Chromospheric evolution and the flare activity of super-active region NOAA 6555

Super-active region NOAA 6555 was highly flare productive during the period March 21st–27th, 1991 of its disk passage. We have st udied its chromospheric activity using high spatial resolution Hα filtergrams taken at Udaipur along with MSFC vector magnetograms. A possible relationship of flare productivity and the variation in shear has been explored. Flares were generally seen in those subareas of the active region which possessed closed magnetic field configuration, whereas only minor flares and/or surges occurred in subareas showing open magnetic field configuration. Physical mechanisms responsible for the observed surges are also discussed.     

Upwelling and river runoff as sources of dissolved nitrous oxide to the Alsea estuary,Oregon

Surface waters of Alsea Bay, an unpolluted estuary on the Oregon coast, were analysed for nitrous oxide, nitrate and nitrite on a weekly or biweekly basis during the summer of 1979. The estuary was found to be a variable source of N₂O to the atmosphere. Large and rapid increases in the concentrations of N₂O, NO₃^?, and NO₂^? occurred at the beginning of the sampling period and are attributed to the influx of nutrient-rich upwelling water into the estuary with the tide. The subsequent decline in concentrations of nitrate, nitrite and nitrous oxide over the remainder of the summer is attributed to a decrease in upwelling intensity, a decline in nitrification rates and to assimilatory nitrate reduction. Measurements of nitrous oxide at six stations along the Alsea River were also made in September and October before and after the onset of the rainy season. Samples taken after flood conditions were established were systematically 50% higher than pre-flood samples. The data suggest that soil runoff results in elevated concentrations of N₂O in rivers.     

VLA and MERLIN observations of RZ Cassiopeiae

We present radio interferometric observations of the Algol-type binary system RZ Cassiopeiae made with the VLA and MERLIN arrays at 6 cm over an incomplete orbital cycle of the system (1.195 d). We detected RZ Cas with both instruments. The images were unresolved in both cases, with angular extents comparable to the synthesized beams. The peak flux density in the VLA image was 1.14 mJy beam⁻¹ and in the MERLIN image it was 0.93 mJy beam⁻¹. The derived brightness temperatures are  4.02 × 10⁸  and  4.35 × 10⁸ K  and the effective electron energies are 0.347 and 0.346 MeV for the MERLIN and VLA data respectively. The radio light curve shows an interesting modulation centred close to the primary eclipse which seems to correlate with ASCA SIS observations of the system. The results can be interpreted as an emitting region on the outer hemisphere of the cool component aligned along the centroid axis of the binary system.     

全球Ms≥7￣3／4级地震的定向迁移

对全球尺度的６条大地震带内１９００～１９９０年中１８４次Ｍｓ≥７３／４级地震进行了沿地震带方向定向迁移的分析，获得了全球统一的地震定向迁移规律，总体是由西向东，迁移速度由７００ｋｍ／ａ变为１５０ｋｍ／ａ，此现象可以作多种暂态地球动力作用过程的推论，如以大西洋脊间歇式张裂引起上地幔软流物质自西向东运动，呈现纵波式的振荡传播；也可解释为非洲板块、阿拉伯板块和印度板块自西南向东北对欧亚地震带依次的推压引起向东的应变波的传播；太平洋脊两侧洋底板块向西北和东北两侧的斜向推压，可能是造成两侧地震带地震向北迁移的触发源     

Alkaline Phosphatase Activity in the Red-Tide Dinoflagellate, Ptychodiscus brevis

Abstract. Alkaline phosphatase activity (APA) was found in a nearshore, natural population of the red-tide dinoflagellate Ptychodiscus brevis. Initial hydrolysis rates were enhanced by two orders of magnitude within 24 h upon addition of ammonium. Other nutrient (additions) or no additions also lead to a higher, although less pronounced increase in activity. Enhanced growth after nutrient additions combined with specific APA indicated that the bloom was both N and P limited. Since the natural population was a mixture of diatoms and the dinoflagellate, APA was also measured in unialgal cultures of P. brevis. APA was not reduced but enhanced by the addition of low concentrations of orthophosphate (0.5 and 1 μM). Higher orthophosphate concentrations (5 to 20 μM) reduced APA, although activity returned to control levels within 2 to 6h. Repression occurred within 30 sec after a 20 μM orthophosphate addition. Cells which had APA repressed by an orthophosphate addition regained their initial activity within 2 h after washing with phosphate-free media. Phosphorus-deficient cells of P. brevis possess an alkaline phosphatase system which is capable of continued activity at low in situ orthophosphate levels.     

地层学的发展推动油气地质理论研究的进步

自上个世纪50年代以来,地层学经历了彻底的变革,逐渐由“相模式”、“沉积体系”、“地震地层学”发展到目前的“层序地层学”,形成高分辨率层序地层学和事件地层学的理论体系和研究方法。文章围绕层序地层学、高分辨率层序地层学基本方法及理论体系,与含油气系统相关关系进行了讨论。