Using optical resonances to control heat generation and propagation in silicon nanostructures

Here we propose a new computational approach to light-to-matter interactions in silicon nanopillars, which simulates heat generation and propagation dynamics occurring in continuous wave laser processing over a wide temporal range (from 1 fs to about 25 hours). We show that visible light can be exploited to selectively crystallize internal region of the pillars, which is not possible by conventional treatments. A detailed study on lattice crystallization and reconstruction dynamics reveals that local heating drives the formation of secondary antennas embedded into the pillars, highlighting the importance of taking into account the spatial and temporal evolution of the optical properties of the material under irradiation. This approach can be easily extended to many types of nanostructured materials and interfaces, offering a unique computational tool for many applications involving optothermal processes.Comment: 21 pages, 4 figure

Motion Control for Autonomous Navigation in Blue and Narrow Waters Using Switched Controllers

Autonomous ships represent one of the new frontiers of technological innovation in marine engineering, which demand the development of innovative control systems to guarantee efficient and safe navigation of vessels. A convenient control system should be able to command the several actuators installed on board in different conditions\u2014for instance, during oceanic navigation, harbor approach, narrow channels, and crowed areas. Such tasks are accomplished by different switching controllers for high and low speed motion, which have to be orchestrated to ensure an effective maneuvering. An approach to the design of hierarchies of controllers for maneuvering and navigation of ships equipped with a standard propulsion configuration in both blue and narrow water is proposed. Different levels of control, from global to local, are defined and integrated to steer the vessel in such a way to increase the maneuvering capability in various scenarios

Malignant ventricular arrhythmias induction by programmed electrical stimulation of the right ventricular outflow tract only during type 1 brugada ECG maximization

OBJECTIVE: The role of electrophysiology study in Brugada syndrome (BS) sudden cardiac death risk stratification remains controversial and seems to depend on the phenotypic expression of the channelopathy. Ajmaline has a key role in the diagnosis of BS. We observed that programmed electrical stimulation (PES) of the right ventricular outflow tract (RVOT), only when type 1 BS ECG is unmasked by ajmaline administration, induces ventricular arrhythmias. CASE REPORT: We describe a case of ventricular fibrillation induction by PES of the RVOT when type 1 BS ECG is revealed by ajmaline, in a patient with a baseline dynamic intermittent type 1 and 2 BS ECG. CONCLUSIONS: The heterogeneous clinical presentations of BS are due to the underlying mechanisms. PES of the RVOT during positive ajmaline test maximizes the channelopathy and therefore sudden cardiac death risk-stratification in BS

The Sensitivity of Simulated River Discharge to Land Surface Representation and Meteorological Forcings

Abstract The discharge of freshwater into oceans represents a fundamental process in the global climate system, and this flux is taken into account in simulations with general circulation models (GCMs). Moreover, the availability of realistic river routing schemes is a powerful instrument to assess the validity of land surface components, which have been recognized to be crucial for the global climate simulation. In this study, surface and subsurface runoff generated by the 13 land surface schemes (LSSs) participating in the Second Global Soil Wetness Project (GSWP-2) are used as input fields for the Hydrology Discharge (HD) routing model to simulate discharge for 30 of the world's largest rivers. The simplest land surface models do not provide a good representation of runoff, and routed river flows using these inputs are affected by many biases. On the other hand, HD shows the best simulations when forced by two of the more sophisticated schemes. The multimodel ensemble GSWP-2 generates the best phasing of the annual cycle as well as a good representation of absolute values, although the ensemble mean tends to smooth the peaks. Finally, the intermodel comparison shows the limits and deficiencies of a velocity-constant routing model such as HD, particularly in the phase of mean annual discharge. The second part of the study assesses the sensitivity of river discharge to the variation of external meteorological forcing. The Center for Ocean–Land–Atmosphere Studies version of the SSiB model is constrained with different meteorological fields and the resulting runoff is used as input for HD. River flow is most sensitive to precipitation variability, but changes in radiative forcing affect discharge as well, presumably because of the interaction with evaporation. Also, this analysis provides an estimate of the sensitivity of river discharge to precipitation variations. A few areas (e.g., central and eastern Asia, the Mediterranean, and much of the United States) show a magnified response of river discharge to a given percentage change in precipitation. Hence, an amplified effect of droughts as indicated by the consensus of climate change predictions may occur in places such as the Mediterranean. Conversely, increasing summer precipitation foreseen in places like southern and eastern Asia may amplify floods in these poor and heavily populated regions. Globally, a 1% fluctuation in precipitation forcing results in an average 2.3% change in discharge. These results can be used for the definition and assessment of new strategies for land use and water management in the near future