292 research outputs found

    Gravitational resonance spectroscopy with an oscillating magnetic field gradient in the GRANIT flow through arrangement

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    Gravitational resonance spectroscopy consists in measuring the energy spectrum of bouncing ultracold neutrons above a mirror by inducing resonant transitions between different discrete quantum levels. We discuss how to induce the resonances with a flow through arrangement in the GRANIT spectrometer, excited by an oscillating magnetic field gradient. The spectroscopy could be realized in two distinct modes (so called DC and AC) using the same device to produce the magnetic excitation. We present calculations demonstrating the feasibility of the newly proposed AC mode

    Manfred Memorial Moon Mission (4M): Development, Operations and Results of a Privately Funded Low Cost Lunar Flyby

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    The first privately funded mission to the moon, Manfred Memorial Moon Mission (4M), was developed within six months. The attractive launch opportunity itself and three mission objectives powered the development: 1) to honor and commemorate Prof. Manfred Fuchs the founder of LuxSpace’s parent company OHB, 2) to demonstrate crowd-based navigation for deep space missions, 3) to measure the radiation dose on the way to the moon and back. Following three maxims enabled success of this endeavor: a) low complexity, b) simple documentation and c) reduced launch site operations. This approach requires continuous communication and trust-based relationship between all project partners (customer, governments, launch provider, system integrator, suppliers and the public). The 12 kg spacecraft is attached to the last stage of a Chinese Long March 3C/G2 launcher dedicated for Chang’e 5 T1, a re-entry demonstrator capsule. Housekeeping data, greeting messages and data from the radiation experiment were transmitted at 145.98 MHz. 4M started to hibernate after 438h (100h design lifetime). More than 75 registered radioamateurs from 29 countries supported 4M with a variety of ground stations. The mission increased public awareness in moon exploration, international cooperation, and affordable space missions, which always were central concerns for Prof. Manfred Fuchs

    Image-Based Cardiac Diagnosis With Machine Learning: A Review

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    Cardiac imaging plays an important role in the diagnosis of cardiovascular disease (CVD). Until now, its role has been limited to visual and quantitative assessment of cardiac structure and function. However, with the advent of big data and machine learning, new opportunities are emerging to build artificial intelligence tools that will directly assist the clinician in the diagnosis of CVDs. This paper presents a thorough review of recent works in this field and provide the reader with a detailed presentation of the machine learning methods that can be further exploited to enable more automated, precise and early diagnosis of most CVDs

    The anatomical limits of the posterior vaginal vault toward its use as route for intra-abdominal procedures

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    Background: The use of natural openings for abdominal surgery started at the beginning of the 21th century. A trans-Douglas endoscopic device has been designed to perform most of the intra-abdominal operations in women through the pouch of Douglas. The posterior vaginal vault is limited in size and could be damaged by an oversized instrument. This study investigates the optimal dimensions of the instrument by measuring the limiting factor in the passage. Methods: In ten female embalmed bodies the transversal and sagittal diameter of the fornix posterior vaginalis was measured by two observers. The pouch of Douglas was filled to its maximal capacity with mouldable latex through an open abdomen. By internal vaginal examination the connective tissue borders of the fornix posterior were palpated and the impression in the cast was measured. The mean value of these two diameters was evaluated in this study. The level of agreement between the observers was calculated. Results: The mean fornix posterior diameter was 2.6 cm (standard deviation, SD 0.5 cm) with a range of 2.0-3.4 cm. The mean difference between the two observers of all measurements was 0.08 cm (not significant). Both observers had an acceptable intraobserver variation. The interobserver agreement was excellent. Conclusion: Instruments with dimensions within the measured limits can be used safely for intra-abdominal operations via the natural orifice of the vagina

    Lessons from the decoupling limit of Horava gravity

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    We consider the so-called "healthy" extension of Horava gravity in the limit where the Stuckelberg field decouples from the graviton. We verify the alleged strong coupling problem in this limit, under the assumption that no large dimensionless parameters are put in by hand. This follows from the fact that the dispersion relation for the Stuckelberg field does not have the desired z = 3 anisotropic scaling in the UV. To get the desired scaling and avoid strong coupling one has to introduce a low scale of Lorentz violation and retain some coupling between the graviton and the Stuckelberg field. We also make use of the foliation preserving symmetry to show how the Stuckelberg field couples to some violation of energy conservation. We source the Stuckelberg field using a point particle with a slowly varying mass and show that two such particles feel a constant attractive force. In this particular example, we see no Vainshtein effect, and violations of the Equivalence Principle. The latter is probably generic to other types of source and could potentially be used to place lower bounds on the scale of Lorentz violation.Comment: 18 pages, 1 figure. Version to appear in JHEP. Conclusions with respect to strong coupling modified - our strong coupling analysis does not apply to a low scale of Lorentz violation. Expanded Equivalence Principle violation discussion, noting it presents a challenge to low scale Lorentz violation, exactly the scenario designed to cure strong coupling. Other minor corrections and references adde

    The Nab Experiment: A Precision Measurement of Unpolarized Neutron Beta Decay

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    Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, λ=gA/gV\lambda = g_A / g_V, through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter aa with a precision of ÎŽa/a=10−3\delta a / a = 10^{-3} and the Fierz interference term bb to ÎŽb=3×10−3\delta b = 3\times10^{-3} in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio λ\lambda with a precision of Ύλ/λ=0.03%\delta \lambda / \lambda = 0.03\% that will allow an evaluation of VudV_{ud} and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.Comment: Presented at PPNS201

    New Upper Limit of Terrestrial Equivalence Principle Test for Rotating Extended Bodies

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    Improved terrestrial experiment to test the equivalence principle for rotating extended bodies is presented, and a new upper limit for the violation of the equivalence principle is obtained at the level of 1.610-7% \times 10^{\text{-7}}, which is limited by the friction of the rotating gyroscope. It means the spin-gravity interaction between the extended bodies has not been observed at this level.Comment: 4 page
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