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Update of cholangioscopy and biliary strictures

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world journal of gastroenterology 2011年第34期17卷 3864-3869页

作者： marcus w Chin Michael F Byrne Department of gastroenterology and Hepatology Vancouver General Hospital Amy Athelstan Saw Fellow University of Western AustraliaPerth 6009 Australia Department of gastroenterology and Hepatology Vancouver General Hospital University of British ColumbiaVancouver V5Z1M9 Canada

Cholangioscopy remains another modality in the investigation of biliary strictures. At cholangioscopy, the"tumour vessel" sign is considered a specific sign formalignancy. Through its ability to not only visualisemucosa, but to take targeted biopsies, it has a greater accuracy, sensitivity and specificity for malignant strictures than endoscopic retrograde cholangiopancreatography guided cytopathological acquisition. Cholangioscopy however, is time consuming and costly, requires greater technical expertise, and should be reserved for the investigation of undifferentiated strictures after standard investigations have failed.

关键词： Biliary strictures Cholangioscopy Endo- scopic retrograde cholangiopancreatography Endos- copy Cholangiocarcinoma

Collective Computation,Information Flow,and the Emergence of Hunter-gatherer Small-worlds

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journal of Social Computing 2022年第1期3卷 18-37页

作者： marcus j.Hamilton the Department of Anthropology University of Texas at San AntonioSan AntonioTX 78249USA.

Two key features of human sociality are anatomically complex brains with neuron-dense cerebral cortices,and the propensity to form complex social networks with *** brains and complex social networks facilitate flows of fitness-enhancing energy and information at multiple scales of social ***,we consider how these flows interact to shape the emergence of macroscopic regularities in hunter-gatherer macroecology relative to other mammals and non-human *** computation is the processing of information by complex adaptive systems to generate inferences in order to solve adaptive *** hunter-gatherer societies the adaptive problem is to resolve uncertainty in generative models used to predict complex environments in order to maximize inclusive *** macroecological solution is to link complex brains in social networks to form collective brains that perform collective *** developing theory and analyzing data,the author shows hunter-gatherers bands of~16 people,or~4 co-residing families,form the largest collective brains of any social ***,because individuals,families,and bands interact at multiple time scales,these fission-fusion dynamics lead to the emergence of the macroscopic regularities in hunter-gatherer macroecology we observe in cross-cultural *** results show how computation is distributed across spatially-extended social networks forming decentralized knowledge systems characteristic of hunter-gatherer *** flow of information at scales far beyond daily interactions leads to the emergence of small-worlds where highly clustered local interactions are embedded within much larger,but sparsely connected multilevel metapopulations.

关键词： complex adaptive systems hierarchically modular networks collective brains macroecology allometry mammals primates

On Local Nonreflecting Boundary Conditions for Time Dependent wave Propagation

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Chinese Annals of Mathematics,Series B 2009年第5期30卷 589-606页

作者： marcus j. gROTE Imbo SIM Department of Mathematics University of Basel

The simulation of wave phenomena in unbounded domains generally requires an artificial boundary to truncate the unbounded exterior and limit the computation to a finite *** the artificial boundary a boundary condition is then needed,which allows the propagating waves to exit the computational domain without spurious *** 1977,Engquist and Majda proposed the first hierarchy of absorbing boundary conditions,which allows a systematic reduction of spurious reflection without moving the artificial boundary farther away from the *** pioneering work,which initiated an entire research area,is reviewed here from a modern *** developments such as high-order local conditions and their extension to multiple scattering are also ***,the accuracy of high-order local conditions is demonstrated through numerical experiments.

关键词： Absorbing boundary conditions Scattering problems wave equation

Diatom-inspired Plastic Deformation Elements for Energy Absorption in Automobiles

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journal of Bionic Engineering 2015年第4期12卷 613-623页

作者： Christin Hundertmark Rudiger Tinter Marc Ortelt marcus j B Hauser Otto-von-guericke University Magdeburg Institute of Experimental Physics Biophysics Group Universitatsplatz 2 39106 Magdeburg Germany Volkswagen Ag Plastic Business Sector Postbox O11/1219 38436 Wolfsburg Germany

we report on a biomimetic approach for the construction of a deformation element in vehicles which absorbs energy in the case of lateral collisions. we aim at simultaneously maximising the energy absorption capacity of the component and mini- mising its weight. The examined deformation element, a crash-pad is inspired by the structure of a diatom which is known for its structural stability. As the natural counterpart, our crash pad is characterized by an undulated shape. The three undulations of the crash pad are of different height and provide for a sequential absorption of the impact energy. Compression tests were performed on the prototypes of the crash pad that were produced from different materials, namely a conventional talc reinforced poly- propylene and a natural fibre reinforced plastic. Compression tests revealed that the bioinspired crash pads performed better or equal than their technical counterpart. As required, the bioinspired components deformed continuously with the increase in deformation force. Since the differences in the properties of the used materials were small, the increased energy absorption properties were predominantly due to the structure of the biomimetic deformation element.

关键词： biomimetic approach deformation element side crash natural fibre reinforced plastic energy absorption diatoms

Assessment of the spatial extent of permafrost in the Upper Indus Basin(UIB)

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journal of Mountain Science 2023年第6期20卷 1508-1525页

作者： wasim HASSAN g.jEELANI A.P.DIMRI marcus NüSSER Department of Earth Sciences University of KashmirSrinagar 190006India School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067India Department of geography South Asia Institute(SAI)Heidelberg UniversityHeidelberg 69115Germany Heidelberg Centre for the Environment(HCE) Heidelberg UniversityHeidelberg 69120Germany

Climate change differentially influences the frozen ground,a major dynamic component of the cryosphere,on a local and regional *** the warming climate with pronounced effects reported at higher altitudes,the characterization of the frozen ground is very important in the Upper Indus Basin(UIB),an important and critical region with respect to climate and hydro-glaciological *** this study,the efficiency and reliability of the surface frost number model are assessed in delineating the spatial extent of different classes of frozen ground in the *** daily MODIS land surface temperature(LST)with ground surface temperature(gST)and surface geomorphological expressions as ground validation datasets are used jointly in efficiently determining the extent of different classes of frozen ground(continuous and discontinuous permafrost and seasonal frost).The LST and gST resonate with each other in the annual cycle of temperature variation,however,with mean annual LST exhibiting an offset(cold bias)of 5 to 7℃relative to mean *** study shows that the highest permafrost extent is observed in areas where the lowest thinning rates of glacier ice are reported and vice *** surface frost number model categorizes an area of 38%±3%and 15%±3%in the UIB as permafrost and seasonal frost,*** on the altitude model,the lower limit of alpine permafrost is approximated at a mean altitude of 4919±590 m *** the *** present study acts as preliminary work in the data sparse and inaccessible regions of the UIB in characterizing the frozen and unfrozen ground and may act as a promising input data source in glaciohydro-meteorological models for the Himalaya and *** addition,the study also underlines the consideration of this derelict cryospheric climatic variable in defining and accounting for the sustainable development of socio-economic systems through its intricate ramification on agricultural activity,landscape stability and infrastruc

关键词： Upper Indus Basin Land surface temperature ground surface temperature Surface frost number Permafrost Seasonal frost

Can Labor Out-Migration Reduce Firewood Consumption by Rural Households in western Mountainous China

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Chinese journal of Population,Resources and Environment 2012年第2期10卷 110-119页

作者： Tai Xiujun LiShuzhuo marcus w. Feldman School of Economics and Management Shanxi Normal University Linfen Shanxi 041000 China Institute for Population and Development Studies School of Public Policy and Administration Xi'an Jiaotong University Xi'an Shaanxi 710049 China Morrison Institute for Population and Resource Studies Stanford University CA 94305 United States

The relationship between out-migration of labor in the Qinling mountain area and households' firewood consumption is explored. Migration and remittances reduce households' firewood consumption due to increases in both income and opportunity cost of firewood collection. Previous studies have been equivocal because they ignored uncertainty in household economy, which is widespread in forest areas of less developed countries. This study provides additional insight by considering vulnerability and subjective assessment of poverty generated by unstable income and an uncertain future. we provide evidence that the amount of firewood consumed depends on income and opportunity cost of firewood collection, but also on a prudent consumption strategy, due to farmers' subjective assessment of their future possible poverty. we also find out-migration of labor can reduce per capita firewood consumption but subjective poverty also acts against reduction of firewood consumption.

关键词： migration vulnerability firewood rural households

Cell wall Biology： Perspectives from Cell wall Imaging

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Molecular Plant 2011年第2期4卷 212-219页

作者： Kieran j.D. Lee Susan E. marcus j. Paul Knox Centre for Plant Sciences Faculty of Biological Sciences University of Leeds Leeds LS2 9JT UK

Polysaccharide-rich plant cell walls are important biomaterials that underpin plant growth, are major repositories for photosynthetically accumulated carbon, and, in addition, impact greatly on the human use of plants. Land plant cell walls contain in the region of a dozen major polysaccharide structures that are mostly encompassed by cellulose, hemicelluloses, and pectic polysaccharides. During the evolution of land plants, polysaccharide diversification appears to have largely involved structural elaboration and diversification within these polysaccharide groups. Cell wall chemistry is well advanced and a current phase of cell wall science is aimed at placing the complex polysaccharide chemistry in cellular contexts and developing a detailed understanding of cell wall biology. Imaging cell wall glycomes is a challenging area but recent developments in the establishment of cell wall molecular probe panels and their use in high throughput procedures are leading to rapid advances in the molecular understanding of the spatial heterogeneity of individual cell walls and also cell wall differences at taxonomic levels. The challenge now is to integrate this knowledge of cell wall heterogeneity with an understanding of the molecular and physiological mechanisms that underpin cell wall properties and functions.

关键词： Cell structure cell walls fluorescence imaging development cell wall imaging polysaccharides

Cell wall Microstructure Analysis Implicates Hemicellulose Polysaccharides in Cell Adhesion in Tomato Fruit Pericarp Parenchyma

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Molecular Plant 2009年第5期2卷 910-921页

作者： jose j. Ordaz-Ortiz Susan E. marcus j. Paul Knox Centre for Plant Sciences Faculty of Biological Sciences University of Leeds Leeds LS2 9JT United Kingdom

Methods developed to isolate intact cells from both unripe and ripe tomato fruit pericarp parenchyma have allowed the cell biological analysis of polysaccharide epitopes at the surface of separated cells. The LM7 pectic homogalacturonan epitope is a marker of the junctions of adhesion planes and intercellular spaces in parenchyma systems. The LM7 epitope persistently marked the former edge of adhesion planes at the surface of cells separated from unripe and ripened tomato fruit and also from fruits with the Cnr mutation. The LM 11 xylan epitope was associated, in sections, with cell walls lining intercellular space but the epitope was not detected at the surface of isolated cells, being lost during cell isolation. The LM15 xyloglucan epitope was present at the surface of cells isolated from unripe fruit in a pattern reflecting the former edge of cell adhesion planes/intercellular space but with gaps and apparent breaks. An equivalent pattern of LM15 epitope occurrence was revealed at the surface of cells isolated by pectate lyase action but was not present in cells isolated from ripe fruit or from Cnr fruit. In contrast to wild-type cells, the LM5 galactan and LM21 mannan epitopes occurred predominantly in positions reflecting intercellular space in Cnr, suggesting a concerted alteration in cell wall microstructure in response to this mutation. galactanase and mannanase, along with pectic homogalacturonan-degrading enzymes, were capable of releasing cells from unripe fruit parenchyma. These observations indicate that hemicellulose polymers are present in architectural contexts reflecting cell adhesion and that several cell wall polysaccharide classes are likely to contribute to cell adhesion/cell separation in tomato fruit pericarp parenchyma.

关键词： Cell walls fruit development tomato cell adhesion cell separation polysaccharide.

Microalloyed Steels for Heat Treating Applications at Higher Process Temperatures

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journal of Iron and Steel Research International 2011年第S1期18卷 80-89页

作者： David K.Matlock john g.Speer Steven g.jansto marcus Stuart Advanced Steel Processing and Products Research Center Colorado School of MinesGoldenColorado USA CBMM-Reference Metals BridgevillePA CBMM Sao PauloBrasil

The potential is considered for use of microalloyed bar steels,in conjunction with thermomechanical processing,to enhance the properties of steels heat treated at higher process temperatures than have been used *** examples are highlighted:microalloyed spring steels with enhanced resistance to tempering and Nb-modified gear steels for high temperature vacuum carburizing,*** the order of 1050℃ versus 930℃ for a typical gas carburizing *** the spring steel example,the Nb+V steel results in significantly finer prior austenite grain sizes than the other steels considered,enhanced fatigue performance,and improved *** the Nb-modified carburizing steel,Nb additions up to 0.1 wt pct to a Ti-modified 8620 steel,in conjunction with thermomechanical processing to control initial precipitate distributions prior to carburizing,are shown to lead to materials with improved resistance to abnormal austenitic grain growth at the higher process *** content and heating rate to the carburizing temperature were shown to be important variables and suppression of abnormal grain growth was correlated with the development of a critical distribution of fine NbC precipitates,stable at the austenitizing temperature leading to improved fatigue performance in steels with fine and uniform grain *** for extending the results of this study to alloy design and controlled rolling in bar mills are assessed.

关键词： microalloying niobium thermomechanical processing carburizing abnormal grain growth