Flooding of Piazza San Marco (Venice): Physical model tests to evaluate the overtopping discharge

This paper aims at evaluating the wave overtopping discharge over the pavement of "Piazza S. Marco" (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the "Basilica S. Marco". In fact, the MO.S.E. (MOdulo Sperimentale Elettromeccanico) system is designed to keep the water level below a certain value, for the safety of the lagoon, but it does not guarantee the defence of the Piazza, where flooding is still possible, being its pavement locally much lower than the maximum expected water level. To completely defend the Piazza, specific additional works are planned to prevent the back-flow through the natural drainage system (now the primary pathway) or by filtration or by overtopping. This paper investigates on the overtopping mechanism, under conditions compatible with a fully operational MO.S.E. system, through 2-D experiments. The pavement of the Piazza is gently sloping towards the masonry quay which, in some parts is formed by 5 descending steps, and in some other parts, is just a vertical wall. Close to the "Marciana" Library, a critical part is present, with a slightly lower crest freeboard. In total, three cross-sections were examined in the 36 m long wave flume of the Padova University. The test programme includes 10 irregular wave attacks and three different water levels. The test results differ considerably from the results of the available formulas, since the investigated cross-sections by far exceed their range of applicability. The presence of the steps affects only the reflection coefficient rather than the overtopping discharges. In general, if the waves incident to the Piazza are higher than 40 cm, which is a possible scenario, some other adaptation works must be considered, such as the pavement rise, temporary barriers or the reduction of the waves impacting the quay through, for instance, floating breakwaters

Variáveis morfológicas na produção de mudas de Allophylus edulis (St Hil.) Radl. (vacum) em diferentes substratos.

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Características físicas de substratos para produção de mudas de Allophylus edulis (ST Hil.) Radl. e Schinus terebinthifolius.

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Efficient second harmonic generation from thin films of V-shaped benzo[b]thiophene based molecules

We have designed an original approach for efficient Second Harmonic Generation of tailored V-shape benzo[b]thiophene molecular systems enabling versatile and flexible one-step, dry and technologically friendly thin film processing. The designed moieties show χ(2) values at least as high as the reference LiNbO3 single crystal, without poling processing and matching the constrains of integrated optical configuration for nonlinear optical devices. This may open the way to a new class of organic materials exploitable for photonic applications

Advertising exposure for a seasonal good in a segmented market

ISSN: 2239-273

Amplified spontaneous emission and efficient tunable laser emission from a substituted thiophene-based oligomer

We investigated gain and lasing in spin-coated films of a soluble substituted oligothiophene. With increasing excitation power, the photoluminescence spectra show a clear line narrowing due to amplified spontaneous emission. We measure a low threshold (20 μJ cm−2) for line narrowing and a large gain cross section (6×10−16 cm2), indicating that this molecule is a promising active material for organic solid-state lasers. As a demonstrator, we realize a transverse electromagnetic (TEM00) single-mode laser with tunable emission from the yellow to the red (a range of 37 nm), with a pump threshold as low as 18 μJ cm−2 and efficiency of 1.9%. These results are among the best so far reported for organic lasers

New light-emitting functionalized oligothiophenes

We present a new class of highly photo and electroluminescent oligomers based on the presence of one inner thienyl-S,S-dioxide unit as the luminophore. The light emission frequency of the new compounds, which are characterized by greater electron affinities than the corresponding oligomers bearing an unmodified thienyl ring, was tuned over the entire visible range by changing the nature of the alkyl or aryl groups attached in the α- and/or in the β-positions of the thienyl-S,S-dioxide moiety. A few aspects of the solid state supramolecular organization of the new compounds are reported

Subcortical-cortical dynamical states of the human brain and their breakdown in stroke

The mechanisms controlling dynamical patterns in spontaneous brain activity are poorly understood. Here, we provide evidence that cortical dynamics in the ultra-slow frequency range (\u3c0.01-0.1 Hz) requires intact cortical-subcortical communication. Using functional magnetic resonance imaging (fMRI) at rest, we identify Dynamic Functional States (DFSs), transient but recurrent clusters of cortical and subcortical regions synchronizing at ultra-slow frequencies. We observe that shifts in cortical clusters are temporally coincident with shifts in subcortical clusters, with cortical regions flexibly synchronizing with either limbic regions (hippocampus/amygdala), or subcortical nuclei (thalamus/basal ganglia). Focal lesions induced by stroke, especially those damaging white matter connections between basal ganglia/thalamus and cortex, provoke anomalies in the fraction times, dwell times, and transitions between DFSs, causing a bias toward abnormal network integration. Dynamical anomalies observed 2 weeks after stroke recover in time and contribute to explaining neurological impairment and long-term outcome

Bicolor Pixels from a Single Active Molecular Material by Surface-Tension-Driven Deposition†

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