On the height scale of magnetic fields above sunspots derived from RATAN-600 observations

Model calculations of the S-component are compared with observations of the RATAN-600 telescope at five discrete microwave frequencies referring to active region McMath No. 15974 on May 1, 1979. The spectral variations of source diameter, flux density, and degree of polarization are used to derive the height scale of the magnetic field in accordance with a magnetic dipole distribution under the assumption of advanced temperature and electron density distributions according to most recent EUV observations.     

The potassium abundance in the solar photosphere

High precision center-limb spectrograms of the K i resonance doublet line at λ 7699 Å were used to study the line formation and to determine the abundance of potassium in the solar atmosphere. The LTE assumption is not valid for these lines. Synthetic profiles computed in NLTE reproduce very well the observed center-limb line behaviour and yield log? _K = 5.14±0.10 for the solar abundance of potassium (on the scale of log? _H = 12 for Hydrogen).     

On the structure of filaments from centimeter and millimeter observations

From filament observations at centimeter and millimeter wavelengths it is shown that the transition layer between the dense, cool filamentary material and the ambient hot, rarified corona is rather thin, of the order of some hundred kilometers. Hence, the difference in the sizes of filaments in the radio and optical domains is of the order of 1000 km or 2, thus not detectable by the instruments so far used for observations of filaments.NASINRC Resident Research Associate at NASA-GSFC.     

Diurnal variation of electron density in Saturn’s ionosphere: Model comparisons with Saturn Electrostatic Discharge (SED) observations

Using the Saturn Thermosphere Ionosphere Model (STIM), we present a study of the diurnal variation of electron density, with a focus on comparisons with peak electron densities (N_MAX) inferred from the low-frequency cutoff of radio emission due to lightning in the lower atmosphere, called Saturn Electrostatic Discharges (SEDs). It is demonstrated that photochemistry in Saturn’s ionosphere cannot reproduce the SED-inferred diurnal variation in N_MAX unless additional production and loss sources outside of the current best estimates are considered. Additional explanations of the SED-inferred diurnal variation of N_MAX are presented and analyzed, such as the possibility that the low-frequency cutoff seen in SEDs is due to the presence of sharp low-altitude layers of plasma, as frequently seen in radio occultation measurements. Finally, we outline the observational constraints that must be fulfilled by any candidate explanations of the SED-inferred diurnal variation of N_MAX.     

Astrophysical and structural parameters of the open clusters NGC 6866, NGC 7062, and NGC 2360

We derive astrophysical and structural parameters of the poorly studied open clusters NGC 6866, NGC 7062, and NGC 2360 based on filtered 2MASS (J, J ? H) diagrams, and stellar radial density profiles. The field star decontamination technique is utilised for selecting high-probability cluster members. The E(B ? V) reddening values of the three clusters derived from 2MASS JHK_s agree with those inferred from UBV and uvby ? β photometries. We find that the core mass function slopes are flatter than the halo’s for the three clusters. The large core and cluster radii of NGC 6866 and NGC 2360 indicate an expanded core, which may suggest the presence of stellar mass black-holes. NGC 2360 is located in the third quadrant (? = 229°.80), where Giant Molecular Clouds are scarce that, together with its relatively large mass (～1800 m_⊙), might explain its longevity (～1.8 Gyr) in the Galaxy.     

The Spectrum and Dips of RE 0751+14: A Joint Evaluation of ROSAT and ASCA Archival Data

Using archival ASCA and ROSAT observations of RE 0751+14, X- ray energy spectra, pulse profiles and the results of pulse timing analysis are presented. The energy spectra are well-fitted by a blackbody model at low energy and a Raymond-Smith model at high energy, together with a partial covering absorber. A fluorescence emission line at 6.4 keV with an equivalent width ∼ 220 eV was resolved for the first time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transcriptome profile of Dunaliella salina in Yuncheng Salt Lake reveals salt-stress-related genes under different salinity stresses

Journal of Oceanology and Limnology - Salt stress is an abiotic stress to plants in especially saline lakes. Dunaliella, a halophilic microalga distributed throughout salt lakes and seas, can...     

EVIDENCE OF NEOTECTONIC IMPACT ON A LARGE SEDIMENTARY BASIN BETWEEN TIBETAN PLATEAU AND GOBI ALTAY,NW CHINA

The Ejina(Gaxun Nur)Basin­enclosed by the Tibetan Plateau in the south and the Gobi Altay in the north has continuously evolved as a strong continental endorheic depositional environment. Medium scale geomorphological mapping by Landsat­ and Corona­Images as well as SRTM­topographic data,combined with field­surveys and geophysical investigation provides evidence for tectonic impact on sedimentary processes during the Late Quaternary.
Analyses of SRTM­Data and Landsat­Images reveal a system of up to 20m high inverted channels developed on the inactive eastern part of the large Hei river drainage delta south of the ancient lake Juyanze. The complex evolution of these landforms requires a relative lowering of the lake basin at least two times since the last 40ka. A 26m high cliff section of gravel­covered lake sediments within the Juyanze paleolake indicates a strong subsidence of the lake bottom of 10m/1000yrs since 18kaB.P.
North of Ejina river oasis a distinct north­south striking scarp up to 13m high constitutes the eastern margin of the Gaxun Nur. Palaeodrainage channels derived from the Gobi Altay. They display a sinistral offset of some decametres along a set of WE­trending faults. The rhombic shape of the modern dry Gaxun Nur,fossil cliffs,well preserved beach ridges along the margins of the palaeolake system as well as gravel covered topsets of lacustrine sediments indicate local displacements of morphological features. The displacements of lake sediments at the southern margin of the modern Gaxun Nur Basin imply a subsidence of at least 0.81m/1000 yrs since 25kaB.P.as a result of a pull­apart development due to the left stepping faults in a sinistral system.