2,986 research outputs found

    Measuring the Impact of Carbon Emissions on Firm Value Using Quantile Regression

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    A fundamental transformation of the global economy towards a low-carbon economy is inevitable in order to achieve the climate targets set by the United Nations. Hence, it becomes increasingly important to understand how firm level carbon mitigation affects the value of a company. The purpose of this thesis is not only to estimate the average relationship between carbon emissions and firm value but to investigate whether this relationship is heterogeneous and thus whether the effect of carbon emission on firm value depends on the value of the respective company. A quantile regression approach with firm value measured as Tobin’s Q as the dependent variable is applied. The estimation outcomes clearly indicate that higher carbon emissions reduce firm value for all quantiles. However, the extent of the effect depends strongly on the value of the respective company suggesting that the value-enhancing effect of reduced carbon emissions is higher for firms with relatively high firm value. Keywords: carbon emission; firm value; quantile regression

    Spektroskopische Untersuchungen zur Bestimmung von RNA-Ligand-Wechselwirkungen und RNA-Dynamiken

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    This thesis describes the structural characterization of interactions between biological relevant ribonucleic acid biomacromolecules (RNAs) and selected ligands to optimize the methodologies for the design of pharmacological lead compounds. To achieve this aim, not only the structures of the RNA, the ligand and their complexes need to be known, but also information about the inherent dynamics, especially of the target RNA, are necessary. To determine the structure and dynamics of these molecules and their complexes, liquid state nuclear magnetic resonance spectroscopy (NMR) is a suitable and powerful method. The necessity for these investigations arises from the lack of knowledge in RNA-ligand interactions, e.g. for the development of new medicinal drugs targeting crucial RNA sequences. In the first chapters of this thesis (Chapters II to IV), an introduction into RNA research is given with a focus on RNA structural features (Chapter II), into the interacting molecules, the biology of the specific RNA targets and the further development of their ligands (Chapter III) and into the NMR theory and methodologies used within this thesis (Chapter IV). Chapter II begins with a description of RNA characteristics and functions, placing the focus on the increasing attention that these biomacromolecules have attracted in recent years due to their diverse biological functionalities. This is followed by a detailed description of general structural features of RNA molecules. The biological functions of the RNAs investigated in this thesis (Human immunodeficiency virus PSI- and TAR-RNA and Coxsackievirus B3 Stemloop D in the 5’-cloverleaf element), together with their known structural characteristics are introduced in Chapter III. Furthermore, a description of the investigated ligands is given, focusing on the methods how their affinity and specificity were determined. The introduction is completed in Chapter IV, where the relevant NMR theory and methodologies are explained. First, kinetics and thermodynamics of ligand binding are summarized from an NMR point of view. Subsequently, a detailed description of the resonance assignment procedures for RNAs and peptidic ligands is given. This procedure mainly concentrates on the assignment of the proton resonances, which are essential for the later structure calculation from NMR restraints. The procedure for NMR structure calculation of RNA and its complexes follows with a short introduction into the programs ARIA and HADDOCK. The final part of this chapter explains the relaxation theory and the methodology to extract dynamic information from autocorrelated relaxation rates via the model-free formalism. In the Chapters V to VII of this thesis, the original publications are included and grouped into three topics. Chapter V comprehends the publications on the investigations of HIV PSI-RNA and its hexapeptidic ligand. These three publications[1-3] focus on the characterization of the ligand and its binding properties, its structure and the optimization of its composition aiming to improve its usage for further spectroscopic investigations.Die vorliegende Doktorarbeit behandelt die strukturelle AufklĂ€rung von Wechselwirkungen zwischen biologisch relevanten RibonukleinsĂ€uren (RNA) und ausgewĂ€hlten Liganden, sowie die Bestimmung der inhĂ€renten Dynamik der RNA, um zur Methodenentwicklung fĂŒr den Entwurf neuer Pharmaka beizutragen. Zur Bestimmung sowohl der Strukturen, als auch der Dynamiken stellt die FlĂŒssig-Kernspinresonanz-Spektroskopie (NMR) eine ideale biophysikalische Methode dar. Die ersten HĂ€lfte dieser Doktorarbeit gibt zum einen eine Einleitung in die RNA-Forschung mit besonderem Fokus auf den allgemeinen strukturellen und dynamischen Eigenschaften von RibonukleinsĂ€uren, stellt zweitens die ausgewĂ€hlten RNA-Zielstrukturen und deren mit verschiedenen Methoden bestimmten Liganden vor, und erklĂ€rt drittens die zugrundeliegende NMR-Theorie und die verwendeten Methoden zur Untersuchung der BindungsÂŹcharakteristika, zur Strukturbestimmung der RNA und der Liganden und zur Ableitung dynamischer Parameter aus experimentellen Daten. Die zweite HĂ€lfte dieser Arbeit ist der kumulative Teil und enthĂ€lt die Originalpublikationen, die in drei Themenbereiche eingeteilt sind. Zuerst sind die drei Publikationen gruppiert, in denen die Bestimmung und Charakterisierung peptidischer Liganden der HIV Psi-RNA und deren Wechselwirkungen miteinander behandelt werden. Durch einen Phage-Display Assay wurde zunĂ€chst eine KonsensusÂŹsequenz eines peptidischen Liganden identifiziert (HWWPWW). Zur Verbesserung der Bindungseigenschaften wurde das Hexapeptid mittels einer Sequenzvariierung auf einer MembranoberflĂ€che (SPOT-Assay) weiter optimiert (HKWPWW). Die weiteren strukturellen Untersuchungen der RNA-Ligand-Wechselwirkungen wurden per Fluoreszenz- und NMR-Spektroskopie durchgefĂŒhrt, wobei die NMR-Spektroskopie aufzeigen konnte, dass das Peptid HKWPWW in zwei Konformationen der zentralen Prolinpeptidbindung zu beinahe gleichen Anteilen vorliegt. Die nĂ€chsten zwei Publikationen beschreiben die Ligandselektion gegen die Zielstruktur HIV TAR und die StrukturaufklĂ€rung des Komplexes mittels NMR-Spektroskopie. Als Liganden wurden Tripeptide synthetisiert, in denen zwei Arginine eine synthetische AminosĂ€ure mit aromatischen oder heteroÂŹaromatischen Gruppierungen in ihrer Seitenkette flankieren. Mittels Fluoreszenz-ResonanzÂŹenergietransfersichtung (FRET-Assay) wurde eine Vorauswahl der Liganden vorgenommen und die Interaktionen der ausgewĂ€hlten Liganden mit der RNA per NMR-Spektroskopie konkretisiert. Eine intensive strukturelle Untersuchung des Liganden mit einer Pyrimidinylgruppe in der Seitenkette der zentralen AminosĂ€ure in Komplex mit der TAR RNA ergab eine 2:1 Bindungsstöchiometrie des Liganden. Die erste stĂ€rkere Bindungsstelle im Bulge der RNA war bereits weitgehend bekannt als Ziel von Arginin-tragenden Liganden. Die strukturellen Untersuchungen konnten jedoch auch die zweite Bindungsstelle des Tripeptids unterhalb des Bulges lokalisieren. Zuletzt sind die zwei Publikationen zur Untersuchung der RNA-Dynamik zusammengefasst. Aus autokorrelierten Relaxationsraten der Kerne C1’ und C8 (fĂŒr Purine) bzw. C6 (fĂŒr Pyrimidine) in Nukleotiden der RNA Tetraloopsequenzen UUCG und CACG wurden mittels des Model-Free Formalismus Parameter abgeleitet, die ĂŒber Dynamiken auf der Zeitskala von Pico- bis Nanosekunden der C-H Vektoren berichten. Die Verwendung optimierter und neuer Werte der C-H BindungslĂ€nge und der Anisotropie der 13C-chemischen Verschiebung (13C-CSA) ermöglichte eine genauere Ableitung der inhĂ€renten Dynamiken dieser RNA MolekĂŒle. Diese Informationen konnten in die strukturellen Untersuchungen der glykosidischen Bindung durch kreuzkorrelierte Relaxationsraten eingebaut werden. Des Weiteren konnten die dynamischen Parameter bei verschiedenen Temperaturen mit Parametern abgeglichen werden, die aus Molekular-Dynamischen (MD) Trajektorien abgeleitet wurden. Dies ermöglichte die Visualisierung der internen Bewegungen zweier strukturell Ă€hnlicher Tetraloops aus der YNMG-Familie, die sich aber in ihrer StabilitĂ€t unterscheiden. Bei Temperaturen nahe dem Schmelzpunkt des weniger stabilen CACG-Tetraloops offenbarten sich die Änderungen in der Dynamik, die zum Aufschmelzen des Loops fĂŒhren

    Public sector industrial relations in Europe: common trends and the persistence of national variability

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    "This article reviews industrial relations trends taking place in the public sector in Europe in a context of widespread state restructuring and public management reform. Decentralisation, 'marketisation' and privatisation are examined in terms of their impact on aspects of industrial relations such as employment growth, pay determination, and the reform of machineries of negotiation and consultation. Having identified a number of common tendencies, however, the article points to persisting national variations in the extent and style of change. It seeks to explain these in terms of the differing roles played by the public sector in post-war models of development. It also considers the specific national institutional and political arrangements - constitutional provisions, the status of civil servants, and the mechanics of electoral systems, etc. - that may hinder or encourage state sector reform." (author's abstract)"Dieser Artikel gibt eine Übersicht ĂŒber die wichtigsten Entwicklungstendenzen im öffentlichen Sektor, der ĂŒberall durch Versuche von Staatsmodernisierung und Reformen des öffentlichen Managements gekennzeichnet ist. Es wird untersucht, wie Dezentralisierung, Marktmodelle und Privatisierung auf wichtige Aspekte der Arbeitsbeziehungen wirken, insbesondere auf das Wachstum der BeschĂ€ftigung, die Festlegung von VergĂŒtungen und die Verhandlungs- und Beratungsverfahren. Nachdem eine Reihe gemeinsamer Entwicklungstendenzen identifiziert worden ist, werden anhaltende nationale Besonderheiten im Ausmaß und im Stil der Reformen hervorgehoben. Danach wird versucht, diese Unterschiede in der unterschiedlichen Rolle des öffentlichen Sektors in den Nachkriegswirtschaften zu verankern. Schließlich werden die spezifischen nationalen Institutionen und politischen Arrangements, wie Verfassungsrechte, Status der Beamten und Wahlverfahren daraufhin untersucht, ob sie die Reform des öffentlichen Sektors behindern oder ermutigen." (Autorenreferat

    Employee representation and consultative voice in multinational companies operating in Britain

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    Multinational companies (MNCs) from different countries of origin are widely held to have distinct preferences regarding the presence of employee representative structures and the form that employee 'voice' over management decisions takes. Such preferences are said to derive from the national models that prevail in the different countries of origin in which MNCs are based. Findings from a large-scale survey of the UK operations of MNCs indicate that country-of-origin influences on patterns of employee representation and emphasis on direct or indirect channels of employee 'voice' are attenuated by other factors, notably sector and method of growth. They also reveal significant recent innovation in representation and voice arrangements by this key group of employers

    Scherzo Caprice

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    https://digitalcommons.library.umaine.edu/mmb-ps/1643/thumbnail.jp

    Ontologies of Living Beings

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    Though the history of the interactions between ‘biology’ and metaphysics is almost as old as Western philosophy itself (Lennox 2001), it seems fair to say that there has been a resurgence of interest in this connection in the last couple of decades (e.g. Hull 1989; Millstein 2009; Clarke 2011; DuprĂ© 2012; Pradeu 2012; Godfrey-Smith 2013; Ferner 2016; Wiggins 2016). Rediscovering this connection brings both opportunities and challenges

    Forage supply of West African rangelands : Towards a better understanding of ecosystem services by application of hyperspectral remote sensing

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    Grazing is the predominant type of land use in savanna regions all over the world. Although large savanna areas in Africa are still grazed by wild herbivores, the West African Sudanian savanna region mainly comprises rangeland ecosystems, providing the important ecosystem service of forage supply for domestic livestock. However, these dryland rangelands are threatened by global change, including a predicted in-crease in climatic aridity and variability as well as land degradation caused by overgrazing. In this context, the international research project WASCAL (West African Science Service Centre on Climate Change and Adapted Land Use) was initiated to investigate the effects of climatic change in this region and to develop effective adaptation and mitigation measures. This cumulative dissertation aims at providing a methodology for a regular knowledge-driven monitoring of forage resources in West Africa. Due to the vast and remote nature of Sudanian savannas, remote sensing technologies are required to achieve this goal. Hence, as a first step, it was necessary to test whether hyperspectral near-surface remote sensing offers the means to model and estimate the two most important aspects of forage supply, i.e. forage quantity (green biomass) and quality (metabolisable energy) (Chapter 2.1). Evidence was provided that partial least squares regression was able to generate robust and transferable forage models. In a second step, direct and indirect drivers of forage supply on the plot and site level were identified by using path modelling within the well-defined concept of social-ecological systems (Chapter 2.2). Results indicate that the provisioning ecosystem service of forage supply is mainly driven by land use, while climatic aridity exerts foremost indirect control by determining the way people use their environment. Building on these findings, upscaling of models was tested to generate maps of forage quality and quantity from satellite images (Chapter 2.3). Here, two different available data sources, i.e. multi- and hyperspectral satellites, were compared to serve the overall objective to install a regular forage monitoring system. In conclusion, preliminary forage maps could be created from both systems. An independent validation would be a research desiderate for future studies. Moreover, both systems feature certain shortcomings that might only be overcome by future satellite missions
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