2,180 research outputs found

    Robust and Efficient Uncertainty Quantification and Validation of RFIC Isolation

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    Modern communication and identification products impose demanding constraints on reliability of components. Due to this statistical constraints more and more enter optimization formulations of electronic products. Yield constraints often require efficient sampling techniques to obtain uncertainty quantification also at the tails of the distributions. These sampling techniques should outperform standard Monte Carlo techniques, since these latter ones are normally not efficient enough to deal with tail probabilities. One such a technique, Importance Sampling, has successfully been applied to optimize Static Random Access Memories (SRAMs) while guaranteeing very small failure probabilities, even going beyond 6-sigma variations of parameters involved. Apart from this, emerging uncertainty quantifications techniques offer expansions of the solution that serve as a response surface facility when doing statistics and optimization. To efficiently derive the coefficients in the expansions one either has to solve a large number of problems or a huge combined problem. Here parameterized Model Order Reduction (MOR) techniques can be used to reduce the work load. To also reduce the amount of parameters we identify those that only affect the variance in a minor way. These parameters can simply be set to a fixed value. The remaining parameters can be viewed as dominant. Preservation of the variation also allows to make statements about the approximation accuracy obtained by the parameter-reduced problem. This is illustrated on an RLC circuit. Additionally, the MOR technique used should not affect the variance significantly. Finally we consider a methodology for reliable RFIC isolation using floor-plan modeling and isolation grounding. Simulations show good comparison with measurements

    Narrow-line magneto-optical cooling and trapping of strongly magnetic atoms

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    Laser cooling on weak transitions is a useful technique for reaching ultracold temperatures in atoms with multiple valence electrons. However, for strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT) is destabilized by competition between optical and magnetic forces. We overcome this difficulty in Er by developing an unusual narrow-line MOT that balances optical and magnetic forces using laser light tuned to the blue side of a narrow (8 kHz) transition. The trap population is spin-polarized with temperatures reaching below 2 microkelvin. Our results constitute an alternative method for laser cooling on weak transitions, applicable to rare-earth-metal and metastable alkaline earth elements.Comment: To appear in Phys. Rev. Lett. 4 pages, 5 figure

    Antinuclear Antibodies (ANA) in Gordon Setters with Symmetrical Lupoid Onychodystrophy and Black Hair Follicular Dysplasia

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    Antinuclear antibodies (ANA) were demonstrated in 3 out of 10 Gordon setters with symmetrical lupoid onychodystrophy and in 5 out of 13 Gordon setters with black hair follicular dysplasia. Two dogs showed both symmetrical lupoid onychodystrophy and black hair follicular dysplasia, and one of these was ANA positive. The results suggest that symmetrical lupoid onychodystrophy and black hair follicular dysplasia in the Gordon setter might be autoimmune diseases that are pathogenetically related, which might indicate a common genetic predisposition

    Discontinuities without discontinuity: The Weakly-enforced Slip Method

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    Tectonic faults are commonly modelled as Volterra or Somigliana dislocations in an elastic medium. Various solution methods exist for this problem. However, the methods used in practice are often limiting, motivated by reasons of computational efficiency rather than geophysical accuracy. A typical geophysical application involves inverse problems for which many different fault configurations need to be examined, each adding to the computational load. In practice, this precludes conventional finite-element methods, which suffer a large computational overhead on account of geometric changes. This paper presents a new non-conforming finite-element method based on weak imposition of the displacement discontinuity. The weak imposition of the discontinuity enables the application of approximation spaces that are independent of the dislocation geometry, thus enabling optimal reuse of computational components. Such reuse of computational components renders finite-element modeling a viable option for inverse problems in geophysical applications. A detailed analysis of the approximation properties of the new formulation is provided. The analysis is supported by numerical experiments in 2D and 3D.Comment: Submitted for publication in CMAM

    Bose Einstein Condensate in a Box

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    Bose-Einstein condensates have been produced in an optical box trap. This novel optical trap type has strong confinement in two directions comparable to that which is possible in an optical lattice, yet produces individual condensates rather than the thousands typical of a lattice. The box trap is integrated with single atom detection capability, paving the way for studies of quantum atom statistics.Comment: 4 pages, 5 figure

    Infrared Surface-Wave Interferometry on W(100)

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    An IR grating on a clean W(100) surface is shown to generate both homogeneous and inhomogeneous surface electromagnetic waves. An observed interference between these two components, which can be described in terms of a two-beam interferometer with variable arm amplitude and fixed optical path, is used to measure the plasma frequency accurately in the IR

    Estimation of solar prominence magnetic fields based on the reconstructed 3D trajectories of prominence knots

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    We present an estimation of the lower limits of local magnetic fields in quiescent, activated, and active (surges) promineces, based on reconstructed 3-dimensional (3D) trajectories of individual prominence knots. The 3D trajectories, velocities, tangential and centripetal accelerations of the knots were reconstructed using observational data collected with a single ground-based telescope equipped with a Multi-channel Subtractive Double Pass imaging spectrograph. Lower limits of magnetic fields channeling observed plasma flows were estimated under assumption of the equipartition principle. Assuming approximate electron densities of the plasma n_e = 5*10^{11} cm^{-3} in surges and n_e = 5*10^{10} cm^{-3} in quiescent/activated prominences, we found that the magnetic fields channeling two observed surges range from 16 to 40 Gauss, while in quiescent and activated prominences they were less than 10 Gauss. Our results are consistent with previous detections of weak local magnetic fields in the solar prominences.Comment: 14 pages, 12 figures, 1 tabl

    Fecal microbiota transplantation in human metabolic diseases: From a murky past to a bright future?

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    Fecal microbiota transplantation (FMT) is gaining considerable traction as a therapeutic approach to influence the course of a plethora of chronic conditions, ranging from metabolic syndrome and malignancies to auto-immune and neurological diseases, and helped to establish the contribution of the gut microbiome to these conditions. Although FMT procedures have yielded important mechanistic insights, their use in clinical practice may be limited due to practical objections in the setting of metabolic diseases. While its applicability is established to treat recurrent Clostridiodes difficile, FMT is emerging in ulcerative colitis and various other diseases. A particularly new insight is that FMTs may not only alter insulin sensitivity but may also alter the course of type 1 diabetes by attenuating underlying auto-immunity. In this review, we will outline the major principles and pitfalls of FMT and where optimization of study design and the procedure itself will further advance the field of cardiometabolic medicine.Peer reviewe
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