Exchange rate dynamics in a target zone: a heterogeneous expectations approach

We present a simple behavioral model with chartists and fundamentalists and analyze their trading behavior in a floating regime and in a target zone regime. Regarding the floating regime the model replicates the well-known stylized facts like excessive volatility, fat tails, volatility clustering and the exchange rate disconnect. When introducing a credible target zone the exchange rate remains for a considerably long period in the center of the band albeit the fundamental exchange rate does not exhibit mean reversion tendencies. The resulting hump-shaped distribution of the exchange rate greatly reduces the frequency of central bank intervention. The introduction of a target zone regime significantly reduces exchange rate volatility by decreasing speculative activity in the FX market. --Exchange rate,heterogeneous agents,target zones

Exchange Rates Dynamics in a Target Zone – A Heterogeneous Expectations Approach

The target zone model of Krugman (1991) has failed empirically. In this paper, we develop a model of the exchange rate with heterogeneous agents in a free floating and a target zone regime. We show that this simple model mimics the empirical puzzles of exchange rates: excessive volatility, fat tails, volatility clustering, and disconnection from the fundamentals. In addition, the target zone regime replicates a reduced nominal volatility for the same level of fundamental volatility as in the free floating regime and the distribution of the exchange rate within the band is hump-shaped.exchange rate, heterogeneous agents, target zones

Enhanced collective Purcell effect of coupled quantum emitter systems

Cavity-embedded quantum emitters show strong modifications of free space radiation properties such as an enhanced decay known as the Purcell effect. The central parameter is the cooperativity $C$, the ratio of the square of the coherent cavity coupling strength over the product of cavity and emitter decay rates. For a single emitter, $C$ is independent of the transition dipole moment and dictated by geometric cavity properties such as finesse and mode waist. In a recent work [Phys. Rev. Lett. 119, 093601 (2017)] we have shown that collective excitations in ensembles of dipole-dipole coupled quantum emitters show a disentanglement between the coherent coupling to the cavity mode and spontaneous free space decay. This leads to a strong enhancement of the cavity cooperativity around certain collective subradiant antiresonances. Here, we present a quantum Langevin equations approach aimed at providing results beyond the classical coupled dipoles model. We show that the subradiantly enhanced cooperativity imprints its effects onto the cavity output field quantum correlations while also strongly increasing the cavity-emitter system's collective Kerr nonlinear effect

Paired Sr isotope (⁸⁷Sr/⁸⁶Sr, δ^88/86Sr) systematic of pore water profiles: A new perspective in marine weathering and seepage studies

The simultaneous and independent determination of the radiogenic (87Sr/86Sr) and the fractionation reflecting stable (!88/86Sr) Sr isotope ratio on pore waters, sediments and precipitates (e.g. carbonates and sulfates) opens a new perspective in the field of submarine weathering and Sr contribution to the ocean chemistry. Four initial case studies covering (1.) CO2 seeps of the Okinawa Trough (OT), (2.) mud volcanoes (MV) and mounds in the Gulf of Cadiz (GoC) and the (3.) Central American Fore Arc as well as first results from the (4.) Black Sea are conducted and reflect a stable Sr perspective on seeps from a broad range of geological settings. Referred to NIST-SRM-987, in this study the IAPSO seawater (SW) standard has a !88/86Sr of 0.39 ‰ (±0.03, 2SD). As a prominent systematic deviation the OT pore water (PW) data from a site with CO2 hydrate and liquid CO2 occurence show values ranging from 0.27 to 0.59 ‰ (286 to 64 cm sediment depth), accompanied by a weak inversely correlated trend from 0.2 to 0.15 ‰ for the corresponding bulk sediment (286 to 36 cm). In contradiction to a simple fluid/SW-mixing approach as driving mechanism for the PW stable Sr trend the 87Sr/86Sr signature stays within analytical uncertainty constant with depth (0.70980 (1)) and differs significantly from SW (0.70917 (1)) and the more radiogenic, slightly heterogeneous sediment (0.71892-0.71731). Potential explanation for the observed !88/86Sr trend and PW signatures heavier than SW are (a) strong fractionation processes enriching light isotopes in secondary precipitates and remineralisation products and heavier signatures in the remaining fluid and/or (b) preferential dissolution of heavier mineral phases. Examples for the latter kind of sediment component are determined in a detailed study of the Mercator MV (GoC) by high !88/86Sr ratios of 0.72 for authigenic and 0.92 ‰ for potentially extruded gypsum crystals. Combined with PW data from the other seep settings (0.2 to 0.52 ‰) a broad range of Sr contribution and fractionation processes becomes evident

How to decompress the Pressure - The moderating Effect of IT Flexibility on the negative Impact of Governmental Pressure on Business Agility

In times of digital transformation banks need to behave agile and increase their speed in IT. At the same time, they are bound by an increasing number of regulatory rules at an increasing pace that force them to act carefully. Since governments frequently introduce new regulatory terms, especially in the finance sector, regulation is a changing phenomenon itself, which forces banks to adjust and change their systems constantly. To manage these challenges, we argue that successful businesses need to have a flexible IT architecture in place. This should enable them to update and reconfigure their systems in a cost effective and prompt manner. By doing this, they should be able to compensate for the regulatory pressure and remain agile. Based on an analysis of 119 survey results, we find that business agility is indeed lower for higher regulatory pressure and that this effect is mitigated by a flexible IT

Cooperative quantum phenomena

Quantum cooperativity is evident in light-matter platforms where quantum emitter ensembles are interfaced with confined optical modes and are coupled via the ubiquitous electromagnetic quantum vacuum. Cooperative aspects such as dipole-dipole interactions and subradiance find applications in the design of nanoscale coherent light sources and highly-reflective quantum metasurfaces made up of hundreds of optically trapped atoms, in the implementation of topological quantum optics on subwavelength arrays of emitters, in quantum metrology and quantum information. The quick bursts of radiation from a collection of quasi-indistiguishable emitters provides an alternative approach to standard lasers by introducing superradiant lasers operating at extremely low intracavity power. This tutorial provides a set of theoretical tools to tackle the behavior responsible for the onset of cooperativity in light-matter systems by extending open quantum system dynamics methods, such as the master equation and quantum Langevin equations, to electron-photon interactions in strongly coupled and correlated quantum emitters ensembles. These analytical approaches are then also extended to frequency disordered or vibronically coupled quantum emitter ensembles with wide relevance ranging from atoms in optical lattices, quantum dots in solid state environments or molecular quantum systems

Heterogeneous Forecasters and Nonlinear Expectation Formation in the U.S. Stock Market

We use a Panel Smooth Transition Regression (STR) model to study nonlinearities in the expectation-formation process in the U.S. stock market. To this end, we use data from the Livingston survey to investigate how the importance of regressive and extrapolative expectations fluctuates over time as market conditions summarized by stock-market misalignments and recent returns change. We find that survey participants form stabilizing expectations in the long run. Short-run expectations, in contrast, are consistent with weak mean reversion of stock prices

In situ tuning of magnetization via topotactic lithium insertion in ordered mesoporous lithium ferrite thin films

The synthesis and characterization of cubic mesostructured lithium ferrite (α-LiFe5O8) with 20 nm diameter pores and nanocrystalline walls is reported. The material is prepared in the form of thin films by sol–gel dip-coating using a poly(isobutylene)-block-poly(ethylene oxide) amphiphilic diblock copolymer as the porogen. Electron microscopy, X-ray scattering and diffraction, time-of-flight secondary ion mass spectrometry, Raman and X-ray photoelectron spectroscopy all show that α-LiFe5O8 can be templated to produce high-quality films that are chemically and phase-pure and thermally stable to over 600 °C. Magnetometry measurements indicate ferrimagnetic behavior below 300 K, with the coercivity exhibiting a T1/2 dependence. This novel mesoporous spinel material – when used as an electrode in secondary battery cells – can reversibly store charge via topotactic Li insertion, which allows for the intriguing possibility of tuning the magnetization at room temperature in a facile and controlled manner. The general approach is simple and should be applicable to a variety of other magnetic materials that are capable of reacting electrochemically with Li to produce reduced phases