Thermally-Reconfigurable Quantum Photonic Circuits at Telecom Wavelength by Femtosecond Laser Micromachining

The importance of integrated quantum photonics in the telecom band resides on the possibility of interfacing with the optical network infrastructure developed for classical communications. In this framework, femtosecond laser written integrated photonic circuits, already assessed for quantum information experiments in the 800 nm wavelength range, have great potentials. In fact these circuits, written in glass, can be perfectly mode-matched at telecom wavelength to the in/out coupling fibers, which is a key requirement for a low-loss processing node in future quantum optical networks. In addition, for several applications quantum photonic devices will also need to be dynamically reconfigurable. Here we experimentally demonstrate the high performance of femtosecond laser written photonic circuits for quantum experiments in the telecom band and we show the use of thermal shifters, also fabricated by the same femtosecond laser, to accurately tune them. State-of-the-art manipulation of single and two-photon states is demonstrated, with fringe visibilities greater than 95%. This opens the way to the realization of reconfigurable quantum photonic circuits on this technological platform

The Abundance Scatter in M33 from HII Regions: Is There Any Evidence for Azimuthal Metallicity Variations?

Optical spectra of 25 H II regions in the inner two kpc of the M33 disk have been obtained with the GMOS spectrograph at the Gemini North telescope. The oxygen abundance gradient measured from the detection of the [O III]4363 auroral line displays a scatter of approximately 0.06 dex, a much smaller value than recently reported by Rosolowsky & Simon in this galaxy. The analysis of the abundances for a large sample of H II regions derived from the R23 strong-line indicator confirms that the scatter is small over the full disk of M33, consistent with the measuring uncertainties, and comparable to what is observed in other spiral galaxies. No evidence is therefore found for significant azimuthal variations in the present-day metallicity of the interstellar medium in this galaxy on spatial scales from ~100 pc to a few kpc. A considerable fraction of M33 H II regions with auroral line detections show spectral features revealing sources of hard ionizing radiation (such as He II emission and large [Ne III], [O III] line fluxes). Since R23 is shown to severely underestimate the oxygen abundances in such cases, care must be taken in chemical abundance studies of extragalactic H II regions based on this strong-line indicator.Comment: 9 pages, accepted for publication in the Astrophysical Journa

Adaptation and Evolution in a Gravitational Environment — A Theoretical Framework for the Limited Re-Generative Post- Natal Time Window of the Heart in Higher Vertebrates

In the complex interplay between organization of the living matter, natural selection and adaptation, mammals have evolved with limited or no re-generative capabilities of the heart after birth. The reasons for this apparent flaw is far from being understood, however, they are closely related to the concept of organization and allocation of resources in a hierarchically structured multi-cellular organism with an evolved system of transport and communication, such as the circulation of blood. In humans this flaw may not have been a problem for thousands of years until, in the twentieth century, the increase in life expectancy has given rise to diseases generally less frequent in the first three or four decades of life. Therefore, the significant increase in morbidity and mortality related to cardiovascular disease, seen mainly in Western countries in the last years, has brought to the foreground the problem of cardiac damage and of its repair. In order to develop new therapies for cardiovascular damage aimed at reawakening and, possibly, expanding the limited re-generative capabilities of the heart is necessary to reconsider the basic concept on adaptation and functional reserve allocation in complex organisms

Assessing the Impact of Agricultural Research: Data Requirements and Quality of Current Statistics in Europe

Assessing the impact of agricultural research on sustainability targets often implies to face two main issues: the complexity of the causal path, and the lack of appropriate data. In this paper, we discuss which data would be necessary to measure short- and long-term impacts in Europe, and suggest a set of indicators to evaluate their quality, exploiting both available metadata (qualitative indicator) and the evidence stemming from the data themselves (quantitative indicator based on missing values, temporal contiguity and outliers). An application is shown for a subset of variables. According to our results, qualitative and quantitative indicators often provide conflicting information

Assessing the impact of agricultural research: Data requirements and quality of current statistics in Europe

Assessing the impact of agricultural research on sustainability targets often implies to face two main issues: the complexity of the causal path, and the lack of appropriate data. In this paper, we discuss which data would be necessary to measure short- and long-term impacts in Europe, and suggest a set of indicators to evaluate their quality, exploiting both available metadata (qualitative indicator) and the evidence stemming from the data themselves (quantitative indicator based on missing values, temporal contiguity and outliers). An application is shown for a subset of variables. According to our results, qualitative and quantitative indicators often provide conflicting information

Earthquake characteristics and structural properties of the Southern Tyrrhenian basin from full seismic wave simulations

Modelling the response of seismic wavefields to sharp lateral variations in crustal discontinuities is essential for seismic tomography application and path effects correction in earthquake source characterization. This is particularly relevant when wavefields cross back-arc oceanic basins, i.e. mixed continental-oceanic settings. High-frequency (>0.05 Hz) seismic waves resonate and get absorbed across these settings due to a shallow Moho, crustal heterogeneities, and energy leakage. Here, we provide the first high-frequency wave-equation model of full seismograms propagating through realistic 3D back-arc basins. Inversion by parameters trial based on correlation analyses identifies P-, S- and coda-wave as attributes able to estimate jointly 3D Moho variations, sediment thickness, and earthquake source characteristics using data from a single regional earthquake. We use as data waveforms produced by the Accumoli earthquake (Central Italy, 2016), propagating across the Southern Tyrrhenian basin and recorded across Southern Italy. The best model comprises a deep Moho (∼ 18 km) in the middle of the basin and a crustal pinch with the continental crust in Sicily. The deep Moho corresponds to the Issel Bridge, a portion of continental crust trapped between the Vavilov and Marsili volcanic centres. The Accumoli earthquake is optimally described at a depth of 7.3 km using a boxcar with rise time of 6 s. Our results show that the early S-wave coda comprises trapped and reverberating phases sensitive to crustal interfaces. Forward modelling these waves is computationally expensive; however, adding these attributes to tomographic procedures allows modelling both source and structural parameters across oceanic basins