High frequency electro-optic measurement of strained silicon racetrack resonators

The observation of the electro-optic effect in strained silicon waveguides has been considered as a direct manifestation of an induced $\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\,pm/V$ to the induced high-speed $\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements

Bell inequality violation by entangled single photon states generated from a laser, a LED or a Halogen lamp

In single-particle or intraparticle entanglement, two degrees of freedom of a single particle, e.g., momentum and polarization of a single photon, are entangled. Single-particle entanglement (SPE) provides a source of non classical correlations which can be exploited both in quantum communication protocols and in experimental tests of noncontextuality based on the Kochen-Specker theorem. Furthermore, SPE is robust under decoherence phenomena. Here, we show that single-particle entangled states of single photons can be produced from attenuated sources of light, even classical ones. To experimentally certify the entanglement, we perform a Bell test, observing a violation of the Clauser, Horne, Shimony and Holt (CHSH) inequality. On the one hand, we show that this entanglement can be achieved even in a classical light beam, provided that first-order coherence is maintained between the degrees of freedom involved in the entanglement. On the other hand, we prove that filtered and attenuated light sources provide a flux of independent SPE photons that, from a statistical point of view, are indistinguishable from those generated by a single photon source. This has important consequences, since it demonstrates that cheap, compact, and low power entangled photon sources can be used for a range of quantum technology applications

Medicamentos e ingestión de alcohol: estudio del almotriptan

Diversos investigadors de l'Hospital Universitari Germans Trias i Pujol i de l'empresa farmacèutica Laboratorios Almirall han dut a terme un estudi per comprovar quin és l'efecte terapèutic de l'almotriptan -un fàrmac utilitzat en el tractament de les crisis de migranya- en relació al consum d'alcohol. Els resultats obtinguts en la recerca indiquen que no és necessari modificar la dosificació del medicament quan s'administra en un pacient en què la crisi de migranya s'ha produït després de la presa d'alcohol.Diversos investigadores del Hospital Universitario Germans Trias i Pujol y de la empresa farmacéutica Laboratorios Almirall han llevado a cabo un estudio para comprobar cuál es el efecto terapéutico del almotriptan - un fármaco utilizado en el tratamiento de las crisis de migraña- en relación al consumo de alcohol. Los resultados obtenidos en la investigación indican que no es necesario modificar la dosificación del medicamento cuando se administra en un paciente en que la crisis de migraña se ha producido después de la ingestión de alcohol

Sustainable cycle-tourism for society: Integrating multi-criteria decision-making and land use approaches for route selection

Cycle tourism is a sustainable active vacation, which is quickly growing in recent years. Although it has several benefits for society and users (e.g., social connections, amusement, and physical and mental health), cycle tourism requires an adequate route network to enjoy destinations with historical and landscape peculiarities. Past literature mainly investigated motivations and preferences for cycle tourists and proposed optimisation methods in planning routes. However, applying assessment methods for prioritising cycle-tourist routes is a seldom-explored topic. This study aims to address this gap by applying an integrated method for evaluating and prioritising cycle routes, searching for a compromise between route characteristics, service provided to users, and natural and building contexts crossed. It jointly includes Multi-Criteria Decision Methods (MCDMs) and a land use approach: AHP determines the weights of criteria and parameters describing cycle routes; GIS elaborates spatial analysis of parameters; ELECTRE I and VIKOR help find a compromise solution amongst different cycle routes. The integrated method involved a panel of experts to collect data, and it is applied to the wide-study area of Franciacorta (Italy). Some comparisons with other MCDMs are made to justify the results. The findings could support multi-institutions prioritising cycle route alternatives in deciding their building

Vacancy complexes in nonequilibrium germanium-tin semiconductors

Understanding the nature and behavior of vacancy-like defects in epitaxial GeSn metastable alloys is crucial to elucidate the structural and optoelectronic properties of these emerging semiconductors. The formation of vacancies and their complexes is expected to be promoted by the relatively low substrate temperature required for the epitaxial growth of GeSn layers with Sn contents significantly above the equilibrium solubility of 1 at.%. These defects can impact both the microstructure and charge carrier lifetime. Herein, to identify the vacancy-related complexes and probe their evolution as a function of Sn content, depth-profiled pulsed low-energy positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy were combined to investigate GeSn epitaxial layers with Sn content in the 6.5-13.0 at.% range. The samples were grown by chemical vapor deposition method at temperatures between 300 and 330 {\deg}C. Regardless of the Sn content, all GeSn samples showed the same depth-dependent increase in the positron annihilation line broadening parameters, which confirmed the presence of open volume defects. The measured average positron lifetimes were the highest (380-395 ps) in the region near the surface and monotonically decrease across the analyzed thickness, but remain above 350 ps. All GeSn layers exhibit lifetimes that are 85 to 110 ps higher than the Ge reference layers. Surprisingly, these lifetimes were found to decrease as Sn content increases in GeSn layers. These measurements indicate that divacancies are the dominant defect in the as-grown GeSn layers. However, their corresponding lifetime was found to be shorter than in epitaxial Ge thus suggesting that the presence of Sn may alter the structure of divacancies. Additionally, GeSn layers were found to also contain a small fraction of vacancy clusters, which become less important as Sn content increases

Monte-Carlo simulations of the recombination dynamics in porous silicon

A simple lattice model describing the recombination dynamics in visible light emitting porous Silicon is presented. In the model, each occupied lattice site represents a Si crystal of nanometer size. The disordered structure of porous Silicon is modeled by modified random percolation networks in two and three dimensions. Both correlated (excitons) and uncorrelated electron-hole pairs have been studied. Radiative and non-radiative processes as well as hopping between nearest neighbor occupied sites are taken into account. By means of extensive Monte-Carlo simulations, we show that the recombination dynamics in porous Silicon is due to a dispersive diffusion of excitons in a disordered arrangement of interconnected Si quantum dots. The simulated luminescence decay for the excitons shows a stretched exponential lineshape while for uncorrelated electron-hole pairs a power law decay is suggested. Our results successfully account for the recombination dynamics recently observed in the experiments. The present model is a prototype for a larger class of models describing diffusion of particles in a complex disordered system.Comment: 33 pages, RevTeX, 19 figures available on request to [email protected]

Factors affecting recurrence risk in her2 positive dcis

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Reconfigurable optical routers based on Coupled Resonator Induced Transparency resonances.

The interferometric coupling of pairs of resonators in a resonator sequence generates coupled ring induced transparency (CRIT) resonances. These have quality factors an order of magnitude greater than those of single resonators. We show that it is possible to engineer CRIT resonances in tapered SCISSOR (Side Coupled Integrated Space Sequence of Resonator) to realize fast and efficient reconfigurable optical switches and routers handling several channels while keeping single channel addressing capabilities. Tapered SCISSORs are fabricated in silicon-on-insulator technology. Furthermore, tapered SCISSORs show multiple-channel switching behavior that can be exploited in DWDM applications