Individual Risk Attitudes: Measurement, Determinants and Behavioral Consequences

This paper studies risk attitudes using a large representative survey and a complementaryexperiment conducted with a representative subject pool in subjects’ homes. Using aquestion asking people about their willingness to take risks “in general”, we find thatgender, age, height, and parental background have an economically significant impacton willingness to take risks. The experiment confirms the behavioral validity of thismeasure, using paid lottery choices. Turning to other question about risk attitudesin specific contexts, we find similar results on the determinants of risk attitudes, andalso shed light on the deeper question of stability of risk attitudes across contexts. Weconduct a horse race of the ability of different measures to explain risky behaviorssuch as holdings stocks, occupational choice, and smoking. The question about risktakingin general generates the best all-around predictor of risky behavior. (JEL codes:D0, D1, D80, D81, C91, C93, J16, J24, I1).education, training and the labour market;

Spin - Rotation Coupling Observed in Neutron Interferometry

Einstein's theory of general relativity and quantum theory form the two major pillars of modern physics. However, certain inertial properties of a particle's intrinsic spin are inconspicuous while the inertial properties of mass are well known. Here, by performing a neutron interferometric experiment, we observe phase shifts arising as a consequence of the spin's coupling with the angular velocity of a rotating magnetic field. The resulting phase shifts linearly depend on the frequency of the rotation of the magnetic field. Our results agree well with the predictions derived from the Pauli - Schr\"odinger equation

Individual Risk Attitudes: New Evidence from a Large, Representative, Experimentally-Validated Survey

This paper presents new evidence on the distribution of risk attitudes in the population, using a novel set of survey questions and a representative sample of roughly 22,000 individuals living in Germany. Using a question that asks about willingness to take risks in general, on an 11-point scale, we find evidence of heterogeneity across individuals, and show that willingness to take risks is negatively related to age and being female, and positively related to height and parental education. We test the behavioral relevance of this survey measure by conducting a complementary field experiment, based on a representative sample of 450 subjects, and find that the general risk question is a good predictor of actual risk-taking behavior. We then use a more standard lottery question to measure risk preferences in our sample of 22,000, and find similar results regarding heterogeneity and determinants of risk preferences, compared to the general risk question. The lottery question also makes it possible to estimate the coefficient of relative risk aversion for each individual in the sample. Using five questions about willingness to take risks in specific domains - car driving, financial matters, sports and leisure, career, and health - the paper also studies the impact of context on risk attitudes, finding a strong but imperfect correlation across contexts. Using data on a collection of risky behaviors from different contexts, including traffic offenses, portfolio choice, smoking, occupational choice, participation in sports, and migration, the paper compares the predictive power of all of the risk measures. Strikingly, the general risk question predicts all behaviors whereas the standard lottery measure does not. The best predictor for any specific behavior is typically the corresponding context-specific measure.Risk Preferences, Experimental Validation, Field Experiment, SOEP, Gender Differences, Context, Age, Height, Subjective Well-Being, Migration, Occupational Choice, Health

Individual Risk Attitudes: New Evidence from a Large, Representative, Experimentally-Validated Survey

This paper presents new evidence on the distribution of risk attitudes in the population, using a novel set of survey questions and a representative sample of roughly 22,000 individuals living in Germany. Using a question that asks about willingness to take risks on an 11-point scale, we find evidence of heterogeneity across individuals, and show that willingness to take risks is negatively related to age and being female, and positively related to height and parental education. We test the behavioral relevance of this survey measure by conducting a complementary field experiment, based on a representative sample of 450 subjects, and find that the measure is a good predictor of actual risk-taking behavior. We then use a more standard lottery question to measure risk preference, and find similar results regarding heterogeneity and determinants of risk preferences. The lottery question makes it possible to estimate the coefficient of relative risk aversion for each individual in the sample. Using five questions about willingness to take risks in specific domains - car driving, financial matters, sports and leisure, career, and health - the paper also studies the impact of context on risk attitudes, finding a strong but imperfect correlation across contexts. Using data on a collection of risky behaviors from different contexts, including traffic offenses, portfolio choice, smoking, occupational choice, participation in sports, and migration, the paper compares the predictive power of all of the risk measures. Strikingly, the general risk question predicts all behaviors whereas the standard lottery measure does not. The best overall predictor for any specific behavior is typically the corresponding context-specific measure. These findings call into the question the current preoccupation with lottery measures of risk preference, and point to variation in risk perceptions as an understudied determinant of risky behavior.Risk preferences; Preference stability; Experimental validation; Field experiment; SOEP; Gender differences; Age; Height; Subjective well-being

Individual Risk Attitudes: Measurement, Determinants and Behavioral Consequences

This paper studies risk attitudes using a large representative survey and a complementary experiment conducted with a representative subject pool in subjects'' homes. Using a question asking people about their willingness to take risks "in general", we find that gender, age, height, and parental background have an economically significant impact on willingness to take risks. The experiment confirms the behavioral validity of this measure, using paid lottery choices. Turning to other questions about risk attitudes in specific contexts, we find similar results on the determinants of risk attitudes, and also shed light on the deeper question of stability of risk attitudes across contexts. We conduct a horse race of the ability of different measures to explain risky behaviors such as holdings stocks, occupational choice, and smoking. The question about risk-taking in general generates the best all-around predictor of risky behavior.Economics ;

Potential transgenic routes to increase tree biomass

AbstractBiomass is a prime target for genetic engineering in forestry because increased biomass yield will benefit most downstream applications such as timber, fiber, pulp, paper, and bioenergy production. Transgenesis can increase biomass by improving resource acquisition and product utilization and by enhancing competitive ability for solar energy, water, and mineral nutrients. Transgenes that affect juvenility, winter dormancy, and flowering have been shown to influence biomass as well. Transgenic approaches have increased yield potential by mitigating the adverse effects of prevailing stress factors in the environment. Simultaneous introduction of multiple genes for resistance to various stress factors into trees may help forest trees cope with multiple or changing environments. We propose multi-trait engineering for tree crops, simultaneously deploying multiple independent genes to address a set of genetically uncorrelated traits that are important for crop improvement. This strategy increases the probability of unpredictable (synergistic or detrimental) interactions that may substantially affect the overall phenotype and its long-term performance. The very limited ability to predict the physiological processes that may be impacted by such a strategy requires vigilance and care during implementation. Hence, we recommend close monitoring of the resultant transgenic genotypes in multi-year, multi-location field trials

Aufbau, Optimierung und Charakterisierung der THz-Optik für GREAT auf SOFIA

Sternentstehung findet im dichten Teil der Molekülwolken des interstellaren Mediums statt. In diesen Gebieten werden die ablaufenden physikalischen und chemischen Prozesse maßgeblich von der Wechselwirkung zwischen der Materie und dem Strahlungsfeld eingebetteter junger Sterne bestimmt. Konsequenz der Bestrahlung mit FUV-Photonen (6eV10^6) ermöglicht. Dabei ist zu beachten, dass Frequenzen im Bereich von 1-10THz erdgebunden aufgrund der Absorption des atmosphärischen Wassersdampfs nicht beobachtbar sind. Daher müssen THz-Empfänger in großer Höhe nach Möglichkeit oberhalb der Troposphäre betrieben werden. GREAT wird am flugzeuggetragenen 2.5m-Teleskop des Stratospheric Observatory for Far Infrared Astronomy (SOFIA) in einer Höhe von ca. 13km operieren. Für die Planung und den Aufbau des Empfängers wurde ein Forschungskonsortium bestehend aus entsprechenden Arbeitsgruppen am MPIfR, dem MPIAe, dem DLR und KOSMA gegründet. Insgesamt befinden sich vier Frequenzkanäle im Bereich von 1.2-4.7THz im Aufbau, von denen in Abhängigkeit der wissenschaftlichen Fragestellung zwei ausgewählt, in das GREAT-Instrument eingesetzt und simultan betrieben werden können. Die hierfür erforderliche Modularität von GREAT stellt eine große Herausforderung für den Aufbau und die Justage des Empfängers dar. Zusätzlich waren die strengen Zertifizierungsregeln der amerikanischen Flugsicherheitsbehörde FAA zu erfüllen. Innerhalb des Konsortiums ist KOSMA für den Aufbau der 1.4 und 1.9THz-Kanäle, für die Entwicklung der kanalübergreifenden Optik und den Aufbau von Array acousto-optical Spektrometern zuständig. Wesentliche Teile der Aufgaben wurden im Rahmen von drei Dissertationen ausgeführt. Die Dissertation von P. Munoz umfasst die Entwicklung der supraleitenden Hot-Electron Bolometer (HEB) für 1.2-1.9THz. M. Philipp war für den Aufbau des 1.9THz-Lokaloszillator (LO) zuständig. Im Rahmen vorliegender Arbeit wurden sowohl die optomechanischen Komponenten der kanalübergreifenden Optik als auch die Optik der 1.4-1.9THz-Kanäle entwickelt. Ferner wurde die für die HEBs erforderliche kryogene Infrastruktur aufgebaut, und abschließend eine Charakterisierung des 1.9THz Kanals vorgenommen. Die wesentlichen technischen Entwicklungen und Ergebnisse aus vorliegender Arbeit sind nachfolgend kurz zusammengefasst. Kohärente Strahlungsquellen mit einer Ausgangsleistung von mehr Als 1000nW sind im Frequenzbereich von 1-10THz nur eingeschränkt verfügbar. Die Maximierung der nutzbaren 1.9THz-LO-Leistung machte die Entwicklung abbildender astigmatischer Spiegel für quasioptische Systeme erforderlich. Das Kryostatenfenster muss im Beobachtungsfrequenzband transparent sein. Materialien mit einem niedrigen Absorptionskoeffizienten im THz-Bereich (z.B. Silizium) besitzen im Allgemeinen hohe Dielektrizitätskonstanten und führen zu hohen Reflexionsverlusten. Im Rahmen dieser Arbeit gelang die Anwendung der Effective-Medium-Theorie, um entspiegelte ''Low loss THz-Windows'' herzustellen. Ein erstes Exemplar ist im Mikrostrukturlabor von KOSMA per Bosch-Prozess aus Silizium hergestellt worden. In Kooperation mit dem CSIRO, Australien, kam erstmalig eine neuartige smooth-walled spline-profile Hornantenne für 1.9THz zum Einsatz, deren Antennenkeule im Rahmen dieser Arbeit im Labor indirekt vermessen werden konnte. Die Bestimmung der spektralen Systemrauschtemperatur des 1.9THz-Kanals ergab über das Zwischenfrequenzband von 1.2-1.7GHz 2200-2500K. Die Allan-Minimumszeit als Maß der Systemstabilität beträgt 35s. Damit ist der 1.9THz-Kanal empfindlich und weist zugleich eine Stabilität auf, die ähnlich gut ist wie die von SIS-Empfängern. Logische Konsequenz der begrenzten Messzeit auf SOFIA ist die mittelfristige Steigerung der Effizienz des submm-Empfängers. Der Ausbau des 1.9THz-GREAT-Kanals zum 4-Pixel Array wurde im Rahmen der hier dokumentierten Arbeit vorbereitet. Mit der Fertigstellung des 1.9THz-Kanals steht der Wissenschaft der weltweit einzige, einsatzbereite Heterodynempfänger für 1.9THz zur Verfügung