200 research outputs found

    Vascular Alterations and Sexual Function in Systemic Sclerosis

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    Sexual dysfunction is common in systemic sclerosis (SSc). Male erectile dysfunction (MED) has been reported in around 80% of subjects and more than half of female patients fulfill criteria for diagnosis as female sexual arousal Disorder (FSAD). While some evidence supports a role for cavernosal fibrosis, abundant data suggest that MED is yet another clinical feature of SSc related to vasculopathy. The contribution of vasculopathy to the more complex issues of female sexual dysfunction is less clear. Inhibitors of Type V phosphodiesterase are effective in men with MED secondary to SSc. Limited study in women suggests inconsistent effects on behavior (frequency) but not on measures related to perfusion. Sexual activity is an important component of quality of life and an important domain for the caregiver to address; it is not clear that it warrants primary consideration as a consistent measure of scleroderma-related vasculopathy

    Toward a test of angular momentum coherence in a twin-atom interferometer

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    We present a scheme well-suited to investigate quantitatively the angular momentum coherence of molecular fragments. Assuming that the dissociated molecule has a null total angular momentum, we investigate the propagation of the corresponding atomic fragments in the apparatus. We show that the envisioned interferometer enables one to distinguish unambiguously a spin-coherent from a spin-incoherent dissociation, as well as to estimate the purity of the angular momentum density matrix associated with the fragments. This setup, which may be seen as an atomic analogue of a twin-photon interferometer, can be used to investigate the suitability of molecule dissociation processes -- such as the metastable hydrogen atoms H(22S2^2 S)-H(22S2^2 S) dissociation - for coherent twin-atom optics.Comment: 6 pages, 3 Figures. Final version accepted for publication in Europhysics Letter

    The theory of quantum levitators

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    We develop a unified theory for clocks and gravimeters using the interferences of multiple atomic waves put in levitation by traveling light pulses. Inspired by optical methods, we exhibit a propagation invariant, which enables to derive analytically the wave function of the sample scattering on the light pulse sequence. A complete characterization of the device sensitivity with respect to frequency or to acceleration measurements is obtained. These results agree with previous numerical simulations and confirm the conjecture of sensitivity improvement through multiple atomic wave interferences. A realistic experimental implementation for such clock architecture is discussed.Comment: 11 pages, 6 Figures. Minor typos corrected. Final versio

    Precision atomic gravimeter based on Bragg diffraction

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    We present a precision gravimeter based on coherent Bragg diffraction of freely falling cold atoms. Traditionally, atomic gravimeters have used stimulated Raman transitions to separate clouds in momentum space by driving transitions between two internal atomic states. Bragg interferometers utilize only a single internal state, and can therefore be less susceptible to environmental perturbations. Here we show that atoms extracted from a magneto-optical trap using an accelerating optical lattice are a suitable source for a Bragg atom interferometer, allowing efficient beamsplitting and subsequent separation of momentum states for detection. Despite the inherently multi-state nature of atom diffraction, we are able to build a Mach-Zehnder interferometer using Bragg scattering which achieves a sensitivity to the gravitational acceleration of Δg/g=2.7×109\Delta g/g = 2.7\times10^{-9} with an integration time of 1000s. The device can also be converted to a gravity gradiometer by a simple modification of the light pulse sequence.Comment: 13 pages, 11 figure

    Non-local double-path Casimir phase in atom interferometers

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    We present a quantum open system theory of atom interferometers evolving in the quantized electromagnetic field bounded by an ideal conductor. Our treatment reveals an unprecedented feature of matter-wave propagation, namely the appearance of a non-local double-path phase coherence. Such a non-local phase arises from the coarse-graining over the quantized electromagnetic field and internal atomic degrees of freedom, yielding a non-Hamiltonian evolution of the atomic waves moving in presence of correlated quantum dipole and field fluctuations. We develop a diagrammatic interpretation of this phase, and estimate it for realistic experimental parameters.Comment: 5 pages, 1 figure. Final version, published in the Europhysics Letter

    Marine radioecology after the Fukushima Dai-ichi nuclear accident : are we better positioned to understand the impact of radionuclides in marine ecosystems?

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    © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Science of The Total Environment 618 (2017): 80-92, doi:10.1016/j.scitotenv.2017.11.005.This paper focuses on how a community of researchers under the COMET (CO-ordination and iMplementation of a pan European projecT for radioecology) project has improved the capacity of marine radioecology to understand at the process level the behaviour of radionuclides in the marine environment, uptake by organisms and the resulting doses after the Fukushima Dai-ichi nuclear accident occurred in 2011. We present new radioecological understanding of the processes involved, such as the interaction of waterborne radionuclides with suspended particles and sediments or the biological uptake and turnover of radionuclides, which have been better quantified and mathematically described. We demonstrate that biokinetic models can better represent radionuclide transfer to biota in non-equilibrium situations, bringing more realism to predictions, especially when combining physical, chemical and biological interactions that occur in such an open and dynamic environment as the ocean. As a result, we are readier now than we were before the FDNPP accident in terms of having models that can be applied to dynamic situations. The paper concludes with our vision for marine radioecology as a fundamental research discipline and we present a strategy for our discipline at the European and international levels. The lessons learned are presented along with their possible applicability to assess/reduce the environmental consequences of future accidents to the marine environment and guidance for future research, as well as to assure sustainability of marine radioecology in Europe and globally. This guidance necessarily reflects on why and where further research funding is needed, signalling the way for future investigations.The research leading to this paper has received funding from the European Union's seventh Framework programme (FP7/2007-2013) under grant agreement No. is 604974 (Projects within COMET: Marine Initial Research Activity and The impact of recent releases from the Fukushima nucleaR Accident on the Marine Environment - FRAME). Sampling off Japan has been supported by the Gordon and Betty Moore Foundation, the Deerbrook Charitable Trust and contributions to the WHOI Centre for Marine and Environmental Radioactivity. We acknowledge the JSPS KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas Grant No. 24110005 for supporting in part the activities during the research cruises to the FDNPP area

    Synaptotagmin 5 regulates Ca2+-dependent Weibel-Palade body exocytosis in human endothelial cells.

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    Membrane protein insertion is an essential cellular process. The broad biophysical and topological range of membrane proteins necessitates multiple insertion pathways, which remain incompletely defined. Here, we have discovered a new membrane protein insertion pathway, identified the class of substrates it handles, explained why other known pathways do not work for these substrates and reconstituted the pathway using purified components
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