Periodicity in spectral variations of IC 4997?

The emission lines in the spectra of some planetary nebula experience variations with the time. These variations (due to evolution effects and by their nature) differ from the spectral changes which we usually observe in stars. It appears that the long-scale and systematic observations on the intensity behaviour of different emission lines of nebula may be used as an independent indicator to receive a principally new and quite unpredicted category of information related to the physics of nebulae and their nuclei. Particularly, the analysis of long standing observations carried out in relation to the forbidden lines 4363 [Oiii] andN ₁+N ₂ [Oiii] of double-ionized oxygen lead to a conception about the possible existence ofrelativistic electrons of moderate energy in planetary nebulae and the generation oftransition radiation as a result of electrodynamic interaction of these electrons with the dust particles in nebula (Gurzadyan, 1991). Just on the basis of the same observational material, the long-scale periodicity in the activity or variations of a star-like planetary nebula IC 4997 is discovered about which is the present note.     

A study on quality of aquatic environment in Tumen River Area

After the survey of pollution sources, a study on surface water quality assessment and forecast is given by means of grey system method, fuzzy mathematical method and multiple-index method. Based on it, aquatic environment quality features, treatment measures and environmental strategies of the area are proposed. The quality of aquatic environment of 5 rivers in the Tumen River area is studied. The results show that the pollution of surface water is serious; water quality of most rivers is between grade IV and V except the Hunchun River, being higher than grade IV standard; pollution levels of most rivers have been basically controlled except the of Burhatong River, which is deteriorating gradually. Pollutants of the rivers are comparatively regular, mainly are SS, COD, BOD, AR-OH, NH₃-N. The main pollution trades are chemical fibre industry, pulp and paper making industry and mining industry. If the growth rate of gross industrial product is higher than 25 percent under the encouraging-model of regional exploitation, the pollutants’ load will overtake the bearing capacity of aquatic environment. Thus some protection program against pollution must be worked out in order to achieve the harmonious development of economy society and environment. A project from “Studies on Earlier Stage of Regional Development” of the Chinese Academy of Sciences     

Isotopic evidence for holocene climatic changes in Bosten Lake, Southern Xinjiang, China

Based on the δ¹³C and δ¹⁸O fluctuation of lacustrine carbonate, CaCO₃ content and sporo-pollen data, a palaeoclimatic history of Bosten Lake during the Holocene has been outlined, several stages of climatic changes are divided, and the following result es are obtained: (1) Palaeoclimatic changes revealed by carbonate isotope around Bosten Lake are basically identical with that revealed by other geological records in Xinjiang. Environmental changes presented apparent Westlies Style model: during cold period, relative humidity increased, δ¹⁸O, δ¹³C and CaCO₃ appeared low; but in warm periods, the dry regime aggravated. (2) The temperature reflected by δ¹⁸O exist evident features being increase in the late period during the Holocene. Together with the δ¹³C, pollen and CaCO₃ analyses, several cold and warm phases which are of broad regional significance can be identified. The warm peaks occurred at about 11.0 ka B.P., 9.4 ka B.P., 7.5 ka B.P., 5.0 ka B.P., 3.0 ka B.P. and 2.0 ka B.P.; the cold peaks at 11.5 ka B.P., 10.5 ka B.P., 8.8 ka B.P., 5.5 ka B.P., 3.3 ka B.P., 2.2 ka B.P. and 1.5 ka B.P.. (3) Several climatic events with the nature of “abrupt climatic changes” are revealed in the periods of 11.0 ka B.P. −10.5 ka B.P., 9.4 ka B.P. −8.8 ka B.P., 5.5 ka B.P. −5.0 ka B.P. and 2.0 ka B.P. −1.5 ka B.P.. (4) The results show that carbonate isotopic record of lacustrine sediment in arid area is very sensitive to climatic changes, and may be play a very important role in understanding the features and mechanism of palaeoclimatic changes.     

Line-of-sight magnetic flux imbalances caused by electric currents

Several physical and observational effects may contribute to the significant imbalances of magnetic flux that are often observed in active regions. We consider an effect not previously treated: the influence of electric currents in the photosphere. Electric currents can cause a line-of-sight flux imbalance because of the directionality of the magnetic field they produce. Currents associated with magnetic flux tubes produce larger imbalances than do smoothly-varying distributions of flux and current. We estimate the magnitude of this effect for current densities, total currents, and magnetic geometry consistent with observations. The expected imbalances lie approximately in the range 0–15%, depending on the character of the current-carrying fields and the angle from which they are viewed. Observationally, current-induced flux imbalances could be indicated by a statistical dependence of the imbalance on angular distance from disk center. A general study of magnetic flux balance in active regions is needed to determine the relative importance of other - probably larger -effects such as dilute flux (too weak to measure or rendered invisible by radiative transfer effects), merging with weak background fields, and long-range connections between active regions.Operated for the National Science Foundation by the Association of Universities for Research in Astronomy.     

Magnetic field and differential rotation in the radiative zone of the Sun

The problem of the interaction between magnetic fields and differential rotation in the radiative zone of the Sun is investigated. It is demonstrated that effects of magnetic buoyancy can be neglected in the analysis of this interaction. It is shown that hydromagnetic torsional waves propagating from the solar core cannot be responsible for the 22-year solar cycle. A possible geometry of the magnetic field that conforms with stationary differential rotation is considered. A verifying method for hypotheses on the structure of the magnetic field and torsional oscillations in the radiative zone of the Sun is proposed based on helioseismic data.     

西宁盆地泥石流类型及其防治意见

概略地叙述了西宁地区的泥石流形成条件和形成机理,并将西宁地区泥石流划分为稀性泥石流类及泥石质泥石流种类。在此基础上提出防治泥石流灾害的意见。     

Recent warming in southeastern Zaire (Central Africa) inferred from disturbed geothermal gradients

Several temperature-depth profiles measured in Kasai and in Shaba provinces of Zaire using mining exploration boreholes exhibit a significant negative temperature gradient near the surface. This anomalous curvature which extends to 100–200 m depth could reflect the effect of variations in surface conditions. Applying the theory of heat conduction in a semi-infinite homogeneous medium, these profiles indicate a surface warming by 3–4°C. This warming is related to the effect of the environmental changes associated with the mining exploitation and the urbanization during the last 40–90 years.