Liquidity crises on different time scales

We present an empirical analysis of the microstructure of financial markets and, in particular, of the static and dynamic properties of liquidity. We find that on relatively large time scales (15 min) large price fluctuations are connected to the failure of the subtle mechanism of compensation between the flows of market and limit orders: in other words, the missed revelation of the latent order book breaks the dynamical equilibrium between the flows, triggering the large price jumps. On smaller time scales (30 s), instead, the static depletion of the limit order book is an indicator of an intrinsic fragility of the system, which is related to a strongly nonlinear enhancement of the response. In order to quantify this phenomenon we introduce a measure of the liquidity imbalance present in the book and we show that it is correlated to both the sign and the magnitude of the next price movement. These findings provide a quantitative definition of the effective liquidity, which proves to be strongly dependent on the considered time scales

Terahertz dipole nanoantenna arrays: resonance characteristics

Resonant dipole nanoantennas promise to considerably improve the capabilities of terahertz spectroscopy, offering the possibility of increasing its sensitivity through local field enhancement, while in principle allowing unprecedented spatial resolutions, well below the diffraction limit. Here, we investigate the resonance properties of ordered arrays of terahertz dipole nanoantennas, both experimentally and through numerical simulations. We demonstrate the tunability of this type of structures, in a range (∼1–2 THz) that is particularly interesting and accessible by means of standard zinc telluride sources. We additionally study the near-field resonance properties of the arrays, finding that the resonance shift observed between near-field and far-field spectra is predominantly ascribable to ohmic damping

Nonlinear Hall effect as a local probe of plasmonic magnetic hot spots

Recently developed plasmonic nanostructures are able to generate intense and localized magnetic hot spots in a large spectral range from the terahertz to the visible. However, a direct measurement of the magnetic field at the hot spot has not been performed yet, due to the absence of magnetic field detectors that work at those high frequencies and that fit the hot-spot area. We propose to place a graphene ribbon in the hot spot of a plasmonic nanostructure driven by a laser beam, such that a current is generated due to both the magnetic field at the hot spot and the electric field of the laser. We demonstrate that a nonlinear Hall voltage, which can be measured by standard electrical means, builds up across the ribbon, making it possible to directly probe the magnetic field at the hot spot.Comment: 9 pages, 7 figure

The trickle down from environmental innovation to productive complexity

We study the empirical relationship between green technologies and industrial production at very fine-grained levels by employing Economic Complexity techniques. Firstly, we use patent data on green technology domains as a proxy for competitive green innovation and data on exported products as a proxy for competitive industrial production. Secondly, with the aim of observing how green technological development trickles down into industrial production, we build a bipartite directed network linking single green technologies at time t1 to single products at time t2≥t1 on the basis of their time-lagged co-occurrences in the technological and industrial specialization profiles of countries. Thirdly, we filter the links in the network by employing a maximum entropy null-model. Our results emphasize a strong connection between green technologies and the export of products related to the processing of raw materials, notably crucial for the development of climate change mitigation and adaptation technologies. Furthermore, by looking at the evolution of the network over time, we observe a growing presence of more complex green technologies and high-tech products among the significant links, suggesting an increase in their importance in the network

Spatially, Temporally, and Quantitatively Controlled Delivery of Broad Range of Molecules into Selected Cells through Plasmonic Nanotubes

A Universal plasmonic/microfluidic platform for spatial and temporal controlled intracellular delivery is described. The system can inject/transfect the desired amount of molecules with an efficacy close to 100%. Moreover, it is highly scalable from single cells to large ensembles without administering the molecules to an extracellular bath. The latter enables quantitative control over the amount of injected molecules

Extremely large extinction efficiency and field enhancement in terahertz resonant dipole nanoantennas

The distinctive ability of nanometallic structures to manipulate light at the nanoscale has recently promoted their use for a spectacular set of applications in a wide range of areas of research including artificial optical materials, nano-imaging, biosensing, and nonlinear optics. Here we transfer this concept to the terahertz spectral region, demonstrating a metal nanostructure in shape of a dipole nanoantenna, which can efficiently resonate at terahertz frequencies, showing an effective cross section >100 times larger than its geometrical area, and a field enhancement factor of ~280, confined on a lateral section of ~λ/1,000. These results lead to immediate applications in terahertz artificial materials exhibiting giant dichroism, suggest the use of dipole nanoantennas in nanostructure-based terahertz metamaterials, and pave the way for nanoantenna-enhanced terahertz few-molecule spectroscopy and localized terahertz nonlinear optics

Chapter Photonic Crystals for Plasmonics: From Fundamentals to Superhydrophobic Devices

Production engineerin

Photonic Crystals for Plasmonics: From Fundamentals to Superhydrophobic Devices

Production engineerin