Strong Purcell effect observed in single thick shell CdSe/CdS nanocrystals coupled to localized surface plasmons

High quality factor dielectric cavities designed to a nanoscale accuracy are mostly used to increase the spontaneous emission rate of a single emitter. Here we show that the coupling, at room temperature, between thick shell CdSe/CdS nanocrystals and random metallic films offers a very promising alternative approach. Optical modes confined at the nanoscale induce strong Purcell factors reaching values as high as 60. Moreover the quantum emission properties can be tailored: strong antibunching or radiative biexcitonic cascades can be obtained with high photon collection efficiency and extremely reduced blinking.Comment: 16 pages, 7 figure

Ultrashort pulse laser cutting of glass by controlled fracture propagation

International audienceLaser induced controlled fracture propagation has great potential in cutting brittle materials such as glass or sapphire. In this paper we demonstrate that the use of ultrashort pulse laser sources may be advantageous since it allows to overcome several restrictions of the convenient method

A new model for root growth in soil with macropores

Abstract: Background and aimsThe use of standard dynamic root architecture models to simulate root growth in soil containing macropores failed to reproduce experimentally observed root growth patterns. We thus developed a new, more mechanistic model approach for the simulation of root growth in structured soil. Methods: In our alternative modelling approach, we distinguish between, firstly, the driving force for root growth, which is determined by the orientation of the previous root segment and the influence of gravitropism and, secondly, soil mechanical resistance to root growth. The latter is expressed by its inverse, soil mechanical conductance, and treated similarly to hydraulic conductivity in Darcy’s law. At the presence of macropores, soil mechanical conductance is anisotropic, which leads to a difference between the direction of the driving force and the direction of the root tip movement. Results: The model was tested using data from the literature, at pot scale, at macropore scale, and in a series of simulations where sensitivity to gravity and macropore orientation was evaluated. Conclusions: Qualitative and quantitative comparisons between simulated and experimentally observed root systems showed good agreement, suggesting that the drawn analogy between soil water flow and root growth is a useful one

Helminth-induced IL-4 expands bystander memory CD8(+) T cells for early control of viral infection

Infection with parasitic helminths can imprint the immune system to modulate bystander inflammatory processes. Bystander or virtual memory CD8+ T cells (TVM) are non-conventional T cells displaying memory properties that can be generated through responsiveness to interleukin (IL)-4. However, it is not clear if helminth-induced type 2 immunity functionally affects the TVM compartment. Here, we show that helminths expand CD44hiCD62LhiCXCR3hiCD49dlo TVM cells through direct IL-4 signaling in CD8+ T cells. Importantly, helminth-mediated conditioning of TVM cells provided enhanced control of acute respiratory infection with the murid gammaherpesvirus 4 (MuHV-4). This enhanced control of MuHV-4 infection could further be explained by an increase in antigen-specific CD8+ T cell effector responses in the lung and was directly dependent on IL-4 signaling. These results demonstrate that IL-4 during helminth infection can non-specifically condition CD8+ T cells, leading to a subsequently raised antigen-specific CD8+ T cell activation that enhances control of viral infection

VISUAL DISPLAY DESIGN: A COMPARISON OF TWO METHODOLOGIES

This paper summarizes two methodologies for visual display design belonging to two different activity domains. The first methodology can be used for designing mimic displays in process control situations. The role of mimic displays is to provide operators with the information required for achieving their task under every possible normal and abnormal circumstance. Mimic displays must not only inform operators on the status of the process subsystems, devices or variables but also on their structural and functional interrelations. The second methodology can be used for designing computer screens of business oriented interactive applications. Their role is to present to the user the information required to carry out an interactive task by the way of interaction objects. These objects are ergonomically suited to represent this information. A comparison of the two methodologies highlights some structural intersection in their underlying principles and steps

Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature

International audienceThe fluorescence of single colloidal thick-shell CdSe/CdS nanocrystals (NCs), at cryogenic temperature (4 K) and room temperature (RT), is studied using the intensity autocorrelation function (ACF) and lifetime measurements. The radiative and Auger decay rates corresponding to the desexcitation of the charged biexcitonic state are determined through an original method of photon postselection. Especially, the charged biexciton quantum yield increases from about 15% at RT to 60% at 4 K. The high inhibition of Auger recombination already observed for the trion state of CdSe/CdS NCs at low temperature is also demonstrated for the charged biexcitonic state. At 4 K, the ACF is equal to 1 for time scales ranging from 50 ns to 200 ms. In contrast with RT operation, the intensity of the trion emission is then perfectly stable and no blinking is observed. All the results highlight the strong confinement of the charge carriers in the CdSe core