Decreasing the uncertainty of atomic clocks via real-time noise distinguish

The environmental perturbation on atoms is the key factor restricting the performance of atomic frequency standards, especially in long term scale. In this letter, we demonstrate a real-time noise distinguish operation of atomic clocks. The operation improves the statistical uncertainty by about an order of magnitude of our fountain clock which is deteriorated previously by extra noises. The frequency offset bring by the extra noise is also corrected. The experiment proves the real-time noise distinguish operation can reduce the contribution of ambient noises and improve the uncertainty limit of atomic clocks.Comment: 5 pages, 4 figures, 1 tabl

ДОСЛІДЖЕННЯ МАРКСИЗМУ: АНАЛІТИЧНІ ПІДХОДИ

Стаття присвячена дослідженню марксизму в контексті аналітичних підходів. Розглянуто центральні проблеми марксизму та спроби їх вирішити, спираючись на аналітичну традицію. Стверджується, що аналітичний марксизм не зміг обґрунтувати науковість вчення. Філософські пошуки в аналітичному марксизмі ґрунтуються навколо оцінки значення ключових марксистських ідей: революція, класова боротьба, відчуження, капіталізм

Gamma-Ray Burst Optical Afterglows with Two-Component Jets: Polarization Evolution Revisited

Gamma-ray bursts (GRBs) have been widely argued to originate from binary compact object mergers or core collapses of massive stars. Jets from these systems may have two components, an inner, narrow sub-jet and an outer, wider sub-jet. Such a jet subsequently interacts with its ambient gas, leading to a reverse shock (RS) and a forward shock (FS). The magnetic field in the narrow sub-jet is very likely to be mixed by an ordered component and a random component during the afterglow phase. In this paper, we calculate light curves and polarization evolution of optical afterglows with this mixed magnetic field in the RS region of the narrow sub-jet in a two-component jet model. The resultant light curve has two peaks: an early peak arises from the narrow sub-jet and a late-time rebrightening is due to the wider sub-jet. We find the polarization degree (PD) evolution under such a mixed magnetic field confined in the shock plane is very similar to that under the purely ordered magnetic field condition. The two-dimensional `mixed' magnetic fields confined in the shock plane are essentially the ordered magnetic fields only with different configurations. The position angle (PA) of the two-component jet can change gradually or abruptly by $90^\circ$. In particular, an abrupt $90^\circ$ change of the PA occurs when the PD changes from its decline phase to rise phase.Comment: 21 pages, 6 figures, accepted by Ap

Catalytic oxidation mechanism of methane via transition metals Pt, Pd and Ag

The mechanisms for catalytic oxidation of methane via transition metals Pd, Pt and Ag in gas phase have been theoretically investigated using density functional theory (DFT). The results reveal similar pathways of C-H activation via Pd, Pt with the formation of atom-molecule complex, transition state and product. Catalytic oxidation using Pd and Pt exhibited different reaction energies. The possible pathway of C-H activation via Ag has been proposed. First, the abstraction of H from CH4 by Ag occurs followed by the dissociation of CH3 and AgH. With the calculation of energy parameters and rate constants, the order of catalytic performance of the three transition metals has been found to be Pt>Pd>Ag. A theoretical foundation for the catalytic oxidation of methane by single active atoms has been established

Growth and physiological responses in the sea cucumber, Apostichopus japonicus Selenka: Aestivation and temperature

Aestivation is an adaptation of the sea cucumber Apostichopus japonicus Selenka to high temperature, however, the causations and physiological responses of aestivation are not well understood. This study deals with the relationship between temperature and aestivation. Sea cucumbers were allocated into four treatments. In two treatments of temperature elevation, the ambient temperature gradually was increased from 16 degrees C to 26 degrees C linearly (treatment FA) or by a fluctuating temperature profile (treatment FB). Two control treatments maintained constant temperatures of 16 degrees C and 26 degrees C, and were designated as optimum temperature of growth and threshold of aestivation, respectively. During the 40-day experiment, body weight, oxygen consumption, daily food intake, catalase (CAT) and superoxide dimutase (SOD) activities and heat shock protein 70 (Hsp70) levels were determined periodically. When the temperature gradually increased from 16 degrees C to 26 degrees C, the body weight of the tested sea cucumbers decreased gradually. After the ambient temperature reached 26 degrees C, the tested sea cucumbers in treatments of FA and F13 were reared at 26 degrees C for an additional twenty days. During this period, symptoms of aestivation appeared in the tested sea cucumbers. Activities of antioxidases and Hsp70 levels increased when the ambient temperature increased from 16 degrees C to 26 degrees C, and decreased when the temperature was kept at 26 degrees C. These results indicate that aestivation in A. japonicurs is an adaptive strategy to reduce the production of reactive oxygen species (ROS) and denatured proteins which were induced at high temperature. (C) 2008 Elsevier B.V. All rights reserved

Evaluation of the Ecological Quality of the Taishan Region Based on Landsat Series of Satellite Images

The deterioration of ecological environment has seriously restricted regional sustainable development. Taishan region is one of the ecological protection and restoration of life community of mountains-rivers-forests-farmlands-lakes-grasslands in China. Its ecological quality changes are directly related to the overall layout of ecological restoration and protection projects. In this study, the Taishan region of China was taken as study area, and the grade change, spatial distribution, and spatial temporal fluctuation of the ecological environment quality were quantified. Based on the ENVI platform, the Landsat series of three images of the Taishan region in 2005, 2013, and 2017 serve as the data source, and the remote sensing ecological index model (RSEI) was used. According to the change characteristics of land use types, the driving factors of ecological environmental quality change were analyzed. The results showed that: (1) The area ratio of the ecological environment quality above the middle level was in order from large to small: 2005 (97.37%) > 2017 (91.46%) > 2013 (84.64%). (2) The overall quality of the ecological environment declined during the period of 2005-2013. (3) The overall change ranges from 2013 to 2017 are smaller than those from 2005 to 2013. The area of the deteriorating area decreased by 44.90%, and the area of the constant area and the area of the area that improved increased by 16.17% and 28.72%, respectively. During 2013-2017, the general trend is getting better and better. The improved areas were mainly concentrated in the main urban areas (Taishan District, Daiyue District), eastern Ningyang County, and western Xintai City. The research results can provide a scientific basis for the scientific evaluation of the ecological environment quality during the development and construction of the region, and have important value in the design and application of the ecological environment quality optimization path