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pair bonds during the annual cycle of a long-distance migrant,the Arctic Tern(Sterna paradisaea)

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Avian Research 2021年第3期12卷 346-353页

作者： chris p.F.Redfern School of Natural&Environmental Sciences Newcastle UniversityNE24HH&Natural History Society of NorthumbriaGreat North Museum:HancockNewcastle upon Tyne NE24PTUK

Background:The extent to which pairs remain together during the annual cycle is a key question in the behav-ioural ecology of migratory *** a few species migrate and winter as family units,for most the extent to which breeding partners associate in the non-breeding season is *** Arctic Tern(Sterna paradisaea)has one of the longest migrations of any species,and the aim of this study was to establish whether or not partners remain together after ***:Leg-mounted geolocators were fitted to breeding pairs of Arctic Terns nesting on the Farne Islands,North-umberland,*** devices were recovered for analysis the following ***:Analysis of data for the six pairs which returned the following year showed that partners departed from the colony at different times after breeding and migrated independently to different Antarctic *** also departed from the Antarctic and turned to the breeding colony *** third of the pairs divorced on ***:For long-distance migrants reliant on unpredictable foraging opportunities,it may not be viable to remain as pairs away from the breeding *** in arrival times at the breeding colony may maximise the chance of retaining a familiar partner,but could be affected by environmental factors in wintering areas or along migration routes.

关键词： Arctic Tern Migration pair-bond partner association

Novel recursive inference algorithm for discrete dynamic Bayesian networks

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progress in Natural Science:Materials International 2009年第9期19卷 1147-1151页

作者： chris p. Thompson School of Engineering Cranfield University

Dynamic Bayesian networks (DBNs) can effectively perform modeling and qualitative reasoning for many dynamic systems. However, most of its inference algorithms involve complicated graphical transformations that are hard to program and time-consuming to compute. This article proposes a new recursive inference algorithm, which is a purely numerical method derived from probability theory and the characteristics of Bayesian networks to do both on-line and off-line inferences in discrete DBNs. The most prominent advantages of this novel approach include: (1) it is an exact inference algorithm, thus its accuracy and stability can be guaranteed, (2) it avoids the complex graphical transformation so as to remarkably improve the inference speed, and (3) its concise recursive formulae facilitate programming of both forwards and backwards pass. All of these issues are verified by accurate mathematical derivation as well as a couple of application examples with comparison between the new algorithm and the two most prevailing inference approaches of discrete DBNs - the interface algorithm and the forwards-backwards algorithm.

关键词： Discrete DBNs Inference Algorithm

Optimal orientations of discrete global grids and the poles of Inaccessibility

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International Journal of Digital Earth 2020年第7期13卷 803-816页

作者： Richard barnes Energy&Resources Group BerkeleyUSA Electrical Engineering&Comptuer Science BerkeleyUSA

Spatial analyses involving binning often require that every bin have the same area,but this is impossible using a rectangular grid laid over the Earth or over any projection of the *** global grids use hexagons,triangles,and diamonds to overcome this issue,overlaying the Earth with equally-sized *** discrete global grids are formed by tiling the faces of a ***,the orientations of these polyhedra have been chosen to satisfy only simple criteria such as equatorial symmetry or minimizing the number of vertices intersecting ***,projection distortion and singularities in discrete global grids mean that such simple orientations may not be sufficient for all use ***,I present an algorithm for finding suitable orientations;this involves solving a nonconvex optimization *** a side-effect of this study I show that Fuller’s Dymaxion map corresponds closely to one of the optimal orientations I find.I also give new high-accuracy calculations of the poles of Inaccessibility,which show that point Nemo,the Oceanic pole of Inaccessibility,is 15 km farther from land than previously recognized.

关键词： Discrete grid geographic information system(GIS) geoinformatics supercomputer projections spatial statistics

Fhotocatalytic degradation of polybrominated diphenyl ethers in pure water system

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Frontiers of Environmental Science & Engineering 2016年第2期10卷 229-235页

作者： Min ZHANG Jian LU Yiliang HE p. chris WILSON School of Environmental Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China Indian River Research and Education Center University of Florida Fort Pierce FL 34945 USA

Due to the low water solubility of polybromi- nated diphenyl ethers, organic solvent is usually added into the oxidation system to enhance the removal efficiency. In this study the photocatalytic degradation of decabromodi- phenyl ether （BDE209）, a type ofpolybrominated diphenyl ether used throughout the world, in pure water without the addition of organic solvent was investigated. In the pure water system, BDE209 was not dissolved but dispersed as nano-scale particles with a mean diameter of 166 nm. Most of BDE209 （〉 98%） were removed within 4 h and the final debromination ratio was greater than 80%. Although the addition of organic solvent （tetrahydrofuran, THF） could lead to a relatively high BDE209 degradation rate, the final debromination ratio （〈 50%） was much lower than that in pure water system. Major oxidation inter- mediates of tetrahydrofuran, including tetrahydro-2-fura- nol and y-butyrolactone, were detected indicating the engagement of THF in the BDE209 degradation process. The photocatalytic degradation of BDE209 in the pure water system followed first-order kinetics. The BDE209 degradation rate constant increased from 0.0011 to 0.0023 min-1 as the pH increased from 3 to 9.

关键词： polybrominated diphenyl ethers photocataly-tic degradation solvent

A Finite Element Method for Modelling Electromechanical Wave propagation in Anisotropic piezoelectric Media

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Communications in Computational physics 2007年第2期2卷 271-292页

作者： S.Rahman H.p.Langtangen C.H.W.barnes Cavendish Laboratory Cambridge UniversityJ J Thomson AvenueCambridgeCB3 OHEUnited Kingdom Simula Research Laboratory Martin Linges v 17Fornebu P.O.Box 1341325 LysakerNorway

We describe and evaluate a numerical solution strategy for simulating surface acoustic waves(SAWs)through semiconductor devices with complex *** multi-physics problem is of particular relevance to the design of SAW-based quantum electronic *** mathematical model consists of two coupled partial differential equations for the elastic wave propagation and the electric field,respectively,in anisotropic piezoelectric *** equations are discretized by the finite element method in space and by a finite difference method in *** latter method yields a convenient numerical decoupling of the governing *** describe how a computer implementation can utilize the decoupling and,via object-oriented programming techniques reuse independent codes for the poisson equation and the linear time-dependent elasticity *** we apply the simulator to a simplified model problem for verifying the implementation,and thereafter we show that the methodology is capable of simulating a real-world case from nanotechnology,involving SAWs in a geometrically non-trivial device made of Gallium ***:***,***,*** Key words:Finite element method,piezoelectric surface acoustic waves,Gallium Arsenide.

关键词： Finite element method piezoelectric surface acoustic waves Gallium Arsenide.

Trace analysis of off-flavor/odor compounds in water using liquid-liquid microextraction coupled with gas chromatography--positive chemical ionization-tandem mass spectrometry

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Frontiers of Environmental Science & Engineering 2016年第3期10卷 477-481页

作者： Jian LU paul S. WILLS p. chris WILSON Indian River Research and Education Center University of Florida/IFAS 2199 South Rock Road Fort Pierce FL 34945-3138 USA Harbor Branch Oceanographic Institute at Florida Atlantic University 5600 U.S. 1 North Fort Pierce FL 34946 USA

A rapid, inexpensive and laboratory friendly method was developed for analysis of off-flavor/odor compounds in fresh and salt water using gas chromatography with chemical ionization-tandem mass spectrometry. Off-flavor/odor compounds, included geosmin, 2- methylisobomeol （MIB）, 2-isobutyl-3-methyoxypyrazine （IBMp）, and 2-isopropyl-3-methoxypyrazine （IpMp）. Using this method, a single sample can be extracted within minutes using only 1 mL of organic solvent. The ion transitions for IpMp, IBMp, MIB, and geosmin were 153 〉 121, 167 〉 125, 152 〉 95, and 165 〉 109, respectively. The linearity of this method for analyzing MIB ranged from 4 to 200ng·L^-1, and from 0.8 to 200ng·L^-1 for the other analytes. Method recoveries ranged from 97% to 111% and percent relative standard deviations ranged from 3% to 9%, indicating that the method is accurate, precise, and reliable.

关键词： off-flavor/odor compounds liquid-liquid microextraction gas chromatography-tandem mass spectrometry

Revealing and exploiting hierarchical material structure through complex atomic networks

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npj Computational Materials 2017年第1期3卷 163-170页

作者： Sebastian E.Ahnert William p.Grant chris J.pickard Theory of Condensed Matter Group Cavendish LaboratoryUniversity of CambridgeJJ Thomson AvenueCambridge CB30HEUK Sainsbury Laboratory University of CambridgeBateman StreetCambridge CB21LRUK Department of Materials Science&Metallurgy University of Cambridge27 Charles Babbage RoadCambridge CB30FSUK Advanced Institute for Materials Research Tohoku University 2-1-1 KatahiraAobaSendai 980-8577Japan

One of the great challenges of modern science is to faithfully model,and understand,matter at a wide range of *** with atoms,the vastness of the space of possible configurations poses a formidable challenge to any simulation of complex atomic and molecular *** introduce a computational method to reduce the complexity of atomic configuration space by systematically recognising hierarchical levels of atomic structure,and identifying the individual *** a list of atomic coordinates,a network is generated based on the distances between the *** the technique of modularity optimisation,the network is decomposed into *** procedure can be performed at different resolution levels,leading to a decomposition of the system at different scales,from which hierarchical structure can be *** considering the amount of information required to represent a given modular decomposition we can furthermore find the most succinct descriptions of a given atomic *** straightforward,automatic and general approach is applied to complex crystal *** show that modular decomposition of these structures considerably simplifies configuration space,which in turn can be used in discovery of novel crystal structures,and opens up a pathway towards accelerated molecular dynamics of complex atomic *** power of this approach is demonstrated by the identification of a possible allotrope of boron containing 56 atoms in the primitive unit cell,which we uncover using an accelerated structure search,based on a modular decomposition of a known dense phase of boron,γ-B_(28).

关键词： structure atomic complex

Accurate and scalable graph neural network force field and molecular dynamics with direct force architecture

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npj Computational Materials 2021年第1期7卷 650-658页

作者： Cheol Woo park Mordechai Kornbluth Jonathan Vandermause chris Wolverton Boris Kozinsky Jonathan p.Mailoa Robert Bosch Research and Technology Center CambridgeMA 02139USA Northwestern University EvanstonIL 60208USA Harvard School of Engineering and Applied Sciences CambridgeMA 02138USA

Recently,machine learning(ML)has been used to address the computational cost that has been limiting ab initio molecular dynamics(AIMD).Here,we present GNNFF,a graph neural network framework to directly predict atomic forces from automatically extracted features of the local atomic environment that are translationally-invariant,but rotationally-covariant to the coordinate of the *** demonstrate that GNNFF not only achieves high performance in terms of force prediction accuracy and computational speed on various materials systems,but also accurately predicts the forces of a large MD system after being trained on forces obtained from a smaller ***,we use our framework to perform an MD simulation of Li7p3S11,a superionic conductor,and show that resulting Li diffusion coefficient is within 14%of that obtained directly from *** high performance exhibited by GNNFF can be easily generalized to study atomistic level dynamics of other material systems.

关键词： neural AIMD dynamics

Garnet fractionation,progressive melt loss and bulk composition variations in anatectic metabasites:Complications for interpreting the geodynamic significance of TTGs

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Geoscience Frontiers 2020年第3期11卷 745-763页

作者： Jillian Kendrick chris Yakymchuk Department of Earth and Environmental Sciences University of WaterlooWaterlooOntarioN2L 3G1Canada

Tonalite-trondhjemite-granodiorite(TTG) suites constitute a large proportion of the Archean geological record;however,the geodynamic processes that generated them,and Archean continental crust in general,remain a subject of *** concentrations and ratios of Sr,Y,La,Yb,Nb,and Ta in TTGs are commonly used to determine the depth of melting of their metabasic *** trace element composition of melt produced by metabasic source rocks during anatexis is strongly affected by the presence and abundance of pressure-sensitive minerals,such as plagioclase(Sr-bearing),garnet(Y-and HREE-bearing),and rutile(Nb-and Ta-bearing).Elevated Sr/Y and La/Yb ratios and low concentrations of Nb and Ta in TTGs are generally considered to indicate melting at high pressures(≥2.0 Gpa).The depth of melting is a key factor in determining the origin of TTGs as this provides critical information on the tectonic setting of their *** use phase equilibrium and trace element modelling to explore the effects of three potential influences on TTG trace element compositions:fractionation of trace elements into peritectic garnet cores,progressive melt loss from the source,and source bulk *** model three different compositions of Archean basalts along thermal gradients of 500℃/Gpa,750℃/Gpa,and 1000℃/*** models produce maj or and trace element melt compositions that are generally consistent with measured compositions of *** Sr/Y,La/Yb,Nb,and Ta exhibit pressure-dependent behaviour,other factors also affect these *** fractionation causes Sr/Y and La/Yb to reach much greater values and in this scenario,the values also increase with increasing *** bulk composition has an effect in all scenarios and most strongly influences La/Yb,Nb,and ***,these results show that Sr/Y,La/Yb,Nb,and Ta can reach values generally considered to be indicative of high pressure melting at a range of p-T conditions including p <2.0 ***,trace ele

关键词： Archean Anatexis Trace element phase equilibrium modelling Tectonics