3,653 research outputs found

    Don't be so BOLD: Potential limitations in the use of BOLD MRI for studies of renal oxygenation

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    A millimeter-wave antireflection coating for cryogenic silicon lenses

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    We have developed and tested an antireflection (AR) coating method for silicon lenses at cryogenic temperatures and millimeter wavelengths. Our particular application is a measurement of the cosmic microwave background. The coating consists of machined pieces of Cirlex glued to the silicon. The measured reflection from an AR coated flat piece is less than 1.5% at the design wavelength. The coating has been applied to flats and lenses and has survived multiple thermal cycles from 300 to 4 K. We present the manufacturing method, the material properties, the tests performed, and estimates of the loss that can be achieved in practical lenses

    Effect of different drying methods and solvent ratios on biological activities of Phyllanthus acidus extracts

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    The main purpose of this study was to evaluate the antioxidant and α-glucosidase inhibitory activities of Phyllanthus acidus. The P. acidus fruits were dried using three different methods, namely oven (OD), air (AD) and freeze (FD) dryings and extracted with ethanol at different ratios (50 and 100%). The proximate analysis and total phenolic content (TPC) as well as free radical scavenging and α-glucosidase inhibitory activities were determined. The proximate analysis of P. acidus fruit indicated that all the dried samples contained potential nutrient contents. The highest TPC value, α-glucosidase inhibitory and antioxidant activities were observed for 50% ethanolic extract from OD method with TPC value of 28.39 mg GAE/g dried extract, IC50 value of 12.394 μg/mL and 64.17% inhibition, respectively. The study revealed that phenolic compounds could be the main contributors to the antioxidant and α-glucosidase inhibitory activities based on the Pearson correlation coefficients with R values of 95.0 and 73.8%, respectively. The study could provide scientific evidence for some folk uses in the treatment of diseases related to the production of reactive oxygen species and oxidative stress

    Multimodal hyperscanning reveals that synchrony of body and mind are distinct in mother-child dyads

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    Hyperscanning studies have begun to unravel the brain mechanisms underlying social interaction, indicating a functional role for interpersonal neural synchronization (INS), yet the mechanisms that drive INS are poorly understood. The current study, thus, addresses whether INS is functionally-distinct from synchrony in other systems – specifically the autonomic nervous system and motor behavior. To test this, we used concurrent functional near-infrared spectroscopy - electrocardiography recordings, while N = 34 mother-child and stranger-child dyads engaged in cooperative and competitive tasks. Only in the neural domain was a higher synchrony for mother-child compared to stranger-child dyads observed. Further, autonomic nervous system and neural synchrony were positively related during competition but not during cooperation. These results suggest that synchrony in different behavioral and biological systems may reflect distinct processes. Furthermore, they show that increased mother-child INS is unlikely to be explained solely by shared arousal and behavioral similarities, supporting recent theories that postulate that INS is higher in close relationships

    Repeat-Until-Success quantum computing using stationary and flying qubits

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    We introduce an architecture for robust and scalable quantum computation using both stationary qubits (e.g. single photon sources made out of trapped atoms, molecules, ions, quantum dots, or defect centers in solids) and flying qubits (e.g. photons). Our scheme solves some of the most pressing problems in existing non-hybrid proposals, which include the difficulty of scaling conventional stationary qubit approaches, and the lack of practical means for storing single photons in linear optics setups. We combine elements of two previous proposals for distributed quantum computing, namely the efficient photon-loss tolerant build up of cluster states by Barrett and Kok [Phys. Rev. A 71, 060310(R) (2005)] with the idea of Repeat-Until-Success (RUS) quantum computing by Lim et al. [Phys. Rev. Lett. 95, 030505 (2005)]. This idea can be used to perform eventually deterministic two-qubit logic gates on spatially separated stationary qubits via photon pair measurements. Under non-ideal conditions, where photon loss is a possibility, the resulting gates can still be used to build graph states for one-way quantum computing. In this paper, we describe the RUS method, present possible experimental realizations, and analyse the generation of graph states.Comment: 14 pages, 7 figures, minor changes, references and a discussion on the effect of photon dark counts adde

    A compact and reconfigurable silicon nitride time-bin entanglement circuit

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    Photonic chip based time-bin entanglement has attracted significant attention because of its potential for quantum communication and computation. Useful time-bin entanglement systems must be able to generate, manipulate and analyze entangled photons on a photonic chip for stable, scalable and reconfigurable operation. Here we report the first time-bin entanglement photonic chip that integrates time-bin generation, wavelength demultiplexing and entanglement analysis. A two-photon interference fringe with an 88.4% visibility is measured (without subtracting any noise), indicating the high performance of the chip. Our approach, based on a silicon nitride photonic circuit, which combines the low-loss characteristic of silica and tight integration features of silicon, paves the way for scalable real-world quantum information processors.Comment: 4 pages, 5 figure

    Mast Cell–Derived Particles Deliver Peripheral Signals to Remote Lymph Nodes

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    During infection, signals from the periphery are known to reach draining lymph nodes (DLNs), but how these molecules, such as inflammatory cytokines, traverse the significant distances involved without dilution or degradation remains unclear. We show that peripheral mast cells, upon activation, release stable submicrometer heparin-based particles containing tumor necrosis factor and other proteins. These complexes enter lymphatic vessels and rapidly traffic to the DLNs. This physiological drug delivery system facilitates communication between peripheral sites of inflammation and remote secondary lymphoid tissues
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