Nanowires in Cell Biology

This thesis explores the interactions between cells and nanowires, to increase our understanding of how cells are affected and how they can be manipulated by these one-dimensional, semiconductor crystals (lengths 1-10 µm, diameters <100 nm). These are much smaller than most mammalian cells (10-30 µm in diameter), and it is generally held that nanowires can be interfaced with cells without adverse effects. On this assumption, several nanowire-based applications have been explored, yet few studies investigate how basic cellular functions are affected. We have studied how the dimensions of nanowires affect fundamental cell behaviour in cells. We found that increasing nanowire length reduces cell migration and interferes with cell division. Cells interfaced with as few as 50 nanowires are inhibited in their migration. Increasing the density of nanowires has minor effects on migration and division until a threshold density is reached when the cells are able to adhere to the tips of the nanowires rather than the substrate, enabling migration. Based on these results, we hypothesize that it is possible to tune nanowire dimensions to control the degree of cell migration and proliferation, enabling experiments where cells are immobilized for continuous observation over several generations. Our results can further be used to limit adverse effects in nanowire-based cell biological applications. As part of our cell-nanowire interaction studies, we have worked toward a microfluidic injection system based on oxide nanotubes to improve both existing, standard injection systems and nanowire-based experimental versions. We demonstrate the successful fabrication of key parts of this system and its fluidic transport ability, important steps toward a fully functional nanosyringe device, capable of serial injection and retrieval of cell material. To improve future studies regarding the interactions between semiconductor nanowires and cells, we developed inherently fluorescent nanowires and showed that it is possible to fabricate nanowires with alternating fluorescent and non-fluorescent segments, creating a barcode design useful for systematic studies. These results will prove useful for research groups working towards cell biological applications based on similar nanostructures, both for injections, cell migration and otherwise

The Public Procurement Fallacy - Why EU Public Procurement rules can counteract common goals of the Union

The area of public procurement has a significant financial impact on the Union market, proven by the fact that 18% of the Union’s GDP is spent by public authorities on resources that are regulated by the legislative framework surrounding public procurement. Such a significant spending therefore has the possibility of controlling the behaviour of the supply side on the market by demonstrating what public resources are preferably spent on. As a consequence, social and environmental responsibility among the member states has been given a strong position within public procurement as an effective tool to implement policies. However, this development has also encountered opposition, mainly from the Union itself otherwise supporting this kind of development. The opposition stems from the economical heritage that the Union is founded on. The area of public procurement was developed as one of many measures to maintain a fully functioning internal market, hence public contracts are meant to be awarded to the economically most advantageous tenders. Such a prerequisite ensures that there is competition between tenderers and the most competitive tenderer will therefore be awarded the contract. When taking social and environmental aspects into consideration, the lowest tender is seldom the tender that manages to include these considerations to the greatest extent possible. These aspects are discussed in this thesis, and continue to discuss to what extent the current public procurement system nevertheless can be used in order incorporate other considerations than economic ones, without breaching the same system. This subsequently leads to a conclusion on whether the current public procurement system enables not only the member state’s, but also the Union’s policies to be fully implemented. As will be shown, there is discretion to incorporate such non-economic policies, although to a differing extent depending on the specific contract to be awarded

Estimating site index from short term TanDEM-X canopy height models

The tree height growth from three vegetation seasons was fitted to height growth curves in order to estimate the site index, which is a variable related to forest site productivity. The tree height growth was evaluated for four different cases, in which remote sensing data from TanDEM-X and airborne laser scanning were used. The used method requires a digital terrain model and knowledge about the tree species. Furthermore, the remote sensing data were calibrated using Lorey'smean height heights or airborne laser scanning data. It was found that four annual acquisitions of calibrated TanDEM-X data covering three vegetation seasons could be used for estimating the site index on 27 0.5-ha field plots with 4.4-m (12.1%) RMSE. The site index could in a similarmanner be estimated from only two airborne laser scanning acquisitions, before and after four vegetation seasons, with 2.3-m (6.3%) RMSE

Eisenstein series and automorphic representations

We provide an introduction to the theory of Eisenstein series and automorphic forms on real simple Lie groups G, emphasising the role of representation theory. It is useful to take a slightly wider view and define all objects over the (rational) adeles A, thereby also paving the way for connections to number theory, representation theory and the Langlands program. Most of the results we present are already scattered throughout the mathematics literature but our exposition collects them together and is driven by examples. Many interesting aspects of these functions are hidden in their Fourier coefficients with respect to unipotent subgroups and a large part of our focus is to explain and derive general theorems on these Fourier expansions. Specifically, we give complete proofs of the Langlands constant term formula for Eisenstein series on adelic groups G(A) as well as the Casselman--Shalika formula for the p-adic spherical Whittaker function associated to unramified automorphic representations of G(Q_p). In addition, we explain how the classical theory of Hecke operators fits into the modern theory of automorphic representations of adelic groups, thereby providing a connection with some key elements in the Langlands program, such as the Langlands dual group LG and automorphic L-functions. Somewhat surprisingly, all these results have natural interpretations as encoding physical effects in string theory. We therefore also introduce some basic concepts of string theory, aimed toward mathematicians, emphasising the role of automorphic forms. In particular, we provide a detailed treatment of supersymmetry constraints on string amplitudes which enforce differential equations of the same type that are satisfied by automorphic forms. Our treatise concludes with a detailed list of interesting open questions and pointers to additional topics which go beyond the scope of this book.Comment: 326 pages. Detailed and example-driven exposition of the subject with highlighted applications to string theory. v2: 375 pages. Substantially extended and small correction

Integrating animal tracking datasets at a continental scale for mapping Eurasian lynx habitat

Aim The increasing availability of animal tracking datasets collected across many sites provides new opportunities to move beyond local assessments to enable detailed and consistent habitat mapping at biogeographical scales. However, integrating wildlife datasets across large areas and study sites is challenging, as species' varying responses to different environmental contexts must be reconciled. Here, we compare approaches for large-area habitat mapping and assess available habitat for a recolonizing large carnivore, the Eurasian lynx (Lynx lynx).LocationEurope.Methods We use a continental-scale animal tracking database (450 individuals from 14 study sites) to systematically assess modelling approaches, comparing (1) global strategies that pool all data for training versus building local, site-specific models and combining them, (2) different approaches for incorporating regional variation in habitat selection and (3) different modelling algorithms, testing nonlinear mixed effects models as well as machine-learning algorithms.Results Testing models on training sites and simulating model transfers, global and local modelling strategies achieved overall similar predictive performance. Model performance was the highest using flexible machine-learning algorithms and when incorporating variation in habitat selection as a function of environmental variation. Our best-performing model used a weighted combination of local, site-specific habitat models. Our habitat maps identified large areas of suitable, but currently unoccupied lynx habitat, with many of the most suitable unoccupied areas located in regions that could foster connectivity between currently isolated populations.Main Conclusions We demonstrate that global and local modelling strategies can achieve robust habitat models at the continental scale and that considering regional variation in habitat selection improves broad-scale habitat mapping. More generally, we highlight the promise of large wildlife tracking databases for large-area habitat mapping. Our maps provide the first high-resolution, yet continental assessment of lynx habitat across Europe, providing a consistent basis for conservation planning for restoring the species within its former range

The philosophy of interdisciplinarity: sustainability science and problem-feeding

Traditionally, interdisciplinarity has been taken to require conceptual or theoretical integration. However, in the emerging field of sustainability science this kind of integration is often lacking. Indeed sometimes it is regarded as an obstacle to interdisciplinarity. Drawing on examples from sustainability science, we show that problem-feeding, i.e. the transfer of problems, is a common and fruitful-looking way of connecting disparate disciplines and establishing interdisciplinarity. We identify two species of problem-feeding: unilateral and bilateral. Which of these is at issue depends on whether solutions to the problem are fed back to the discipline in which the problem originated. We suggest that there is an interesting difference between the problem-feeding approach to interdisciplinarity and the traditional integrative perspective suggested by among others Erich Jantsch and his colleagues. The interdisciplinarity resulting from problem-feeding between researchers can be local and temporary and does not require collaboration between proximate disciplines. By contrast, to make good sense of traditional integrative interdisciplinarity we must arguably associate it with a longer-term, global form of close, interdisciplinary collaboration

Polarimetric Measures in Biomass Change Prediction Using ALOS-2 PALSAR-2 Data

The use of multiple synthetic aperture radar polarizations can improve biomass estimations compared to using a single polarization. In this study, we compared predictions of aboveground biomass change from ALOS-2 PALSAR-2 backscatter using linear regression based on (1) the cross-polarization channels, (2) the co- and cross-polarizations from fully polarimetric SAR, (3) Freeman-Durden polarimetric decomposition, and (4) the polarimetric radar vegetation index (RVI). Additionally, the impact of forest structure on the sensitivity of the polarimetric backscatter to AGB and AGB change was assessed. The biomass consisted of mainly coniferous trees at the hemi-boreal test site Remningstorp, located in southern Sweden. We found some improvements in the predictions when quad-polarized data (RMSE = 79.4 tons/ha) were used instead of solely cross-polarized data (RMSE = 84.9 tons/ha). However, when using Freeman-Durden decomposition, the prediction accuracy improved further (RMSE = 69.7 tons/ha), and the highest accuracy was obtained with the radar vegetation index (RMSE = 50.4 tons/ha). The corresponding R2 values ranged from 0.45 to 0.82. The bias was less than 1 t/ha for all models. An analysis of forest variables showed that the sensitivity to AGB was reduced for high values of basal-area-weighted mean height, basal area, and stem density when predicting absolute AGB, but the best change prediction model was sensitive to changes larger than the apparent saturation point for AGB state estimates. We conclude that by using fully polarimetric SAR images, forest biomass changes can be estimated more accurately compared to using single- or dual-polarization images. The results were improved the most (in terms of RMSE and R2) by using the Freeman-Durden decomposition model or the RVI, which captured especially the large changes better

Estimation of forest variables using radargrammetry on TerraSAR-X data in combination with a high resolution DEM

This study uses the backscattered intensity information from SAR images acquired with TerraSAR-X to derive Digital Surface Models with radargrammetry. Then the known ground elevation (from airborne lidar) is subtracted to get Canopy Height Models that are analysed and linked through regression analysis to the forest variables above-ground biomass and tree height. It was found, that the used constellation of image pairs and prediction models produced biomass estimations at stand level with 25.9% and 33.8% relative RMSE, while the height estimations were 11.5% and 12.3%. The analyses were tested at the Swedish test sites Krycklan and Remningstorp

A reduction principle for Fourier coefficients of automorphic forms

In this paper we analyze a general class of Fourier coefficients of automorphic forms on reductive adelic groups $\mathbf{G}(\mathbb{A}_\mathbb{K})$ and their covers. We prove that any such Fourier coefficient is expressible through integrals and sums involving 'Levi-distinguished' Fourier coefficients. By the latter we mean the class of Fourier coefficients obtained by first taking the constant term along the nilradical of a parabolic subgroup, and then further taking a Fourier coefficient corresponding to a $\mathbb{K}$-distinguished nilpotent orbit in the Levi quotient. In a follow-up paper we use this result to establish explicit formulas for Fourier expansions of automorphic forms attached to minimal and next-to-minimal representations of simply-laced reductive groups.Comment: 35 pages. v2: Extended results and paper split into two parts with second part appearing soon. New title to reflect new focus of this part. v3: Minor corrections and updated reference to the second part that has appeared as arXiv:1908.08296. v4: Minor corrections and reformulation

Quantify and account for field reference errors in forest remote sensing studies

Field inventoried data are often used as references (ground truth) in forest remote sensing studies. However, the reference values are affected by various kinds of errors, which tend to make the reported accuracies of the remote sensing-based predictions worse than they are. The more accurate the remote sensing techniques are becoming, the more pronounced this problem will be. This paper addresses the impact of uncertainties in field reference data due to measurement errors, model errors, and position errors when evaluating the accuracy of biomass predictions from airborne laser scanning at plot level. We present novel theoretical analysis methods that take the interactions of the error sources into account. Further, an error characterization model (ECM) is used to describe the error structure of the remote sensing-based predictions, and we show how the parameters of the ECM can be adjusted when field references contain errors. We also show how root mean square error (RMSE) estimates can be adjusted. Based on data from Scandinavian forests, we conclude that the field reference errors have an impact on the remote sensing-based predictions. By accounting for these errors the RMSE of the remote sensing-based predictions was reduced by 6-18%. The most influential sources of error in the field references were found to be the residual errors of the allometric biomass model and the field plot position errors. Together, these two sources accounted for 97% of the variance while measurement errors and biomass model parameter uncertainties were negligible in our study