Three essays in empirical economics

In the preface of one of the most established textbooks "Economics" by Samuelson and Nordhaus (1998), the authors state that the ultimate goal of economics is to improve the living conditions of people in their everyday life". In this spirit, the underlying thesis empirically assesses three heterogenous topics which all can be linked via their impact on (economic) well-being. It contributes to the scientific landscape by tackling the questions at hand utilising novel and newly constructed data sets which have not been commonly used in economic research. The thesis comprises three chapters which will be summarised in the following. Gun Violence in the US: Correlates and Causes This chapter provides a county-level investigation of the economically-motivated gun violence in the US. To guide our empirical analysis, we develop a simple theoretical model which suggests that firearm-related robberies in a given county increase with the number of illegal guns and decrease with social capital and police intensity. Using detailed FBI data from 1986-2014, we find empirical evidence for the role of illegal guns, social capital, and police intensity in line with our theoretical predictions. To investigate the causal effect of illegal guns, we exploit plausibly exogenous variation in illegal firearm supplies due to gun thefts in contiguous states. The Size of the Middle Class and Educational Outcomes: Theory and Evidence from the Indian Subcontinent This chapter proposes a stylised model to derive the effect of a sizeable middle class on average educational outcomes. Under the reasonable assumptions, the model predicts that the spending share on education increases if the middle class becomes larger such that the size of the middle class has a positive impact on education. We test the relationship empirically by using village/neighbourhood level data from Indian household surveys. To tackle the the issue of potential endogeneity of the middle class share of the population, we propose a novel instrument that relies on the fraction of the population belonging to the third (middle) caste ("sudra"). Using this IV strategy, our empirical results support a positive effect. Go East: On the Impact of the Transsiberian Railway on Economic Development in Eastern Russia This chapter addresses the question whether or not large-scale infrastructure investments have a causal effect of local economic development. By using a novel instrumental variable approach based on historical trade and travel routes across the Russian East, I am able to identify a causal and negative effect of remoteness to the Transsiberian Railway on local economic activity as measured by nocturnal lights emission.Im Vorwort eines der am meisten verwendeten Lehrbücher "Economics" von Samuelson und Nordhaus (1998) postulieren die Autoren, dass das ultimative Ziel eines jeden Ökonomen sein sollte, die alltäglichen Lebensumstände jedes Menschen zu verbessern. In diesem Sinne untersucht die vorliegende Arbeit drei heterogene Fragestellungen empirisch. Diese sind alle durch ihren Einfluss auf (wirtschaftliche) Wohlfahrt verbunden. Die Arbeit trägt zur wissenschaftlichen Landschaft bei indem sie die zugrundeliegenden Fragen unter Zuhilfenahme neuer und neu konstruierter Datensätze adressiert, welche bisher kaum bis garnicht verwendet wurden. Die Arbeit umfasst drei Projekte, welche im Folgenden zusammengefasst werden. Gun Violence in the US: Correlates and Causes Dieses Kapitel beinhaltet eine Untersuchung ökonomisch motivierter Waffengewalt auf dem County-Level. Um die empirische Analyse zu strukturieren wird ein einfaches theoretisches Modell vorgestellt. Dieses Modell impliziert, dass Raubüberfälle unter Zuhilfenahme von Schusswaffen in einem gegebenen County steigend in der Anzahl illegaler Schusswaffen und fallend im Niveau des Sozialkapitals sowie der Polizeipräsenz ist. Durch die Verwendung detaillierter FBI-Daten aus den Jahren 1986-2014 wird empirische Evidenz für die Rolle illegaler Feuerwaffen, Sozialkapital und Polizeipräsenz gefunden. Diese bestätigt die theoretischen Hypothesen. Um den kausalen Effekt illegaler Waffen zu identifizieren, wird die exogene Variation des illegalen Schusswaffenangebots in benachbarten Staaten genutzt. Diese wird anhand der als gestohlen gemeldeten Schusswaffen gemessen. The Size of the Middle Class and Educational Outcomes: Theory and Evidence from the Indian Subcontinent In diesem Kapitel wird ein stilisiertes theoretisches Modell vorgestellt um den durchschnittlichen Einfluss einer relativ großen Mittelschicht auf das durchschnittliche Bildungsniveau abzuleiten. Unter den getroffenen Annahmen prognostiziert das Modell dass der Anteil der Ausgaben für Bildung mit der relativen Größe der Mittelschicht ansteigt. Somit besteht ein positiver Zusammenhang zwischen der relativen Größe der Mittelschicht und dem durchschnittlichen Bildungsniveau. Dieser Zusammenhang wird dann empirisch überprüft. Als Datengrundlage dienen Dorf-/Nachbarschafts-Level Daten aus dem Indian Household Survey. Um dem Problem potentiell vorhandener Endogenität des Mittelschicht-Anteils zu begegnen, wird ein neuartiger IV-Ansatz vorgeschlagen. Dieser basiert auf dem Anteil der Bevölkerung, der zur dritten (mittleren) Kaste gehört. So können wir einen positiven, kausalen Effekt der relativen Größe der Mittelschicht auf das durchschnittliche Bildungsniveau nachweisen. Go East: On the Impact of the Transsiberian Railway on Economic Development in Eastern Russia Dieses Kapitel adressiert die Frage ob grossangelegte Infrastrukturprojekte einen kausalen Effekt auf das lokale Wirtschaftswachstum haben. Unter Zuhilfenahme eines neuartigen IV-Ansatzes, der auf historischen Handels- und Reiserouten durch den Osten Russlands basiert wird gezeigt, dass ein kausaler und negativer Effekt der Entfernung zur Transsibirischen Eisenbahn existiert. Ökonomische Entwicklung wird mangels vorhandener Daten mittels Nachtlicht-Emissionen approximiert

Double emulsions with controlled morphology by microgel scaffolding

Double emulsions are valuable structures that consist of drops nested inside bigger drops; they can be formed with exquisite control through the use of droplet based microfluidics, allowing their size, composition, and monodispersity to be tailored. However, only little control can be exerted on the morphology of double emulsions in their equilibrium state, because they are deformable and subject to thermal fluctuations. To introduce such control, we use droplet based microfluidics to form oil in water in oil double emulsion drops and arrest their shape by loading them with monodisperse microgel particles. These particles push the inner oil drop to the edge of the aqueous shell drop such that the double emulsions adopt a uniform arrested, anisotropic shape. This approach circumvents the need for ultrafast polymerization or geometric confinement to lock such non spherical and anisotropic droplet morphologies. To demonstrate the utility of this technique, we apply it to synthesize anisotropic and non spherical polyacrylate polyacrylamide microparticles with controlled size and shap

Composite hydrogels based on calcium alginate and polyethyleneimine for wastewater treatment

Water shortage has risen severely in recent years, confronting mankind with a worldwide challenge, especially as the accessible water resources are further limited by diverse contamination. The most widespread industrial process for water treatment is the activated sludge process, in which, however, excessive sludge production has become an enormous environmental problem worldwide. To overcome this problem, hydrogels possess outstanding potential in view of adsorptive removal of contaminants like heavy metal ions, fertilizers, and dyes. In this paper, we report about the synthesis of biobased alginate hydrogel beads along with polyethyleneimine-modified composite hydrogels for water treatment. The adsorption of methylene blue as a positively charged and of congo red as a negatively charged model dye is quantitatively investigated, both separately and in combination. In addition, the pH-dependent adsorption of the dyes is determined. The use of alginate-based hydrogel systems combines several prospects: they are bio-based, inexpensive, easily available to a sufficient extent, sustainable, and are applicable in a broad range of wastewater treatment by its charged groups

Dynamic model metallo-supramolecular dual-network hydrogels with independently tunable network crosslinks

Hybrid polymer networks emerge between chemical and physical crosslinking, where two different modes of chain connectivity control the material behavior. However, rational relations between their microstructural characteristics, supramolecular kinetics, and the resulting network mechanics and dynamics are not well developed. To address this shortcoming, this study introduces a material platform based on a model dual-network hydrogel, comprising independently tunable chemical and physical crosslinks. The idea is realized by a click reaction between a tetra-PEG and a linear-PEG precursor, whereby the linear block also carries a terpyridine ligand at each end that can form additional physical crosslinks by metal ion–bis(terpyridine) complexation. We change the number of chemical crosslinks by varying the molar mass of the tetra-PEG, and we independently tune the metallo-supramolecular bonds by using different metal ions, Mn2+, Zn2+, Co2+, and Ni2+. Based on that modular approach, we study the rheological behavior and the diffusivity of fluorescent polymeric tracers. The dissociation of the metallo-supramolecular bonds provides a relaxation step, whose timescale and intensity are quantified by a sticky Rouse model. These two characteristics differ not only depending on the metal ion but also according to the chemical network mesh size, which highlights an interplay between the chemical and physical crosslinks

Gun violence in the U.S. : correlates and causes

This paper provides a county-level investigation of the root causes of gun violence in the U.S. To guide our empirical analysis, we develop a simple theoretical model which suggests that firearm-related offenses in a given county increase with the number of illegal guns and decrease with social capital and police intensity. Using detailed panel data from the Federal Bureau of Investigation for the period 1986-2014, we find empirical evidence for the causal effects of illegal guns, social capital, and police intensity consistent with our theoretical predictions. Based on our analysis, we derive a range of policy recommendations

Go east : on the impact of the Transiberian Railway on economic development in Eastern Russia

This paper addresses the question whether or not large-scale infrastructure investments have a causal effect of local economic development. By using a novel instrumental variable approach based on historical trade and travel routes across the Russian East, I am able to identify a causal and negative effect of remoteness to the Transsiberian Railway on local economic activity as measured by nocturnal lights emission

Reversible hydrogels with switchable diffusive permeability

Hydrogels are polymer networks swollen in water that are characterized by soft mechanics and high permeability. This makes them good candidates for separation and membrane technologies. The diffusion is controlled by the mesh size of the network, and this can be made tunable through the introduction of thermoresponsive polymers. However, this is still a developing field. To contribute to this development, a dual dynamic network is formed composed of four-arm polyethylene glycol precursors in which each arm is functionalized with both a terpyridine moiety capable of forming reversible metal–ligand complexes along with branches of poly(N-isopropylacrylamide) (pNIPAAm), which can be switched between expanded and collapsed states and therewith offers a path for switching the microscopic gel-network mesh size, along with the macroscopic gel elasticity. The dually sensitive hydrogel has the capability of doubling its elastic modulus when going above the lower critical solution temperature (LCST) of pNIPAAm. In addition, the diffusive permeability of the hydrogel is switched upon change of temperature, whereby diffusants are trapped above the LCST of pNIPAAm. Moreover, it is possible to disassemble and reform the gel upon change of pH. With that, the hydrogel has potential application as a switchable and reversible membrane

Effect of junction aggregation on the dynamics of supramolecular polymers and networks

Transient structures based on associative polymers can deliver complex functions; as such, they hold promise for advanced applications as in drug delivery, tissue engineering, and electronics. The network structure and timescale of its rearrangement are key factors that define their range of utility. However, the inevitable phase separation of polar pairwise associations from nonpolar polymer chains frequently causes junction aggregation, whose stability and functionality significantly affect the network structure and dynamics, and as such, redefine its utility. Engineering the extent of association is a necessity for controlling properties of supramolecular materials, yet the current knowledge of the effect of design parameters on specificities of aggregates and their consequent effects on material properties is limited. To address this gap, the importance of aggregation is highlighted, the available theories and models of the dynamics of associative polymers in the presence of aggregates are reviewed, and the existing experimental records to draw a general guideline for interpreting the effect of aggregates on polymer dynamics are classified. Moreover, pitfalls and considerations like the applicability of time–temperature superposition, and the interplay of kinetics and thermodynamics of aggregation that may undermine the authenticity of the reported data are reviewed

The size of the middle class and educational outcomes : theory and evidence from the Indian subcontinent

This paper proposes a stylised model to derive the effect of a sizeable middle class on average educational outcomes. Under reasonable assumptions, the model predicts that the spending share on education increases if the middle class becomes larger such that the size of the middle class has a positive impact on education. We test the relationship empirically by using village/neighbourhood level data from Indian household surveys. To tackle the issue of potential endogeneity of the middle class share of the population, we propose a novel instrument that relies on the fraction of the population belonging to the third (middle) caste (sudra). Using this IV strategy, our empirical results support a positive effect of a larger middle class on educational outcomes. Furthermore, we show that the share of the middle class is a more important determinant of female education than male education and that the effect of the middle class on education is more pronounced in rural areas