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Doppler Boosting May Have Played No Significant Role in the Finding Surveys of Radio-Loud Quasars

International Journal of Astronomy and Astrophysics 2012年第1期2卷 52-61页

作者： Morley B. bell Herzberg Institute of Astrophysics National Research Council Ottawa Canada

There appears to be a fundamental problem facing Active Galactic Nuclei (AGN) jet models that require highly relativistic ejection speeds and small jet viewing angles to explain the large apparent superluminal motions seen in so many of the radio-loud quasars with high redshift. When the data are looked at closely it is found that, assuming the core component is unboosted, only a small percentage of the observed radio frequency flux density from these sources can be Doppler boosted. If the core component is boosted the percentage of boosted to unboosted flux will be higher but will still be far from the 90 percent required for Doppler boosting to have played a significant role. Without a highly directed, Doppler boosted component that dominates the observed flux, radio sources found in low-frequency finding surveys cannot be preferentially selected with small jet viewing angles. The distribution of jet orientations will then follow the sini curve associated with a random distribution, where only a very few sources (~1%) will have the small viewing angles ( 10c, and this makes it difficult to explain how around 33% of the radio-loud AGNs with high redshift can exhibit such highly superluminal motions. When the boosted component is the dominant one it can be argued that in a flux limited sample only those members with small viewing angles would be picked up while those with larger viewing angles (the un-boosted ones) would be missed. However, this is not the case when the boosted component is small and a new model to explain the high apparent superluminal motions may be needed if the redshifts of high-redshift quasars are to remain entirely cosmological.

关键词： Galaxies Distances and Redshifts Galaxies Quasars General

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The~1.4 GaA-type granitoids in the“Chottanagpur crustal block”(India),and its relocation from Columbia to Rodinia?

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Geoscience Frontiers 2022年第2期13卷 405-429页

作者： Nicole Sequeira Abhijit Bhattacharya Elizabeth bell Department of Geology and Geophysics Indian Institute of TechnologyKharagpur 721302India Department of Earth Planetary and Space SciencesUniversity of California595 Charles Young Drive EastLos AngelesCA 90095-1567USA School of Earth Ocean and Atmospheric SciencesGoa UniversityTaleigaoGoa 403516India

In paleogeographic reconstructions of the Columbia and Rodinia Supercontinents,the position of the Greater India landmass is ***,coupled with a limited understanding of the tectonic evolution of the mobile belts along which the mosaic of crustal domains in India accreted,impedes precise correlation among the dispersed crustal fragments in supercontinent *** structural,metamorphic phase equilibria,chronological and geochemical investigations,this study aims to reconstruct the tectonic evolution of the Chottanagpur Gneiss Complex(CGC)as a distinct crustal block at the eastern end of the Greater Indian Proterozoic Fold Belt(GIPFOB)along which the North India Block(NIB)and the South India Block(SIB)*** study focuses on two issues,*** the Early Neoproterozoic(0.92 Ga)accretion of the CGC with the NIB contemporaneous with the assembly of Rodinia,and documenting the widespread(>24,000 km^(2))plutonism of1.5-1.4 Ga weakly peraluminous,calc-alkalic to alkali-calcic and ferroan A-type granitoids(±garnet)devoid of mafic microgrannular enclaves and coeval mafic emplacements in the crustal *** dominantly within-plate granitoids arguably formed by asthenospheric upwelling induced partial melting of garnetbearing anatectic quartzofeldspathic gneisses that dominate the Early Mesoproterozoic basement of the *** major and trace element chemistry of the granitoids is similar to the 1.35-1.45 Ga A-type granitoids in Laurentia/Amazonia emplaced contemporaneous with the 1.5-1.3 Ga breakup of the Columbia *** study suggests the Chottanagpur Gneiss Complex occured as a fragmented crustal block following the breakup of the Columbia Supercontinent;the crustal block was subsequently integrated within India during the Early Neoproterozoic oblique accretion between the NIB and SIB contemporaneous with the Rodinia Supercontinent assembly.

关键词： Chottanagpur Gneiss Complex Rodinia accretion Columbia Supercontinent break up Mid-Mesoproterozoic ferroan A-type granitoids

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Chain length-dependent cooperativity in fatty acid binding and oxidation by cytochrome P450_(BM3)(CYP102A1)

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Protein & Cell 2011年第8期2卷 656-671页

作者： Benjamin Rowlatt Jake A.Yorke Anthony J.Strong Christopher J.C.Whitehouse Stephen G.bell Luet-Lok Wong Department of Chemistry University of OxfordInorganic Chemistry LaboratorySouth Parks RoadOxford OX13QRUK

Fatty acid binding and oxidation kinetics for wild type P450_(BM3)(CYP102A1)from Bacillus megaterium have been found to display chain length-dependent homotropic *** and 13-methyl-myristate display Michaelis-Menten behavior while there are slight deviations with myristate at low ionic *** shows Michaelis-Menten kinetics and hyperbolic binding behavior in 100 mmol/L phosphate,pH 7.4,but sigmoidal kinetics(with an apparent intercept)in low ionic strength buffers and at physiological phosphate *** low ionic strength buffers both the heme domain and the full-length enzyme show complex palmitate binding behavior that indicates a minimum of four fatty acid binding sites,with high cooperativity for the binding of the fourth palmitate molecule,and the full-length enzyme showing tighter palmitate binding than the heme *** first flavin-to-heme electron transfer is faster for laurate,myristate and palmitate in 100 mmol/L phosphate than in 50mmol/L Tris(pH 7.4),yet each substrate induces similar high-spin heme *** palmitate in low phosphate buffer concentrations,the rate constant of the first electron transfer is much larger than *** results suggest that phosphate has a specific effect in promoting the first electron transfer step,and that P450_(BM3) could modulate Bacillus membrane morphology and fluidity via palmitate oxidation in response to the external phosphate concentration.

关键词： P450_(BM3) monooxygenase fatty acid cooperativity allosteric effect CYP102A1

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R-spondin-2 is a Wnt agonist that regulates osteoblast activity and bone mass

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Bone Research 2018年第3期6卷 289-302页

作者： M.Noelle Knight Kannan Karuppaiah Michele Lowe Sarthak Mohanty Robert L.Zondervan Sheila bell Jaimo Ahn Kurt D.Hankenson Department of Orthopaedic Surgery Perelman School of Medicine University of Pennsylvania Department of Orthopaedic Surgery University of Michigan Medical School Division of Pulmonary Biology Cincinnati Children's Hospital Medical Center

The R-spondin family of proteins are Wnt agonists, and the complete embryonic disruption of Rspo2 results in skeletal developmental defects that recapitulate the phenotype observed with Lrp5/6 deficiency. Previous work has shown that R-spondin-2(Rspo2, RSPO2) is both highly expressed in Wnt-stimulated pre-osteoblasts and its overexpression induces osteoblast differentiation in the same cells, supporting its putative role as a positive autocrine regulator of osteoblastogenesis. However, the role of Rspo2 in regulating osteoblastogenesis and bone formation in postnatal bone has not been explored. Here we show that limb-bud progenitor cells from Rspo2 knockout mice undergo reduced mineralization during osteoblastogenesis in vitro and have a corresponding alteration in their osteogenic gene expression profile. We also generated the first Rspo2 conditional knockout(Rspo2 floxed) mouse and disrupted Rspo2 expression in osteoblast-lineage cells by crossing to the Osteocalcin-Cre mouse line(OcnCre + Rspo2 ^(f/f)). Ocn-Cre + Rspo2 f/fmale and female mice at 1, 3, and 6 months were examined. Ocn-Cre + Rspo2 f/fmice are decreased in overall body size compared to their control littermates and have decreased bone mass. Histomorphometric analysis of1-month-old mice revealed a similar number of osteoblasts and mineralizing surface per bone surface with a simultaneous decrease in mineral apposition and bone formation rates. Consistent with this observation, serum osteocalcin in 3-month-old Ocn-Cre +Rspo2 f/fwas reduced, and bone marrow-mesenchymal stem cells from Ocn-Cre + Rspo2 f/fmice undergo less mineralization in ***, gene expression analysis and immunohistochemistry of mature bone shows reduced beta-catenin signaling in Ocn-Cre +Rspo2 f/f. Overall, RSPO2 reduces osteoblastogenesis and mineralization, leading to reduced bone mass.

关键词： The R-spondin family Wnt-stimulated pre-osteoblasts

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40 Gbit/s Transparent Network Based on Wavelength-Selective Optical Cross Connect

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光学学报 2003年第S1期23卷 711-712页

作者： Yikai Su bell Laboratories, Lucent Technologies, 791 Holmdel-Keyport Rd, Holmdel, New Jersey, USA bell Laboratories Lucent Technologies 791 Holmdel-Keyport Rd Holmdel New Jersey USA

This paper discusses a 40-Gbit/s transparent optical network focusing on the optical transport performance. We show 1200-km transmission with two WSOXC' sspaced by 400 km. In addition, network control issues are brief... 详细信息

关键词： GMPLS as in of be WDM Gbit/s Transparent Network Based on Wavelength-Selective Optical Cross Connect EDFA on

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Npy deletion in an alcohol non-preferring rat model elicits differential effects on alcohol consumption and body weight

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Journal of Genetics and Genomics 2016年第7期43卷 421-430页

作者： Bin Qiu Richard L.bell Yong Cao Lingling Zhang Robert B.Stewart Tamara Graves Lawrence Lumeng Weidong Yong Tiebing Liang Institute of Laboratory Animal Science Chinese Academy of Medical Sciences & Peking Union Medical College Beijing 100021 China Department of Psychiatry Indiana University School of Medicine Indianapolis IN 46202 USA Department of Gastroenterology Indiana University School of Medicine Indianapolis IN 46202 USA Department of Psychology Purdue School of Science Indiana University-Purdue University of Indianapolis Indianapolis IN 46202 USA Experimental Medicine Center The First Affiliated Hospital of Sichuan Medical University Luzhou 646000 China

Neuropeptide Y（NPY） is widely expressed in the central nervous system and influences many physiological *** is located within the rat quantitative trait locus（QTL） for alcohol preference on chromosome ***-nonpreferring（NP） rats consume very little alcohol,but have significantly higher NPY expression in the brain than alcohol-preferring（P） *** capitalized on this phenotypic difference by creating an Npy knockout（KO） rat using the inbred NP background to evaluate NPY effects on alcohol *** finger nuclease（ZNF） technology was applied,resulting in a 26-bp deletion in the Npy ***-PCR,Western blotting and immunohistochemistry confirmed the absence of Npy mRNA and protein in KO *** consumption was increased in Npy＋/- but not Npy-/- rats,while Npy-/- rats displayed significantly lower body weight when compared to Npy^（＋/＋） *** whole brain tissue,expression levels of Npy-related and other alcohol-associated genes,Npy1 r,Npy2r,Npy5 r,Agrp,Mc3 r,Mc4r,Crh and CrMr,were significantly greater in Npy-/- rats,whereas Pome and Crhr2 expressions were highest in Npy＋/- *** findings suggest that the NPY-system works in close coordination with the melanocortin（MC） and corticotropin-releasing hormone（CRH） systems to modulate alcohol intake and body weight.

关键词： Knockout rat Alcohol drinking behavior NPY and receptors CRH and receptors Melanocortin and receptors BDNF

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Introductory Comments by the Editors-in-Chief of the Journal of Energy Chemistry

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Journal of Energy Chemistry 2013年第1期22卷 I0001-I0001页

作者： Xinhe Bao Alexis T. bell State Key Laboratory of Catalysis Dalian Institute of Chemical Physicsthe Chinese Academy of Sciences University of California

Renaming of the Journal of Natural Gas Chemistry to the Journal of Energy Chemist~ is most timely and appropriate. The past decade has seen a rapid growth in research and technology devoted to the use of renewable energy resources, principally biomass and solar radiation, at the same time that reserves of fossil energy have increased as a consequence of using advanced drilling methods to release natural gas and petroleum from shale. The changes suggest that future research will focus on both the conversion of conventional energy resources in a manner that result in their efficient use and on the discovery and development of conversion technologies for utilization of renewable energy resources.

关键词： Introductory Comments by the Editors-in-Chief of the Journal of Energy Chemistry

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Optimization of relativistic laser–ion acceleration

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High Power Laser Science and Engineering 2014年第4期2卷 74-85页

作者： J.Schreiber F.bell Z.Najmudin Fakultt fr Physik Ludwig-Maximilians-Universitt Mnchen Am Coulombwall 1D-85748 Garching Germany Max-Planck-Institut fr Quantenoptik Hans-Kopfermann-Str.1D-85748 Garching Germany The John Adams Institute Blackett Laboratory Imperial College LondonLondon SW7 2AZ United Kingdom

Experiments have shown that the ion energy obtained by laser–ion acceleration can be optimized by choosing either the appropriate pulse duration or the appropriate target thickness. We demonstrate that this behavior can be described either by the target normal sheath acceleration model of Schreiber et al. or by the radiation pressure acceleration model of Bulanov and coworkers. The starting point of our considerations is that the essential property of a laser system for ion acceleration is its pulse energy and not its intensity. Maybe surprisingly we show that higher ion energies can be reached with reduced intensities.

关键词： laser–ion acceleration relativistic laser plasma interaction

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Single iron sites for catalytic, nonoxidative conversion of methane

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Science China Chemistry 2014年第7期57卷 923-923页

作者： Alexis T. bell University of California

The availability of inexpensive natural gas from the fracturing of shale and as a byproduct of oil production has stimulated the investigation of catalytic processes for the direct conversion of methane to products. Efforts in this direction are further driven by the desire to avoid the generation of CO2 and its emission to the atmosphere, as occurs when methane is steam-retbrmed to produce synthesis gas, a mixture of CO and H2 that can be used for the production of fuels and chemicals via Fischer-Tropsch synthesis. During the past forty years, numerous investigators have attempted to convert methane to higher value products by either thermal dehydrogenation or by oxidative dehydrogenation. While methane can be converted to benzene and hydrogen via thermal dehydrogenation,

关键词：甲烷转化催化过程非氧化站点石油生产氧化脱氢直接转换副产品

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纵观数学哲学与数学基础

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数学译林 1991年第3期10卷 251-257页

作者： bell,JL 郑毓信

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