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Silicon-integrated nonlinear Ⅲ-Ⅴ photonics

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Photonics Research 2022年第2期10卷 535-541页

作者： Weiqiang Xie Chao Xiang Lin Chang warren jin Jonathan Peters John E.Bowers Department of Electrical and Computer Engineering University of CaliforniaSanta BarbaraSanta BarbaraCalifornia 93106USA Current address:Department of Electronic Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Mainstream silicon photonic integrated circuits are based on compact and low-loss silicon-on-insulator(SOI)waveguide platforms. However, monolithic SOI-based photonics provides only a limited number of functional device types. Here, to extend the on-chip capabilities, we propose a general heterogeneous integration approach to embed highly nonlinear Ⅲ-Ⅴ(Al Ga As) photonics into the SOI platform. We develop low-loss AlGaAs-on-SOI photonic circuits with integrated Si waveguides and showcase sub-milliwatt-threshold(-25 mW) Kerr frequency comb generation in ultrahigh-QAlGaAs microrings(Q over 10^(6)) at the telecom bands. Our demonstration complements existing mature Si photonics technology with efficient nonlinear functionalities provided by Ⅲ-Ⅴ and propels conventional Si photonics into emerging nonlinear photonic applications towards fully chip-based nonlinear engines.

关键词： SOI AlGaAs waveguide

Blind spots in climate finance for innovation Peter warren

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Advances in Climate Change Research 2020年第1期11卷 60-64页

作者： Peter warren School of Public Policy University College London(UCL)LondonWCIH 9QUUK

International climate finance is a sub-set of green finance and refers to investments specifically in climate change mitigation and adaptation activities,which primarily involve public finance and the leveraging of private finance in developing *** addition to continued international support for scaling low carbon solutions and facilitating replicability in developing countries,there remains an important need to increase the amount of climate finance provided to innovation,particularly demonstration(for technology innovation)and pilot implementation(for policy innovation),and to channel a greater proportion of Official Development Assistance(ODA)to‘hard-to-abate'areas,such as industrial decarbonisation,international transport and cross-sectoral issues like cooling and behavioural insights,to accelerate the commercialisation and implementation of technological,linancial and policy solutions to contribute to meeting the Paris Agreement's goal of limiting global warming to‘well-below'2℃ in these *** research,development and demonstration(RD&D)support with technical assistance is important in providing the route to obtain wider donor finance(concessional finance)and private finance to enable deployment through scalability and replicability.

关键词： Climate finance Climate policy Paris Agreement Official development assistance Industrial decarbonisation Sustainable cooling Behavioural insights International transport

Applying molecular genetic tools to tiger conservation

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Integrative Zoology 2010年第4期5卷 351-362页

作者： Shu-jin LUO warren E.JOHNSON Stephen J.O’BRIEN School of Life Sciences Peking UniversityBeijingChina Laboratory of Genomic Diversity National Cancer InstituteFrederickMDUSA

The utility of molecular genetic approaches in conservation of endangered taxa is now commonly *** the past decade,conservation genetic analyses based on mitochondrial DNA sequencing and microsatellite genotyping have provided powerful tools to resolve taxonomy uncertainty of tiger subspecies,to define conservation units,to reconstruct phylogeography and demographic history,to examine the genetic ancestry of extinct subspecies,to assess population genetic status non-invasively,and to verify genetic background of captive tigers *** genetic status of tiger subspecies and populations and implications for developing strategies for the survival of this charismatic species both in situ and ex situ are discussed.

关键词： conservation genetics mitochondrial DNA microsatellite subspecies tiger

Sustainability: A view from the wind-eroded field

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Journal of Environmental Sciences 2007年第4期19卷 470-474页

作者： Andrew warren Department of Geography University College London LondonWCIH OAPUK.

This article explores the assessment of sustainability in fields subject to wind erosion. In the first part, simple sustainability audits are examined, as of soil depth and nutrients. Direct measurement of these characteristics has many problems, largely because of huge variability in space and time at all scales. Modelling still has its problems, but it may be possible to overcome many of them soon. It is true that wind erosion preferentially removes soil nutrients, but there are imponderables even here. The nutrient balance in many of these soils includes considerable input from dust. In West Africa, it has been shown that the amounts of calcium and potassium that are added in dust are sufficient to fertilize dispersed crops. In mildly acidic sandy soils, such as those found on the widespread palaeo- aeolian deposits, much of the phosphorus is fixed and unavailable to plants by the time it is removed by wind erosion, so that erosion has no added downside. Most of the nutrients carried by dust have been shown to travel close to the ground （even when they are attached to dust-sized particles）, and so are trapped in nearby fallow strips, and are thus not lost to the farming system. Second, the sustalnabillty of a whole semi-arid farming system is explored. Wind erosion in semi-arid areas （like China, the Sahel and Norflawestern Europe） generally takes place on aeolian deposits of the recent geological past. Most of these soils are deep enough to withstand centuries of wind erosion before they are totally lost to production, and some of these soils have greater fertility at greater depth （so that wind erosion may even improve the soil）. Finally some remarks are made about environmental change in relation to sustainability.

关键词： sustartinability wind erosion nutrient budget environmental change

Phylogenetic positions of two marine ciliates, Metanophrys similis and Pseudocohnilembus hargisi (Protozoa, Ciliophora,Scuticociliatia), inferred from complete small subunit rRNA gene sequences

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Progress in Natural Science:Materials International 2006年第4期16卷 373-378页

作者： Alan warren Department of Zoology The Natural History Museum Cromwell Road London SW7 5BD UK

The small subunit rRNA (SSrRNA) gene was sequenced for two marine scuticociliates Metanophrys similis and Pseudocohnilembus hargisi. The results show that this gene comprises 1763 and 1753 nucleotides in the two marine ciliates respectively. Metanophrys similis is phylogenetically closely related to the clade containing Mesanophrys carcini and Anophyroides haemophila, which branches basally to other species within the order Philasterida. Pseudocohnilembus hargisi groups with its congener, P. marinus, with strong bootstrap support. Paranophrys magna groups with the clade including Cohnilembus and Uronema, representing a sister clade to that containing the two Pseudocohnilembus species.

关键词： phytogeny protozoa scuticociliate Metanophrys similis Pseudocohnilembus hargisi.

A simple model for reconstructing geomagnetic field intensity with (10)~Be production rate and its application in Loess studies

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Science China Earth Sciences 2008年第6期51卷 855-861页

作者： J. warren BECK NSF-AMS Laboratory University of Arizona

A simple model for reconstructing the paleomagnetic field intensity with (10)~Be production rate was used for the first time in Loess (10)~Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess (10)~Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess (10)~Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the (10)~Be paleo- intensity curve and the future direction of loess (10)~Be tracing studies. Results show the irregular vari-ability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the (10)~Be record in the loess, and the intrinsic source component of the loess (10)~Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the 'quasi-homogeneous distribution' manner.

关键词： (10)~Be LGM geomagnetic excursion paleointensity quasi-homogeneous distribution

A review of stochastic algorithms with continuous value function approximation and some new approximate policy iteration algorithms for multidimensional continuous applications

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控制理论与应用（英文版） 2011年第3期9卷 336-352页

作者： warren B.POWELL Department of Operations Research and Financial Engineering Princeton University

We review the literature on approximate dynamic programming,with the goal of better understanding the theory behind practical algorithms for solving dynamic programs with continuous and vector-valued states and actions and complex information *** build on the literature that has addressed the well-known problem of multidimensional(and possibly continuous) states,and the extensive literature on model-free dynamic programming,which also assumes that the expectation in Bellman’s equation cannot be ***,we point out complications that arise when the actions/controls are vector-valued and possibly *** then describe some recent research by the authors on approximate policy iteration algorithms that offer convergence guarantees(with technical assumptions) for both parametric and nonparametric architectures for the value function.

关键词： Approximate dynamic programming Reinforcement learning Optimal control Approximation algorithms

Re-evaluation of the phylogenetic position of the genus Dexiotrichides (Protozoa, Ciliophora, Scuticociliatida) inferred from stomatogenetic and molecular information for Dexiotrichides pangi

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Progress in Natural Science:Materials International 2005年第8期15卷 700-707页

作者： Alan warren,David ROBERTS,Norbert WILBERT London SW7 5BD UK Zoologisches Institut Universitt Bonn 53115 Bonn Germany Department of Zoology Natural History of Museum Cromwell Road London SW7 5BD UK Department of Zoology Natural History of Museum Cromwell Road

The divisional process and systematic position of the marine scuticociliate Dexiotrichides pangi are studied. Based on both stomatogenetic data and 18S rDNA gene sequences, the phylogeny and morphogenetic characteristics of this taxon, and of other related genera, are analyzed and discussed. Both the divisionary events and the molecular biological data indicate that this species/genus, together with certain other genera in the Dexiotricha-complex, occupies an intermediate position between the tetrahymenids and the “typical” scuticociliate, which suggests that the Dexiotricha-like taxa should be excluded from the “true” scuticociliates. As a further contribution, the process of stomatogenesis in D. pangi can be summarized as follows: (1) The oral primordia in the opisthe are formed only by the proliferation of basal bodies in the scutica field, which subsequently develop into three membranelles, while the new paroral membrane seems to be generated by the sub-anterior portion of somatic kinety 1 (the 1st postoral intercalary kinety). The latter character exhibits a mode similar to Tetrahymena. (2) In the proter the parental membranelles are retained and remain unchanged throughout the entire division process; only the old paroral membrane is disassembled and differentiated into the anlage, which then gives rise to the new paroral membrane and the scutica of the proter. The 18S rRNA gene sequence reported here is the first one for a ciliate in the Dexiotricha-complex.

关键词： marine ciliate systematic position stomatogenesis 18S rRNA gene sequences Dexiotrichides pangi.

Control design of an unmanned hovercraft for agricultural applications

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International Journal of Agricultural and Biological Engineering 2015年第2期8卷 72-79页

作者： Deyka I Garcia warren N White Department of Mechanical Engineering Universidad Tecnológica de PanamáPanamá0819-07289Panamá Department of Mechanical and Nuclear Engineering Kansas State UniversityManhattanKS 66506USA

The efficient and precise application of agricultural materials such as fertilizer or herbicide can be greatly facilitated by autonomous *** is especially important under difficult conditions at remote *** purpose of this work is to develop an accurate nonlinear controller using a direct Lyapunov approach to ensure stability of an unmanned hovercraft prototype used for the execution of these agricultural *** a craft constitutes an underactuated system which has fewer actuators than degrees of *** proposed closed loop system is simulated to demonstrate that a control law can stabilize both the actuated and unactuated degrees of freedom of the *** is shown that the position and orientation of the hovercraft achieve high dynamic and steady performance.

关键词： controller direct Lyapunov method nonholonomic constraint underactuated system unmanned hovercraft