34 research outputs found
Interaction and coherence of a plasmon-exciton polariton condensate
Polaritons are quasiparticles arising from the strong coupling of
electromagnetic waves in cavities and dipolar oscillations in a material
medium. In this framework, localized surface plasmon in metallic nanoparticles
defining optical nanocavities have attracted increasing interests in the last
decade. This interest results from their sub-diffraction mode volume, which
offers access to extremely high photonic densities by exploiting strong
scattering cross-sections. However, high absorption losses in metals have
hindered the observation of collective coherent phenomena, such as
condensation. In this work we demonstrate the formation of a non-equilibrium
room temperature plasmon-exciton-polariton condensate with a long range spatial
coherence, extending a hundred of microns, well over the excitation area, by
coupling Frenkel excitons in organic molecules to a multipolar mode in a
lattice of plasmonic nanoparticles. Time-resolved experiments evidence the
picosecond dynamics of the condensate and a sizeable blueshift, thus measuring
for the first time the effect of polariton interactions in plasmonic cavities.
Our results pave the way to the observation of room temperature superfluidity
and novel nonlinear phenomena in plasmonic systems, challenging the common
belief that absorption losses in metals prevent the realization of macroscopic
quantum states.Comment: 23 pages, 5 figures, SI 7 pages, 5 figure
Room temperature polariton condensation from Whispering gallery modes in CsPbBr3 microplatelets
Room temperature (RT) polariton condensate holds exceptional promise for
revolutionizing various fields of science and technology, encompassing
optoelectronics devices to quantum information processing. Using perovskite
materials like all-inorganic CsPbBr3 single crystal provides additional
advantages, such as ease of synthesis, cost-effectiveness, and compatibility
with existing semiconductor technologies. In this work, we show the formation
of whispering gallery modes (WGM) in CsPbBr3 single crystals with controlled
geometry, synthesized using a lowcost and efficient capillary bridge method.
Through the implementation of microplatelets geometry, we achieve enhanced
optical properties and performance thanks to the presence of sharp edges and a
uniform surface, effectively avoiding non-radiative scattering losses caused by
defects. This allows us not only to observe strong light matter coupling and
formation of whispering gallery polaritons, but also to demonstrate the onset
of polariton condensation at RT. This investigation not only contributes to the
advancement of our knowledge concerning the exceptional optical properties of
perovskite-based polariton systems, but also unveils prospects for the
exploration of WGM polariton condensation within the framework of a 3D
perovskite-based platform, working at RT. The unique characteristics of
polariton condensate, including low excitation thresholds and ultrafast
dynamics, open up unique opportunities for advancements in photonics and
optoelectronics devices
Engineering Dion-Jacobson Perovskites in Polariton Waveguides
Hybrid two-dimensional perovskites hold considerable promise as
semiconductors for a wide range of optoelectronic applications. Many efforts
are addressed to exploit the potential of these materials by tailoring their
characteristics. In this work, the optical properties and electronic band
structure in three new Dion-Jacobson (DJ) perovskites (PVKs) are engineered by
modulating their structural distortion. Two different interlayer cations: 1-6,
Hexamethylendiammonium, HE, and 3-(Dimethylamino)-1-propylammonium, DMPA, have
been selected to investigate the role of the cation length and the ammonium
binding group on the crystalline structure. This study provides new insights
into the understanding of the structure-property relationship in DJ perovskites
and demonstrates that exciton characteristics can be easily modulated with the
judicious design of the organic cations. DJ PVKs developed in this work were
also grown as size-controlled single crystal microwires through a
microfluidic-assisted synthesis technique and integrated in a nanophotonic
device. The DJ PVK microwire acts as a waveguide exhibiting strong light-matter
coupling between the crystal optical modes and DJ PVK exciton. Through the
investigation of these polariton waveguides, the nature of the double peak
emission, which is often observed in these materials and whose nature is
largely debated in the literature, is demonstrated originating from the hybrid
polariton state
VID22 counteracts G-quadruplex-induced genome instability
Genome instability is a condition characterized by the accumulation of genetic alterations and is a hallmark of cancer cells. To uncover new genes and cellular pathways affecting endogenous DNA damage and genome integrity, we exploited a Synthetic Genetic Array (SGA)-based screen in yeast. Among the positive genes, we identified VID22, reported to be involved in DNA double-strand break repair. vid22Δ cells exhibit increased levels of endogenous DNA damage, chronic DNA damage response activation and accumulate DNA aberrations in sequences displaying high probabilities of forming G-quadruplexes (G4-DNA). If not resolved, these DNA secondary structures can block the progression of both DNA and RNA polymerases and correlate with chromosome fragile sites. Vid22 binds to and protects DNA at G4-containing regions both in vitro and in vivo. Loss of VID22 causes an increase in gross chromosomal rearrangement (GCR) events dependent on G-quadruplex forming sequences. Moreover, the absence of Vid22 causes defects in the correct maintenance of G4-DNA rich elements, such as telomeres and mtDNA, and hypersensitivity to the G4-stabilizing ligand TMPyP4. We thus propose that Vid22 is directly involved in genome integrity maintenance as a novel regulator of G4 metabolism.Associazione Italiana per la Ricerca sul Cancro (AIRC) [15631, 21806 to M.M.F.]; MIUR [PRIN 2015-2015SJLMB9; PRIN 2017-2017KSZZJW to M.M.F.]; Telethon [GGP15227 to M.M.F.]; F.L. was supported by the University of Milano: ‘‘Piano di Sviluppo dell’Ateneo per la Ricerca. Linea B: Supporto per i Giovani Ricercatori’’; M.C.B. was supported by Fondazione Veronesi; Research at the laboratory of A.A. was funded by the Spanish Ministry of Economy and Competitiveness [BFU2016-75058-P]; B.G.G. was funded by the Spanish Association Against Cancer; MIUR [PRIN2017-2017Z55KC to T.B.]; M.C., D.S.H. are supported by MIUR [PRIN 2017] and CNRbiomics [PIR01_00017]; H2020 Projects ELIXIR-EXCELERATE, EOSC-Life, EOSC-Pillar and Elixir-IIB; G.W.B. was supported by the Canadian Institutes of Health Research[FDN-159913]. Funding for open access charge: Associazione Italiana per la Ricerca sul Cancro (AIRC) [21806]
Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis
We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation
Memory based automatic music transcription system for percussive pitched instruments
ABSTRACT The target of our work dealt with the problem of extracting musical content or a symbolic representation of musical notes, commonly called musical score, from audio data of polyphonic music of percussive pitched instruments. We focuses on note events and their main characteristics: the onset (note attack instant) and the pitch (note name). Signal processing techniques based on the Constant-Q Transform (CQT) are used to create a time-frequency representation of the signal. The onset detection algorithm operates on a frame-by-frame basis and exploits a suitable time-frequency representation of the audio signal. The solution proposed consists of an onset detection algorithm based on Short-Time Fourier Transform (STFT), and a classification algorithm based on Support Vector Machine (SVM) to identify the note pitch. We introduce a memory based feature vector for classification. Moreover, to ascertain the effect of the memory, we evaluated the accuracy of the corresponding memoryless system. Finally, to validate our method, we present a collection of experiments using a wide number of musical pieces of heterogeneous styles, involving recordings of polyphonic music of three percussive pitched musical instruments
La responsabilit\ue0 sociale delle PMI distrettuali
Negli ultimi anni l\u2019interesse per le iniziative di CSR da parte delle PMI \ue8 cresciuto in modo considerevole. La rilevanza che la CSR sembra aver assunto anche per le PMI ha portato in primo piano il tema dei fattori che spingono queste imprese ad essere \u201csocialmente responsabili\u201d. In particolare, la ricerca in questo campo affronta due questioni: da un lato, l\u2019analisi delle caratteristiche dell\u2019imprenditore e dei fattori firm-specific che favoriscono l\u2019adozione di politiche di CSR; dall\u2019altro, il ruolo di attori e condizioni esterne all\u2019impresa nello sviluppo di queste iniziative. E\u2019 a questo secondo aspetto che si fa riferimento nel presente capitolo, nel quale si mette in evidenza, anche attraverso casi empirici, come i fattori di contesto, quali l\u2019appartenenza ad un determinato ambito produttivo o territoriale, possano agire da spinta per l\u2019adozione di pratiche di CSR
Interaction and coherence of a plasmon-exciton polariton condensate
\u3cp\u3ePolaritons are quasiparticles arising from the strong coupling of electromagnetic waves in cavities and dipolar oscillations in a material medium. In this framework, localized surface plasmon in metallic nanoparticles defining optical nanocavities have attracted increasing interests in the past decade. This interest results from their sub-diffraction mode volume, which offers access to extremely high photonic densities by exploiting strong scattering cross sections. However, high absorption losses in metals have hindered the observation of collective coherent phenomena, such as condensation. In this work, we demonstrate the formation of a nonequilibrium room temperature plasmon-exciton-polariton condensate with a long-range spatial coherence, extending a hundred of microns, well over the excitation area, by coupling Frenkel excitons in organic molecules to a multipolar mode in a lattice of plasmonic nanoparticles. Time-resolved experiments evidence the picosecond dynamics of the condensate and a sizable blueshift, thus measuring for the first time the effect of polariton interactions in plasmonic cavities. Our results pave the way to the observation of room temperature superfluidity and novel nonlinear phenomena in plasmonic systems, challenging the common belief that absorption losses in metals prevent the realization of macroscopic quantum states.\u3c/p\u3