湿地甲烷氧化测定方法及主要控制因子研究综述

湿地甲烷氧化是控制湿地甲烷通量的重要因子.本文对湿地甲烷氧化的测定方法与主要控制因子进行了综述.湿地甲烷氧化的测定方法主要包括未添加甲烷氧化抑制剂培养法和添加甲烷氧化抑制剂培养法.湿地甲烷氧化是诸多因子综合作用的结果,控制湿地甲烷氧化的因子包括湿地生态系统类型、温度、土壤湿度、底物、pH值等.比较而言,底物的浓度(甲烷和氧化性物质)以及土壤湿度是更为重要的环境因子.     

海洋天然气水合物的地球物理研究(III):似海底反射

对天然气水合物研究中与似海底反射有关的一些观点进行讨论 ,以推动天然气水合物地震研究的认识 .30年的似海底反射研究表明 ,似海底反射仍然是指示天然气水合物沉积存在的最好手段之一 .有似海底反射 ,是可以认为存在天然气水合物的 .虽然存在“游离气带速度模型”与“水合物楔速度模型” ,但似海底反射主要由天然气水合物稳定带底界下方的游离气引起 .BSR上方的天然气水合物、下方的游离气与天然气再循环和含甲烷的流体流有关 .由于天然气水合物稳定带计算控制因素难以准确确定等因素 ,似海底反射与天然气水合物稳定带底界只是近似的对应关系 .需从动态的观点考虑天然气水合物 天然气体系及其与似海底反射的关系 .     

Detection of transient high frequency optical oscillations of the flare star YZ CMin

In this paper we present the results of the analysis of the B ‐light curve for the flares of the red dwarf YZ CMin (dM4.5e), which were observed on February of 2002, with the help of the 30‐inch Cassegrain telescope of the Stephanion Observatory, Greece. Discrete Fourier Transform analysis and the use of the Brownian Walk noise enable us to estimate the proper random noise and detect possible weak transient optical oscillations. Our results indicate that: (1) Transient high frequency oscillations occur during the flare event and during the quiet‐star phase as well. (2) The observed frequencies range between 0.0083 Hz (period 2 min) and 0.3 Hz (period 3 s) is not rigorously bounded. The phenomenon is most pronounced during the flare state. (3) During the flare state: (a) Oscillations with period 2 to 1.5 min, 60 s, 11 s, 7.5 s, and 4 s appear around the maximum light state and persist during the whole flare state, (b) from the flare maximum phase on, a progressive increase of oscillations with periods 30 s, 20 s down to 4.0 s is markedly indicated, and (c) at the end of the flare only the oscillation of the pre‐flare state do remain. Our observations are consistent with the phenomenology of impulsively exited oscillations on a coronal magnetic loop and subsequent chromospheric heating by electronic flux at the foot of the loop or/and by soft X‐ray coronal emission. Our observation give evidence that more than one impulsive events may occur in the course of an observed flare (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the global structure of self-gravitating discs for softened gravity

The effects of gravitational softening on the global structure of self-gravitating discs in centrifugal equilibrium are examined in relation to hydrodynamical/gravitational simulations. The one-parameter spline softening proposed by Hernquist & Katz is used.
It is found that if the characteristic size of a disc, r , is comparable to or less than the gravitational softening length, ε, then the cross-section of the simulated disc is significantly larger than that of a no-softening (Newtonian) disc with the same mass and angular momentum.
We demonstrate, furthermore, that if r ≲ε/2 then the scaling relation r ∝ε^3/4 holds for a given mass and specific angular momentum distribution with mass. Finally, we compare some of the theoretical results obtained in this paper and a previous one with the results of numerical Tree-SPH simulations and find qualitative agreement.     

BHαBAR: big Hα kinematical sample of barred spiral galaxies – I. Fabry–Perot observations of 21 galaxies

We present the Hα gas kinematics of 21 representative barred spiral galaxies belonging to the BHαBAR sample. The galaxies were observed with FaNTOmM, a Fabry–Perot integral-field spectrometer, on three different telescopes. The three-dimensional data cubes were processed through a robust pipeline with the aim of providing the most homogeneous and accurate data set possible useful for further analysis. The data cubes were spatially binned to a constant signal-to-noise ratio, typically around 7. Maps of the monochromatic Hα emission line and of the velocity field were generated and the kinematical parameters were derived for the whole sample using tilted-ring models. The photometrical and kinematical parameters (position angle of the major axis, inclination, systemic velocity and kinematical centre) are in relative good agreement, except perhaps for the later-type spirals.