Near-unity coupling efficiency of a quantum emitter to a photonic-crystal waveguide

A quantum emitter efficiently coupled to a nanophotonic waveguide constitutes a promising system for the realization of single-photon transistors, quantum-logic gates based on giant single-photon nonlinearities, and high bit-rate deterministic single-photon sources. The key figure of merit for such devices is the $\beta$-factor, which is the probability for an emitted single photon to be channeled into a desired waveguide mode. We report on the experimental achievement of $\beta = 98.43 \pm 0.04\%$ for a quantum dot coupled to a photonic-crystal waveguide, corresponding to a single-emitter cooperativity of $\eta = 62.7 \pm 1.5$. This constitutes a nearly ideal photon-matter interface where the quantum dot acts effectively as a 1D "artificial" atom, since it interacts almost exclusively with just a single propagating optical mode. The $\beta$-factor is found to be remarkably robust to variations in position and emission wavelength of the quantum dots. Our work demonstrates the extraordinary potential of photonic-crystal waveguides for highly efficient single-photon generation and on-chip photon-photon interaction

Single-photon nonlinear optics with a quantum dot in a waveguide

Strong nonlinear interactions between photons enable logic operations for both classical and quantum-information technology. Unfortunately, nonlinear interactions are usually feeble and therefore all-optical logic gates tend to be inefficient. A quantum emitter deterministically coupled to a propagating mode fundamentally changes the situation, since each photon inevitably interacts with the emitter, and highly correlated many-photon states may be created . Here we show that a single quantum dot in a photonic-crystal waveguide can be utilized as a giant nonlinearity sensitive at the single-photon level. The nonlinear response is revealed from the intensity and quantum statistics of the scattered photons, and contains contributions from an entangled photon-photon bound state. The quantum nonlinearity will find immediate applications for deterministic Bell-state measurements and single-photon transistors and paves the way to scalable waveguide-based photonic quantum-computing architectures

Características e controle da podridão "olho de boi" nas maçãs do sul do Brasil.

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Chronic administration of green tea extract to TRAMP mice induces the collapse of Golgi apparatus in prostate secretory cells and results in alterations of protein post-translational processing.

Considering its long latency, prostate cancer (PCa) represents an ideal target for chemoprevention strategies. Green tea extract (GTE) has been proved to be one of the most promising natural substances capable of inhibiting PCa progression in animal models (transgenic adenocarcinoma of mouse prostate), as well as in humans. However, the cellular targets of the GTE action are mostly unknown. The main objective of this work was to investigate whether the endoplasmic reticulum (ER) and the Golgi apparatus (GA), known to be actively involved in sensing stress stimuli and initiating and propagating cell death signalling, may represent the subcellular targets of GTE action. To this end, 42 TRAMP mice were divided into four experimental groups: groups II and IV, received GTE in tap water (0.3 g/100 ml solution) starting at 8 weeks of age and up to the time of sacrifice. Groups I and III were respective age-matched water-fed controls. The animals were sacrificed after 4 weeks (groups I and II) or 40 weeks of treatment (groups II and IV). We also treated TRAMP-C2 cells with GTE (20 µg/ml for 7 days) to check the expression profile of clusterin (CLU), a protein involved in prostate tumourigenesis, extensively processed through ER-GA before being secreted through the plasma membrane. In vivo we found that chronic administration of GTE in TRAMP mice results in collapse of ER and GA in prostate epithelial cells. Consistently, in vitro we found that the mature, fully processed form of CLU, sCLU, is strongly reduced by GTE treatment in TRAMP-C2 cells. Taking into account the sCLU biogenesis dependence on the ER-GA integrity and the proposed anti-apoptotic role of sCLU, the possibility for GTE to counteract PCa progression by interfering with sCLU biogenesis is suggested

Polar and non-polar organic binder characterization in Pompeian wall paintings: comparison to a simulated painting mimicking an a secco technique.

The use of Fourier transform infrared spectromicroscopy and mass spectrometry (MS) allowed us to characterize the composition of polar and non-polar binders present in sporadic wall paint fragments taken from Pompeii's archaeological excavation. The analyses of the polar and non-polar binder components extracted from paint powder layer showed the presence of amino acids, sugars, and fatty acids but the absence of proteinaceous material. These results are consistent with a water tempera painting mixture composed of pigments, flours, gums, and oils and are in agreement with those obtained from a simulated wall paint sample made for mimicking an ancient "a secco" technique. Notably, for the first time, we report the capability to discriminate by tandem MS the presence of free amino acids in the paint layer

Characterization of pigments and ligands in a wall painting fragment from Liternum archaeological park (Italy).

Spectroscopic and MS techniques were used to characterize the pigments and the composition of polar and nonpolar binders of a stray wall painting fragment from Liternum (Italy) archaeological excavation. X-ray fluorescence and diffraction analysis of the decorations indicated mainly the presence of calcite, quartz, hematite, cinnabar, and cuprorivaite. Infrared spectroscopy, GC coupled to flame-ionization detector, and MS analysis of the polar and nonpolar components extracted from paint layers from three different color regions revealed the presence of free amino acids, sugars, and fatty acids. Interestingly, LC-MS shotgun analysis of the red painting region showed the presence of αS1-casein of buffalo origin. Compared to our previous results from Pompeii's wall paintings, even though the Liternum painting mixture contained also binders of animal origin, the data strongly suggest that in both cases a tempera painting technique was utilized

Structure-based design and synthesis of antiparasitic pyrrolopyrimidines targeting pteridine reductase 1

The treatment of Human African Trypanosomiasis remains a major unmet health need in sub-Saharan Africa. Approaches involving new molecular targets are important and pteridine reductase 1 (PTR1), an enzyme that reduces dihydrobiopterin in Trypanosoma spp. has been identified as a candidate target and it has been shown previously that substituted pyrrolo[2,3-d]pyrimidines are inhibitors of PTR1 from T. brucei (J. Med. Chem. 2010, 53, 221-229). In this study, 61 new pyrrolo[2,3-d]pyrimidines have been prepared, designed with input from new crystal structures of 23 of these compounds complexed with PTR1, and evaluated in screens for enzyme inhibitory activity against PTR1 and in vitro antitrypanosomal activity. 8 compounds were sufficiently active in both screens to take forward to in vivo evaluation. Thus although evidence for trypanocidal activity in a stage I disease model in mice was obtained, the compounds were too toxic to mice for further development

Spin-photon interface and spin-controlled photon switching in a nanobeam waveguide

Access to the electron spin is at the heart of many protocols for integrated and distributed quantum-information processing [1-4]. For instance, interfacing the spin-state of an electron and a photon can be utilized to perform quantum gates between photons [2,5] or to entangle remote spin states [6-9]. Ultimately, a quantum network of entangled spins constitutes a new paradigm in quantum optics [1]. Towards this goal, an integrated spin-photon interface would be a major leap forward. Here we demonstrate an efficient and optically programmable interface between the spin of an electron in a quantum dot and photons in a nanophotonic waveguide. The spin can be deterministically prepared with a fidelity of 96\%. Subsequently the system is used to implement a "single-spin photonic switch", where the spin state of the electron directs the flow of photons through the waveguide. The spin-photon interface may enable on-chip photon-photon gates [2], single-photon transistors [10], and efficient photonic cluster state generation [11]

A IMAGEM EM MOVIMENTO E O ESPAÇO-TEMPO: BILL VIOLA EM MEDITAÇÕES

Esta dissertação engloba, na dimensão interna, filosófica e emocional, as relações entre o espaço e o tempo ou como pontuado muitas vezes, o espaçotempo como elementos constitutivos de trabalhos de arte, assim como busca pesquisar certas problemáticas acerca da percepção da imagem em movimento videográfica/fílmica e da construção de ambientes/instalações pontuais da história da arte. As produções artísticas selecionadas se justificam por sua importância na investigação dos postulados constitutivos essencialmente espaciais e/ou temporais como condição primeira à sua realização. Buscamos assimilar determinadas investigações históricas que expandiram os alargamentos das categorias artísticas com trabalhos que transitam entre-imagens. Outrossim, direcionamos uma importância ao artista estadunidense Bill Viola, das quais as propostas selecionadas para análise trazem no bojo de suas elaborações um desmembramento da pertinência física e conceitual que o postulado espaçotempo pode abarcar. Assim, a pesquisa caminha num espaço-entre, considerando tanto as expectativas que implicam as hibridizações/expansões da compreensão do espaço e do tempo quanto as contradições que podem expor fragmentariamente tal problemática na circunferência entre-campos (como os da imagem estática e imagem em movimento), amalgamando instalação, vídeo, consequentemente videoinstalação e cinema. Palavras-Chave: Imagem em movimento; Espaço-tempo; Videoinstalação; Cinema; Bill Viola

Development of a Providencia stuartii multilocus sequence typing scheme

Introduction: The Providencia genus is assuming greater clinical relevance among infections caused by Enterobacterales also because of its intrinsic and acquired resistance to last-resort antibiotics. However, despite having been known and studied for over 50 years, genomics and taxonomy of the Providencia genus are currently undergoing a deep rearrangement. In this study we aim to outline and characterized the P. stuartii species. Methods: We retrieved from the GenBank database all genomes labelled as Providencia and performed a comprehensive genome-based species definition founded on average nucleotide identity (ANI) and on alignment-free approaches. Results: After defining the genomes assuredly identifiable as P. stuartii, we devised a MultiLocus Sequence Typing (MLST) and a core-genome MLST (cgMLST) schemes, based on 7 and 2,296 loci respectively. Discussion: This work hence provides a framework for understanding the role of P. stuartii and of other members of this genus, which should be considered as emerging multidrug-resistant pathogens