Search for a Periodic Signal in the Emission from the Crab Nebula at High Energies     

Nizamov  B. A.  Pshirkov  M. S. 《Astronomy Letters》2021,47(2):88-93

Astronomy Letters - The emission from the Crab nebula exhibits a significant gamma-ray variability. In this paper we have analyzed this variability in terms of periodicity. Using the pulsar...  相似文献   

Do mixing models with different input requirement yield similar streamflow source contributions? Case study: A tropical montane catchment     

Jorge Ramón  Alicia Correa  Edison Timbe  Giovanny M. Mosquera  Enma Mora  Patricio Crespo 《水文研究》2021,35(6):e14209

Hydrogeochemical based mixing models have been successfully used to investigate the composition and source identification of streamflow. The applicability of these models is limited due to the high costs associated with data collection and the hydrogeochemical analysis of water samples. Fortunately, a variety of mixing models exist, requiting different amount of data as input, and in data scarce regions it is likely that preference will be given to models with the lowest requirement of input data. An unanswered question is if models with high or low input requirement are equally accurate. To this end, the performance of two mixing models with different input requirement, the mixing model analysis (MMA) and the end-member mixing analysis (EMMA), were verified on a tropical montane headwater catchment (21.7 km²) in the Ecuadorian Andes. Nineteen hydrogeochemical tracers were measured on water samples collected weekly during 3 years in streamflow and eight potential water sources or end-members (precipitation, lake water, soil water from different horizons and springs). Results based on 6 conservative tracers, revealed that EMMA (using all tracers) and MMA (using pair-combinations out of the 6 conservative ones), identified the same end-members: rainfall, soil water and spring water., as well as, similar contribution fractions to streamflow from rainfall 21.9% and 21.4%, soil water 52.7% and 52.3%, and spring water 26.1% and 28.7%, respectively. Our findings show that a hydrogeochemical mixing model requiring a few tracers can provide similar outcomes than models demanding more tracers as input data. This underlines the value of a preliminary detailed hydrogeochemical characterization as basis to derive the most cost-efficient monitoring strategy.  相似文献   

The information system of the French Peatland Observation Service: Service National d'Observation Tourbières – A valuable tool to assess the impact of global changes on the hydrology and biogeochemistry of temperate peatlands through long term monitoring     

Sébastien Gogo  Jean-Baptiste Paroissien  Fatima Laggoun-Défarge  Jean-Marc Antoine  Léonard Bernard-Jannin  Guillaume Bertrand  Philippe Binet  Stéphane Binet  Guillaume Bouger  Yohann Brossard  Thierry Camboulive  Jean-Pierre Caudal  Stéphane Chevrier  Geneviève Chiapiuso  Benoît D'Angelo  Pilar Durantez  Chris Flechard  André-Jean Francez  Didier Galop  Laure Gandois  Daniel Gilbert  Christophe Guimbaud  Louis Hinault  Adrien Jacotot  Franck Le Moing  Emilie Lerigoleur  Gaël Le Roux  Fabien Leroy  Alexandre Lhosmot  Qian Li  Elodie Machado Da Silva  Jean-Sébastien Moquet  Juanita Mora-Gomez  Laurent Perdereau  Thomas Rosset  Marie-Laure Toussaint 《水文研究》2021,35(6):e14244

Mitigating and adapting to global changes requires a better understanding of the response of the Biosphere to these environmental variations. Human disturbances and their effects act in the long term (decades to centuries) and consequently, a similar time frame is needed to fully understand the hydrological and biogeochemical functioning of a natural system. To this end, the ‘Centre National de la Recherche Scientifique’ (CNRS) promotes and certifies long-term monitoring tools called national observation services or ‘Service National d'Observation’ (SNO) in a large range of hydrological and biogeochemical systems (e.g., cryosphere, catchments, aquifers). The SNO investigating peatlands, the SNO ‘Tourbières’, was certified in 2011 ( https://www.sno-tourbieres.cnrs.fr/ ). Peatlands are mostly found in the high latitudes of the northern hemisphere and French peatlands are located in the southern part of this area. Thus, they are located in environmental conditions that will occur in northern peatlands in coming decades or centuries and can be considered as sentinels. The SNO Tourbières is composed of four peatlands: La Guette (lowland central France), Landemarais (lowland oceanic western France), Frasne (upland continental eastern France) and Bernadouze (upland southern France). Thirty target variables are monitored to study the hydrological and biogeochemical functioning of the sites. They are grouped into four datasets: hydrology, fluvial export of organic matter, greenhouse gas fluxes and meteorology/soil physics. The data from all sites follow a common processing chain from the sensors to the public repository. The raw data are stored on an FTP server. After operator or automatic processing, data are stored in a database, from which a web application extracts the data to make them available ( https://data-snot.cnrs.fr/data-access/ ). Each year at least, an archive of each dataset is stored in Zenodo, with a digital object identifier (DOI) attribution ( https://zenodo.org/communities/sno_tourbieres_data/ ).  相似文献   

Transient AT2018cow: A Scenario with an Equatorial Disk     

Urvachev  E. M.  Blinnikov  S. I.  Nomoto  K. 《Astronomy Letters》2021,47(11):738-745

Astronomy Letters - To explain the presence of early X-ray emission from the object AT2018cow, we have studied a scenario with the presence of dense ejecta in the system in the equatorial plane....  相似文献   

New Orbit and Estimate of the Mass of the Star 61 Cygni Based on Observations of it in 1819-2019     

Izmailov  I. S.  Shakht  N. A.  Polyakov  E. V.  Gorshanov  D. L.  Pogodin  M. A. 《Astrophysics》2021,64(2):160-171

Astrophysics - This paper is a continuation of our earlier work devoted to determining the orbit and mass of the star 61 Cyg and the changes in the photometric characteristics of its components....  相似文献   

Determination of the Thermophysical Characteristics of the Lunar Soil Using Solar Heat     

Dudkin  K. K.  Alifanov  O. M. 《Solar System Research》2020,54(7):630-636

Solar System Research - The possibility of determining the thermophysical characteristics of the lunar soil by a penetrating probe when using solar heat as a heater is considered. The effectiveness...  相似文献   

Early Quaternary Age of the Final Stage of Volcanism in the Central Part of the Sredinny Range of Kamchatka (K–Ar Data)     

Pevzner  M. M.  Lebedev  V. A.  Kuscheva  Yu. V.  Volynets  A. O.  Tolstykh  M. L.  Babansky  A. D. 《Doklady Earth Sciences》2020,490(1):1-3

Doklady Earth Sciences - A first set of K–Ar isotopic ages obtained, which allowed to estimate the age of the largest volcanoes of the Anaunsky Dol (3.2, 2.2 and 1.9 Ma) and eruptive centers...  相似文献   

Radiative Instability of a Barotropic Jet Flow in a Rotating Stratified Atmosphere     

Kalashnik  M. V. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(3):229-234

Izvestiya, Atmospheric and Oceanic Physics - This paper investigates the stability of a jet flow with a piecewise linear velocity profile in a rotating stratified atmosphere. The linearized set of...  相似文献   

辽东铀成矿带连山关地区韧性剪切带与铀成矿作用     

吴迪  刘永江  李伟民  常瑞虹 《岩石学报》2020,36(8):2571-2588

连山关地区位于华北克拉通北缘铀成矿省辽东铀成矿带，已知铀矿床（点）均发育在韧性剪切带附近。为了解韧性剪切带运动学、几何学构造变形机制及与铀矿的关系，本文以连山关岩体周缘韧性剪切带为研究对象，通过野外宏观调查和室内微观研究相结合的研究方法，探讨构造变形期次、韧性剪切带形成机理及其对铀成矿的控制作用。研究表明：连山关岩体周缘发育的韧性剪切带与近南北向挤压构造变形有关，其右行韧性剪切带应变类型为压扁应变，属于一般压缩-平面应变范围，Flinn指数K值在0.19~0.69之间，岩石类型属于S/SL型构造岩。研究区内铀矿体均为隐伏盲矿体，主要赋存于沿着连山关岩体和辽河群接触带右行剪切作用形成的背斜褶皱核部，和北东东向断裂关系密切。综合分析认为，连山关岩体南缘北西向韧性剪切带为一级控矿构造，是区内铀矿热液运移的通道，而剪切带边部的晚期北东东向断裂则是铀矿储存空间；铀源可能来自于太古宙古风化壳，并在大型韧性剪切活动（提供热液运移通道）和基性脉岩侵入（提供热源和还原剂）等综合因素作用下运移、富集成矿。  相似文献   

The Magma Feeding System of the Klyuchevskaya Group of Volcanoes (Kamchatka)     

Gordeev  E. I.  Koulakov  I. Yu.  Shapiro  N. M. 《Doklady Earth Sciences》2020,493(2):627-631

Doklady Earth Sciences - Using observations from a large-scale seismic station network, we built a seismic tomography model of velocity anomalies for longitudinal (P-wave) and transverse (S-wave)...  相似文献