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When and how did plate tectonics begin?Theoretical and empirical considerations

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Chinese Science Bulletin 2007年第5期52卷 578-591页

作者： R. j. STERN Geosciences Department University of Texas at Dallas Box 830688 Richardson TX 75083-0688 USA

板 tectonics 在对流传热的披风(岩流圈) 上是地球的热界面层(岩石圈) 的水平运动并且被岩石圈 inking 主要在 subduction 地区驾驶。板 tectonics 是组织的自我的一个突出的例子，远离平衡建筑群系统(SOFFECS ) ，由热界面层的否定快... 详细信息

板 tectonics 在对流传热的披风(岩流圈) 上是地球的热界面层(岩石圈) 的水平运动并且被岩石圈 inking 主要在 subduction 地区驾驶。板 tectonics 是组织的自我的一个突出的例子，远离平衡建筑群系统(SOFFECS ) ，由热界面层的否定快活开车并且由在弯曲岩石圈的驱散控制并且粘滞披风。板 tectonics 是一个不平常的方法让一个硅酸盐行星失去热，当它存在在上仅仅之一大在内部太阳系的五硅酸盐身体。构造活动和热损失的这个模式什么时候开始了，不被知道在地球上。所有硅酸盐行星可能经历了一个短命岩浆海洋阶段。在这团结的、停滞的盖行为是行星的热损失的普通模式以后，与内部，热被融化在更热的早地球中的火山作用和浅 *** 产生了的分层和“热点”正在失去一个不同岩石圈比今天，与更厚的海洋的外壳和更薄的披风岩石圈；如此的岩石圈将比花更长时间目前变得否定地快活，在早地球上建议那板 tectonics 偶发地发生了如果根本。板 tectonics 变得持续(现代风格) 当土足够地冷却了时，融化在散布山脉下面的那解压缩做了薄海洋的外壳，允许海洋的岩石圈在百万年中的一些十个以后变得否定地快活。板 tectonics 什么时候开始了的 Ultimatelythe 问题必须被从地质的记录检索的信息回答。标准因为板 tectonics 的操作包括 ophiolites，蓝片岩 andultra 高的压力变形的带， eclogites，被动边缘，变换差错，不同 cratons 的不同运动的 paleomagneticdemonstration，和在火的岩石中的诊断 geochemicaland 同位素示踪剂的存在。这个记录必须个别地被解释；我解释记录在锝? 从活跃太古代的 tectonics 和类似于板 tectonics 的 magmatismto 一些东西显示构造式样的前进 9 ga 到有深 subduction 的持续、现代风格板 tectonics—并且强大的平板拉—在 Neoproterozoic 时间开始。

关键词：板块构造形成时间形成机制俯冲前寒武纪地球动力学岩浆作用

Did natural fission of^(235)U in the earth lead to formation of the supercontinent Columbia?

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Geoscience Frontiers 2012年第4期3卷 369-374页

作者： john j.W.Rogers Department of Geological Sciences University of North Carolina at Chapel HillChapel HillNC 27599-3315USA

Steady decline in the percentage of 235U in terrestrial uranium made natural fission impos- sible after about 1.8 ga. Fission before 1.8 ga disturbed the lead isotope system at various places world- wide, such as Oklo, gabon, and may have caused the first lead isotope paradox. Fission in areas of high uranium concentration may also have generated enough heat to localize sparse Archean and Paleoproter- ozoic UHT belts. The oldest widespread orogenic systems formed at approximately 2.0-1.8 ga after fission stopped contributing to the earth＇s heat flow. These early orogenic systems partly created the supercontinent Columbia.

关键词： Natural fission Archean Paleoproterozoic Columbia supercontinent Tectonics

Clinical differences among racially diverse children with celiac disease

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World journal of Pediatrics 2022年第10期18卷 710-714页

作者： Kaley A.Desher Michele j.Alkalay Department of Pediatric gastroenterology University of Texas Southwestern Medical CenterDallasTXUSA Preferred postal address is 6605 Vickery Creek Rd CummingGA30040USA

Celiac disease(CD)is an immune-mediated disorder of the small intestine precipitated by the ingestion of gluten in genetically predisposed *** CD was formally considered a chronic enteropathy that mainly affects child... 详细信息

关键词： intestine Clinical formally

Annealing Effects on the Structural, Optical, and UV Photoresponse Properties of ZnO Nanostructures Prepared by RF-Magnetron Sputtering at Different Deposition Temperatures

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 230-242页

作者： Husam S.Al-Salman M.j.Abdullah School of Physics University Sains Malaysia Department of Physics College of Science University of Basrah

Undoped ZnO nanostructures were deposited on SiO2/Si substrates via radio 11：equency magnetron sputtenng at different deposition temperatures （room temperature, 200, 300, and 400 ℃）. The prepared samples were annealed at 500 ℃ for 2 h under an N2 flow. The structural, surface morphological, optical, and photoresponse characteristics of ZnO nanostructures as deposited and after annealing were then investigated. The energy bandgaps of all samples after annealing （3.22-3.28 eV） decreased compared with those of the as-deposited specimens. The barrier height increased when the deposition temperature increased and reached 0.77 eV at 400 ℃ after annealing with a leakage current of 0.17 ga at a 5 V bias. The UV photodetector device which was deposited at the optimal temperature of 300 ℃, has 12.51 × 10^3% pho- tosensitivity, 2.259 pA dark current, 0.508 s response time, and 0.466 s recovery time. The dark current significantly decreased for all samples after annealing. The proposed UV photodetectors exhibit high performance, high photosensi- tivity, shorter response and recovery times, and excellent stability at lower bias voltages of 5 and 2 V.

关键词： Undoped ZnO UV photoresponse Deposition temperatures Annealing effect

Tailoring thermoelectric properties of Zr(0.43)Hf(0.57)NiSn half-Heusler compound by defect engineering

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Rare Metals 2020年第6期39卷 659-670页

作者： Krzysztof galazka Wenjie Xie Sascha Populoh Myriam H.Aguirre Songhak Yoon Gesine Büttner Anke Weidenkaff Institute of Plasma Physics and Laser Microfusion Warsaw 01-497Poland Department of Materials Science Technische Universitat DarmstadtDarmstadt 64287Germany Laboratory for Solid State Chemistry and Catalysis EmpaDlibendorf 8600Switzerland Instituto de Nanociencia de Aragon Universidad de ZaragozaSaragossa 50018Spain Departamento de Fisica de la Materia Condensada Universidad de ZaragozaSaragossa 50009Spain Laboratorio de Microscopias Avanzadas Universidad de ZaragozaSaragossa 50018Spain Fraunhofer Research Institution for Materials Recycling and Resource Strategies IWKS Hanau 63457Germany

The thermoelectric transport properties of Zr0.43Hf0.57 NiSn half-Heusler compounds were investigated for samples sintered with different spark plasma sintering(SPS)periods:8,32 and 72 *** means of scanning transmission electron microscopy with a highangular annular dark-field detector(STEM-HAADF),it was found that sintering time affected the defect concentration,namely the amount of Ni interstitial atoms,and created locally ordered inclusions of full-Heusler *** structural information,phase composition and electrical transport properties could be consistently explained by the assumption that Ni interstitials give rise to an impurity band situated about 100 meV below the bottom of the conduction band via a self-doping *** impurity band was found to merge with the conduction band for the sample with intermediate SPS *** effect was ascribed to the gradual dissolution of full-Heusler phase inclusions and production of interstitial Ni defects,which eventually vanished for the sample with the longest sintering *** was demonstrated that the modification of the density of states near the edge of the conduction band and enhanced overall charge carrier concentration provided by defect engineering led to overall 26%increase in the thermoelectric figure of merit(ZT)with respect to the other samples.

关键词： Thermoelectric Half-Heusler Interstitial Defect engineering

Generation and preservation of continental crust in the Grenville Orogeny

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Geoscience Frontiers 2015年第3期6卷 357-372页

作者： Christopher j.Spencer Peter A.Cawood Chris j.Hawkesworth Anthony R.Prave Nick M.W.Roberts Matthew S.A.Horstwood Martin j.Whitehouse EIMF Department of Earth and Environmental Sciences University of St Andrews NERC Isotope Geosciences Laboratory British Geological Survey Swedish Museum of Natural History and Nordic Center for Earth Evolution(NordCEE) Edinburgh Ion Microprobe Facility University of Edinburgh

Detrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of ＇peaks＇ and ＇troughs＇. The peaks are interpreted to represent either periods of enhanced generation of granitic magma perhaps associated with mantle overturn and superplume events, or preferential preservation of continental crust during global collisional orogenesis. The close association of those peaks with the assembly of supercontinents implies a causal relationship between collisional orogenesis and the presence of zircon age peaks. Here these two end-member models （episodic periodicity of increased magmatism versus selective preservation during collisional orogenesis） are assessed using U-Pb, Hf, and 0 analysis of detrital zircons from sedimentary successions deposited during the - 1.3-1.1 ga accretionary, -1.1-0.9 ga collisional, and 〈 0.9 ga extensional collapse phases of the Grenville orogenic cycle in Labrador and Scotland. The pre-collisional, accretionary stage provides a baseline of continental crust present prior to orogenesis and is dominated by Archean and Paleoproterozoic age peaks associated with pre-1300 Ma Laurentian geology. Strata deposited during the Grenville Orogeny display similar Archean and Paleoproterozoic detrital populations along with a series of broad muted peaks from - 1500 to 1100 Ma. However, post-collisional sedimentary successions display a dominant age peak between 1085 and 985 Ma, similar to that observed in modern North American river sediments. Zircons within the post-orogenic sedimentary successions have progressively lower EHf and higher -lSO values from - 1800 to - 1200 Ma whereupon they have higher EHf and -3180 within the dominant 1085-985 Ma age peak. Furthermore, the Lu-Hf isotopic profile of the Grenville-related age peak is consistent with significant assimilation and contamination by older crustal material, The timing of this dominant age peak coincides with the peak of metamorphism and

关键词： Zircon Continental crust Grenville Orogeny Crustal preservation

Secrecy sum-rate analysis of massive MIMO systems under dual-threat attacks using normalization methods

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Digital Communications and Networks 2019年第4期5卷 237-244页

作者： Kishan Neupane Rami j.Haddad Dept.of Electrical and Computer Eng.Georgia Southern UniversityStatesboroGA30460USA

Massive Multiple Input Multiple Output(MIMO)has been considered as an emerging technology to enhance the spectral and energy efficiency for the upcoming wireless communication *** paper derives a closedform approximation for the Ergodic Achievable Secrecy Sum-Rate(EASSR)by considering the joint impact of eavesdroppers and *** widely used linear precoding techniques,Zero-Forcing(ZF)and Maximum Ratio Transmission(MRT),were used in conjunction with matrix and vector normalization to analyze the secrecy ***-form expressions are used to explain how the secrecy performance is affected when using the ZF and MRT precoding in the eavesdropping and jamming attack *** also analyze and compare the performances of different combinations of normalization method and precoding technique in various *** the analytical expressions and simulation results,we observe that the vector and matrix normalization perform better for the ZF precoding than for the MRT precoding in high Signal-to-Noise Ratio(SNR)***,in low SNR,the MRT with matrix normalization outperforms the ZF with vector normalization regardless of the number of users in the ***,we observe that the MRT fails to serve more than two users in high SNR *** results obtained from Monte Carlo simulation are used to corroborate the accuracy of the asymptotic secrecy analysis.

关键词： Massive MIMO Linear precoding Normalization methods Secrecy analysis

Occupancy of avian foraging guilds in soybean fields and borders in Entre Ríos, Argentina: responses to vegetation structure and prey resources

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Avian Research 2020年第4期11卷 398-411页

作者： Andrea P.Goijman Michael j.Conroy Vanina D.Varni jeffrey j.Thompson María Elena Zaccagnini Instituto de Recursos Biológicos CIRNInstituto Nacional de Tecnología Agropecuaria(CNIA-INTA)HurlinghamBuenos AiresArgentina D.B.Warnell School of Forestry and Natural Resources University of GeorgiaAthensGA 30602USA Present Address:Athens GAUSA Present Address:Laboratorio de Genómica Ecológica y Evolutiva IrapuatoGtoMéxico Present Address:Guyra Paraguay-CONACYT Av.Cnel.Carlos BóvedaParque Ecológico Capital-Viñas CuéAsunciónParaguay Present Address:Instituto Saite AsunciónParaguay Present Address:The Ronin Institute MontclairNJUSA Present Address:Instituto Nacional de Tecnología Agropecuaria(INTA) CABAArgentina

Background:Reconciling agriculture and biodiversity conservation is a challenge given the growing demand for agricultural *** recent decades,Argentina has witnessed agricultural expansion and intensification affecting biodiversity and associated ecosystem *** agroecosystems,the level of habitat quality is critical for birds,and may depend on vegetation structure,availability of invertebrate prey,and the use of *** the relationship between vegetation structure and avian occurrence has been widely studied,to our knowledge,there are no studies that also incorporate prey availability throughout the cycle of soybean crops in *** estimated and predicted the effects of land cover and temporal variation on the occurrence of avian foraging guilds in Entre Ríos,Argentina,in order to guide management related to potential ecosystem services provided by *** also estimated temporal effects of vegetation structure and insecticides on the main arthropod orders consumed by birds to evaluate prey ***:We conducted bird and arthropod surveys for 2 years along transects located in 20 randomly selected soybean fields(N=60)and their adjacent borders(N=78)throughout the crop growing season,in four *** estimated avian occupancy,accounting for imperfect detection,and arthropod counts fitting generalized linear mixed ***:The number of native trees in field borders positively influenced the occurrence of most bird species,mainly *** foliage gleaners,also were positively affected by grass *** and aerial foragers were weakly affected by distance to forest and native *** general,the availability of invertebrates to birds was highest during the third *** counts in borders were greater during the last three crop stages than during the pre-sowing ***:We found that with 10 to 15 native tree species in borders,coupled with a complex vegetation structure w

关键词： Agriculture Birds Ecosystem services Insecticide Insectivores Invertebrates Management Native trees Occurrence

Influence of gastric inhibitory polypeptide on pentagastrinstimulated gastric acid secretion in patients with type 2 diabetes and healthy controls

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World journal of gastroenterology 2006年第12期12卷 1874-1880页

作者： juris j Meier Michael A Nauck Bartholomaeus Kask jens j Hoist Carolyn F Deacon Wolfgang E Schmidt Baptist gallwitz Department of Medicine I St. Josef-HospitalRuhr-University Bochum Germany Diabeteszentrum Bad Lauterberg Germany Department of Medical Physiology The Panum Institute University of Copenhagen Denmark Department of Medicine IV Eberhard-Karls- University Ttibingen Germany

AIM： gastric inhibitory polypeptide is secreted from intestinal K-cells in response to nutrient ingestion and acts as an incretin hormone in human physiology. While animal experiments suggested a role for GIP as an inhibitor of gastric secretion, the GIP effects on gastric acid output in humans are still controversial. METHODS： Pentagastrin was administered at an infusion rate of 1 μg . kg^-1 . h^-1 over 300 min in 8 patients with type 2 diabetes （2 female, 6 male, 54± 10 years, BMI 30.5 ± 2.2 kg/m^2; no history of autonomic neuropathy） and 8 healthy subjects （2/6, 46 ± 6 years., 28.9 ± 5.3 kg/ m^2）. A hyperglycaemic clamp （140 mg/dl） was performed over 240 min. Placebo, GIP at a physiological dose （1 pmol . kg^-1 . min^-1）, and GIP at a pharmacological dose （4 mol . kg^-1 . min^-1） were administered over 60 min each. Boluses of placebo, 20 pmol GIP/kg, and 80 pmol GIP/kg were injected intravenously at the beginning of each infusion period, respectively. gastric volume, acid and chloride output were analysed in 15-min intervals. Capillary and venous blood samples were drawn for the determination of glucose and total GIP. Statistics were carried out by repeated-measures ANOVA and one-way ANOVA. RESULTS： Plasma glucose concentrations during the hyperglycaemic clamp experiments were not different between patients with type 2 diabetes and controls. Steady-state GIP plasma levels were 61 ±8 and 79 ± 12 pmol/I during the low-dose and 327±35 and 327± 17 pmol/I during the high-dose infusion of GIP, in healthy control subjects and in patients with type 2 diabetes, respectively （P= 0.23 and p 0.99）. Pentagastrin markedly increased gastric acid and chloride secretion （P〈 0.001）. There were no significant differences in the rates of gastric acid or chloride output between the experimental periods with placebo or any dose of GIP. The temporal patterns of gastric acid and chloride secretion were similar in patients with type 2 diabetes and healthy controls （P= 0.86 and P= 0.6

关键词： gastric inhibitory polypeptide gastric acid secretion Type 2 diabetes Hyperglycemic clamp Pentagastrin-stimulated acid secretion