检索结果-南通市图书馆

Quantifying the effect of persistent dryer climates on forest productivity and implications for forest planning:a case study in northern Germany

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forest Ecosystems 2018年第4期5卷 451-471页

作者： Matthias Albert Ralf-Volker nagel Johannes Sutmoller Matthias Schmidt Department of Forest Growth Northwest German Forest Research Institute GottingenGermany Department of Environmental Control Northwest German Forest Research InstituteGottingenGermany.

Background: Forest management decisions are based on expectations of future developments. For sound decisions it is essential to accurately predict the expected values in future developments and to account for their inherent uncertainty,for example the impact of climate change on forests. Changing climatic conditions affect forest productivity and alter the risk profile of forests and forest enterprises. Intensifying drought stress is seen as one major risk factor threatening forest management in the north German lowlands. Drought stress reduces tree growth and vitality and might even trigger mortality. But so far, it is not possible to quantify effects of a persistent dryer climate on forest productivity at a level suitable for forest ***: We apply a well-established single-tree forest growth simulator to quantify the effect of persistent dryer climates on future forest productivity. We analyse the growth of Scots pine(Pinus sylvestris L.), European beech(Fagus sylvatico L.) and oak(Quercus robur L. and Quercus petraea(Matt.) Liebl.) in two forest regions in the north German lowlands for a time interval of 60 years until 2070. The growth response under three different climate projections is compared to a baseline ***: The results show clear differences in volume increment to persistent dryer climates between tree species. The findings exhibit regional differences and temporal trends. While mean annual increment at biological rotation age of Scots pine and oak predominantly benefits from the projected climate conditions until 2070, beech might suffer losses of up to 3 m^3·ha^(-1)yr^(-1) depending on climate scenario and region. However, in the projection period2051 to 2070 the uncertainty ranges comprise positive as well as negative climatic effects for all ***: The projected changes in forest growth serve as quantitative contributions to provide decision support in the evaluation of, for example, species future site suita

关键词： Climate change Forest growth Forest productivity Persistent dryer climate simulation study Uncertainty

Modelling of the elastoplastic behaviour of the bio-cemented soils using an extended Modified Cam Clay model

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2184-2197页

作者： Xuerui Wang Christian B.Silbermann Thomas nagel Udo Nackenhorst Institute of Mechanics and Computational Mechanics Leibniz UniversitätHannoverAppelstr.9aHannover30167Germany Gesellschaft für Anlagen-und Reaktorsicherheit(GRS)gGmbH Theodor-Heuss-Straße 4Braunschweig38122Germany Geotechnical Institute Technische Universität BergakademieFreibergGustav-Zeuner-Str.1Freiberg09599Germany

An elastoplastic constitutive model based on the Modified Cam Clay(MCC)model is developed to describe the mechanical behaviour of soils cemented via microbially induced calcite precipitation(MICP).It considers the increase of the elastic stiffness,the change of the yield surface due to MICP cementation and the degradation of calcium carbonate bonds during ***,to capture the typical contraction-dilation transition in MICP soils,the original volumetric hardening rule in the MCC model is modified to a combined deviatoric and volumetric hardening *** model could reproduce a series of drained triaxial tests on MICP-treated soils with different calcium carbonate ***,we carry out a parametric study and observe numerical instability in some *** combination with an analytical analysis,our numerical modelling has identified the benefits and limitations of using MCCbased models in the simulation of MICP-cemented soils,leading to suggestions for further model development.

关键词： Microbially induced calcite precipitation(MICP) Elastoplasticity Modified cam clay(MCC) OpenGeoSys MFront Contraction-dilation transition

Hydro-mechanical fault reactivation modeling based on elasto-plasticity with embedded weakness planes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2020年第4期12卷 877-885页

作者： Luca Urpi Bastian Graupner Wenqing Wang Thomas nagel Antonio PRinaldi Swiss Seismological Service Swiss Federal Institute of TechnologyETH ZürichZürichSwitzerland Swiss Federal Nuclear Safety Inspectorate ENSI BruggSwitzerland Department of Environmental Informatics Helmholtz Centre for Environmental ResearcheUFZLeipzigGermany Technische Universitat Bergakademie Freiberg FreibergGermany

In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak *** failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock *** rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined *** may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid *** of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation *** work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.

关键词： Fault reactivation Plane of weakness Finite element Argillaceous material Clay Permeability

Assessing risks and uncertainties in forest dynamics under different management scenarios and climate change

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2015年第3期2卷 169-189页

作者： Matthias Albert Jan Hansen Jürgen nagel Matthias Schmidt Hermann Spellmann Northwest German Forest Research Station

Background: Forest management faces a climate induced shift in growth potential and increasing current and emerging new risks. Vulnerability analysis provides decision support based on projections of natural resources taking risks and uncertainties into account. In this paper we(1) characterize differences in forest dynamics under three management scenarios,(2) analyse the effects of the three scenarios on two risk factors, windthrow and drought stress, and(3) quantify the effects and the amount of uncertainty arising from climate projections on height increment and drought ***: In four regions in northern Germany, we apply three contrasting management scenarios and project forest development under climate change until 2070. Three climate runs(minimum, median, maximum) based on the emission scenario RCP 8.5 control the site-sensitive forest growth functions. The minimum and maximum climate run define the range of prospective climate ***: The projections of different management regimes until 2070 show the diverging medium-term effects of thinnings and harvests and long-term effects of species conversion on a regional scale. Examples of windthrow vulnerability and drought stress reveal how adaptation measures depend on the applied management path and the decision-maker’s risk attitude. Uncertainty analysis shows the increasing variability of drought risk projections with time. The effect of climate projections on height growth are quantified and uncertainty analysis reveals that height growth of young trees is dominated by the age-trend whereas the climate signal in height increment of older trees is ***: Drought risk is a serious issue in the eastern regions independent of the applied silvicultural scenario,but adaptation measures are limited as the proportion of the most drought tolerant species Scots pine is already high. Windthrow risk is no serious overall threat in any region, but adequate counter-measures such as spec

关键词： Climate change Silvicultural management strategies

Efficacy and safety of bridging thrombolysis initiated before transfer in a drip-and-ship stroke service

在线全文

学校读者我要写书评

暂无评论

Stroke & Vascular Neurology 2022年第1期7卷 22-28页

作者： Jan Christoph Purrucker Miriam Heyse Simon nagel Christoph Gumbinger Fatih Seker Markus Mohlenbruch Peter Arthur Ringleb Department of Neurology Heidelberg University HospitalHeidelbergBaden-WürttembergGermany Department of Neuroradiology Heidelberg University HospitalHeidelbergBaden-WürttembergGermany

Objective Data regarding the efficacy and safety of bridging thrombolysis(BT)initiated before transfer for evaluation of endovascular therapy is ***,therefore,analyse efficacy and safety of BT in patients treated within a drip-and-ship stroke *** Consecutive adult patients suffering from acute ischaemic stroke and large-vessel occlusions(LVO)transferred to our comprehensive stroke centre for evaluation of endovascular therapy in 2017–2020 were identified from a local prospective stroke database and categorised according to BT and *** was defined as intravenous thrombolysis initiated before *** was assessed before and after *** outcome before stroke and at 3 months using the modified Rankin scale(mRS)was *** outcome was defined as mRS 0–1 or return to prestroke *** safety analysis,intracranial haemorrhages and mortality at 3 months were *** analysis was limited to patients with anterior circulation *** Of N=714 patients,n=394(55.2%)received *** patients in the BT group with documented LVO before transfer recanalised without endovascular therapy(n=46,11.7%)than patients who did not receive BT before transfer(n=4,1.3%,p<0.001).In multivariate analysis,BT was the strongest independent predictor of early recanalisation(adjusted OR 10.9,95%CI 3.8 to 31.1,p<0.001).BT tended to be an independent predictor of an excellent outcome at 3 months(adjusted OR 1.38,95%CI 0.97 to 1.96,p=0.077).There were no differences in safety between the BT and no-BT *** BT initiated before transfer was a strong independent predictor of early recanalisation.

关键词： drip initiated service

Transatlantic Integration:The TTIP under Scrutiny

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Accounting and Auditing 2018年第9期14卷 466-510页

作者： Daniel nagel Bucharest University of Economic Studies BucharestRomania

In view of the already relatively low most-favored-nation(MFN)rates on average,today’s most impeding barriers to transatlantic trade are not custom tariffs but so-called behind-the-border *** was originally destined to become a verily comprehensive trade and investment agreement in acknowledgment of this *** its distinctively ambitious agenda exposed both camps’opposing positions on several fronts at the same *** that the negotiations had already hit several road blocks under the espousing Obama administration,the protectionist convictions and“America First”policy of the incumbent US President promised to complicate many of these contentious *** as a popular tool in the business environment,the SWOT analysis also stood the test in the innovative context of identifying internal strengths and weaknesses of TTIP as well as external opportunities and threats to its conclusion further down the *** its intrinsic strengths and weaknesses of TTIP unveils a mixed picture,alike so often in real life where no absolute truth ***,the research demonstrates that there are compelling economic incentives for revitalizing the bilateral talks with respect to the likely transformations it would bring about in terms of market organization and functioning,production and distribution efficiency,national income,consumer satisfaction and,not least,regulation *** the matter from a different angle by asking“What are the probable implications of the scenario where the negotiations on a transatlantic trade and investment agreement will not be reinstated in the near future?”provided further illuminating *** approach revealed that neither the EU nor the US can actually afford to perpetuate the current status *** TTIP,the relative size of the transatlantic pole is bound to dwindle in the global *** alone the long-term geostrategic damage caused by its absence,as the EU and th

关键词： TTIP transatlantic trade transatlantic integration SWOT analysis Free Trade Agreement

Success factors for high-quality oak forest(Quercus robur, Q. petraea) regeneration

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Forest Ecosystems 2019年第4期6卷 367-383页

作者： Andreas M?lder Holger Sennhenn-Reulen Christoph Fischer Hendrik Rumpf Egbert Sch?nfelder Johannes Stockmann Ralf-Volker nagel Department A (Forest Growth) Northwest German Forest Research Institute(NW-FVA)

Background: Within the framework of close-to-nature forestry, oak forest(Quercus robur, Q. petraea) regeneration techniques that consider both silvicultural and nature conservation demands have become a very important *** there are many experimental and local studies that aim at disentangling the relationships between different environmental and silvicultural factors and the success of oak regeneration, systematic supra-regional studies at the greater landscape level are missing so *** this background, the first objective(a) of this study was to present an efficient and sufficiently accurate sampling scheme for supra-regional forest regrowth inventories, which we applied to young oaks stands. The second, and major, objective(b) was to identify the crucial success factors for high-quality oak forest regeneration in northwest ***: Objective(a): Factors that have been identified as potentially crucial for the success or failure of oak regeneration were either included in a field inventory procedure or extracted from forest inventory databases. We found that the collected data were suitable to be analyzed in a three-step success model, which was aimed at identifying the crucial success factors for high-quality oak forest ***(b): Our modeling procedure, which included a Bayesian estimation approach with spike-and-slab priors,revealed that competitive pressure from the secondary tree species was the most decisive success factor;no competition, or low competition by secondary tree species appeared to be particularly beneficial for the success of high-quality oak regeneration. Also fencing and the absence of competitive vegetation(weeds, grass, bracken)seemed to be beneficial factors for the success of oak ***: Trusting in biological automation was found to be mostly useless regarding economically viable oak forest regeneration. To efficiently organize oak regeneration planning and silvicultural decision-ma

关键词： Close-to-nature forestry Competition Ecological continuity Forest inventory Forest management Plantplant interactions Quercus robur Quercus petraea Regeneration Silviculture

智能手机，将会成为未来市场的霸主 PalmSource总裁兼CEO David nagel对话《IT时代周刊》

在线全文

学校读者我要写书评

暂无评论

IT时代周刊 2005年第10期15卷 34-35页

作者：许萍 David nagel PalmSource

2005年，智能手机大放光彩，中国手机市场成为各跨国公司决战的战场，纷纷投入重兵，决意从这个新兴手机市场上分到一份巨大的蛋糕。

关键词：智能手机 David CEO IT 手机市场 2005年跨国公司

Temporal echocardiography findings in patients with fulminant myocarditis: beyond ejection fraction decline

在线全文

学校读者我要写书评

暂无评论

Frontiers of Medicine 2020年第3期14卷 284-292页

作者： Houjuan Zuo Rui Li Fei Ma Jiangang Jiang Kun Miao Haojie Li Eike nagel Marijana Tadic Hong Wang Dao Wen Wang Division of Cardiology Department of Internal MedicineTongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiologic Disorders Wuhan 430030China Department of Radiology Tongji Hospital Tongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Institute for Experimental and Translational Cardiovascular Imaging DZHK Centre for Cardiovascular ImagingUniversity Hospital Frankfurt/MainFrankfurtGermany Department of Internal Medicine and Cardiology Charité-Universit(a)tsmedizin BerlinAugustenburgerplatz 113353 BerlinGermany

The features of myocardial strains from speckle-tracking echocardiography (STE) have not been well defined in fulminant myocarditis (FM) *** this study,changes in the left ventricular ejection fraction (LVEF) and global and layer-specific myocardial strains over time were *** aimed to determine the echocardiographic patterns of FM and ascertain their significance in FM *** patients who were clinically diagnosed with FM and received mechanical life support were prospectively *** echocardiographic measurements were obtained,and serial strain echocardiography was performed from admission to hospital discharge until LVEF recovery (> 50%).Global/regional peak systolic longitudinal strains (GLS/RLS) and layer-specific longitudinal strains were quantified,and their changes with time were monitored in 14 FM *** patients had severely impaired cardiac *** improvement in LVEF and GLS were observed within 6 ***-specific strain analysis showed that reduction at admission or recovery at discharge in the endocardium and epicardium strains were *** conclusion,FM patients who received mechanical circulatory supports exhibited steep improvement in ventricular function within 6 *** patchy and diffused distribution pattern of reduced RLS and equally and severely impaired strain in the endocardium and epicardium are valuable features in the diagnosis of FM.

关键词： fulminant myocarditis acute myocarditis 2D speckle tracking echocardiography left ventricular function global longitudinal strain