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Distribution characteristics of inertial sediment particles in the turbulent boundary layer of an open channel flow determined using Voronoi analysis

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International Journal of Sediment Research 2017年第3期32卷 401-409页

作者： Xin Liu Chunning Ji Xiaoli Xu Dong Xu john J.R.williams State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin Research Institute for Water Transport Engineering M.O.T. State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University School of Engineering and Materials Science Queen Mary University of London

This paper presents the numerical investigation of the distribution of inertial sediment particles in the turbulent boundary layer of an open channel flow with the particle Stokes number ranging from 0.6 to 20.4. The methodology is a combination of three numerical approaches, i.e. direct numerical simulation of turbulent flow, the point-particle immersed boundary method, and the discrete particle method. By applying the Vorono analysis, the preferential concentration characteristics of sediment particles were investigated quantitatively. It was found that the normalized area of the Voronoi cells follows a lognormal particle distribution. The inertial sediment particles distributed unevenly in the turbulent boundary layer and the unevenness, governed by the particle Stokes number, was more significant as the particle Stokes number approaches unity. The inertial sediment particles in the turbulent boundary layer accumulated preferentially in streamwise-aligned streaky structures and this pattern was less significant with increasing particle Stokes number.

关键词： Inertial sediment particles Turbulent boundary layers Voronoi analysis Direct numerical simulation

Characterization of organic-rich mineral debris revealed by rapid glacier retreat, Indren Glacier, European Alps

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Journal of Mountain Science 2021年第6期18卷 1521-1536页

作者： FREPPAZ Michele williams mark W. GABRIELI Jacopo GORRA Roberta MANIA Ilaria ASCHER-JENULL Judith EGLI markus CELI Luisella Department of Agriculture Forest and Food SciencesUniversity of TurinLargo Paolo Braccini 210095 Grugliasco(TO)Italy NatRisk Research Centre on Natural Risks in Mountain and Hilly Environments University of TurinLargo Paolo Braccini 210095 Grugliasco(TO)Italy Institute of Arctic and Alpine Research and Department of Geography University of Colorado at BoulderUCB 450BoulderCO 80309USA CNR-ISP(Consiglio Nazionale delle Ricerche Istituto di Scienze Polari)via Torino 15530172 Venezia-MestreItaly Institute of Microbiology University of InnsbruckTechnikerstraße 256020 InnsbruckAustria Department of Geography University of ZurichWinterthurerstrasse 1908057 ZurichSwitzerland

In the summer of 2003 and 2004, characterized by a rapid glacier retreat, a stony surface covered by well-structured organic-rich mineral debris was observed very close to the Indren glacier terminus(Monte Rosa Massif, NW Italy, 3100 m ASL), on an area covered by the glacier tongue till the year before. The origin and type of this organicrich material were investigated, in order to detect their characteristics, potential sources and fate within the foreland system. The deposits were dated using Carbon-14 and analyzed for the chemical characteristics of the organic component, the elemental composition of the mineral fraction and presence of microbial markers. The material, granular and dark in color, had a total organic carbon(TOC) content ranging between 17.4 ± 0.39 and 28.1 ± 0.63 g kg^(-1) dry weight(dw), significantly higher than the surrounding glacial till(~ 1.4 g kg^(-1) dw), although only 0.33% of it was in water soluble form. Microbial carbon(C) and nitrogen(N) accounted for 10.6% and 3.13% of TOC and total N, respectively. Dissolved nitrogen(N), mainly present as ammonium, represented 2.40% of the total N. The low aromatic component and large presence of nitrogen(N)-derived compounds suggested that most of the organic carbon(OC) in these organic-rich mineral deposits was derived from microbial cells, although the high average radiocarbon age of about 2900 years may also point to the contribution of aeolian depositions of anthropogenic or natural origin. Elemental composition and the crustal enrichment factor of trace elements in the mineral fraction of the aggregates corroborated the hypothesis that most part of the accumulated material derived from ice meltwater. Some indicators of the colonization of these deposits by microbial communities were also reported, from the abundance of DNA and phylogenetic markers, to the presence of bacterial taxa commonly able to thrive in similar habitats. All these elements suggested that such kind of deposits may have a p

关键词： Glacier foreland Dissolved organic carbon Organic matter q PCR Microbial community Trace elements

Rangeland hillslope lengths:A case study at the Walnut Gulch Experimental Watershed,southeastern Arizona

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International Soil and Water Conservation Research 2022年第4期10卷 597-609页

作者： Li Li mark A.Nearing Philip Heilman Mary H.Nichols D.P.Guertin C.J.williams School of Natural Resources and the Environment University of ArizonaTucsonAZ85705USA USDA-Agricultural Research Service Southwest Watershed Research CenterTucsonAZ85719USA

Rangeland hillslopes provide much of the sediment supplied to channel systems and their lengths exert a fundamental constraint on hillslope diffusive ***,information regarding lengths of rangeland hillslopes,and how best to estimate them,is *** this study,three groups of watersheds(10 in total)were selected from the Walnut Gulch Experimental Watershed according to their geology,soil and vegetation *** 1 watersheds were at lower elevations dominated by shrubs,Group 3 were at high elevations dominated by grass,and Group 2 were mixed shrub and *** hillslope lengths were calculated from 1 m-resolution DEMs using three methods:a flow routing algorithm,slope-area relationships,and inverted relationship with drainage *** that characterize the current watersheds,including Hack's exponent and coefficient,watershed shape coefficient,channel concavity and steepness,and surface roughness,were quantified and related to hillslope *** shows:(1)estimated hillslope lengths were different for the three methods and between the three groups of watersheds;(2)hillslope lengths that measured from the flow routing algorithm for the ten selected watersheds primarily ranged from 30 to 100 m,with a median value of 63.0 m,which was 20%e50%greater than those derived from slope-area plots or drainage densities;(3)hillslope lengths estimated from the flow routing method were greater in Group 3 watersheds than in Group 2 and then in Group 1 *** attributed these differences in hillslope lengths to the historic epeirogenic pulses,watershed and drainage network morphology,and differences in vegetation characteristics;(4)measured hillslope lengths from the flow routing algorithm were best correlated with hillslope relief,then surface roughness,channel steepness and *** results would benefit the applications of hydrological and erosion models in rangelands.

关键词： Rangeland hillslope Slope length Drainage density Slope-area relationship Hillslope hydrology

Transdermal delivery of 4-aminopyridine accelerates motor functional recovery and improves nerve morphology following sciatic nerve crush injury in mice

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Neural Regeneration Research 2020年第1期15卷 136-144页

作者： Andrew RClark Chia George Hsu M A Hassan Talukder mark Noble john CElfar Center for Orthopaedic Research and Translational Science Penn State Hershey College of MedicineMilton S.Hershey Medical CenterHersheyPAUSA Department of Orthopaedics The University of Rochester Medical CenterRochesterNYUSA Department of Medicine Aab Cardiovascular Research InstituteUniversity of Rochester School of Medicine and DentistryRochesterNYUSA Department of Biomedical Genetics The University of Rochester Medical CenterRochesterNYUSA

Oral 4-aminopyridine(4-AP)is clinically used for symptomatic relief in multiple sclerosis and we recently demonstrated that systemic 4-AP had previously unknown clinically-relevant effects after traumatic peripheral nerve injury including the promotion of re-myelination,improvement of nerve conductivity,and acceleration of functional *** hypothesized that,instead of oral or injection administration,transdermal 4-AP(TD-4-AP)could also improve functional recovery after traumatic peripheral nerve *** with surgical traumatic peripheral nerve injury received TD-4AP or vehicle alone and were examined for skin permeability,pharmacokinetics,functional,electrophysiological,and nerve morphological properties.4-AP showed linear pharmacokinetics and the maximum plasma 4-AP concentrations were proportional to TD-4-AP *** a single dose of TD-4-AP administration demonstrated rapid transient improvement in motor function,chronic TD-4-AP treatment significantly improved motor function and nerve conduction and these effects were associated with fewer degenerating axons and thicker myelin sheaths than those from vehicle *** findings provide direct evidence for the potential transdermal applicability of 4-AP and demonstrate that 4-AP delivered through the skin can enhance in-vivo functional recovery and nerve conduction while decreasing axonal *** animal experiments were approved by the University Committee on Animal Research(UCAR)at the University of Rochester(UCAR-2009-019)on March 31,2017.

关键词： 4-aminopyridine electron microscopy functional recovery nerve conduction velocity peripheral nerve injury pharmacokinetics transdermal administration

“Listening to the Sounds of the Water”:Bringing Together Local Knowledge and Biophysical Data to Understand Climate-Related Hazard Dynamics

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International Journal of Disaster Risk Science 2021年第3期12卷 326-340页

作者： Natasha Pauli mark williams Savuti Henningsen Kevin Davies Chanchhaya Chhom Floris van Ogtrop Sochanny Hak Bryan Boruff Andreas Neef UWA School of Agriculture and Environment The University of Western AustraliaCrawleyWestern Australia 6009Australia Department of Geography and Planning School of Social SciencesThe University of Western AustraliaCrawleyWestern Australia 6009Australia School of Geosciences The University of SydneySydneyNew South Wales 2006Australia Faculty of Development Studies Royal University of Phnom PenhPhnom Penh 12150Cambodia School of Life and Environmental Sciences The University of SydneySydneyNew South Wales 2006Australia Development Studies School of Social SciencesThe University of AucklandAuckland 1142New Zealand

Integrating local knowledge and scientific information can aid in co-developing locally relevant approaches for climate change adaptation and disaster risk *** along the Mekong River have adapted to variability in temperature,rainfall,and flooding patterns over *** environmental change in the Mekong Basin presents a new set of challenges related to drought,altered seasonal rainfall,more frequent high-flow flood events,and water withdrawals for hydropower and *** present a multi-method approach to understand how local knowledge of the spatial and temporalpatterns of floods,droughts,and rainfall can be integrated with scientific information along a flood-prone section of the lower Mekong River in Kratie Province,*** hazard mapping of community members’knowledge of the movement of floodwaters through the landscape enabled interpretation of flood extent mapping using Synthetic Aperture Radar images from the Sentinel-1A *** calendars of weather patterns and livelihood activities,together with local indicators of flooding,rainfall,and drought were compared with trends in 35 years of rainfall data,and highlighted"pressure points"at the beginning and end of the rainy season where agriculture may be particularly impacted by climate *** discuss potential applications of our findings for adaptation and hazard planning.

关键词： Cambodia Local knowledge Mekong River Natural hazards Participatory mapping Remote sensing

Coal rib response during bench mining: A case study

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International Journal of Mining Science and Technology 2018年第1期28卷 107-113页

作者： Morgan M.Sears john Rusnak mark Van Dyke Gamal Rashed Khaled Mohamed Michael Sloan Ground Control Branch NIOSH Pittsburgh Mining Research Division

In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United *** the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground fall fatalities in *** coal *** of these 12 fatalities(75%) have occurred in room-andpillar *** objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 300 *** paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site.

关键词： Deep cover Bench mining Thick seam Retreat mining Rib response Rib support

Unexplained iron deficiency anemia:does Helicobacter pylori have a role to play?

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Gastroenterology Report 2018年第3期6卷 215-220,I0003页

作者： Savio john Juan Diego Baltodano Nilesh Mehta Katherine mark Uma Murthy Division of Gastroenterology and Hepatology State University of New York(SUNY)Upstate Medical UniversitySyracuseNew YorkNYUSA Department of Medicine SUNY Upstate Medical UniversitySyracuseNYUSA Department of Gastroenterology Syracuse VA Medical CenterSyracuseNYUSA

Background and aim:Testing for Helicobacter pylori(Hp)infection is recommended for work-up of unexplained iron deficiency anemia(IDA),although the evidence supporting this recommendation is *** aim of this study was to investigate the association between Hp infection and unexplained iron deficiency(ID)or IDA in the older adult population without significant upper gastrointestinal source of blood ***:Retrospective single-center cohort study;523 out of 1253 consecutive patients who underwent esophagogastroduodenoscopy with no significant upper and/or lower gastrointestinal source for blood loss or risk factors for *** were made between the Hp-positive and Hp-negative groups using Fisher exact test,chi-square test and Student’s *** and multiple logistic regression analyses were used to identify significant risk factors associated with ID and ***:One hundred and three subjects(19.7%)had Hp infection and 420(80.3%)were negative for ***-eight(22.1%)out of 307 subjects with available serum iron profile had unexplained ID and 28(5.4%)out of 510 subjects with available hemoglobin profile had unexplained *** association was found between ID/IDA and Hp infection in univariate and multiple logistic regression ***:We found no association between unexplained ID or IDA and Hp infection in older adult population without peptic ulcer disease or significant upper gastrointestinal source of blood loss.

关键词： Helicobacter pylori anemia iron deficiency

Scientific challenges and instrumentation for the International Meridian Circle Program

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Science China Earth Sciences 2021年第12期64卷 2090-2097页

作者： William LIU Michel BLANC Chi WANG Eric DONAVAN john FOSTER mark LERTER Hermann OPGENOOTYH Liwen REN National Space Science Centre Chinese Academy of SciencesBeijing100190China University of Toulouse Toulouse31400France University of Calgary CalgaryT2N 1N4Canada MIT Haystack Observatory CambridgeMA01886USA University of Leicester LeicesterLE17RHUK University of Umeå UmeåSE-90187Sweden

Earth’s ecosystems and human activities are threatened by a broad spectrum of hazards of major importance for the safety of ground infrastructures,space systems and space flight:solar activity,earthquakes,atmospheric and climatic disturbances,changes in the geomagnetic field,fluctuations of the global electric *** and understanding these major hazards to better predict and mitigate their effects is one of the greatest scientific and operational challenges of the 21st *** diverse,these hazards share one feature in common:they all leave their characteristic imprints on a critical layer of the Earth’s environment:its ionosphere,middle and upper atmosphere(IMUA).The objective of the International Meridian Circle Program(IMCP),a major international program led by the Chines Academy of Sciences(CAS),is to deploy,integrate and operate a global network of research and monitoring instruments to use the IMUA as a screen on which to detect these *** this article,we first show that the geometry required for the IMCP global observation system leads to a deployment of instruments in priority along the 120°E-60°W great meridian circle,which will cover in an optimal way both the dominant geographic and geomagnetic latitude variations,possibly complemented by a second Great Circle along the 30°E-150°W meridians to capture longitude ***,starting from the Chinese Meridian Project(CMP)network and using it as a template,we give a preliminary and promising description of the instruments to be integrated and deployed along the 120°E-60°W great circle running across China,Australia and the Americas.

关键词： International Meridian Circle Program Ionosphere Middle-upper atmosphere Space weather Chinese Meridian Project

Hospitalized prevalence and 5-year mortality for IBD:Record linkage study

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World Journal of Gastroenterology 2010年第4期16卷 431-438页

作者： Lori A Button Stephen E Roberts Michael J Goldacre Ashley Akbari Sarah E Rodgers john G williams School of Medicine Swansea UniversitySwansea SA2 8PPUnited Kingdom Unit of Health-Care Epidemiology University of OxfordOxford OX2 7LFUnited Kingdom

AIM:To establish the hospitalized prevalence of severe Crohn's disease(CD) and ulcerative colitis(UC) in Wales from 1999 to 2007;and to investigate long-term mortality after hospitalization and associations with social deprivation and other socio-demographic ***:Record linkage of administrative inpatient and mortality data for 1467 and 1482 people hospitalised as emergencies for ≥ 3d for CD and UC,*** main outcome measures were hospitalized prevalence,mortality rates and standardized mortality ratios for up to 5 years follow-up after ***:Hospitalized prevalence was 50.1 per 100 000 population for CD and 50.6 for *** hospitalized prevalence of CD was significantly higher(P < 0.05) in females(57.4) than in males(42.2),and was highest in people aged 16-29 years,but the prevalence of UC was similar in males(51.0) and females(50.1),and increased continuously with *** hospital-ized prevalence of CD was slightly higher in the most deprived areas,but there was no association between social deprivation and hospitalized prevalence of *** was 6.8% and 14.6% after 1 and 5 years follow-up for CD,and 9.2% and 20.8% after 1 and 5 years for *** both CD and UC,there was little discernible association between mortality and social deprivation,distance from hospital,urban/rural residence and ***:CD and UC have distinct demographic *** higher prevalence of hospitalized CD in more deprived areas may reflect higher prevalence and higher hospital dependency.

关键词： Crohn’s disease Ulcerative colitis Prevalence Mortality Record linkage