The Role of R&D Technology in Asymmetric Research Joint Ventures

We characterize asymmetric equilibria in two-stage process innovation games and show that they are prevalent in the different models of R&D technology considered in the literature. Indeed, cooperation in R&D may be accompanied by high concentration in the product market. We show that while such an increase may be profitable, it may be socially inefficient.Research and Development, Research Joint Ventures, Process Innovation Games

Virtual Forestry Generation: Evaluating Models for Tree Placement in Games

A handful of approaches have been previously proposed to generate procedurally virtual forestry for virtual worlds and computer games, including plant growth models and point distribution methods. However, there has been no evaluation to date which assesses how effective these algorithms are at modelling real-world phenomena. In this paper, we tackle this issue by evaluating three algorithms used in the generation of virtual forests—a randomly uniform point distribution method (control), a plant competition model, and an iterative random point distribution technique. Our results show that a plant competition model generated more believable content when viewed from an aerial perspective. Interestingly, however, we also found that a randomly uniform point distribution method produced forestry which was rated higher in playability and photorealism, when viewed from a first-person perspective. We conclude that the objective of the game designer is important to consider when selecting an algorithm to generate forestry, as the algorithms produce forestry that is perceived differently

Emergency condition of the operation of a non-symmetric tundish

The aim of the research was to analyze the influence of the flow behavior of liquid steel in a three-strand, asymmetric tundish when not all outlet openings are working. This problem was solved through physical modeling. The tests were carried out with the use of the water model of the continuous casting (CC) machine equipped with an asymmetrical, three-strand tundish model, made on a reducing scale. Modelling research concerned casting 110 x 110 mm square ingots. The obtained results of visualization tests and resistance time distribution (RTD) characteristics (F type) allowed to determine the method of mixing the steel (changes in mixing intensity were estimated) for the analyzed experimental variants

Annual Aboveground Biomass Growth in Temperate Forests of Eastern North America

The below dissertation is organized into three individual standalone manuscripts supporting the overarching theme of reconstructing annual aboveground biomass growth in temperate forests of eastern North America using dendrochronological applications. Each manuscript is organized with the intent of submission to a peer-reviewed journal. The first manuscript validated the technique I use throughout my dissertation by comparing tree-ring derived estimates of annual aboveground productivity with estimates from co-located or nearby permanent remeasurement plots at Howland, Maine, Harvard Forest, Massachusetts, and Fernow, West Virginia. The second manuscript investigated the size-related distribution of biomass growth at 16 eastern U.S. forest sites and compared results with United States Forest Service inventory plot data. The goal of this manuscript was to determine where, structurally, biomass was allocated in forests and whether these quantities changed over time and between forests. The third manuscript was inspired by the results of my second chapter. Here, I investigated whether the degree of asymmetry, or the slope of the linear regression between tree diameter and growth, is a useful indicator of total forest productivity. Previous studies linking asymmetry and productivity have been inconclusive, and this chapter evaluates consistency or lack of consistency across the same 16-site eastern U.S. forest network

Alignment between PIN1 Polarity and Microtubule Orientation in the Shoot Apical Meristem Reveals a Tight Coupling between Morphogenesis and Auxin Transport

Morphogenesis during multicellular development is regulated by intercellular signaling molecules as well as by the mechanical properties of individual cells. In particular, normal patterns of organogenesis in plants require coordination between growth direction and growth magnitude. How this is achieved remains unclear. Here we show that in Arabidopsis thaliana, auxin patterning and cellular growth are linked through a correlated pattern of auxin efflux carrier localization and cortical microtubule orientation. Our experiments reveal that both PIN1 localization and microtubule array orientation are likely to respond to a shared upstream regulator that appears to be biomechanical in nature. Lastly, through mathematical modeling we show that such a biophysical coupling could mediate the feedback loop between auxin and its transport that underlies plant phyllotaxis

Large-scale PIV surface flow measurements in shallow basins with different geometries

Shallow depth flow fields and low velocity magnitudes are often challenges for traditional velocity measuring instruments. As such, new techniques have been developed that provide more reliable velocity measurements under these circumstances. In the present study, the two-dimensional (2D) surface velocity field of shallow basins is assessed by means of Large-Scale Particle Image Velocimetry (LSPIV). The measurements are carried out at the water surface, which means that a laser light sheet is not needed. Depending on the time scales of the flow and the camera characteristics, it is even possible to work with a constant light source. An experimental application of this method is presented to analyze the effects of shallow basin geometry on flow characteristics in reservoirs where large coherent two-dimensional flow structures in the mixing layer dominate the flow characteristics. The flow and boundary conditions that give rise to asymmetric flow are presented. Asymmetric flow structures were observed starting from basin shape ratios that are less than or equal to 0.96. By decreasing the basin length and increasing the shape ratio to greater than 0.96, the flow structure generally tends towards a symmetric patter

Dynamics of P. pinea and P. pinaster forests: Implications for adaptive management in a climate change context

Over the last decades, climate change has been particularly severe in the Mediterranean basin, where the intensity and frequency of drought events had a significant effect on forest dynamics. As a consequence, tree allometry is modified, reducing tree and stand growth, provoking tree or stand decay and dieback and altering plant recruitment. In this context, differences in structural and physiological strategies of tree species, could mitigate the damage inflicted by climate change and reduce risk. Programs aiming to adapt forests to climate-changing conditions should take profit from the knowledge of these strategies, and propose a set of actions oriented to emulate or enhance the inherent capacity of the forest for adaptation. Between these actions, this thesis highlights the promotion of natural regeneration or the increase of intra and interspecific diversity. A most diverse ecosystem could help to reduce vulnerability and increase resistance against the lack of water availability. In addition, tree species interactions could lead to complementary effects during low-growth years by the optimization of resources. This thesis provides a variety of methodologies based on analyzing how different factors control the response dynamics of P. pinea and P. pinaster in mixed and monospecific Mediterranean forests throughout stand development, from regeneration to adult stages. The main hypothesis was that species responses, could help to cope with climatic variability and that the composition, mixed or monospecificic, could attenuate these responses. The thesis used data from a network of 1936 plots of 0.02 ha to study natural regeneration, and a network of 75 mixed and monospecific temporal plots on adult stands, both installed in the Northern Plateau of Spain. In this last group of plots, the use of tree-ring width series permitted us to evaluate species-mixing effects on inter-annual and intra-annual tree growth dynamics.Doctorado en Conservación y Uso Sostenible de Sistemas Forestale

The effects of tree crown plasticity on the structure and dynamics of near-natural beech forests: an individual-based modeling approach

A new individual-based forest model for the species beech (Fagus sylvatica L.) was developed and implemented. The model called BEEch Plasticity (BEEP) describes tree crown plasticity phenomenologically and is able to model aboveground competition for PAR on a process basis. The current debate about the tree interactions in near-natural beech forests and their role in emergent forest structures and dynamics led to the research questions if (1) observed patterns can be modeled and reproduced by only describing the aboveground tree interactions, (2) what effects tree crown plasticity has on the structure and dynamics of near-natural beech forests, and (3) what effects selective thinning has on the structure and dynamics of near-natural beech forests. The BEEP model was developed, parameterized, calibrated, and validated according to data from the unmanaged forest `Schattiner Zuschlag' near Lübeck, North-Germany, while additional data from the sites Langula (Thuringia) and Fabrikschleichach (Bavaria) was used for model parameterization and calibration. Three simulation experiments were conducted. In the first experiment, the BEEP model was run 10 times for 2000 time steps with plastic tree crowns and the emergent forest structure was analyzed using structural indices. In the second experiment, the BEEP model was run again 10 times for 2000 time steps but with a modified crown model that only uses rotation-symmetric tree crowns. In the third experiment, the BEEP model was enhanced with a selective thinning procedure that uses target trees with specific diameter and heights as thinning objects. Forest structure was analyzed through the application of structural indices that capture different aspects of forest structure and by means of characterization of forest development phases. Analysis was accomplished only for the time steps 1000-2000 in order to allow transient oscillation in forest dynamics to develop. The results showed that the focus on aboveground competition and tree interactions sufficed to model beech forests and reproduced a wide range of patterns observed in near-natural and old-growth beech forest. In particular, the BEEP model was able to simulate a multi-layered forest structure with a mosaic structure of several developmental stages on a relatively small area of 0.5 ha. The simulated forest had wide diameter and age distributions. The diameter distribution was reversed-J-shaped. The age range of canopy trees exceeded 200 years. The comparison between simulations with plastic and rotation-symmetric tree crowns revealed that crown plasticity reduced tree competition for crown space and PAR and enhanced the forest structure and heterogeneity in the long term by allowing more tree cohorts of dfferent developmental stages to coexist. This supports the notion that crown plasticity drives beech forest dynamics in near-natural forests. The comparison between simulations with plastic tree crowns and with additional selective thinning showed that thinning does not affect the forest structural heterogeneity and reduces tree crown competition, while spatial patterns of tree positions remained unaltered. However, crown centroids were more regularly distributed. Model assumptions in the submodel routines, especially in the radiation and mortality submodel, question the reliability of the model results, because of the high sensitivity that these routines evoke on model outcomes. Therefore, revised versions of the submodels and a thoroughly validated crown growth model, may produce different results. Thus, the results presented in this study should be treated with care and cannot be used for generalizations about tree interactions in near-natural beech forests