492 research outputs found
A stochastic estimated version of the Italian dynamic General Equilibrium Model (IGEM)
We estimate with Bayesian techniques the Italian dynamic General Equilibrium Model (IGEM), which has been developed at the Italian Treasury Department, Ministry of Economy and Finance, to assess the effects of alter-native policy interventions. We analyze and discuss the estimated effects of various shocks on the Italian economy. Compared to the calibrated version used for policy analysis, we find a lower wage rigidity and higher adjustment costs. The degree of prices and wages indexation to past inflation is much smaller than the indexation level assumed in the calibrated model. No substantial difference is found in the estimated monetary parameters. Estimated fiscal multipliers are slightly smaller than those obtained from the calibrated version of the model
Photonic Jets and Single‐Photon Emitters
Photonic jets (PJs) obtained by illuminating a dielectric microsphere have recently shown to provide an efficient and cost-effective means of laser-writing and localizing single-photon emitters with sub-diffraction precision. The fabrication technique relies on the photoinduced formation of GaAsN quantum dots (QDs) that are self-aligned to the microsphere, which in turn enhances the collection efficiency of their emission. Similarly, the angular magnification introduced by a microsphere placed on top of two close emitters allows to detect and resolve their separation below the diffraction limit by analyzing their angular emission pattern in momentum space. Along with a brief review of the two methods, a systematic numerical study on the formation and properties of PJs to streamline the optimization of the fabrication process is presented
Site-Controlled Quantum Emitters in Dilute Nitrides and their Integration in Photonic Crystal Cavities
We review an innovative approach for the fabrication of site-controlled quantum emitters (i.e., single-photon emitting quantum dots) based on the spatially selective incorporation and/or removal of hydrogen in dilute nitride semiconductors (e.g., GaAsN). In such systems, the formation of stable N-H complexes removes the effects that nitrogen has on the alloy properties, thus enabling the in-plane engineering of the band bap energy of the system. Both a lithographic approach and/or a near-field optical illumination—coupled to the ultra-sharp diffusion profile of H in dilute nitrides—allow us to control the hydrogen implantation and/or removal on a nanometer scale. This, eventually, makes it possible to fabricate site-controlled quantum dots that are able to emit single photons on demand. The strategy for a deterministic spatial and spectral coupling of such quantum emitters with photonic crystal cavities is also presented
MISSEL: a method to identify a large number of small species-specific genomic subsequences and its application to viruses classification
Continuous improvements in next generation sequencing technologies led to ever-increasing collections of genomic sequences, which have not been easily characterized by biologists, and whose analysis requires huge computational effort. The classification of species emerged as one of the main applications of DNA analysis and has been addressed with several approaches, e.g., multiple alignments-, phylogenetic trees-, statistical- and character-based methods
Imaging the Quantum Capacitance of Strained MoS2 Monolayers by Electrostatic Force Microscopy
We implemented radio frequency-assisted electrostatic force microscopy
(RF-EFM) to investigate the electric field response of biaxially strained
molybdenum disulfide (MoS2) monolayers (MLs) in the form of mesoscopic bubbles,
produced via hydrogen (H)-ion irradiation of the bulk crystal. MoS2 ML, a
semiconducting transition metal dichalcogenide, has recently attracted
significant attention due to its promising optoelectronic properties, further
tunable by strain. Here, we take advantage of the RF excitation to distinguish
the intrinsic quantum capacitance of the strained ML from that due to atomic
scale defects, presumably sulfur vacancies or H-passivated sulfur vacancies. In
fact, at frequencies fRF larger than the inverse defect trapping time, the
defect contribution to the total capacitance and to transport is negligible.
Using RF-EFM at fRF = 300 MHz, we visualize simultaneously the bubble
topography and its quantum capacitance. Our finite-frequency capacitance
imaging technique is non-invasive and nanoscale, and can contribute to the
investigation of time and spatial-dependent phenomena, such as the electron
compressibility in quantum materials, which are difficult to measure by other
methods
Wnt/beta-catenin signaling controls development of the blood–brain barrier
The blood–brain barrier (BBB) is confined to the endothelium of brain capillaries and is indispensable for fluid homeostasis and neuronal function. In this study, we show that endothelial Wnt/beta-catenin (beta-cat) signaling regulates induction and maintenance of BBB characteristics during embryonic and postnatal development. Endothelial specific stabilization of beta-cat in vivo enhances barrier maturation, whereas inactivation of beta-cat causes significant down-regulation of claudin3 (Cldn3), up-regulation of plamalemma vesicle-associated protein, and BBB breakdown. Stabilization of beta-cat in primary brain endothelial cells (ECs) in vitro by N-terminal truncation or Wnt3a treatment increases Cldn3 expression, BBB-type tight junction formation, and a BBB characteristic gene signature. Loss of beta-cat or inhibition of its signaling abrogates this effect. Furthermore, stabilization of beta-cat also increased Cldn3 and barrier properties in nonbrain-derived ECs. These findings may open new therapeutic avenues to modulate endothelial barrier function and to limit the devastating effects of BBB breakdown
Proton-driven patterning of bulk transition metal dichalcogenides
At the few-atom-thick limit, transition metal dichalcogenides (TMDs) exhibit
a host of attractive electronic optical, and structural properties. The
possibility to pattern these properties has a great impact on applied and
fundamental research. Here, we demonstrate spatial control over the light
emission, lattice deformation, and hydrogen storage in bulk TMDs. By low-energy
proton irradiation, we create uniquely favorable conditions for the production
and accumulation of molecular hydrogen just one or few monolayers beneath the
crystal basal plane of bulk WS2, WSe2, WTe2, MoSe2, and MoS2 samples. H2
therein produced coalesces to form bubbles, which lead to the localized
swelling of one X-M-X plane prevalently. This results eventually in the
creation of atomically thin domes filled with molecular hydrogen at 10 atm. The
domes emit light strongly well above room temperature and can store H2
indefinitely. They can be produced with the desired density, well-ordered
positions, and size tunable from the nanometer to the micrometer scale, thus
providing a template for the manageable and durable mechanical and electronic
structuring of two-dimensional materials
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