In this work we present the first results of study and comparison of the parameters of quasi-periodic long-term oscillations of microwave emission of large (>0.7 arcmin) sunspots as a result of simultaneous observations with two radioheliographs – NoRH (17 GHz) and Siberian Solar Radio Telescope (SSRT) (5.7 GHz) with 1 minute cadence. Radioheliographs have been working with quite large time overlap (about 5 hours) and have the high spatial resolution: 10 arcsec (NoRH) and 20 arcsec (SSRT). We have found that quasi-periodic long-term oscillations are surely observed at both frequencies with the periods in the range of 20–150 min. We detected common periods for common time of observations with two radioheliographs and interpret this as the consequence of the vertical-radial quasi-periodic displacements of sunspot as a whole structure.

The observations of 3 and 5 minute oscillations in sunspots present information on propagation of MHD waves in the magnetic tubes of sunspots. We present a comparison of wavelet spectra of radio flux oscillations at λ = 1.76 cm and oscillations of longitudinal component of the velocity at the chromosphere in sunspot umbra and penumbra in AR 10661 (2004, Aug 18). The radio maps of the Sun obtained with the Nobeyama Radioheliograph were used. The spatial resolution of the radio data was about 10-15 arcsec, and 10 sec cadence was used. On the radio maps sunspot-associated sources were identified and time profiles of their maximum brightness temperatures for each radio source were calculated. Radio data consists of information of oscillations of plasma parameters (in the regions with magnetic field B = 2000 G) at the level of the chromosphere-corona transition region. The optical observations were carried out at Sayan observatory. These data included information on longitude component of the magnetic field at the photosphere (line Fe I 6569 Å) and longitudinal component of the velocity at the chromosphere (line Hα was used). Comparing the wavelet diagrams covering the same periods of observations at radio and optics showed that some wave trains of time profiles are very similar in both kinds of observations (similar oscillation frequencies and their drifts, variations of amplitudes), however, some significant differences were also registered. The best similarity in optical and radio oscillations was found when the active region (AR) was near the center of the solar disk. The phase shifts between the two kinds of observations reflecting the propagation of MHD waves were also analyzed.

To investigate two clusters of diarrhoea cases observed in our geriatric hospital wards, the faecal specimens were analysed. Reversed passive latex agglutination assay revealed that 63·2% and 41·7% of the faecal specimens from each cluster were positive for Clostridium perfringens enterotoxin. PCR assay revealed that 71·4% and 68·8% of C. perfringens isolates from each cluster were positive for the enterotoxin gene (cpe). These observations suggested that both the clusters were outbreaks caused by enterotoxigenic C. perfringens. Subsequent pulsed-field gel electrophoresis analysis revealed that the two outbreaks were caused by different C. perfringens isolates. However, these outbreak isolates as well as other sporadic diarrhoea isolates shared a 75-kb plasmid on which the cpe gene and the tcp locus were located. The 75-kb plasmid had horizontally spread to various C. perfringens isolates and had caused outbreaks and sporadic infections. However, the site and time of the plasmid transfer are unclear.

Using multi-spectral data, we estimate plasma parameters in the post-eruptive arcade observed on October 22, 2001 at 100 Mm above the limb: the temperature is 6 MK and the plasma density is $(5-9) \cdot 10^9$ cm$^{-3}$. We state a problem of the long-term equilibrium of the hot top of the arcade high in the corona: either the magnetic field surrounding the arcade well exceeds that one extrapolated in the potential approximation, or $\beta > 1$ both inside and outside the arcade. A downflow observed in soft X-rays can contribute to the equilibrium.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

As based on analysis of radio maps at the wavelength of 1.76 cm obtained from observations at the radio heliograph Nobeyama the parameters of oscillation processes in solar active regions were studied. As a technique for data processing wavelet analysis was used. The inherent periodicity in oscillations submits the existence of a resonance structure for some kinds of MHD waves in the plasma of the solar atmosphere.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We provide an observational proof of the existence of the global sausage mode oscillations in a flaring loop studying a microwave burst with quasi-periodical pulsations observed with the Nobeyama Radioheliograph (NoRH).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We report on the statistical properties of the microwave enhancement (brightness temperature, area, fine structure, life time and magnetic field strength) in coronal holes observed over a period of several solar rotations.

A high time- and spatial-resolution radio interferometer for solar observations has been constructed at Nobeyama (Figure I.; Nakajima et al. 1994). The Nobeyama Radioheliograph consists of 84 antennas, 0.8m in diameter, arranged on a T-shape lines of 500m in the EW and 220m in the NS directions. The time resolution is 50 ms and the spatial resolution is 10”. The field of view is 40’ at the observing frequency 17GHz, which enables us to watch the whole sun. The radioheliograph has observed hundreds of flares during the few months since the beginning of regular observations in July ‘92, and such powerful performance has never before been demonstrated in the history of solar radio observations.