Covered Interest Arbitrage: Then vs. Now

We introduce a new weekly database of spot and forward US-UK exchange rates as well as interest rates to examine the integration of forward exchange markets during the classical gold standard period (1880-1914). Using threshold autoregressions (TAR), we estimate the transactions cost band of covered interest differentials (CIDs) and compare our results to studies of more recent periods. Our findings indicate that CIDs for the US-UK rate were generally larger during the classical gold standard than any period since. We argue that slower information and communications technology during the gold standard period led to fewer short-term financial flows, higher transactions costs, and larger CIDs.

Harvesting the Mouse Genome

The sequencing of the black 6 mouse (strain C57Bl/6) has reached an important juncture. The BAC fingerprint map is almost complete, the BACs have been endsequenced and a seven-fold coverage whole-genome shotgun has been assembled. Now the BAC-by-BAC sequencing phase is under way and in-depth comparative analysis can be carried out on regions that have been the subject of targeted sequencing. This paper reviews the progress so far and looks forward to the promises of finished sequence

Multi-agent-based dynamic optical subcarrier allocation for near real-time P2MP operation

We propose a multi-agent system (MAS) to manage subcarrier allocation in point-to-multipoint connectivity based on Digital Subcarrier Multiplexing. Similar performance to a centralized approach is shown, which allows for near-real time operation with increased scalability.This work has received funding from the EC through the H2020 B5G-OPEN (G.A. 101016663), the MICINN IBON (PID2020-114135RB-I00) project, and the ICREA Institution.Peer ReviewedPostprint (author's final draft

Dynamic subcarrier allocation for multipoint-to-point optical connectivity

A mathematical programming model is proposed to dynamically allocate subcarriers in the upstream direction of point-to-multipoint connections based on Digital Subcarrier Multiplexing. Numerical results show significant capital and energy cost reduction.The research leading to these results has received funding from the H2020 B5G-OPEN (G.A. 101016663), the MICINN IBON (PID2020-114135RB-I00), and the ICREA Institution.Peer ReviewedPostprint (author's final draft

Network design for mesoscale inversions of CO2 sources and sinks

International audienceRecent instrumental deployments of regional observation networks of atmospheric CO2 mixing ratios have been used to constrain carbon sources and sinks using inversion methodologies. In this study, we performed sensitivity experiments using observation sites from the Mid Continent Intensive experiment to evaluate the required spatial density and locations of CO2 concentration towers based on flux corrections and error reduction analysis. In addition, we investigated the impact of prior flux error structures with different correlation lengths and biome information. We show here that, while the regional carbon balance converged to similar annual estimates using only two concentration towers over the region, additional sites were necessary to retrieve the spatial flux distribution of our reference case (using the entire network of eight towers). Local flux corrections required the presence of observation sites in their vicinity, suggesting that each tower was only able to retrieve major corrections within a hundred of kilometres around, despite the introduction of spatial correlation lengths (~100 to 300 km) in the prior flux errors. We then quantified and evaluated the impact of the spatial correlations in the prior flux errors by estimating the improvement in the CO2 model-data mismatch of the towers not included in the inversion. The overall gain across the domain increased with the correlation length, up to 300 km, including both biome-related and non-biome-related structures. However, the spatial variability at smaller scales was not improved. We conclude that the placement of observation towers around major sources and sinks is critical for regional-scale inversions in order to obtain reliable flux distributions in space. Sparser networks seem sufficient to assess the overall regional carbon budget with the support of flux error correlations, indicating that regional signals can be recovered using hourly mixing ratios. However, the smaller spatial structures in the posterior fluxes are highly constrained by assumed prior flux error correlation lengths, with no significant improvement at only a few hundreds of kilometres away from the observation sites

Airfoil Tip Leakage Aeroacoustics Predictions using a Lattice Boltzmann Based Method

International audienceThe noise produced by rotating systems such as fans and turbo machines is of growing importance in the academic and engineering communities. The prediction and understanding of the physical mechanisms associated with noise generation are required in order to develop innovative solutions able to efficiently reduce radiated acoustics levels. The flow-induced noise generation mechanisms related to rotating devices are various and complex, and one of them is related to the blade tip flow. The tip flow noise, or tip leakage noise, is particularly important for free-tip configurations, for which the tip flow induced by the pressure gradient between the suction and pressure sides can be particularly intense. The experimental investigation of this mechanism is practically challenging. Consequently, a simplified non-rotating representative configuration has been proposed, and has been previously investigated experimentally. In this paper, transient, compressible, and time-explicit Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) simulations of an airfoil tip leakage flow for this simplified geometry are performed using a Lattice Boltzmann Method (LBM) based approach. The studied configuration is a NACA 5510 airfoil profile at high Reynolds number flow conditions, for which a variable size gap is introduced between the airfoil and one of the end plates, modeling the tip gap encountered in free-tip fans. First, the simulation results are compared with experimental results to validate the numerical approach. Further investigation of the numerical results underlines the connection between the tip vortex structures and noise radiation, including a parametric study on the Angle of Attack (AoA) and the tip gap width