Surface and Fundamental Modes of Oscillations in Thin Coronal Loops     

Zhugzhda  Yu. D. 《Astronomy Letters》2020,46(4):256-262

Astronomy Letters - The oscillations in thin magnetic flux tubes in the solar corona are considered. The surface and fundamental modes of oscillations are shown to be the main modes of fast and...  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   

唐代治乱分期与气候变化的关系^*          下载免费PDF全文

王晓晴  章典  裴卿  张盛达  李腾 《古地理学报》2020,22(2):385-396

将唐代定量划分为治世与乱世5个时期,探讨了唐代治乱分期与气候变化的关系。治世、乱世的划分标准参考一套系统的战争数据集,并用单因素方差分析的方法验证各项数据指标在治世与乱世间的差异性,从而说明唐代治世、乱世分期的合理性。治世、乱世分期结果如下: 公元618—626年为乱世,公元627—742年为治世,公元743—784年为乱世,公元785—859年为治世,公元860—907年为乱世。方差分析的结果显示,除了总边境战争外,气候变化、总战争、反叛战争、进攻型边境战争、防御型边境战争、农业丰歉等级和人口增长率在治世与乱世之间均表现出显著差异。用战争定量体现唐代社会治世、乱世变化,探讨气候变化与社会治、乱的关系即是探讨气候变化与战争的关系,乱世的主要战争类型是反叛战争和防御型边境战争,治世的主要战争类型是进攻型边境战争。相关分析结果表明,唐代温度降低、降水减少的时期,农业收成减少导致资源供给不足,更容易发生反叛战争;温度暖期、降水充沛的时期,农业产量提高,刺激了快速增长的人口,在技术改善能力有限、土地资源一定的情况下,更易发生以对外扩张为目的的边境战争,因此气候变化是影响唐代社会治乱变化的重要原因之一。  相似文献   

Uranium-Lead and Lu–Hf Isotope Systematics of Zircon and Sm–Nd Isotopes in Rocks of the Dyumtaley Ore-Bearing Intrusion (Taimyr,Russia): New Evidence for the Role of the Depleted Mantle in Its Genesis     

Malitch  K. N.  Lokhov  D. K.  Proskurnin  V. F.  Puchkov  V. N.  Badanina  I. Yu.  Chervyakovskaya  M. A. 《Doklady Earth Sciences》2020,492(1):346-350

Doklady Earth Sciences - This study utilized SHRIMP, LA MC–ICP–MS and ID-TIMS analytical techniques and presents for the first time U–Pb age, Lu-Hf-isotope features of zircon and...  相似文献   

Compression characteristics of saturated re-compacted glacial tills in Tianmo Gully of Tibet,China     

CHEN Lei-lei  ZHOU Gordon G.D.  MU Qing-yi  CUI Kahlil Fredrick E.  SONG Dong-ri 《山地科学学报》2019,(7)

Glacial tills are highly compressible soils composed of loosely cemented sandy silt particles. Their role, for instance, as initial filler materials in geo-technical projects along temperate glacier regions warrant a systematic evaluation of their compressive characteristics. As such, we carry out a series of onedimensional compression tests on re-compacted glacial till samples obtained from Tianmo Gully, Tibet, with the aims of evaluating their compressive behavior under controlled initial stress conditions. The yield stress was determined from the void ratio versus consolidation pressure(e-log) planes. Its compression and swelling behaviors were observed during the primary and secondary compressions of the consolidation tests. From the compression curves, a correlation can be found between the consolidation stress and the void index. In addition, we find that the compression curves of glacial tills collapse into a single curve when normalized by the compression index. The experimental results in this study provide a basic understanding of the compression characteristics of the glacial tills in Tibet, China.  相似文献   

Modelling population retention in Australia’s Northern Territory – how do current forms of migration contribute to population turnover and retention?     

James Thurmer  D. Carson  A. Taylor 《The Australian geographer》2019,50(4):435-452

ABSTRACT

In the past, population growth in Australia's Northern Territory, as in other peripheral parts of high-income countries, has been driven by internal labour migration and migration from outside of Australia. These have been contributing to the high population turnover experienced in peripheral areas. Since 2010, the Northern Territory has experienced low (and even negative) population growth, and public policy is currently focused on migration as a lever to reverse this trend. However, the extent to which the characteristics of migrants influence the potential for longer-term population growth is poorly understood. This paper uses a new method to analyse the contributions of various types of migrants to both population turnover and retention. Two major sets of findings emerge: First, the significance of separating newer in-migrants from longer-term residents when analysing migration patterns; and secondly, the contribution of age, gender, Indigenous status, international origin, wages and industry of employment to the Northern Territory's population turnover. The research suggests that current forms of migration favour people who are likely to stay for only short periods, and have high wage demands. The main policy inference is that long-term population growth will likely not eventuate unless new forms of migration can be stimulated.  相似文献   

Political ecology of tiger conservation in India: Adverse effects of banning customary practices in a protected area     

Nitin D. Rai  Tor A. Benjaminsen  Siddhartha Krishnan  C. Madegowda 《Singapore journal of tropical geography》2019,40(1):124-139

Protected areas have had significant impacts on local communities primarily through the physical removal of people. In some instances, people continue to live within protected areas due to the inability of the state to evict them. The restrictions on livelihoods placed on people living inside protected areas lead to in situ displacement. We show how conservation enclosures in the Biligiri Rangaswamy Temple Tiger Reserve have produced a class of people that the state ‘lets die’ by banning customary practices such as fire use, hunting and harvesting of forest produce. Using longitudinal ethnographic, socio‐economic and ecological data, we demonstrate that conservation policy has alienated indigenous forest dwellers from their agricultural and forest‐land. The outcomes of conservation policy include dispossession through increased crop losses, reduced income from agriculture and forest produce, as well as a forest that is dominated by weeds due to fire suppression. The ban on hunting in particular has increased wildlife densities, which has enabled the state to accumulate revenues through the establishment of wildlife tourism facilities. All in all, centralized protected area governance has changed the relationships among people, forest and the state in a way that has produced adverse effects for both livelihoods and the ecosystem.  相似文献   

Astrometric Observations of the Galilean Moons of Jupiter at the Pulkovo Normal Astrograph in 2016−2017     

N. V. Narizhnaya  M. Yu. Khovrichev  A. A. Apetyan  D. A. Bikulova  A. P. Ershova  I. A. Balyaev  A. M. Kulikova  K. I. Os’kina  L. A. Maksimova 《Solar System Research》2018,52(4):312-319

We present the results of observations of the Galilean moons of Jupiter carried out at the Normal Astrograph of the Pulkovo Observatory in 2016?2017. We obtained 761 positions of the Galilean moons of Jupiter in the system of the Gaia DR1 catalog (ICRF, J2000.0) and 854 differential coordinates of the satellites relative to each other. The mean errors in the satellites’ normal places and the corresponding root-mean-square deviations are ε_α = 0.0020′′, ε_δ = 0.0027′′, σ_α = 0.0546′′, and σ_δ = 0.0757′′. The equatorial coordinates of the moons are compared to the motion theories of planets and satellites. On average, the (O–C) residuals in the both coordinates relative to the motion theories are less than 0.031′′. The best agreement with observations is achieved by a combination of the EPM2015 and V. Lainey-V.2.0|V1.1 motion theories, which yields the average (O–C) residuals of approximately 0.02″. Peculiarities in the behavior of the (O–C) residuals and error values in Ganymede have been noticed.  相似文献   

Experimental and Methodical Assurance of Studies of Hydrodynamic Processes in Fuel Tanks with Capillary Systems of Cryogenic Component Management     

D. A. Jagodnikov  V. B. Sapozhnikov  N. I. Avraamov  I. V. Lokhanov  A. V. Novikov 《Solar System Research》2018,52(7):673-679

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Underwater Acoustic Signaling of Bearded Seals (Erignatus barbatus) in the White Sea     

Agafonov  A. V.  Chernetsky  A. D. 《Oceanology》2018,58(6):847-855

Oceanology - The bearded seal occurs in virtually all Arctic seas. During the spring (pupping and mating season), this species is characterized by high underwater acoustic activity; studies...  相似文献