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Positron emission particle tracking——Application and labelling techniques

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Particuology 2008年第1期6卷 16-23页

作者： David j. parker School of Physics and Astronomy the University of Birmingham Edgbaston Birmingham B15 2TT UK

The positron emission particle tracking （PEPT） technique has been widely used in science and engineering to obtain detailed information on the motion and flow fields of fluids or granular materials in multiphase systems, for example, fluids in rock cracks, chemical reactors and food processors; dynamic behaviour of granular materials in chemical reactors, granulators, mixers, dryers, rotating kilns and ball mills. The information obtained by the PEPT technique can be used to optimise the design, operational conditions for a wide range of industrial process systems, and to evaluate modelling work. The technique is based on tracking radioactively labelled particles （up to three particles） by detecting the pairs of backto-back 511 keV γ-rays arising from annihilation of emitted positrons. It therefore involves a positron camera, location algorithms for calculating the tracer location and speed, and tracer labelling techniques. This paper will review the particle tracking technique from tracking algorithm, tracer labelling to their application.

关键词： PEPT Tracer Algorithm Tracking

The ethical cost of doing nothing

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National Science Review 2020年第7期7卷 1260-1262页

作者： Andrew j.parker University of Oxford Department of PhysiologyAnatomy and Genetics

Concern has been raised about the ethics and risks of performing genetic interventions in macaque monkeys to study models of human neuropsychiatric conditions. Here I point out that,when the outcome of some situations is truly uncertain, human decision makers tend to evaluate these situations inconsistently. The consequences of this inconsistency are sometimes profound, as they lead policy makers and reviewers to ignore or discount the ethical costs of doing nothing. I conclude that there are fundamental problems with the ‘precautionary

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Neuromodulator interactions and spinal cord inj.ry in lamprey

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Neural Regeneration Research 2018年第4期13卷 643-644页

作者： David parker Thomas j.McClelland Department of Physiology Neuroscience and DevelopmentUniversity of Cambridge

Neuromodulation is mediated by neurotransmitters that typically act on G-protein-coupled *** can confer behavioural flexibility by modifying the functional properties of anatomically hard-wired neural *** neuromodulators generally have divergent cellular and synaptic effects（Harris-Warrick and j.hnson,2010）,and different modulators,

关键词： Figure Neuromodulator interactions and spinal cord inj.ry in lamprey

Positron imaging systems for studying particulate, granular and multiphase flows

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Particuology 2012年第2期10卷 146-153页

作者： Thomas W.Leadbeater David j.parker j.seph Gargiuli Positron Imaging Centre University of BirminghamEdgbastonBirmingham B152TTUKa

The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography （PET） to the study of particulate, granular and multiphase flows in industrial and physical processes, This paper provides a review of the PET and complimentary positron emission particle tracking （PEPT） techniques and details their application to the study of particulate sys- tems, The current state of the art, recent developments and example results from many of the applications to which these techniques have been applied are highlighted.

关键词： Positron emission particle tracking (PEPT)Particle dynamicsMulti-phase flow measurement

Physical separation from the mate diminishes male＇s attentiveness towards other females： a study in monogamous prairie voles Microtus ochrogaster

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Current Zoology 2017年第5期63卷 537-544页

作者： Christine j. DELEVAN Natalia A. RODRIGUEZ Karine M. LEGZIM Fayeza ALIOU j.mie T. parker Maryam BAMSHAD Department of Biological Sciences Lehman College--The City University of New York Bronx NY 10468 USA

We tested whether continuous cohabitation in monogamous voles affects the mated male＇s atten-tiveness to his breeding partner versus another female. Each male was housed in a 3-chamber ap-paratus with a Focal female （FF） and a Control female （CF） for 13 days then placed in a T-maze toassess his attentiveness to and memory of those females. The Distal male remained physically sep-arated from both females, but received their distal cues. The Separate male cohabited with the FFfor 3 days then remained physically separated from both females. The Disrupt male＇s continuouscohabitation with the FF was disrupted by having him physically separated from her after 10 daysand placed with the CF for the last 3 days. The Continuous male cohabited continuously with the FFfor 13 days. With females in the T-maze, the Separate and Disrupt males spent more time near theFF＇s box and the Disrupt males spent more time manipulating the FF＇s box than the CF＇s box. TheSeparate males groomed themselves more when near the FF＇s box than the CF＇s box. The Distaland Continuous males＇ attentiveness to the two females did not differ. Results suggest that phys-ical distance from the partner may reduce male＇s attentiveness toward other potential *** voles might be similar to socially monogamous primates in using tactile cues as a signal formaintaining their social bonds.

关键词： attachment, monogamy, partner preference, partner separation, social cognition.

An approach to viscoelastic c haracterization of dispersive media by inversion of a general wave propagation model

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j.urnal of Innovative Optical Health Sciences 2017年第6期10卷 73-88页

作者： Fernando Zvietcovich j.nnick P.Rolland Kevin j.parker Department of Electrical and Computer Engineering University of Rochester Rochester New York 14627USA The Institute of Optics University of Rochester Rochester New York 14627USA

In the characterization of elastic properties of tissue using dynarmic optical coherence elasto-graphy,shear/surface waves are propagated and tracked in order to estimate speed and Y oung's ***,for dispersive tssues,the displacement pulse is highly damped and distorted during propagation,diminishing the ffectiveness of peak tracking approaches,and leading to biased cstimates of wave ***,plane wave propagation is sometimes assumed,which contributes to estimation ***,we invert a wave propagation model that incorpo-rates propagation,decay,and distortion of pulses in a dispersive media in order to accurately estimate its elastic and viscous *** model uses a general first-order approximation of dispersion,avoiding the use of any particular rheological model of *** are conducted in elastic and viscoelastic tissue mimicking phantoms by producing a Gaussian push using acoustic radiation force excitation and measuring the wave propagation using a Fourier domain optical coherence tomography *** confirmed the ffectiveness of the inversion method in est imat ing viscoelastic parameters in both the viscoelastic and elastic phantoms when compared to mechanical ***,the viscoelastic characterization of a fresh porcine comea was *** results validate this approach when compared to other methods.

关键词： Elastography viscoelasticity cylindrical waves optical coherence tomography shear waves surface acoustic waves viscoelastic pha ntoms

Differences in Soil Microbial Biomass and Activity for Six Agroecosystems with a Management Disturbance Gradient

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Pedosphere 2004年第4期14卷 441-448页

作者： ZHANGWei-j.an FENGj.n-Xia j.WU K.parker DepartmentofAgronomy NanjingAgriculturalUniversityNanjing210095（China）. DepartmentofPlantPathology NorthCarolinaStateUniversityRaleighNC27695（USA）

Different management practices in six agroecosystems located near Goldsboro, NC, USA were conducted including a successional field (SU), a plantation woodlot (WO), an integrated cropping system with animals (IN), an organic farming system (OR), and two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT) to examine if and how microbial biomass and activity differ in response to alterations in disturbance intensity from six land management strategies. Results showed that soil microbial biomass and activity differed, with microbial activity in intermediately disturbed ecosystems (NT, OR, IN) being significantly higher (P ＜ 0.01) than systems with either high or low disturbance intensities. There was also a significant and a highly significant ecosystem effect from the treatments on microbial biomass C (MBC) (P ＜ 0.05) and on microbial activity (respiration) (P ＜ 0.01), respectively. Multiple comparisons of mean respiration rates distinctly separated the six ecosystem types into three groups: CT ＜ NT, SU and WO ＜ OR and ***, for detecting microbial response to disturbance changes these results indicated that the active component of the soil microbial community was a better indicator than total biomass.

关键词： agroecosystems carbon retention disturbance intensity microbial biomass soil microbial activity

Reminiscing my sixty year pursuit of the physics of the Sun and the Galaxy

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Research in Astronomy and Astrophysics 2014年第1期14卷 1-14页

作者： Eugene N.parker Department of Physics Department of Astronomy and AstrophysicsUniversity of Chicago

Reminiscing begins with childhood and passes on to student days through graduate school and the first real contact with research. Then early academic posi- tions and stumbling efforts to pursue my ideas. The first significant progress came as a research associate with Prof. W. M. Elsasser at the University of Utah, beginning with an introduction to magnetohydrodynarnics and the generation of the geomagnetic field through induction in the liquid metal core of Earth. A move to the University of Chicago to work with Prof. j. A. Simpson, on the implications of cosmic ray varia- tions and interplanetary magnetic fields, led to the theory of coronal expansion and the solar wind and then to exploring the dynamical effects of cosmic rays on the galactic magnetic field. Spontaneous current sheets and intrinsic rapid reconnection in interlaced magnetic field line topologies were the next big proj.ct, leading up to retirement. Finally, it is a pleasure to recall my many associates, whose fresh thinking helped stimulate the daily research activities.

关键词： dynamo -- magnetohydrodynamics -- plasma

Lumped Parameter Outflow Models for 1-D Blood Flow Simulations:Effect on Pulse Waves and Parameter Estimation

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Communications in Computational Physics 2008年第7期4卷 317-336页

作者： j.Alastruey K.H.parker j.Peiro S.j.Sherwin Department of Aeronautics Imperial College LondonSouth Kensington CampusLondon SW72AZU.K Department of Bioengineering Imperial College LondonSouth Kensington CampusLondon SW72AZU.K.

Several lumped parameter,or zero-dimensional(0-D),models of the microcirculation are coupled in the time domain to the nonlinear,one-dimensional(1-D)equations of blood flow in large arteries.A linear analysis of the coupled system,together with in vivo observations,shows that:(i)an inflow resistance that matches the characteristic impedance of the terminal arteries is required to avoid non-physiological wave reflections;(ii)periodic mean pressures and flow distributions in large arteries depend on arterial and peripheral resistances,but not on the compliances and inertias of the system,which only affect instantaneous pressure and flow waveforms;(iii)peripheral inertias have a minor effect on pulse waveforms under normal conditions;and(iv)the time constant of the diastolic pressure decay is the same in any 1-D model artery,if viscous dissipation can be neglected in these arteries,and it depends on all the peripheral compliances and resistances of the *** this analysis,we propose an algorithm to accurately estimate peripheral resistances and compliances from in vivo *** algorithm is verified against numerical data simulated using a 1-D model network of the 55 largest human arteries,in which the parameters of the peripheral windkessel outflow models are known a *** and flow waveforms in the aorta and the first generation of bifurcations are reproduced with relative root-mean-square errors smaller than 3%.

关键词： Pulse wave propagation one-dimensional modelling lumped parameter outflow models time-domain coupling arterial compliance peripheral compliance peripheral resistance multiscale modelling.