Constraining the nature of dark energy using the Square Kilometer Array Telescope     

A. Torres-Rodríguez  C. M. Cress 《Monthly notices of the Royal Astronomical Society》2007,376(4):1831-1837

We investigate the potential of the Square Kilometer Array Telescope (SKA) to constrain the sound speed of dark energy. The Integrated Sachs Wolfe (ISW) effect results in a significant power spectrum signal when Cosmic Microwave Background (CMB) temperature anisotropies are cross-correlated with galaxies detectable with the SKA in H  i . We consider using this measurement, the autocorrelation of H  i galaxies and the CMB temperature power spectrum to derive constraints on the sound speed. We study the contributions to the cross-correlation signal made by galaxies at different redshifts and use redshift tomography to improve the signal-to-noise. We use a  χ²  analysis to estimate the significance of detecting a sound speed different from that expected in quintessence models, finding that there is potential to distinguish very low sound speeds from the quintessence value.  相似文献   

Genus topology of the cosmic microwave background from the WMAP 3-year data     

J. Richard Gott  III    Wesley N. Colley &#;  Chan-Gyung Park  Changbom Park  Charles Mugnolo 《Monthly notices of the Royal Astronomical Society》2007,377(4):1668-1678

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Very deep X-ray observations of the anomalous X-ray pulsar 4U 0142+614     

N. Rea  E. Nichelli  G. L. Israel  R. Perna  T. Oosterbroek  A. N. Parmar  R. Turolla  S. Campana  L. Stella  S. Zane  L. Angelini 《Monthly notices of the Royal Astronomical Society》2007,381(1):293-300

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中子活化测井在萤石矿勘探中应用效果          下载免费PDF全文

师立谱  徐风曾  王世传 《山东国土资源》1990,(2)

本文简要叙述了中子活化测井原位测定萤石矿(CaF_2)含量的原理及方法技术,以及在两个萤石矿区试生产的成果实例。并着重指出: 1.该方法适用于各种不同类型的萤石矿。选择F作为CaF_2的特征指示元素,在萤石矿无其它元素干扰,方法反映单解。 2.工作证明:该方法可防止由于岩矿心破碎造成的地质取心中漏失的矿体,发现地质工作未确定的薄矿层。并能提供CaF_2含量。 3.在取心率很低的钻孔,提供了真实可靠的CaF_2含量和矿层上下顶板确切位置,避免了钻孔报废、取得了良好的经济效益。最后文章指出:该方法的精度、灵敏度和工作效率完全满足生产工作的需要。  相似文献   

Similarity of new palaeomagnetic data from the Santa Rosa Mountains with those from Steens Mountain gives wide regional evidence for a two-stage process of geomagnetic field reversal     

Neil Roberts  Mike Fuller 《Geophysical Journal International》1990,100(3):521-526

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Effect of parallel electric field on electrostatic ion-cyclotron instability in anisotropic plasma in the presence of ion beam and general distribution function—Particle aspect analysis     

Ruchi Mishra 《Planetary and Space Science》2006,54(2):188-199

Dispersion relation, resonant energy transferred, growth rate and marginal instability criteria for the electrostatic ion-cyclotron wave with general loss-cone distribution in low-β anisotropic, homogeneous plasma in the auroral acceleration region are discussed by investigating the trajectories of the charged particles. Effects of the parallel electric field, ion beam velocity, steepness of the loss-cone distribution and temperature anisotropy on resonant energy transferred and growth rate of the instability are discussed. It is found that the effect of the parallel electric field is to stabilize the wave and enhance the transverse acceleration of ions whereas the effect of steepness of loss-cone, ion beam velocity and the temperature anisotropy is to enhance the growth rate and decrease the transverse acceleration of ions. The steepness of the loss-cone also introduces a peak in the growth rate which shifts towards the lower side of the perpendicular wave number with the increasing steepness of the loss-cone.  相似文献   

The dependence of clustering on galaxy properties     

Cheng Li  Guinevere Kauffmann  Y. P. Jing  Simon D. M. White  Gerhard Börner  F. Z. Cheng 《Monthly notices of the Royal Astronomical Society》2006,368(1):21-36

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Comments on the size of the simulation box in cosmological N-body simulations     

J. S. Bagla  Suryadeep Ray 《Monthly notices of the Royal Astronomical Society》2005,358(3):1076-1082

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便携式高频地波雷达台湾海峡浪高观测   总被引：2，自引：1，他引：1  

ZHOU Hao  ROARTY Hugh  WEN Biyang 《海洋学报(英文版)》2015,34(1):73-78

As an important equipment for sea state remote sensing, high frequency surface wave radar(HFSWR) has received more and more attention. The conventional method for wave height inversion is based on the ratio of the integration of the second-order spectral continuum to that of the first-order region, where the strong external noise and the incorrect delineation of the first- and second-order Doppler spectral regions due to spectral aliasing are two major sources of errors in the wave height. To account for these factors, two more indices are introduced to the wave height estimation, i.e., the ratio of the maximum power of the second-order continuum to that of the Bragg spectral region(RSCB) and the ratio of the power of the second harmonic peak to that of the Bragg peak(RSHB). Both indices also have a strong correlation with the underlying wave height. On the basis of all these indices an empirical model is proposed to estimate the wave height. This method has been used in a three-months long experiment of the ocean state measuring and analyzing radar, type S(OSMAR-S), which is a portable HFSWR with compact cross-loop/monopole receive antennas developed by Wuhan University since 2006. During the experiment in the Taiwan Strait, the significant wave height varied from 0 to 5 m. The significant wave heights estimated by the OSMAR-S correlate well with the data provided by the Oceanweather Inc. for comparison, with a correlation coefficient of 0.74 and a root mean square error(RMSE) of 0.77 m. The proposed method has made an effective improvement to the wave height estimation and thus a further step toward operational use of the OSMAR-S in the wave height extraction.  相似文献   

应用实时定量PCR技术检测秦皇岛近岸海域褐潮原因种——抑食金球藻(Aureococcus anophagefferens)     

GUO Hao  LIU Yongjian  ZHANG Qi  YUAN Xiutang  ZHANG Weiwei  ZHANG Zhifeng 《海洋学报(英文版)》2015,34(2):132-136

Aureococcus anophagefferens, a small pelagophyte algae, has caused brown tide blooms in coastal waters of Qinhuangdao in recent years, presenting significant negative impacts on the shellfish mariculture industry. Under standard light microscopy, it is visually indistinguishable from other small algae in field samples due to its extremely small size. In this study, quantitative polymerase chain reaction(q PCR) based on 18 S r DNA sequences was developed and used to detect and enumerate A. anophagefferens. A linear regression(R2 = 0.91) was generated based on cycle thresholds value(Ct) versus known concentrations of A. anophagefferens. Twenty-two field samples collected in coastal waters of Qinhuangdao were subjected to DNA extraction and then analyzed using q PCR. Results showed that A. anophagefferens had a wide distribution in coastal waters along Qinhuangdao. Elevated A. anophagefferens abundance, category 3 brown tide blooms(200 000 cells/m L) occurred at Dongshan Beach and Tiger-stone Beach in August in 2013. In shellfish mariculture areas along coastal waters of Qinhuangdao, 4 stations had category 3 blooms, and 6 stations had category 2 blooms(35 000–200 000 cells/m L) in August and all stations had category 1 blooms(0 to ≤35 000 cells/m L) in October. Quantitative PCR allows for detection of A. anophagefferens cells at low levels in filed samples, which is essential to effective management and prediction of brown tide blooms.  相似文献