EIS/<Emphasis Type="Italic">Hinode</Emphasis> Observations of Doppler Flow Seen through the 40-Arcsec Wide-Slit     

D. E. Innes  R. Attie  H. Hara  M. S. Madjarska 《Solar physics》2008,252(2):283-292

The Extreme ultraviolet Imaging Spectrometer (EIS) onboard Hinode is the first solar telescope to obtain wide-slit spectral images that can be used for detecting Doppler flows in transition region and coronal lines on the Sun and to relate them to their surrounding small-scale dynamics. We select EIS lines covering the temperature range 6×10⁴ to 2×10⁶ K that give spectrally pure images of the Sun with the 40-arcsec slit. In these images Doppler shifts are seen as horizontal brightenings. Inside the image it is difficult to distinguish shifts from horizontal structures but emission beyond the image edge can be unambiguously identified as a line shift in several lines separated from others on their blue or red side by more than the width of the spectrometer slit (40 pixels). In the blue wing of He ii, we find a large number of events with properties (size and lifetime) similar to the well-studied explosive events seen in the ultraviolet spectral range. Comparison with X-Ray Telescope (XRT) images shows many Doppler shift events at the footpoints of small X-ray loops. The most spectacular event observed showed a strong blue shift in the transition region and lower corona lines from a small X-ray spot that lasted less than 7 min. The emission appears to be near a cool coronal loop connecting an X-ray bright point to an adjacent region of quiet Sun. The width of the emission implies a line-of-sight velocity of 220 km s⁻¹. In addition, we show an example of an Fe xv shift with a velocity of about 120 km s⁻¹, coming from what looks like a narrow loop leg connecting a small X-ray brightening to a larger region of X-ray emission.  相似文献   

40Ar-39Ar Geochronology and its Geological Significance of Zhaceqiao Gold Deposit in Dongzhi,Jiangnan Transition ZoneEI北大核心CSCD     

Nie Z.  Shi L.  Gu H.  Qian X.  Shen H.  Yang X. 《大地构造与成矿学》2017,(3):502-515

The Zhaceqiao gold-polymetal deposit was discovered recently in the Jiangnan Transitional Zone. In order to obtain the ore-forming age, sericite was separated from the altered granite porphyry which hosts the gold deposit. 40Ar-39Ar analyses of sericite in gold ore yield spectrum age of 156.9±1.6 Ma with the isochron age of 152±28 Ma. The spectrum age of sericite in altered granodiorite porphyry is 142.1±1.3 Ma with the isochron age of 137±13 Ma. The homogenization temperature of fluid inclusions in quartz from the Niutougaojia and Chengtan ore sections is c.a. 160℃. The H-O isotopic compositions indicate that the ore-forming fluids mainly come from magmatic hydrothermal sources. Integrating with regional studies, the Zhaceqiao gold deposit is predominantly characterized by shallow, low temperature and epithermal, similar to Carlin-like type gold deposit. The Zhaceqiao gold deposit was formed in Yanshanian through multi-stage superimposition. The gold mineralization was related to the ductile-brittle compressional tectonic deformation and alteration in middle Jurassic to gold, while the polymetallic mineralization was related to the Late Jurassic-Early Cretaceous igneous activity, and the epithermal mineralization in the middle and late stage of the Early Cretaceous. © 2017, Science Press. All right reserved.  相似文献   

全要素生产率视角下的我国渔业转型发展研究——基于SFA的实证分析   总被引：1，自引：0，他引：1       下载免费PDF全文

刘盼成  杨正勇 《海洋开发与管理》2017,34(7):98-106

文章以2003—2014年我国27个省、市、自治区渔业为研究对象,采用SFA方法对我国渔业全要素生产率及其分解项的变化率进行实证分析。实证结果表明:渔业生产要素对渔业经济贡献大小排序依次为:渔业从业人员、渔船年末拥有量和渔业养殖面积;整体上看,我国渔业经济处于规模报酬递减阶段,缩小渔业经济规模有利于渔业规模效率的改善;我国渔业全要素生产率以每年7.01%的平均速度增长,其分解项:技术进步、规模效率分别以每年7.10%、-0.09%的平均速度在变化,技术效率呈现非时变特征。结果说明,从全要素生产率变化来看,我国渔业经济增长显著,技术进步是我国渔业转型发展发挥着主要推动作用;在其他条件不变的条件下,通过改善技术效率和规模效率是提高渔业发展效率有效途径。  相似文献   

Observed adaptation to climate change: UK evidence of transition to a well-adapting society   总被引：5，自引：0，他引：5  

Emma L. Tompkins  W. Neil Adger  Emily Boyd  Sophie Nicholson-Cole  Keith Weatherhead  Nigel Arnell 《Global Environmental Change》2010,20(4):627-635

This paper investigates whether and to what extent a wide range of actors in the UK are adapting to climate change, and whether this is evidence of a social transition. We document evidence of over 300 examples of early adopters of adaptation practice to climate change in the UK. These examples span a range of activities from small adjustments (or coping), to building adaptive capacity, to implementing actions and to creating deeper systemic change in public and private organisations in a range of sectors. We find that adaptation in the UK has been dominated by government initiatives and has principally occurred in the form of research into climate change impacts. These government initiatives have stimulated a further set of actions at other scales in public agencies, regulatory agencies and regional government (and the devolved administrations), though with little real evidence of climate change adaptation initiatives trickling down to local government level. The sectors requiring significant investment in large scale infrastructure have invested more heavily than those that do not in identifying potential impacts and adaptations. Thus we find a higher level of adaptation activity by the water supply and flood defence sectors. Sectors that are not dependent on large scale infrastructure appear to be investing far less effort and resources in preparing for climate change. We conclude that the UK government-driven top-down targeted adaptation approach has generated anticipatory action at low cost in some areas. We also conclude that these actions may have created enough niche activities to allow for diffusion of new adaptation practices in response to real or perceived climate change. These results have significant implications for how climate policy can be developed to support autonomous adaptors in the UK and other countries.  相似文献   

Comparison of two approaches for generation of daily rainfall data     

R. Srikanthan  T. I. Harrold  A. Sharma  T. A. McMahon 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(3):215-226

There has been extensive research on the problem of stochastically generating daily rainfall sequences for use in water management applications. Srikanthan and McMahon [Australia Water Resources Council, Canberra, 1985] proposed a transition probability matrix (TPM) model that performs better for Australian rainfall than many alternative models, particularly where long records (say 100 years) are available. Boughton [Report 99/9, CRC for Catchment Hydrology, Monash University, Melbourne, 21pp, 1999] incorporated an empirical adjustment into the TPM model that allows the model to reproduce the observed variability in the annual rainfall. More recently, Harrold et al. [Water Resour Res 39(10, 12):1300, 1343, 2003a,b] proposed nonparametric models for the generation of daily rainfall occurrences and rainfall amounts on wet days. By conditioning on short, medium and long-term characteristics, this approach is also able to preserve the variability in annual rainfall. In this study, the above two approaches were used to generate daily rainfall data for Sydney and Melbourne, and the results evaluated. Both approaches preserved most of the daily, monthly and annual characteristics that were compared, with the nonparametric approach providing marginally better performance at the cost of greater model complexity. The nonparametric approach was also able to preserve the variability and persistence in the annual number of wet days.  相似文献   

Between difference and adjustment - The re-/presentation and implementation of post-socialist (communist) transformation     

T. Herrschel 《Geoforum》2007,38(3):439-444

Since the collapse of the communist regimes some 15 years ago, the at first rather simplistic assumptions about the quite similar nature of the ‘other side’ of the Iron Curtain soon were revealed as such. The conditions in the different countries proved to be much more complex and differentiated, making policies more difficult to target and outcomes to predict than initially presumed and propagated. As it emerged, the process of ‘transition’, has thus emerged as a multidimensional, complex phenomenon of ‘transition’, shaped by a set of overlapping and intersecting variables, pointing to the need for a more detailed understanding and interpretation of the changes observed. And this includes the use of terminology, even such fundamental terms as ‘post-/socialism’ versus ‘post-/communism’ or ‘transition’ versus ‘transformation’. These differences reflect variations in the perception and implementation of post-communist regimes, as viewed and interpreted from both within and without the relevant countries or regions. And this is illustrated by the collection of papers in this special issue.  相似文献   

Crystal chemistry of wadsleyite II and water in the Earth’s interior   总被引：1，自引：1，他引：0  

J. R. Smyth  C. M. Holl  F. Langenhorst  H. M. S. Laustsen  G. R. Rossman  A. Kleppe  C. A. McCammon  T. Kawamoto  P. A. van Aken 《Physics and Chemistry of Minerals》2005,31(10):691-705

Wadsleyite II is a variably hydrous magnesium-iron silicate phase similar to spinelloid IV and a potential host for H in the Transition Zone of the Earths mantle. Two separate samples of wadsleyite II synthesized at 17.5 GPa and 1400°C and at 18 GPa and 1350°C have been characterized by electron microprobe, single-crystal X-ray diffraction, visible, IR, Raman, and Mössbauer spectroscopies, and transmission electron microscopy including electron energy-loss spectroscopy. The two samples have the following chemical formulae: Mg_1.71Fe_0.18Al_0.01H_0.33Si_0.96O₄ and Mg_1.60Fe_0.22Al_0.01 H_0.44Si_0.97O₄. Mössbauer spectroscopy and electron energy loss spectroscopy (EELS) indicate that about half of the iron present is ferric. Refinement of the structures shows them to be essentially the same as spinelloid IV. Calculated X-ray powder diffraction patterns show only subtle differences between wadsleyite and wadsleyite II. The hydration mechanism appears to be protonation of the non-silicate oxygen (O2) and possibly the oxygens surrounding the partially vacant tetrahedral site Si2, charge-balanced by cation vacancies in Si2, M5 and M6. The unit cell volume of this phase and its synthesis conditions indicate that it may be an intermediate phase occurring between the fields of wadsleyite and ringwoodite, if sufficient trivalent cations are available. The unit cell parameters have been refined at pressures up to 10.6 GPa by single-crystal X-ray diffraction in the diamond anvil cell. The refined bulk modulus for the sample containing 2.8 wt% H₂O is 145.6 ± 2.8 GPa with a K of 6.1 ± 0.7. Similar to wadsleyite and ringwoodite, hydration has a large effect on the bulk modulus. The presence of this phase in the mantle could serve to obscure the seismic expression of the phase boundary between wadsleyite and ringwoodite near 525 km. The large apparent effect of hydration on bulk modulus is consistent with hydration having a larger effect on seismic velocities than temperature in the Transition Zone.  相似文献   

Temporal patterns of arid-humid transitions in the south-eastern Arabian Peninsula based on optical dating     

Helen E. Bray  Stephen Stokes 《Geomorphology》2004,59(1-4):271

The Rub Al Khali aeolian system of the Arabian Peninsula is the world's largest erg. While the region is presently hyper-arid, evidence for multiple past humid periods has been documented in previous studies. Radiocarbon dating of lacustrine, travertine and palaeogroundwater deposits suggests that the climate was humid at 10–6 and 35–25 ka. These phases have been associated with summer rainfall increases occurring in tandem with an intensification and northward migration of the monsoon system during Northern hemisphere precessional maxima. Published optical dating studies have focused on preserved sand dune and aeolianite deposits to establish ages for the intervening arid phases. Here we present a summary of this work and additional optical dating results for samples of aeolian sediment from a deep drill core, which provides insights into the style of barchan dune accretion in the Liwa region of the United Arab Emirates. The large dune accreted rapidly during the mid-late Holocene. The results suggest that the transitions from humid to arid conditions and resulting accumulation of aeolian sediment in the form of large bedforms occurred abruptly at around 6 ka. Further aeolian sedimentation has not been constant since that time, with initial gradual dune growth followed by rapid vertical accretion, and possible termination of accumulation around c. 2 ka.  相似文献   

Why does the co-seismic slip of the 1999 Chi-Chi (Taiwan) earthquake increase progressively northwestward on the plane of rupture?     

R. Cattin  A. Loevenbruck  X. Le Pichon 《Tectonophysics》2004,386(1-2):67-80

The Chi-Chi 1999 earthquake ruptured the out-of-sequence Chelungpu Thrust Fault (CTF) in the fold-and-thrust belt in Western Central Taiwan. An important feature of this rupture is that the calculated slip increases approximately linearly in the SE–NW convergence plate direction from very little at its deeper edge to a maximum near the surface. We propose here a new explanation for this co-seismic slip distribution based on the study of both stress and displacement over the long-term as well as over a seismic cycle. Over the last 0.5 My, the convergence rate in the mountain front belt is accommodated by the frontal Changhua Fault (Ch.F), the CTF and the Shuangtung Fault (Sh.F). Based on previously published balanced cross sections, we estimate that the long-term slip of the Ch.F and of the CTF accommodate 5–30% and 30–55% of the convergence rate, respectively. This long-term partitioning of the convergence rate and the modeling of inter-seismic and post-seismic displacements suggest that the peculiar linear co-seismic slip distribution is accounted for by a combination of the effect of the obliquity of the CTF to the direction of inter-seismic loading, and of increasing aseismic creep on the deeper part of the Ch.F and CTF. Many previous interpretations of this slip distribution have been done including the effects of material properties, lubrication, site effect, fault geometry and dynamic waves. The importance of these processes with respect to the effects proposed here is still unknown. Taking into account the dip angle of the CTF, asperity dynamic models have been proposed to explain the general features of co-seismic slip distribution. In particular, recent works show the importance of heterogeneous spatial distribution of stress prior to the Chi-Chi earthquake. Our analysis of seismicity shows that previous large historic earthquakes cannot explain the amplitude of this heterogeneity. Based on our approach, we rather think that the high stress in the northern part of the CTF proposed by Oglesby and Day [Oglesby, D.D., Day, S.M., 2001. Fault geometry and the dynamics of the 1999 Chi-Chi (Taiwan) earthquake. Bull. Seismol. Soc. Am. 91, 1099–1111] reflects the latitudinal variation of inter-seismic coupling due to the obliquity of the CTF.  相似文献   

SOME EXAMPLES OF TRANSITION SPANS MINERALIZING AND ANALYSIS OF THEIR DYNAMICS     

BI Hua ZHAO Zhi-zhong ZHU Wei-huang YANG Yuan-gen HUANG Lan LIU Qiang 《大地构造与成矿学(英文版)》2002,(2):89-92

The transitional span is a special environment for deposits. Taking peat, oil-gas, metallic deposits as examples, this paper discusses the spatial-temporal transitional characteristics of mineralization in transitional regions, points out the importance of the mineralization in transition spans, and analyses their dynamics finally.  相似文献