Firm Size and the Choice of Export Mode

In international trade models, it is typically assumed that manufacturers ship their goods directly to their foreign customers. In reality, however, many manufacturers call in trade intermediaries to perform this task for them. Which manufacturers make use of this option? Theory suggests that it is mostly the small firms which are not profitable enough to cover the high fixed costs of building an own distribution network abroad. Large and eefficient firms, on the contrary, prefer to export their goods directly. The present paper brings this hypothesis to a test. Using survey data from the World Bank Enterprise Survey conducted in Turkey in 2008, it shows that there is indeed a negative correlation between firm size and the relative importance of intermediated exports. This result is highly robust to the inclusion of a variety of controls, different estimation methods, and different measures of firm size.Heterogeneous firms, intermediated trade

Trade Liberalization and Self-Control Problems

This paper analyzes the welfare effects of trade liberalization when some individuals suffer from self-control problems and hence consume too much of goods which generate immediate benefits but entail future costs. Within a classic Ricardian model of trade, the welfare efects depend crucially on the direction of trade. In the importing country, individuals who are suciently price-sensitive and have a sufficiently strong self-control problem lose from trade. In the exporting country, all individuals unambiguously gain from trade. These ndings are however not robust to changes in the assumptions on production technology and market structure. Within a new trade model with increasing returns to scale and monopolistic competition, individuals with self-control problems can lose in both countries. In contrast to the Ricardian setting, even individuals without self-control problems can lose if the average self-control problem is stronger in their country than in the country they start trading with.Globalization, welfare gains from trade, self-control problems, timeinconsistency

Spectroscopic confirmation of the low-latitude object FSR 1716 as an old globular cluster

Star clusters are invaluable tracers of the Galactic components and the discovery and characterization of low-mass stellar systems can be used to appraise their prevailing disruption mechanisms and time scales. However, owing to the significant foreground contamination, high extinction, and still uncharted interfaces of the underlying Milky Way components, objects at low Galactic latitudes are notoriously difficult to characterize. Here, we present the first spectroscopic campaign to identify the chemodynamical properties of the low-latitude star cluster FSR 1716. While its photometric age and distance are far from settled, the presence of RR Lyrae variables indicates a rather old cluster variety. Using medium-resolution (R$\sim$10600) calcium triplet (CaT) spectroscopy obtained with the wide-field multi-fibre AAOmega instrument, we identified six member candidates with a mean velocity of $-30$ km s$^{-1}$ and a velocity dispersion of 2.5$\pm$0.9 km s$^{-1}$. The latter value implies a dynamic mass of $\sim$1.3$\times$10$^4$ M$_{\odot}$, typical of a low-mass globular cluster. Combined with our derived CaT metallicity of $-1.38\pm0.20$ dex, this object is finally confirmed as an old, metal-poor globular cluster.Comment: 5 pages, 4 figures, accepted for publication in Astronomy & Astrophysic

Essays in international trade

This thesis is a collection of three independent essays in international trade. The first essay analyzes the welfare consequences of trade liberalization when consumers suffer from self-control problems. The second essay deals with the endogenous determination of non-tariff barriers to trade when firms differ both in their political activities and in their preferences regarding trade policies. The third essay studies the empirical relationship between firm size and the choice of export mode

Characterizing quantum gases in correlated-disorder realizations using density-density correlations

The role of disorder on physical systems has been widely studied in the macroscopic and microscopic world. While static disorder is well understood in many cases, the impact of time-dependent disorder on quantum gases is still poorly investigated. In our experimental setup, we produce and characterize time-dependent optical-speckle disorder for ultracold quantum gases with tunable correlation time. Experimentally, coherent light illuminates a combination of a static and a rotating diffuser, thereby collecting a spatially varying phase due to the diffusers' structure and a temporally variable phase due to the relative rotation. The rotation speed of the diffuser determines a characteristic time scale of the dynamics. It can be tuned within a broad range matching typical time scales of the quantum gases investigated. We characterize the dynamic speckle pattern ex-situ by measuring its intensity distribution and in-situ by observing its impact on a molecular Bose-Einstein condensate. As one diffuser rotates relative to the other around the common optical axis, we trace the optical speckle's intensity correlations and the quantum gas' density-density correlations. Our results show comparable outcomes for both measurement methods. The setup allows us to tune the disorder potential adapted to the characteristics of the quantum gas. These studies pave the way for investigating nonequilibrium physics in interacting quantum gases using controlled dynamical-disorder potentials.Comment: 12 pages, 8 figure

What can we learn from diffusion about Anderson localization of a degenerate Fermi gas?

Disorder can fundamentally modify the transport properties of a system. A striking example is Anderson localization, suppressing transport due to destructive interference of propagation paths. In inhomogeneous many-body systems, not all particles are localized for finite-strength disorder, and the system can become partially diffusive. Unravelling the intricate signatures of localization from such observed diffusion is a long-standing problem. Here, we experimentally study a degenerate, spin-polarized Fermi gas in a disorder potential formed by an optical speckle pattern. We record the diffusion in the disordered potential upon release from an external confining potential. We compare different methods to analyze the resulting density distributions, including a new method to capture particle dynamics by evaluating absorption-image statistics. Using standard observables, such as diffusion exponent and coefficient, localized fraction, or localization length, we find that some show signatures for a transition to localization above a critical disorder strength, while others show a smooth crossover to a modified diffusion regime. In laterally displaced disorder, we spatially resolve different transport regimes simultaneously which allows us to extract the subdiffusion exponent expected for weak localization. Our work emphasizes that the transition toward localization can be investigated by closely analyzing the system's diffusion, offering ways of revealing localization effects beyond the signature of exponentially decaying density distribution.Comment: 18 pages, 11 figure