253 research outputs found
Natural regeneration of broadleaved tree species in southern Sweden
The objective of the present thesis was to examine the effects of silvicultural treatments and seed dispersal from surrounding stands on the establishment of natural regeneration of broadleaved tree species in southern Sweden. Most of the broadleaved tree species that occur naturally in forests in southern Sweden were studied but birch (Betulapendula Ehrh.1 B. pi~besceizs Roth) was the most common species and present in equal numbers in all studies. The wind dispe.rsa1 of see.ds of se.ven species was studied and great variations were found. This could mainly be explained by differences in seed morphology. The effect of soil scarification was examined in all five studies and was generally found to be positive for the establishment of the studied broadleaved species. However, in some cases the scarification was not positive for the establishment. The reason for t l i s was hypothesised to be that the seed supply was limited, or an effect of large and/or animal-dispersed seeds. The effect of shelterwood w a s examined in three studies and was found to be positive for animal-dispersed species but negative for shade-intolerant species, although a sparse shelterwood can be used to rcgcncratc birch. Slash removal was included in onc study and found to be positive for thc cstnblishrncnt of birch. This thcsis showccl that regeneration trcatmcnts can be used to incrcasc the e.stablishnent of naturally regene.rated broadleaved tree seedlings, but the stand structure and species composition must be regulated with pre-commercial thinning. However, the effect of variations in seed production and seed dispersal must be closely examined from a time and a space perspective prior to any forecasts regarding the effects of regeneration trcatrn
Resolving flow and mass transport in a healthy subject-specific aorta using large eddy simulation
Methodic Approach to the Evaluation of the Efficiency of Integration of Industrial Enterprises in the Republic of Belarus
Представлен авторский методический подход к ретроспективной оценке эффективности интеграции промышленных предприятий в Республике Беларусь, учитывающий особенности ведения хозяйственной деятельности в современных условиях национальной экономики, и результаты его апробации на материалах холдинга «Гомсельмаш». Разработанный методический подход включает алгоритм ретроспективной оценки эффективности, определяющий последовательность действий по анализу и оценке результатов интеграции, методику оценки эффективности интеграции промышленных предприятий, в основу которой положен принцип детерминированности показателей оценки эффективности иерархической последовательностью их взаимосвязи с критериями эффективности интеграции и целями интеграции, методический инструментарий анализа и оценки эффективности результатов интеграции промышленных предприятий, включающий набор расчетных формул частных, обобщающих и интегрального показателей эффективности интеграции; критерии оценки эффективности и целесообразности интеграции, определяемые степенью достижения поставленных целей интеграции; рекомен-дации по применению разработанной методики.The author’s methodic approach to the retrospective evaluation of the efficiency of integration of industrial enterprises in the Republic of Belarus is presented in the paper, taking into account specific features of providing economic activity in the present-day conditions of national economy and also the results of its testing based on the data of Gomselmash Holding. Methodic approach developed includes the algorithm of retrospective efficiency evaluation determining the sequence of operations for the analysis and evaluation of integration results, the methods of evaluation of industrial enterprise integration efficiency, based on the principle of determinacy of the indices of the efficiency evaluation by hierarchical sequence of their interrelation with the criteria of integration efficiency and the objectives of integration, methodic tools for the analysis and evaluation of the results of industrial enterprise integration including a set of design formulas of partial, overall and integral indices of the efficiency of integration; the criteria of evaluation of the efficiency and practicability of integration determined by the formulated integration goals achievement; the guidelines on the application of the methods developed
Birch establishes anywhere! So, what is there to know about natural regeneration and direct seeding of birch?
We tested three soil scarification approaches of varying intensity (intensive preparation exposing bare mineral soil, medium intensity with a mixture of organic material and mineral soil, and control without site preparation) on six clear-felled sites in two localities in northern and central Sweden between 2018 and 2021. The effect of soil scarification intensity and soil moisture on the occurrence of naturally regenerated birch seedlings was tested one, two and three years after soil scarification, and the density of direct-seeded birch seedlings one year after seeding. In addition, we tested the effect of the annual seed rain, and differences between the two birch species, on the density of direct-seeded seedlings. Soil scarification and its interaction with soil moisture had a significant positive effect on both the occurrence of naturally regenerated birch seedlings and the density of direct-seeded birch seedlings. There was no significant effect of neither annual natural seed rain nor species choice on direct-seeded seedling density. Time since soil scarification had a significant effect on the occurrence of naturally regenerated birch seedlings. In moist soils with high volumetric water content (>= 28%), birch seeds germinate at high rates and seedlings survive without soil scarification. In mesic soils, birch seeds germinate with higher rates after soil scarification. In dry soils, birch seeds rarely germinate regardless of any disturbance of the humus layer
О русских и английских фразеологизмах, заимствованных из литературных источников
Материалы XII Междунар. науч. конф. студентов, магистрантов, аспирантов и молодых ученых, Гомель, 16–17 мая 2019 г
Совершенствование маркетинговой деятельности промышленного предприятия (на примере ОАО «БМЗ – управляющая компания холдинга-БМК»)
Phase contrast MRI is a powerful tool for the assessment of blood flow. However, especially in the highly complex and turbulent flow that accompanies many cardiovascular diseases, phase contrast MRI may suffer from artifacts. Simulation of phase contrast MRI of turbulent flow could increase our understanding of phase contrast MRI artifacts in turbulent flows and facilitate the development of phase contrast MRI methods for the assessment of turbulent blood flow. We present a method for the simulation of phase contrast MRI measurements of turbulent flow. The method uses an Eulerian-Lagrangian approach, in which spin particle trajectories are computed from time-resolved large eddy simulations. The Bloch equations are solved for each spin for a frame of reference moving along the spins trajectory. The method was validated by comparison with phase contrast MRI measurements of velocity and intravoxel velocity standard deviation (IVSD) on a flow phantom consisting of a straight rigid pipe with a stenosis. Turbulence related artifacts, such as signal drop and ghosting, could be recognized in the measurements as well as in the simulations. The velocity and the IVSD obtained from the magnitude of the phase contrast MRI simulations agreed well with the measurements
Publisher Correction: Bridging the gap between measurements and modelling: a cardiovascular functional avatar.
An amendment to this paper has been published and can be accessed via a link at the top of the paper
Non-invasive Assessment of Systolic and Diastolic Cardiac Function During Rest and Stress Conditions Using an Integrated Image-Modeling Approach
Background: The possibility of non-invasively assessing load-independent parameters characterizing cardiac function is of high clinical value. Typically, these parameters are assessed during resting conditions. However, for diagnostic purposes, the parameter behavior across a physiologically relevant range of heart rate and loads is more relevant than the isolated measurements performed at rest. This study sought to evaluate changes in non-invasive estimations of load-independent parameters of left-ventricular contraction and relaxation patterns at rest and during dobutamine stress.Methods: We applied a previously developed approach that combines non-invasive measurements with a physiologically-based, reduced-order model of the cardiovascular system to provide subject-specific estimates of parameters characterizing left ventricular function. In this model, the contractile state of the heart at each time point along the cardiac cycle is modeled using a time-varying elastance curve. Non-invasive data, including four-dimensional magnetic resonance imaging (4D Flow MRI) measurements, were acquired in nine subjects without a known heart disease at rest and during dobutamine stress. For each of the study subjects, we constructed two personalized models corresponding to the resting and the stress state.Results: Applying the modeling framework, we identified significant increases in the left ventricular contraction rate constant [from 1.5 ± 0.3 to 2 ± 0.5 (p = 0.038)] and relaxation constant [from 37.2 ± 6.9 to 46.1 ± 12 (p = 0.028)]. In addition, we found a significant decrease in the elastance diastolic time constant from 0.4 ± 0.04 s to 0.3 ± 0.03 s (p = 0.008).Conclusions: The integrated image-modeling approach allows the assessment of cardiovascular function given as model-based parameters. The agreement between the estimated parameter values and previously reported effects of dobutamine demonstrates the potential of the approach to assess advanced metrics of pathophysiology that are otherwise difficult to obtain non-invasively in clinical practice
Durée de vie et mortalité des vieux chênes: une approche empirique combinée à une modélisation pour un appui à leur gestion dans le sud de la Suède
Tätare och rikligare ollonår ökar chansen för lyckade bokföryngringar
• Vissa år – ollonår – producerar bokarna mycket ollon, medan få eller inga ollon hittas under andra år. Under ollonåren är det lämpligt att föryngra bokbestånden. • Intervallet mellan ollonåren är kortare idag än förr. De senaste 35 åren har intervallet varit 2–3 år från att tidigare ha varit 5–6 år. • Mycket talar för att ollonproduktionen under enskilda ollonår är större idag än tidigare. • Ollonfallets storlek beror bland annat på vädret under sommaren när blomknopparna bildas och på markens produktionsförmåga. Ju varmare vädret är och ju bördigare marken är, desto mer bokollon produceras. • Den ökade ollonproduktionen beror sannolikt på ett varmare klimat
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