Waveguide-coupled single collective excitation of atomic arrays

Considerable efforts have been recently devoted to combining ultracold atoms and nanophotonic devices to obtain not only better scalability and figures of merit than in free-space implementations, but also new paradigms for atom-photon interactions. Dielectric waveguides offer a promising platform for such integration because they enable tight transverse confinement of the propagating light, strong photon-atom coupling in single-pass configurations and potentially long-range atom-atom interactions mediated by the guided photons. However, the preparation of non-classical quantum states in such atom-waveguide interfaces has not yet been realized. Here, by using arrays of individual caesium atoms trapped along an optical nanofibre, we observe a single collective atomic excitation coupled to a nanoscale waveguide. The stored collective entangled state can be efficiently read out with an external laser pulse, leading to on-demand emission of a single photon into the guided mode. We characterize the emitted single photon via the suppression of the two-photon component and confirm the single character of the atomic excitation, which can be retrieved with an efficiency of about 25%. Our results demonstrate a capability that is essential for the emerging field of waveguide quantum electrodynamics, with applications to quantum networking, quantum nonlinear optics and quantum many-body physics

Extracellular calcium antagonizes forskolin-induced aquaporin 2 trafficking in collecting duct cells

BACKGROUND: Urinary concentrating defects and polyuria are the most important renal manifestations of hypercalcemia and the resulting hypercalciuria. In this study, we tested the hypothesis that hypercalciuria-associated polyuria in kidney collecting duct occurs through an impairment of the vasopressin-dependent aquaporin 2 (AQP2) water channel targeting to the apical membrane possibly involving calcium-sensing receptor (CaR) signaling. METHODS: AQP2-transfected collecting duct CD8 cells were used as experimental model. Quantitation of cell surface AQP2 immunoreactivity was performed using an antibody recognizing the extracellular AQP2 C loop. Intracellular cyclic adenosine monophosphate (cAMP) accumulation was measured in CD8 cells using a cAMP enzyme immunoassay kit. To study the translocation of protein kinase C (PKC), membranes or cytosol fractions from CD8 cells were subjected to Western blotting using anti-PKC isozymes antibodies. The amount of F-actin was determined by spectrofluorometric techniques. Intracellular calcium measurements were performed by spectrofluorometric analysis with Fura-2/AM. RESULTS: We demonstrated that extracellular calcium (Ca2+ o) (5 mmol/L) strongly inhibited forskolin-stimulated increase in AQP2 expression in the apical plasma membrane. At least three intracellular pathways activated by extracellular calcium were found to contribute to this effect. Firstly, the increase in cAMP levels in response to forskolin stimulation was drastically reduced in cells pretreated with Ca2+ o compared to untreated cells. Second, Ca2+ o activated PKC, known to counteract vasopressin response. Third, quantification of F-actin demonstrated that Ca2+ o caused a nearly twofold increase in F-actin content compared with basal conditions. All these effects were mimicked by a nonmembrane permeable agonist of the extracellular CaR, Gd3+. CONCLUSION: Together, these data demonstrate that extracellular calcium, possibly acting through the endogenous CaR, antagonizes forskolin-induced AQP2 translocation to the apical plasma membrane in CD8 cells. In hypercalciuria, this mechanism might blunt water reabsorption and prevent further calcium concentration, thus protecting against a potential risk of urinary calcium-containing stone formation

Un cadre méthodologique pour évaluer l'équivalence entre pertes et gains de biodiversité induits par les projets d'aménagement et leurs mesures compensatoires

In France, the Mitigation hierarchy aims to achieve the "no net loss" (NNL) of biodiversity at the development projects scale. One of the key issues to achieve this goal is to demonstrate the ecological equivalence between the gains associated with offsets and the losses caused by the impacts. Despite regulatory improvements, the French law does not include a method to follow for determining equivalence, and none is unanimously recognized. This leads to heterogeneous practices and difficulty in reaching the NNL. In this context, we have developed a methodological framework for assessing equivalence adapted to the French regulatory and ecological context and combining three challenges: operationality, scientific basis and comprehensiveness. This methodological framework makes it possible 1 / to evaluate the biodiversity found on impacted and compensating sites by taking into account ordinary biodiversity and the one of interest, with a focus on functionalities; 2 / to estimate the value of the indicators after impact and MC, in the short and long term, taking into account associated uncertainties; and 3 / calculating losses and gains leading to a quantitative and transparent equivalence assessment. The use of the methodological framework favors dialogue between actors and also allows monitoring of offsets over time.En France, la séquence « Eviter Réduire Compenser » (ERC) a pour objectif d'atteindre « l'absence de perte nette (APN) » de biodiversité à l'échelle des projets d'aménagement. Un des enjeux clé pour y arriver consiste à démontrer l'équivalence écologique entre les gains associés aux mesures compensatoire (MC) et les pertes occasionnées par les impacts. Malgré les avancées règlementaires, le cadre français n'inclut pas de méthode à suivre pour déterminer l'équivalence et aucune n'est unanimement reconnue. Cela amène à des pratiques hétérogènes et une difficulté d'atteindre l'APN. Dans ce contexte, nous avons développé un cadre méthodologique d'évaluation de l'équivalence adapté au contexte règlementaire et écologique français, répondant à trois défis : opérationnalité, bases scientifiques et exhaustivité. Ce cadre méthodologique permet 1/ d'évaluer la biodiversité des sites impactés et compensatoires en tenant compte de la biodiversité ordinaire et à enjeu en insistant sur les fonctionnalités, 2/ d'estimer la valeur des indicateurs après impact et MC à court et long terme, en prenant en compte les incertitudes associées et 3/ de calculer les pertes et des gains, aboutissant ainsi à une évaluation quantitative et transparente de l'équivalence. L'utilisation du cadre méthodologique favorise la concertation entre acteurs et permet également un suivi des MC dans le temps

Impact of heart-specific disruption of the circadian clock on systemic glucose metabolism in mice

The daily rhythm of glucose metabolism is governed by the circadian clock, which consists of cellautonomous clock machineries residing in nearly every tissue in the body. Disruption of these clock machineries either environmentally or genetically induces the dysregulation of glucose metabolism. Although the roles of clock machineries in the regulation of glucose metabolism have been uncovered in major metabolic tissues, such as the pancreas, liver, and skeletal muscle, it remains unknown whether clock function in non-major metabolic tissues also affects systemic glucose metabolism. Here, we tested the hypothesis that disruption of the clock machinery in the heart might also affect systemic glucose metabolism, because heart function is known to be associated with glucose tolerance</p

The optimisation of stochastic grammars to enable cost-effective probabilistic structural testing

Abstract The effectiveness of statistical testing, a probabilistic structural testing strategy, depends on the characteristics of the probability distribution from which test inputs are sampled. Metaheuristic search has been shown to be a practical method of optimising the characteristics of such distributions. However, the applicability of the existing search-based algorithm is limited by the requirement that the software’s inputs must be a fixed number of ordinal values. In this paper we propose a new algorithm that relaxes this limitation and so permits the derivation of probability distributions for a much wider range of software. The representation used by the new algorithm is based on a stochastic grammar supplemented with two novel features: conditional production weights and the dynamic partitioning of ordinal ranges. We demonstrate empirically that a search algorithm using this representation can optimise probability distributions over complex input domains and thereby enable cost-effective statistical testing, and that the use of both conditional production weights and dynamic partitioning can be beneficial to the search process

Invasive Bacterial Infections in Children With Sickle Cell Disease: 2014–2019

Background: Children with sickle cell disease (SCD) are at a high risk of invasive bacterial infections (IBI). Universal penicillin prophylaxis and vaccination, especially against Streptococcus pneumoniae, have deeply changed its epidemiology. Analysis of IBI in children with SCD in a post-13-valent pneumococcal vaccine era is limited. Methods: Twenty-eight pediatric hospitals from 5 European countries retrospectively collected IBI episodes in SCD children aged 1 month to 18 years between 2014 and 2019. IBI was defined as a positive bacterial culture or polymerase chain reaction from a normally sterile fluid: blood, cerebrospinal, joint, or pleural fluid and deep surgical specimen. Results: We recorded 169 IBI episodes. Salmonella spp. was the main isolated bacteria (n = 44, 26%), followed by Streptococcus pneumonia (Sp; n = 31, 18%) and Staphylococcus aureus (n = 20, 12%). Salmonella prevailed in osteoarticular infections and in primary bacteremia (45% and 23% of episodes, respectively) and Sp in meningitis and acute chest syndrome (88% and 50%, respectively). All Sp IBI occurred in children ≤10 years old, including 35% in children 5 to 10 years old. Twenty-seven (17%) children had complications of infection and 3 died: 2 because of Sp, and 1 because of Salmonella. The main risk factors for a severe IBI were a previous IBI and pneumococcal infection (17 Sp/51 cases). Conclusions: In a post-13-valent pneumococcal vaccine era, Salmonella was the leading cause of bacteremia in IBI in children with SCD in Europe. Sp came second, was isolated in children ≤10 years old, and was more likely to cause severe and fatal cases.info:eu-repo/semantics/publishedVersio