8,716 research outputs found

    Liouville quantum gravity spheres as matings of finite-diameter trees

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    We show that the unit area Liouville quantum gravity sphere can be constructed in two equivalent ways. The first, which was introduced by the authors and Duplantier, uses a Bessel excursion measure to produce a Gaussian free field variant on the cylinder. The second uses a correlated Brownian loop and a "mating of trees" to produce a Liouville quantum gravity sphere decorated by a space-filling path. In the special case that γ=8/3γ=\sqrt{8/3}, we present a third equivalent construction, which uses the excursion measure of a 3/23/2-stable Lévy process (with only upward jumps) to produce a pair of trees of quantum disks that can be mated to produce a sphere decorated by SLE6_6. This construction is relevant to a program for showing that the γ=8/3γ=\sqrt{8/3} Liouville quantum gravity sphere is equivalent to the Brownian map

    Non-simple \SLE curves are not determined by their range

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    We show that when observing the range of a chordal \SLE_\kappa curve for κ(4,8)\kappa \in (4,8), it is not possible to recover the order in which the points have been visited. We also derive related results about conformal loop ensembles (CLE): (i) The loops in a \CLE_\kappa for κ(4,8)\kappa \in (4,8) are not determined by the \CLE_\kappa gasket. (ii) The continuum percolation interfaces defined in the fractal carpets of conformal loop ensembles \CLE_{\kappa} for κ(8/3,4)\kappa \in (8/3, 4) (we defined these percolation interfaces in earlier work, where we also showed there that they are \SLE_{16/\kappa} curves) are not determined by the \CLE_{\kappa} carpet that they are defined in

    Endoscopic laser-ablation for the treatment of orthotopic and ectopic ureteroceles in dogs: 13 cases (2008-2017).

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    BACKGROUND: Ureteroceles are a rare condition in dogs in which conventional treatments can result in substantial morbidity. Cystoscopic and fluoroscopic-guided laser ablation (CLA) of ureteroceles can successfully relieve obstruction. OBJECTIVES: To describe the technique and outcomes of attempting CLA for treatment of ureteroceles in dogs. ANIMALS: Thirteen client-owned dogs that underwent CLA for treatment of ureteroceles. METHODS: Retrospective multicentered study. Medical records were reviewed in all dogs that underwent CLA for ureterocele(s). A laser was used to extend the opening of the ureteral orifice (UO) unless surgical conversion was necessary. Data collected included signalment, clinicopathologic data, imaging, procedural findings, complications, and short- and long-term outcome. RESULTS: Thirteen dogs with 13 ureteroceles associated with 14 UOs resulting in ureteral obstruction were included. One ureterocele extended bilaterally. Treatment was initiated via retrograde cystoscopy (7 females), percutaneous perineal urethrocystoscopy (4 males), or percutaneous antegrade cystoscopy (2 males). Surgical conversion was necessary in 2 males. Ten of 14 (71%) UOs associated with the ureteroceles were ectopic. Thirteen of 14 had stenotic or imperforate UOs. No postoperative complications were noted. Preoperative incontinence or pollakiuria was present in 9 of 13 and 3 of 13 dogs and resolved in 8 of 9 and 3 of 3 dogs, respectively. Follow-up imaging showed resolution of all ureteroceles and improved ureteral/renal pelvic dilatation. Median follow-up time was 27 months (range, 3-96 months). CONCLUSIONS AND CLINICAL IMPORTANCE: Cystoscopic-guided laser ablation was effective for the treatment of ureteroceles(s) in 11 of 13 dogs

    Verification of shrinkage curvature code prediction models

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    An attempt is made to theoretically and experimentally verify the shrinkage curvature models presented in Eurocode 2 and BS 8110. These codes claim that the models originally derived and proven for uncracked sections are suitable, with modification, for predicting the behaviour of cracked sections, although this claim has never been proven experimentally. To achieve verification, an alternative theoretical approach is initially proposed in this paper. In this theoretical model, the effect of shrinkage, creep and the variation in the neutral axis position of the section are taken into account. The stresses developed in the steel and concrete at a cracked section according to this theoretical model are then applied to a finite-element (FE) model representing a portion of the beam from the crack to mid-way between the crack and an adjacent crack. Ultimately, the mean curvature is determined. Experimentally, pairs of beams were cast and subjected to a level of flexural loading to produce a stabilised crack pattern in the constant-moment zone. The behaviour of the beams was monitored for up to 180 days. For any pair of beams, one beam was cast using a high-shrinkage concrete and the other with a low-shrinkage concrete. Each concrete type, however, exhibits similar creep. Therefore, shrinkage curvature can be obtained by subtracting the long-term movements of one beam from the other. These experimentally defined curvatures were compared with the mean curvatures obtained from the FE analysis. The comparison showed reasonable agreement. The curvatures were also compared with uncracked and cracked curvatures predicted by the codes. The curvatures derived in this investigation fell within the boundaries of the uncracked and cracked curvatures predicted by the codes and, for the fully cracked case, the curvatures were closer to the uncracked boundary

    Catatonic Episodes Related to Substance Use: A Cross-Sectional Study Using Electronic Healthcare Records

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    OBJECTIVE: Substance use has increasingly been linked to the onset of catatonic episodes; however, no large observational studies have examined this association. This study aimed to identify catatonic episodes temporally associated with acute intoxication, withdrawal or chronic substance use, investigate which substances were involved, and compare clinical characteristics of substance-related and non-substance-related catatonic episodes. METHODS: This study retrospectively identified all catatonic episodes recorded in an electronic case register hosted at a large secondary mental health trust in London, UK. Episodes were categorized as substance-related if the clinical record reported either a positive urine drug screen, an ICD-10 diagnosis of a mental or behavioral disorder due to substance use, or documented substance use between two weeks prior to the catatonic episode and the date of the catatonic episode. RESULTS: 108 of 2130 catatonic episodes (5.1%) were deemed substance-related. The number of contemporaneously reported substance-related episodes increased between 2007 and 2016 [r = 0.72, p = 0.02]. Episodes in the context of acute intoxication (n = 54) were most frequently related to cannabis (n = 31) or cocaine (n = 5) use, whilst those in the context of drug withdrawal (n = 8) were most commonly related to alcohol, opioids and benzodiazepines. There were 50 episodes of catatonia associated with chronic substance use without intoxication or withdrawal, of which the majority were related to cannabis use (n = 37). 21 episodes had overlapping intoxication, withdrawal and chronic use of different substances within an episode. Compared to catatonic episodes not related to substance use, episodes of substance-related catatonia occurred in individuals who were younger (mean age 31.3 years [SD 12.2] vs 35.7 years [SD 16.3], p = 0.01) and more likely to be men (74.0% vs 54.3%, p < 0.001). The clinical features of catatonia were similar between the two groups. CONCLUSIONS: A relatively small proportion of catatonic episodes were temporally associated with reported substance use within their electronic records. Substance-related catatonic episodes were mostly related to cannabis use, but other substances including cocaine, alcohol, opioids and benzodiazepines were sometimes implicated. This is likely an underestimate of substance-related catatonia use due to issues with documentation and appropriate investigation

    Liver transplantation in hemophilia A

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    Four patients with hemophilia A have undergone liver transplantation in our institution, three successfully. The first was a 21-year-old man with chronic active hepatitis (CAH) in whom the effects of previous abdominal operations prevented the satisfactory technical insertion of the new liver. He died intraoperatively. The second patient was a 15-year-old boy with CAH who began to synthesize factor VIII coagulant activity (F VIII:C) within 18 hours of successful liver transplantation and has continued to do so for almost 2 years (F VIII:C range 0.89 to 3.20 U/mL). The first 2 months of his postoperative course were complicated by infections, but since that time he has done well and has returned to school. The third patient was a 48-year-old man with portal fibrosis and severe ascites. He synthesized F VIII:C (range 0.96 to 1.50 U/mL) within six hours after reestablishment of circulation through the new liver. His postoperative course was complicated by numerous infections, and he died with sepsis and an acquired immunodeficiency-like syndrome 4 months after transplantation. The fourth patient was a 47-year-old mild hemophiliac with CAH who produced adequate factor VIII:C levels following transplantation (range 0.79 to 2.80 U/mL). These patients demonstrate that liver transplantation in hemophiliacs with end-stage liver disease may be lifesaving and results in correction of the F VIII:C deficiency and associated hemorrhagic tendency

    Increased gravitational force reveals the mechanical, resonant nature of physiological tremor

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    Human physiological hand tremor has a resonant component. Proof of this is that its frequency can be modified by adding mass. However, adding mass also increases the load which must be supported. The necessary force requires muscular contraction which will change motor output and is likely to increase limb stiffness. The increased stiffness will partly offset the effect of the increased mass and this can lead to the erroneous conclusion that factors other than resonance are involved in determining tremor frequency. Using a human centrifuge to increase head-to-foot gravitational field strength, we were able to control for the increased effort by increasing force without changing mass. This revealed that the peak frequency of human hand tremor is 99% predictable on the basis of a resonant mechanism. We ask what, if anything, the peak frequency of physiological tremor can reveal about the operation of the nervous system.This work was funded by a BBSRC Industry Interchange Award to J.P.R.S. and R.F.R. C.J.O. was funded by BBSRC grant BB/I00579X/1. C.A.V. was funded by A∗Midex (Aix-Marseille Initiative of Excellence

    The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

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    ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth’s deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure (Cmcm; commonly referred to as the “post-perovskite” structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 (P63/mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 (P21/m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2S3 structure → P63/mmc structure. However, only the perovskite and CaIrO3 structures are stable with respect to dissociation into NaF and MgF2

    Drug-Free Platelets Can Act as Seeds for Aggregate Formation During Antiplatelet Therapy

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    The online-only Data Supplement is available with this article at http://atvb.ahajournals.org/lookup/suppl/doi:10.1161/ATVBAHA.115.306219/-/DC1.Medical Research Council, the British Heart Foundation (PG-12-68-29779), the Wellcome Trust (101604/Z/13/Z), and the William Harvey Research Foundation. T.D. Warner has received research grant funding and consultancy fees from Astra Zenec

    Conscious monitoring and control (reinvestment) in surgical performance under pressure.

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    Research on intraoperative stressors has focused on external factors without considering individual differences in the ability to cope with stress. One individual difference that is implicated in adverse effects of stress on performance is "reinvestment," the propensity for conscious monitoring and control of movements. The aim of this study was to examine the impact of reinvestment on laparoscopic performance under time pressure
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