A compact ultranarrow high-power laser system for experiments with 578nm Ytterbium clock transition

In this paper we present the realization of a compact, high-power laser system able to excite the Ytterbium clock transition at 578 nm. Starting from an external-cavity laser based on a quantum dot chip at 1156 nm with an intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of visible light at 578 nm via frequency doubling. The laser is locked with a 500 kHz bandwidth to a ultra-low-expansion glass cavity stabilized at its zero coefficient of thermal expansion temperature through an original thermal insulation and correction system. This laser allowed the observation of the clock transition in fermionic $^{173}$Yb with a < 50 Hz linewidth over 5 minutes, limited only by a residual frequency drift of some 0.1 Hz/s

SIRENE: A Spatial Data Infrastructure to Enhance Communities' Resilience to Disaster-Related Emergency

Abstract Planning in advance to prepare for and respond to a natural hazard-induced disaster-related emergency is a key action that allows decision makers to mitigate unexpected impacts and potential damage. To further this aim, a collaborative, modular, and information and communications technology-based Spatial Data Infrastructure (SDI) called SIRENE—Sistema Informativo per la Preparazione e la Risposta alle Emergenze (Information System for Emergency Preparedness and Response) is designed and implemented to access and share, over the Internet, relevant multisource and distributed geospatial data to support decision makers in reducing disaster risks. SIRENE flexibly searches and retrieves strategic information from local and/or remote repositories to cope with different emergency phases. The system collects, queries, and analyzes geographic information provided voluntarily by observers directly in the field (volunteered geographic information (VGI) reports) to identify potentially critical environmental conditions. SIRENE can visualize and cross-validate institutional and research-based data against VGI reports, as well as provide disaster managers with a decision support system able to suggest the mode and timing of intervention, before and in the aftermath of different types of emergencies, on the basis of the available information and in agreement with the laws in force at the national and regional levels. Testing installations of SIRENE have been deployed in 18 hilly or mountain municipalities (12 located in the Italian Central Alps of northern Italy, and six in the Umbria region of central Italy), which have been affected by natural hazard-induced disasters over the past years (landslides, debris flows, floods, and wildfire) and experienced significant social and economic losses

Hyperferritinemia and diagnosis of type 1 Gaucher disease

Given the difficulties in diagnosis of type 1 GD in adults because of disease heterogeneity and lack of awareness, appropriate diagnostic algorithms or flow-charts starting from non-specific findings may help. Case reports help to establish the usefulness of our proposed flowchart in patients presenting with \u201cunexplained hyperferritinemia\u201d

On the Dynamic RON, Vertical Leakage and Capacitance Behavior in pGaN HEMTs With Heavily Carbon-Doped Buffers

In this letter, we investigate the effect of Carbon (C) doping concentration on dynamic RON, vertical leakage and Capacitance-Voltage (C-V) characteristics of p-GaN gate High Electron Mobility Transistors (HEMTs). Measurements performed on state-of-the-art samples show that further increasing C-doping concentration in the GaN buffer above 1019 cm−3 yields a reduced dynamic-RON degradation, in contrast with the behavior reported in the literature for lower C-doping concentrations. This is confirmed by a complete data set showing a consistent increase in the vertical leakage and in the output capacitance while increasing the C doping, stemming from a less insulating buffer and a reduced 2-DEG depletion, respectively. These observations can be attributed to an increased incorporation of compensating donors leading to a reduction of the net acceptors as the C doping concentration is raised above 1019 cm−3

Measuring absolute frequencies beyond the GPS limit via long-haul optical frequency dissemination

Global Positioning System (GPS) dissemination of frequency standards is ubiquitous at present, providing the most widespread time and frequency reference for the majority of industrial and research applications worldwide. On the other hand, the ultimate limits of the GPS presently curb further advances in high-precision, scientific and industrial applications relying on this dissemination scheme. Here, we demonstrate that these limits can be reliably overcome even in laboratories without a local atomic clock by replacing the GPS with a 642-km-long optical fiber link to a remote primary caesium frequency standard. Through this configuration we stably address the 1S0—3P0 clock transition in an ultracold gas of 173Yb, with a precision that exceeds the possibilities of a GPS-based measurement, dismissing the need for a local clock infrastructure to perform beyond-GPS high-precision tasks. We also report an improvement of two orders of magnitude in the accuracy on the transition frequency reported in literature