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Biomimetic flexible plate actuators are faster and more efficient with a passive attachment

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Acta Mechanica Sinica 2016年第6期32卷 1001-1011页

作者： peter d.Yeh Alexander Alexeev George W.Woodruff School of Mechanical Engineering Georgia Institute of Technology

Using three-dimensional computer simulations, we probe biomimetic free swimming of an internally actuated flexible plate in the regime near the first natural frequency. The plate is driven by an oscillating internal moment approximating the actuation mechanism of a piezoelectric macro fiber composite (MFC) bimorph. We show in our simulations that the addition of a passive attachment increases both swimming velocity and efficiency. Specifically, if the active and passive sections are of similar size, the overall performance is the best. We determine that this optimum is a result of two competing factors. If the passive section is too large, then the actuated portion is unable to generate substantial deflection to create sufficient thrust. On the other hand, a large actuated section leads to a bending pattern that is inefficient at generating thrust especially at higher frequencies.

关键词： Flexible plate Biomimetic Lattice Boltzmann Fluid-structure interaction Robotic fish Piezoelectric actuator

Spent coffee ground as source for hydrocarbon fuels

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Journal of Energy Chemistry 2016年第1期25卷 146-152页

作者： peter döhlert Maik Weidauer Stephan Enthalera Technische Universitat Berlin Department of ChemistryCluster of Excellence"Unifying Concepts in Catalysis"Straβe des 17.Juni 135/C2D-10623 BerlinGermany Universitat Hamburg Department of ChemistryMartin-Luther-King-Platz 6D-20146 HamburgGermany

The conversion of triglycerides（coffee oil） obtained from spent coffee ground to produce hydrocarbon fuel（diesel） was studied. In more detail, a catalytic hydrodeoxygenation of the coffee oil was performed applying polymethylhydrosiloxane（PMHS） as cheap reductant under mild reaction conditions. However, along with the hydrocarbons significant amounts of PMHS-waste are generated, since only～1.7% of the PMHS is required for the reduction process. Based on that, in a subsequent depolymerization step the PMHS-waste was converted to methyltrifluorosilane and difluoromethylsilane, which can be applied as building blocks for the production of new silicones, with boron trifluoride diethyl etherate（BF3OEt2） as depolymerization reagent.

关键词： Catalysis Triglyceride Hydrocarbons Hydrodeoxygenation depolymerization

Making the link between AdF and 4d STEM:Resolution,transfer and coherence

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Chinese Physics B 2024年第11期33卷 26-33页

作者： peter d.Nellist Timothy J.Pennycook department of Materials University of OxfordOxfordUK EMAT University of AntwerpGroenenborgerlaan 1712020 AntwerpBelgium

Steve Pennycook is a pioneer in the application of high-resolution scanning transmission electron microscopy(STEM)and in particular the use of annular dark-field(AdF)*** we show how a general framework for 4d STEM allows clear links to be made between AdF imaging and the emerging methods for reconstructing images from 4d STEM data *** show that both AdF imaging and ptychographical reconstruction can be thought of in terms of integrating over the overlap regions of diffracted discs in the detector *** approach allows the similarities in parts of their transfer functions to be understood,though we note that the transfer functions for ptychographic imaging cannot be used as a measure of information *** also show that conditions of partial spatial and temporal coherence affect AdF imaging and ptychography similarly,showing that achromatic interference can always contribute to the image in both cases,leading to a robustness to partial temporal coherence that has enabled high-resolution imaging.

关键词： image forming and processing phase retrieval electron microscopy scanning transmission electron microscope(STEM)

Effect of p-d exchange with an itinerant carrier in a GaMnAs quantum dot

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Journal of Semiconductors 2013年第7期34卷 1-6页

作者： d.Lalitha A.John peter department of Physics GTN College department of Physics Government Arts College

Hydrogenic acceptor binding energy as a function of dot radius in a GaMnAs/Ga_（0.6）Al_（0.4）As quantum dot is calculated including the exchange interaction of Mn alloy content with an itinerant *** are performed by varying its dot radius,for various Mn alloy contents in GaMnAs quantum dot within a single band effective mass approximation using variational *** spin polaronic energy of the acceptor impurity for different Mn^（2＋） is evaluated for different dot radii using a mean field theory in the presence of magnetic field *** magnetization is computed in the influence of magnetic field and the Mn *** effective g-factor of the valence band electron with the inclusion of effects of Mn ion impurities is found in the influence of the magnetic *** exchange coupling constant is calculated for various magnetic field *** results show that the p-d exchange interaction in the GaMnAs/Ga_（0.6）Al_（0.4）As quantum dot has a strong dependence on spatial confinement,effect of magnetic field strength and the Mn alloy *** results are in good agreement with the other investigators.

关键词： quantum dot acceptor diluted magnetic semiconductors

Current hypotheses for the evolution of sex and recombination

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Integrative Zoology 2012年第2期7卷 192-209页

作者： Matthew HARTFIELd peter d.KEIGHTLEY Institute of Evolutionary Biology University of EdinburghEdinburghUK

The evolution of sex is one of the most important and controversial problems in evolutionary *** sex is almost universal in higher animals and plants,its inherent costs have made its maintenance difficult to ex*** most famous of these is the twofold cost of males,which can greatly reduce the fecundity of a sexual population,compared to a population of asexual *** the past century,multiple hypotheses,along with experimental evidence to support these,have been put forward to explain widespread costly *** this review,we outline some of the most prominent theories,along with the experimental and observational evidence supporting ***,there have been 4 classes of theories:the ability of sex to fix multiple novel advantageous mutants(Fisher-Muller hypothesis);sex as a mechanism to stop the build-up of deleterious mutations in finite populations(Muller’s ratchet);recombination creating novel genotypes that can resist infection by parasites(Red Queen hypothesis);and the ability of sex to purge bad genomes if deleterious mutations act synergistically(mutational deterministic hypothesis).Current theoretical and experimental evidence seems to favor the hypothesis that sex breaks down selection interference between new mutants,or it acts as a mechanism to shuffle genotypes in order to repel parasitic ***,there is still a need to collect more data from natural populations and experimental studies,which can be used to test different hypotheses.

关键词： evolution of sex fitness-associated sex Hill-Robertson interference mutational deterministic hypothesis Red Queen hypothesis

Estimating the Great Lakes net radiation using satellite remote sensing and MERRA reanalysis

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International Journal of digital Earth 2017年第8期10卷 764-784页

作者： Sitthisak Moukomla peter d.Blanken Geo-Informatics and Space Technology development Agency(GISTdA) Lak Si BangkokThailand department of Geography and Environmental Studies Program University of ColoradoBoulderCOUSA

The net all-wave radiation of the Great Lakes(GL)is a key to understanding the effects of climate change on the *** is a high possibility of underestimating the net all-wave radiation of the GL when using existing methodologies with inputs from near-shore and land-based meteorological *** study provides the first technique to estimate net all-wave radiation over the GL from July 2001 to december 2014 using a combination of data from satellite remote sensing,reanalysis data sets,and direct *** components of the surface radiation budget estimated from the proposed method showed good statistical *** instantaneous net radiation estimated by our methods was compared with the in situ measurements from June 2008 to April 2012(Stannard Rock Lighthouse:SR)and September 2009–April 2011(Spectacle Reef Lighthouse:SP).The comparisons from SR and SP also showed strong statistic agreement(R^(2)=0.74 and 0.7;RMSE=9.26 and 10.60 W m^(−2) respectively).Monthly spatial variations of net shortwave radiation varied with cloud cover and surface albedo while net longwave radiation varied with the temperature difference between the water surface and the atmosphere.

关键词： The Great Lakes net all-wave radiation satellite remote sensing MERRA reanalysis

Ecology of Pinnidae(Mollusca: Bivalvia) from the Gulf of Thailand

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Acta Oceanologica Sinica 2019年第2期38卷 52-69页

作者： Cheewarat Printrakoon peter d Roopnarine Thamasak Yeemin Animal Systematic Special Unit Department of ZoologyFaculty of ScienceKasetsart University department of Invertebrate Zoology and Geology California Academy of Sciences department of Biology Faculty of ScienceRamkhamhaeng University

The ecology of the family Pinnidae was studied by sampling three pinnid species from 36 sampling sites across four different microhabitats in the Gulf of Thailand. The species spatial distributions were mostly uniform, with some populations having random distributions. Species abundances differed between sandy and coral habitats according to non-metric multi-dimension scaling analyses. Although the Gulf of Thailand is a relatively small geographic area, habitats are varied enough to provide variable shell densities. Small islands are important distribution areas, and coral reefs provide both direct and indirect shelter which support high abundances,densities and increased shell size. The highest density was recorded in sand beds within coral reefs. Low density and small shell size in sand beaches might be related to high mortality in shallow water or to adaptations for survival in shallow waters. A clear correlation between sediment composition and species abundance was found in Pinna atropurpurea; abundance increased with the sand content of the sediment. For P. deltodes, abundance increased as the rock fraction of the sediment increased. These results suggest that adaptations in Pinnidae, such as shell size, shell morphology, and the exposure of the shell above the sediment-water interface, are responses for survival in different habitats.

关键词： density distribution pinnid shell shell adaptation the Gulf of Thailand

Making Sense of Hospital Project MisPerformance: Over Budget, Late, Time and Time Again—Why? And What Can Be done About It?

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Engineering 2022年第5期8卷 183-201页

作者： peter E.d.Love Lavagnon A.Ika School of Civil and Mechanical Engineering Curtin UniversityPerthWA 6845Australia Telfer School of Management University of OttawaOttawaON KIN 6N5Canada

Hospital projects worldwide often experience misperformance,showing a tendency to exceed their estimated cost,miss their deadline,suffer quality problems,and yield benefit *** this ubiquitous problem,this paper aims to make sense of this phenomenon by addressing the following research question:How can we make sense of hospital project misperformance,and what can be done to mitigate its occurrence?We use an illustrative case study approach and the analytical lens of sense-making to examine the misperformance of three mega-hospital *** research reveals issues such as scope changes,an inability to adapt and respond to risk and uncertainty,ineffectual project management and governance,and optimism bias,which combine to impact project performance *** suggest that the two prominent theoretical perspectives dominating the literature in this field fall short of adequately explaining hospital project *** provide suggestions for improving the procurement process of hospitals and submit there is a need to develop a robust and balanced theory of project misperformance.

关键词： Cost Hospital Optimism bias Procurement Project management Performance Sense-making

Immune dysfunction in acute alcoholic hepatitis

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World Journal of Gastroenterology 2015年第42期21卷 11904-11913页

作者： Ashwin d dhanda peter L Collins School of Clinical Sciences University of Bristol NIHR Academic Clinical Lecturer in Hepatology Institute of Translational and Stratified Medicine Plymouth University Peninsula Schools of Medicine and Dentistry South West Liver Unit Plymouth Hospitals NHS Trust department of Liver Medicine University Hospitals Bristol NHS Foundation Trust

Acute alcoholic hepatitis(AAH) is a serious complication of alcohol misuse and has high short term mortality. It is a clinical syndrome characterised by jaundice and coagulopathy in a patient with a history of recent heavy alcohol use and is associated with profound immune dysfunction with a primed but ineffective immune response against pathogens. Here, we review the current knowledge of the pathogenesis and immune defects of AAH and identify areas requiring further study. Alcohol activates the immune system primarily through the disruption of gut tight junction integrity allowing the escape of pathogenassociated molecular particles(PAMPs) into the portal venous system. PAMPs stimulate cells expressing toll-like receptors(mainly myeloid derived cells) and initiate a network of intercellular signalling by secretion of many soluble mediators including cytokines and chemokines. The latter coordinates the infiltration of neutrophils, monocytes and T cells and results in hepatic stellate cell activation, cellular damage and hepatocyte death by necrosis or apoptosis. On the converse of this immune activation is the growing evidence of impaired microbial defence. Neutrophils have reduced phagocytic capacity and oxidative burst and there is recent evidence that T cell exhaustion plays a role in this.

关键词： Alcoholic hepatitis Alcoholic liver disease Toll-l