203 research outputs found
Periodicities in the Daily Proton Fluxes from 2011 to 2019 Measured by the Alpha Magnetic Spectrometer on the International Space Station from 1 to 100 GV
We present the precision measurement of the daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total of 2824 days or 114 Bartels rotations) in the rigidity interval from 1 to 100 GV based on 5.5×109 protons collected with the Alpha Magnetic Spectrometer aboard the International Space Station. The proton fluxes exhibit variations on multiple timescales. From 2014 to 2018, we observed recurrent flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. The rigidity dependence of the 27-day periodicity is different from the rigidity dependences of 9-day and 13.5-day periods. Unexpectedly, the strength of 9-day and 13.5-day periodicities increases with increasing rigidities up to ∼10 GV and ∼20 GV, respectively. Then the strength of the periodicities decreases with increasing rigidity up to 100 GV.</p
Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station
A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.</p
Transcriptomics Research in Chicken
The chicken (Gallus gallus) is an important model organism in genetics, developmental biology, immunology and evolutionary research. Moreover, besides being an important model organism the chicken is also a very important agricultural species and an important source of food (eggs and meat). The availability of the draft chicken genome sequence provided many possibilities to in detail study a variety of genomic changes during evolution using a comparison between chicken and mammals. For example, compared to mammals, the use of a Z/W sex determination system is a special aspect of the avian genome where the female is the heterogametic sex (ZW) and the male is the homogametic (ZZ) sex. A comparison of the genomic sequences of platypus, chicken and human showed that sex chromosomes evolved separately in birds and mammal
Study on the Pollution Characteristics of Heavy Metals in Seawater of Jinzhou Bay
AbstractThe Jinzhou Bay is one of the bays polluted heavily by the heavy metals. Twenty surface seawater samples were collected to analyze the dissolved and particulate concentrations of Cu, Pb, Zn, Cd, Hg and As using the methods of Atomic Absorption and Atomic Fluorescence. The heavy metal distribution characteristics, influencing mechanism and the distribution ratio between particulate and dissolved state were analyzed. The results showed that the concentration of Cd in 25% stations was higher than the first standard value of sea water quality. The concentration of As was lower than the standard value in all stations. The concentration of dissolved heavy metal was highest in west closer to the land and Wuli River estuary, and decreased from west to east. There was lower value area of heavy metals like tongue caused by the tidal. The particulate Pb concentration accounted for 83.00% in total concentration, and the other heavy metals in particulate state were lower than that in the dissolved state. The pollution of the particulate heavy metals was becoming more and more serious from open sea to offshore marine areas. Therefore the heavy metals distribution in the Bay was affected not only by the coastal pollutants but also by the hydrodynamic factors
Mercury Emission Flux in the Jiaozhou Bay Measured by Flux Chamber
AbstractIn November 2009, April 2010, July 2010, October 2010, at a fixed-station of the Jiaozhou Bay, the gaseous element mercury which emitted from seawater was captured by dynamic flux chamber (DFC), together with double gold amalgam coupled technique to measure the mercury emission flux. Results showed that the mercury emission fluxes at sea/air interface were -0.78∼1.72ng/(m2 ·h) in November 2009, -0.24∼1.32ng/(m2 ·h) in April 2010, -0.46∼2.21ng/(m2 ·h) in July 2010, -0.15∼2.18ng/(m2 ·h) in October 2010 respectively. In the Jiaozhou Bay, the mercury emitted from sea to air during the day, and was higher in summer and autumn than that in spring and winter. In winter, the mercury emission flux appeared the character of diurnal variance, with the highest value at noon. But in summer and autumn, the highest value appeared at the end of ebb tide due to tidal action. The main environment factor affecting the mercury emission flux at sea/air interface was light intensity. The influence of the tidal movement on the mercury emission flux was different in different seasons
Study of average valence and valence electron distribution of several oxides using X-ray photoelectron spectra
X-ray photoelectron spectra of the O 1s electrons of MnFe2O4, ZnFe2O4, ZnO, and CaO were used to estimate the average valence, ValO, of the oxygen anions in these samples. The absolute values of ValO for these samples were found to be distinctly lower than the traditional value of 2.0, suggesting that the total average valences of the cations are also lower than the conventionally accepted values owing to valence balance in the compounds. In addition, we analyzed the valence band spectra of the samples and investigated the distribution characteristics of the valence electrons. Keywords: Spinel ferrite, X-ray photoelectron spectra, Valence electron, Average valence, Ionization energ
Identification and Mitigation of Error in the Terzaghi Bias Correction for Inhomogeneous Material Discontinuities
Use of the scanline mapping technique in geometric surveys of rock discontinuities can often lead to a bias, in that discontinuities are not always observed when they are at small angles to the scanline. Terzaghi introduced the concept of a blind zone to explain this bias, and developed a widely used procedure to correct for it. Unfortunately, little is known about errors that may occur when the Terzaghi procedure is used outside the blind zone. This paper presents a detailed derivation to show that such errors arise with this application of the Terzaghi procedure. This error was evaluated using simulated orientation data and a case study at Wenchuan, Sichuan, China (2008). The results of these tests suggest optimal values of grid size and sample density for reducing the error.Анализ несплошностей в скальных породах с помощью сканирующей методики картирования часто приводит к погрешностям, в результате чего оказываются незамеченными несплошности, находящиеся под малым углом к линии сканирования. Концепция слепой зоны , предложенная Терцаги, позволила объяснить природу этих погрешностей и минимизировать их по предложенной методике. Однако малоизвестно, что применение последней вне слепой зоны также приводит к возникновению погрешностей. Детально проанализированы погрешности при использовании метода Терцаги для модельного материала скальной породы из эпицентра земелетрясения 2008 года в местности Вэньчуань (провинция Сычуань, Китай). Предложены оптимальные параметры расчетной сетки и плотности образца для минимизации погрешностей.Аналіз несуцільностей в скельових породах за допомогою сканувальної методики картування часто призводить до похибки, в результаті чого залишаються непоміченими несуцільності, що знаходяться під малим кутом до лінії сканування. Концепція сліпої зони , запропонована Терцагі, дозволила з'ясувати природу цих похибок і мінімізувати їх за запропонованою методикою. Однак маловідомо, що використання останньої поза сліпою зоною також призводить до виникненя похибок. Детально проаналізовано похибки при використанні методу Терцагі для модельного матеріалу скельової породи з епіцентру землетрусу 2008 року у місцевості Веньчуань (провінція Сичуань, Китай). Запропоновано оптимальні параметри розрахунково'ї сітки і щільності зразка для мінімізації похибо
Damages and Failure Features of Liquid Rubber-based Concrete in Statics Tension by 2D Dynamics Numerical Simulation
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