamma-ray recordings. The observations were compared with the expected radio signatures and energetic-particle populations envisaged by the {Standard Flare--CME model and the reconnection outflow termination shock model. A proper combination of these mechanisms seems to provide an adequate model for the interpretation of the observational data.Comment: Accepted for publication in Solar Physic

The Demographic and Social Characteristics of Patients with Ocular Foreign Bodies in a Greek Tertiary Hospital

Panagiotis Kousiouris,1,&ast; Nikolaos Gouliopoulos,2,&ast; Anastasia Kourtesa,1,&ast; Georgios S Dimtsas,1 Klio Chatzistefanou,1 Nikolaos Bouratzis,2 Maria Kantzanou,3 Marilita M Moschos1 1 1st Department of Ophthalmology, University of Athens Medical School, G. Gennimatas Hospital, Athens, Greece; 2 2nd Department of Ophthalmology, University of Athens Medical School, Attikon Hospital, Athens, Greece; 3Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece&ast;These authors contributed equally to this workCorrespondence: Marilita M Moschos, 1st Department of Ophthalmology, University of Athens Medical School, G. Gennimatas Hospital, 154 Leof. Mesogeion, Athens, 115 27, Greece, Tel +30 6944887319, Email [email protected]: To present the demographic and social characteristics of patients with ocular foreign bodies (OFB), who visit the Ophthalmological Outpatient Department of a tertiary hospital in Athens, Greece.Patients and Methods: During the period January-March 2019, 5181 patients presented to the Ophthalmological Outpatient Department of our hospital, and 543 of them were diagnosed with an ocular foreign body. Moreover, 106 of them were interviewed about their demographic and social factors, regarding among others data about their occupation, level of education, nationality, family, and insurance status.Results: The patients with ocular foreign bodies were significantly younger compared to the rest of the examined patients (49.5± 13.9 vs 56.3± 17 years, p< 0.001). Moreover, the ocular foreign bodies were more frequent in men compared to women (15.5% vs 5.0%, p< 0.001) and in non-Greek patients (23.7% vs 9.2%, p< 0.001). Regarding the social characteristics of the patients with ocular foreign bodies, we found that the majority of them were married, employed, insured, while their educational status was middle and high school. Furthermore, the vast majority of the patients practiced manual professions (73.1% of them).Conclusion: We documented that the introduction of an ocular foreign body is frequently encountered in the Outpatient Department of our tertiary hospital in Athens, Greece. We also demonstrated that these patients are younger, while they are more frequently men, of non-Greek origin, with an educational status of middle and high school, and their occupation is associated with manual labour.Keywords: ocular foreign body, ocular trauma, demographic characteristics, social characteristic

Histopathological evaluation of a retinoic acid eluting stent in a rabbit iliac artery model

This study aimed to evaluate the safety and efficacy of innovative retinoic acid (RA) eluting stents with bioabsorbable polymer. Sixty stents divided in ten groups were implanted in the iliac arteries of 30 rabbits. Two polymers (“A”, poly (lactic-co-glycolic acid) and “B”, polylactic acid), and three doses (“Low”, “Medium” and “High”) of RA (groups: AL, AM, AH, BL, BM, BH) were used on cobalt chromium stents (Rontis Corporation), one group of bare stent (C), one group (D) of Everolimus eluting stent (Xience-Pro, Abbot Vascular), and two groups of Rontis Everolimus eluting stents coated with polymer A (EA) and B (EB). Treated arteries were explanted after 4 weeks, processed by methyl methacrylate resin and evaluated by histopathology. None of the implanted stents was related with thrombus formation or extensive inflammation. Image analysis showed limited differences between groups regarding area stenosis (BH, D and EB groups had the lower values). Group BH had lower intimal mean thickness than AH (105.1 vs 75.3 μm, p = 0.024). Stents eluting RA, a non-cytotoxic drug, were not related with thrombus formation and had an acceptable degree of stenosis 4 weeks post implantation. RA dose and type of polymer may play role in the biocompatibility of the stents

ARTEMIS IV RADIO OBSERVATIONS OF THE 14 JULY 2000 LARGE SOLAR EVENT

Abstract. In this report we present a complex metric burst, associated with the 14 July 2000 major solar event, recorded by the ARTEMIS-IV radio spectrograph at Thermopylae. Additional spaceborne and Earth-bound observational data are used, in order to identify and analyze the diverse, yet associated, processes during this event. The emission at metric wavelengths consisted of broad-band continua including a moving and a stationary type IV, impulsive bursts and pulsating structures. The principal release of energetic electrons in the corona was 15–20 min after the start of the flare, in a period when the flare emission spread rapidly eastwards and a hard X-ray peak occurred. Backward extrapolation of the CME also puts its origin in the same time interval, however, the uncertainty of the extrapolation does not allow us to associate the CME with any particular radio or X-ray signature. Finally, we present high time and spectral resolution observations of pulsations and fiber bursts, together with a preliminary statistical analysis. 1