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Three-dimensional light structure of an upland Quercus stand post-tornado disturbance

Journal of Forestry Research 2020年第1期31卷 141-153页

作者： Kevin G.willson Lauren E.cox Justin L.Hart daniel c.Dey Department of Geography University of AlabamaTuscaloosaAL 35487USA Department of Environmental Science Policyand ManagementUniversity of CaliforniaBerkeleyCA 94720USA Northern Research Station USDA Forest ServiceColumbiaMO 65211USA

Light is the most common limiting factor in forest plant communities,influencing species composition,stand structure,and stand productivity in closed canopy *** vertical light structure is relatively simple under a closed canopy because most light is captured by overstory ***,wind disturbance events create canopy openings from local to landscape scales that increase understory light intensity and vertical light structural *** studied the effects of an EF-1 tornado on horizontal and vertical(***-dimensional)light structure within a Quercus stand to determine how light structure changed with increasing disturbance *** used a two-tiered method to collect photosynthetic photon flux density at 4.67 m and 1.37 m above the forest floor to construct three-dimensional light structure across a canopy disturbance severity gradient to see if light intensity varied with increasing tornado *** indicate that increased canopy disturbance closer to the tornado track increased light penetration and light structure heterogeneity at lower forest *** light intensity correlated with increased sapling density that was more randomly distributed across the plot and had shifted light capture higher in the stand *** penetration through the overstory was most strongly correlated with decreased stem density in the two most important tree species(based on relative dominance and relative density)in the stand,Quercus alba L.(r=-0.31)and Ostrya virginiana(Mill.)***(r=-0.27,pcated that understory light penetration was most affected by these two *** managers are increasingly interested in patterning silvicultural entries on natural disturbances,they must understand residual stand and light structures that occur after natural disturbance *** providing spatial light data that quantifies light structure post-disturbance,managers can use these results to improve planning required for long-term man

关键词： Photosynthetic photon flux density Midstory Blowdown Heterogeneity

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Disturbance history,species diversity,and structural complexity of a temperate deciduous forest

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Journal of Forestry Research 2020年第2期31卷 397-414页

作者： Jonathan D.Goode carson R.Barefoot Justin L.Hart daniel c.Dey Department of Geography University of AlabamaTuscaloosaAL 35487USA Northern Research Station USDA Forest ServiceColumbiaMO 65211USA

Stand structural complexity enhancement is an increasingly popular management objective,especially on public *** stand structures are hypothesized to support a relatively high degree of native forest diversity and be more resistant and resilient to *** structures are characterized by the presence of deadwood and heterogeneity of tree-size classes and tree *** little is known about how discrete disturbance events affect structural complexity and compositional diversity in Quercus-dominated stands at fine spatial scales(***).we established 200.05 ha fixed-radius plots on the Sipsey wilderness of william *** National Forest in northern Alabama to quantify woody plant species composition and *** were mapped on each plot to quantify overstory structural complexity and compositional *** extracted two cores from all canopy Quercus spp.c 5 cm diameter at breast height to quantify age,recruitment pulses,and reconstruct canopy disturbance *** species diversity in the sampled area was 1.75 for trees,2.08 for saplings,and 1.69 for *** alba had the greatest basal area,and Ostrya virginiana had the highest *** stand exhibited a reverse J-shaped distribution with a q-factor of *** oldest Quercus dated to 1795,and the largest recruitment pulse occurred in the *** mean return interval for intermediateseverity disturbance was 38 *** we documented no relationships between disturbance frequency and compositional diversity at the neighborhood scale(0.05 ha),less frequent disturbance was associated with higher structural complexity(r^2=0.258,p=0.026)at the neighborhood *** suggest that localized disturbance increases species diversity and structural complexity,but these processes are manifest at the stand level and not at the neighborhood *** conclude that the spatial variability(***,shape,orientation,microsite conditions)is likel

关键词： canopy gap Quercus(oak) Stand development Succession

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Do forest health threats affect upland oak regeneration and recruitment?Advance reproduction is a key co-morbidity

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Forest Ecosystems 2023年第6期10卷 743-751页

作者： Lance A.Vickers Benjamin O.Knapp daniel c.Dey Lauren S.Pile Knapp School of Natural Resources University of Missouri203 Anheuser-Busch Natural Resources BuildingColumbiaMO65211USA USDA Forest Service Northern Research Station 202 Anheuser-Busch Natural Resources BuildingColumbiaMO65211USA

we analyzed national forest inventory data collected from circa 2000–2018 across 37 states in the eastern United States to better understand the influence of forest health related canopy disturbances on the regeneration and recruitment dynamics of upland oaks(Quercus).we found low levels of oak recruitment across all disturbance types examined but limited evidence of any direct effects from the type of disturbance on the population of regenerating *** general lack of differences in oak regeneration response between forest health disturbances and disturbances caused by harvested or non-disturbed plots does not indicate that the effects of forest health disturbances were benign,***,low level of oak recruitment across all disturbance types highlights the pervasiveness of the trend of shifting composition in once oak-dominated forests where oak is absent or sparse in the regeneration *** results show that oak recruitment was higher when oak was present as advance reproduction prior to disturbance from any cause ***,these results lead us to conclude that the widespread inadequacy of oak advance reproduction in mature oak-dominated forests is the prevailing threat to oak forest health and *** suggest the status of advance reproduction be treated as a co-morbidity when weighing the risk and potential outcomes from other threats to upland oak forests in the eastern United States.

关键词： Temperate deciduous forest Regeneration ecology Forest inventory and analysis Oak/hickory Forest pests Insect Disease Harvesting

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Dredging effects on selected nutrient concentrations and ecoenzymatic activity in two drainage ditch sediments in the lower Mississippi River Valley

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International Soil and water conservation Research 2017年第3期5卷 190-195页

作者： Matt Moore Martin A.Locke Michael Jenkins Robert w.Steinriede daniel S.Mcchesney USDA-Agricultural Research Service National Sedimentation Laboratory598 McElroy DriveOxfordMS 38655USA

Agricultural drainage ditches are conduits between production acreage and receiving aquatic *** overlooked for their mitigation capabilities,agricultural drainage ditches provide an important role for nutrient transformation via microbial *** in ecoenzyme activities have been used to elucidate microbial metabolism and resource demand of microbial communities to better understand the relationship between altered nutrient ratios and microbial activity in aquatic *** agricultural drainage ditches,one in the northeast portion of the Arkansas Delta and the other in the lower Mississippi Delta,were monitored for a *** samples were collected prior to each ditch being dredged(cleaned),and subsequent post-dredging samples occurred as soon as access was *** samples were then collected throughout a year to examine effects of dredging on selected nutrient concentrations and ecoenzymatic activity recovery in drainage ditch *** concentrations in sediments after dredging decreased 33–66%,depending on ditch and phosphorus extraction ***,ecoenzymatic activity was significantly decreased in most sediment samples after *** diacetate hydrolysis activity,an estimate of total microbial activity,decreased 56–67%after dredging in one of the two *** sample sites also had significant phosphorus and ecoenzymatic activity differences between the post-dredge samples and the year-long follow-up *** indicate microbial metabolism in dredged drainage ditches may take up to a year or more to recover to pre-dredged ***,while sediment nutrient concentrations may be decreased through dredging and removal,runoff and erosion events over time tend to quickly replenish nutrient concentrations in replaced *** nutrient dynamics and microbial metabolism within agricultural drainage ditches is a crucial step toward addressing issues of nutri

关键词： Phosphorus FDA Denitrification Mehlich III Microbial Metabolism

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Plant species with extremely small populations(PSESP) in china:A seed and spore biology perspective

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Plant Diversity 2016年第5期38卷 209-220页

作者： Ellie Merrett wade Jayanthi Nadarajan Xiangyun Yang daniel Ballesteros weibang Sun Hugh w.Pritchard Royal Botanic Gardens KewWellcome Trust Millennium Building The Germplasm Bank of wild Species Kunming Institute of BotanyChinese Academy of Sciences Kunming Botanical Garden Kunming Institute of BotanyChinese Academy of Sciences

Approximately one fifth of the world's plants are at risk of *** these,a significant number exist as populations of few individuals,with limited distribution ranges and under enormous pressure due to habitat *** china,these most-at-risk species are described as 'plant species with extremely small populations'(PSESP).Implementing conservation action for such listed species is *** seeds is one of the main means of ex situ conservation for flowering *** storage could provide a simple and economical method for fern ex situ *** and spore germination in nature is a critical step in species regeneration and thus in situ *** what is known about the seed and spore biology(storage and germination) of at-risk species? we have used china's PSESP(the first group listing) as a case study to understand the gaps in knowledge on propagule biology of threatened plant *** found that whilst germination information is available for 28 species(23%of PSESP),storage characteristics are only known for 8%of PSESP(10 species).Moreover,we estimate that 60%of the listed species may require cryopreservation for long-term *** conclude that comparative biology studies are urgently needed on the world's most threatened taxa so that conservation action can progress beyond species listing.

关键词： Threatened species Orchids Storage characteristics cryopreservation ex situ conservation

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The importance of public engagement in clinical xenotransplantation

Health Care Science

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Health care Science 2024年第2期3卷 124-130页

作者： daniel J.Hurst David K.c.cooper Department of Family Medicine Rowan-Virtua School of Osteopathic MedicineStratfordNew JerseyUSA center for Transplantation Sciences Massachusetts General Hospital/Harvard Medical SchoolBostonMassachusettsUSA

Over the past several decades,significant scientific progress in xenotransplantation has brought the field to the threshold of clinical *** the past 3 years in the United States,experimental pig kidney and heart xenotransplantation have been performed on human subjects recently declared dead by neurological criteria(decedents).In addition,two pig heart transplants have been carried out in living patients under the United States Food and Drug Administration's expanded access ***,though there has been a flurry of activity there remain unanswered questions regarding how the public views xenotransplantation,what concerns may exist,and how to address these concerns in a meaningful *** paper aims to underscore the importance of public engagement in xenotransplantation,emphasizing the ongoing need for studies to assess public *** current evidence on public engagement studies is reviewed and gaps in our understanding are *** propose practical steps to advance this *** studies to determine the extent of racial/ethnic differences in attitudes to xenotransplantation should be *** and descriptive analysis of certain religious viewpoints—especially minority faiths—would be *** public engagement is an important aspect of public acceptance of novel research that is accompanied by risk,we suggest that xenotransplantation biotechnology companies might consider leading the way in funding this research.

关键词： clinical trials ethics public engagement viewpoints xenotransplantation

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Modelling policy combinations of vaccination and transmission suppression of SARS-coV-2 in Rio de Janeiro,Brazil

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Infectious Disease Modelling 2022年第1期7卷 231-242页

作者： Naiara c.M.Valiati daniel A.M.Villela Universidade Federal Rural do Rio de Janeiro SeropedicaRJBrazil Programa de computaçao científica Fundaçao Oswaldo CruzRio de JaneiroRJBrazil

cOVID-19 vaccination in Brazil required a phased program,with priorities for age groups,health workers,and vulnerable *** distancing and isolation interventions have been essential to mitigate the advance of the pandemic in several *** developed a mathematical model capable of capturing the dynamics of the SARS-coV-2 dissemination aligned with social distancing,isolation measures,and *** data from the city of Rio de Janeiro provided a case study to analyze possible scenarios,including non-pharmaceutical interventions and vaccination in the epidemic *** results demonstrate that the combination of vaccination and policies of transmission suppression potentially lowered the number of hospitalized cases by 380þand 66þthousand cases,respectively,compared to an absence of such *** top of transmission suppressiononly policies,vaccination impacted more than 230þthousand averted hospitalized cases and 43þthousand averted ***,health surveillance activities should be maintained along with vaccination planning in scheduled groups until a large vaccinated coverage is ***,this analytical framework enables evaluation of such scenarios.

关键词： SARS-coV-2 Vaccination cOVID-19

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A pentaploid-based linkage map of the ancestral octoploid strawberry Fragaria virginiana reveals instances of sporadic hyper-recombination

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horticulture Research 2020年第1期7卷 1796-1810页

作者： Thomas M.Davis Yilong Yang Lise L.Mahoney daniel c.Frailey Department of Agriculture Nutritionand Food SystemsUniversity of New HampshireDurhamNH 03824USA

The first high-resolution genetic linkage map of the ancestral octoploid(2n=8x=56)strawberry species,Fragaria virginiana,was constructed using segregation data obtained from a pentaploid progeny *** novel mapping population of size 178 was generated by crossing highly heterozygous *** hybrid“LB48”as a paternal parent with diploid(2n=2x=14)Fragaria vesca“Hawaii 4”.The LB48 linkage map comprises 6055 markers genotyped on the Axiom®IStraw90 strawberry SNP *** map consists of 28 linkage groups(LGs)organized into seven homoeology groups of four LGs each,and excludes a small 29th LG of undefined *** member of each homoeology group was assignable to an“A”subgenome associated with ancestral diploid Fragaria vesca,while no other subgenomes were *** an intriguing discrepancy within homoeology group VI,synteny comparisons with the previously published Fragaria×ananassa DA×MO linkage map revealed substantial *** initial map construction,examination of crossover distributions revealed that six of the total 5162(=29 chromosomes/individual×178 individuals)chromosomes making up the data set exhibited abnormally high crossover counts,ranging from 15 to 48 crossovers per chromosome,as compared with the overall mean of 0.66 crossovers per *** of these six hyper-recombinant(HypR)chromosomes occurred in a different LG and in a different *** calculated upon exclusion of the six HypR chromosomes,the canonical(i.e.,broadly representative)LB48 map had 1851 loci distributed over a total map length of 1873 cM,while their inclusion increased the number of loci by 130,and the overall map length by 91 *** of these hyper-recombinant chromosomes points to the existence of a sporadically acting mechanism that,if identified and manipulable,could be usefully harnessed for multiple purposes by geneticists and breeders.

关键词： Fragaria straw linkage

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Estimation of solids circulation rate and char transfer rate from gasifier to combustor in a dual fluidized-bed pilot plant for biomass steam gasification

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Particuology 2019年第5期17卷 22-29页

作者： M. Hafizur Rahman Lius daniel Ujash Shah Xiaotao Bi John R. Grace c.Jim Lim Fluidization Research centre Department of Chemical & Biological Engineering University of British Columbia 2360 East Mall Vancouver British Columbia V6T1Z3 Canada

Operation of a dual fluidized bed, consisting of a riser as combustor and bubbling bed as gasifier, for synthesis gas production from a solid fuel requires determination of the solids circulation rate and char transfer rate. The performance relies on supplying sufficient heat from the combustor to the gasifier by circulation of solids between these two reactors. The flow rate of char is required to track the heat generated in the combustor, which supports endothermic reactions in the gasifier. Direct measurement of these two critical parameters is difficult, with the number of reported techniques capable of working at high temperatures extremely small. An indirect method was developed, using mass and energy balances over the entire system and individual reactors, to estimate the solids circulation rate and char transfer rate. There was general agreement between heat losses estimated from energy-balance calculations and from direct measurement of the outer reactor surface temperature. Under typical gasification conditions, the solids circulation fluxes were estimated to be 45.2 and 55.6 kg/(m^2 s) in two independent tests, which were in good agreement with values obtained using a thermal tracer;char transfer rates were calculated to be 1.2 and 0.6 kg/h, which were in reasonable agreement with average biomass feed rates. This method can be applied to dual gasification systems at any temperature or flow rate.

关键词： Solids circulation rate char transfer rate Pilot-plant gasifier Dual fluidized bed Mass and energy balance

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Detection of mechanical stress in the steel structure of a bridge crane

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Theoretical & Applied Mechanics Letters 2021年第6期11卷 320-329页

作者： Leopold Hrabovsky daniel cepica Karel Frydrysek VSB-Technical university of Ostrava Faculty of mechanical EngineeringInstitute of Transport17.listopadu 2172/1570800Ostrava-PorubaCzech Republic VSB-Technical university of Ostrava Faculty of Mechanical EngineeringDepartment of Applied MechanicsOstrava-PorubaCzech Republic

A significant negative aspect in the operation of bridge-type cranes are the technical problems associated with wear of the wheels and the crane track,which causes crane *** main causes of crane skewing include unevenness of the crane track,unequal loading of the traction drives depending on the position of the crane trolley,slips and different sizes of travel wheels and combinations of these ***,this paper presents a design solution that can be used to detect the magnitude of mechanical stress and deformation of the steel structure of the crane,caused by the effects of *** mechanical stress generated by the transverse forces of the deformed geometric shape of the crane bridge structure is recorded by mechanical stress detectors installed in the inner corners of the crane *** resulting electrical signal from element mechanical voltage detectors,loaded by axial forces,can be used for feedback control of separate crane travel drives controlled by frequency ***,this paper presents the calculation of the lateral transverse forces according to cSN 270103 and the determination of the values of mechanical stresses of the deformed steel structure of the crane bridge of a two-girder bridge crane using the finite element method in the program *** ***,this paper presents the structural and strength design of mechanical stress detectors and the conclusions of laboratory tests of axial force loading of mechanical stress detectors on the test *** the same time,it presents records of the measured axial forces acting in the mechanical stress detectors,arising from the deformation and warping of the crane bridge by the known magnitude of the axial force acting on the crossbeam and from the deformation of the crane bridge caused by the crane operating modes.

关键词： crane skewing Mechanical stress detector Mechanical stress FEM Overhead crane

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