1,330 research outputs found

    Transitions in vortex skyrmion structures in superfluid 3^3He-A driven by an analogue of the zero-charge effect

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    In quantum electrodynamics, the zero-charge effect originates from the logarithmic dependence of the coupling constant in the action of the electromagnetic field on the ratio of the ultraviolet and infrared energy cutoffs. An analogue of this effect in Weyl superfluid 3^3He-A is the logarithmic divergence of the bending energy of the orbital anisotropy axis at low temperatures, where temperature plays the role of the infrared cutoff and the vector of the orbital anisotropy plays the role of the vector potential of the synthetic electromagnetic field for Weyl fermions. We calculate numerically the spatial distribution of the order parameter in rotating 3^3He-A as a function of temperature. At temperatures close to the superfluid transition, we observe formation of vortex skyrmions known as the double-quantum vortex and the vortex sheet. These structures include alternating circular and hyperbolic merons as a bound pair or a chain, respectively. As temperature lowers towards absolute zero, we find a continuous transition in the vortex structures towards a state where the vorticity is distributed in thin tubes around the circular merons. For the vortex sheet, we present a phase diagram of the transition in the temperature - angular velocity plane and calculations of the nuclear magnetic resonance response.Comment: 14 pages, 10 figure

    Payload/orbiter contamination control requirement study, volume 2, exhibit A

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    The computer printout data generated during the Payload/Orbiter Contamination Control Requirement Study are presented. The computer listings of the input surface data matrices, the viewfactor data matrices, and the geometric relationship data matrices for the three orbiter/spacelab configurations analyzed in this study are given. These configurations have been broken up into the geometrical surfaces and nodes necessary to define the principal critical surfaces whether they are contaminant sources, experimental surfaces, or operational surfaces. A numbering scheme was established based upon nodal numbers that relates the various spacelab surfaces to a specific surface material or function. This numbering system was developed for the spacelab configurations such that future extension to a surface mapping capability could be developed as required

    Prolyl hydroxylase PHD3 activates oxygen-dependent protein aggregation

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    The HIF prolyl hydroxylases (PHDs/EGLNs) are central regulators of the molecular responses to oxygen availability. One isoform, PHD3, is expressed in response to hypoxia and causes apoptosis in oxygenated conditions in neural cells. Here we show that PHD3 forms subcellular aggregates in an oxygen-dependent manner. The aggregation of PHD3 was seen under normoxia and was strongly reduced under hypoxia or by the inactivation of the PHD3 hydroxylase activity. The PHD3 aggregates were dependent on microtubular integrity and contained components of the 26S proteasome, chaperones, and ubiquitin, thus demonstrating features that are characteristic for aggresome-like structures. Forced expression of the active PHD3 induced the aggregation of proteasomal components and activated apoptosis under normoxia in HeLa cells. The apoptosis was seen in cells prone to PHD3 aggregation and the PHD3 aggregation preceded apoptosis. The data demonstrates the cellular oxygen sensor PHD3 as a regulator of protein aggregation in response to varying oxygen availability

    Women’s Perceptions of Caesarean Birth: A Roy International Study

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    The purpose of this Roy adaptation model-based multi-site international mixed method study was to examine the relations of type of caesarean birth (unplanned/planned), number of caesarean births (primary/repeat), and preparation for caesarean birth to women’s perceptions of and responses to caesarean birth. The sample included 488 women from the United States (n = 253), Finland (n = 213), and Australia (n = 22). Path analysis revealed direct effects for type of and preparation for caesarean birth on responses to caesarean birth, and an indirect effect for preparation on responses to caesarean birth through perception of birth the experience

    Outcomes of High-Frequency Gastric Electric Stimulation for the Treatment of Severe, Medically Refractory Gastroparesis in Finland

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    Background and Aims: Severe, medically uncontrollable gastroparesis is a rare entity, which can be treated using a high-frequency gastric electric stimulator implanted surgically. Previous follow-ups have proven positive outcomes with gastric electric stimulator in patients with gastroparesis. The aim of this study was to evaluate the efficacy and safety of gastric electric stimulator in patients, in whom gastroparesis could not be controlled by conservative means in our country. Materials and Methods: This is a retrospective multi-center cohort comprising all patients who had been implanted gastric electric stimulator for severe, medically refractory gastroparesis during 2007-2015 in Finland. Results: Fourteen patients underwent implantation of gastric electrical stimulator without any postoperative complications. Laparoscopic approach was used in 13 patients (93%). Prior implantation, all patients needed frequent hospitalization for parenteral feeding, 13 had severe nausea, 11 had severe vomiting, 10 had notable weight loss, and 6 had frequent abdominal pain. After operation, none of the patients required parenteral feeding, 11 patients (79%) gained median of 5.1 kg in weight (P <0.01), and symptoms were relieved markedly in 8 and partially in 3 patients (79%). Of partial responders, two continued to experience occasional vomiting and one mild nausea. Five patients needed medication for gastroparesis after the operation. One patient did not get any relief of symptoms, but gained 6 kg in weight. No major late complications occurred. Conclusion: Gastric electrical stimulator seems to improve the nutritional status and give clear relief of the symptoms of severe, medically uncontrollable gastroparesis. Given the low number of operations, gastric electrical stimulator seems to be underused in Finland.Peer reviewe

    The Development and Study of High-Position Resolution (50 micron) RPCs for Imaging X-rays and UV photons

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    Nowadays, commonly used Resistive Plate Chambers (RPCs) have counting rate capabilities of ~10E4Hz/cm2 and position resolutions of ~1cm. We have developed small prototypes of RPCs (5x5 and 10x10cm2) having rate capabilities of up to 10E7Hz/cm2 and position resolutions of 50 micron("on line" without application of any treatment method like "center of gravity"). The breakthrough in achieving extraordinary rate and position resolutions was only possible after solving several serious problems: RPC cleaning and assembling technology, aging, spurious pulses and afterpulses, discharges in the amplification gap and along the spacers. High-rate, high-position resolution RPCs can find a wide range of applications in many different fields, for example in medical imaging. RPCs with the cathodes coated by CsI photosensitive layer can detect ultraviolet photons with a position resolution that is better than ~30 micron. Such detectors can also be used in many applications, for example in the focal plane of high resolution vacuum spectrographs or as image scanners.Comment: 6 pages, 5 figures, other comment
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