2,279 research outputs found

    UO2 CORROSION IN HIGH SURFACE-AREA-TO-VOLUME BATCH EXPERIMENTS

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    Unsaturated drip tests have been used to investigate the alteration of unirradiated UO{sub 2} and spent UO{sub 2} fuel in an unsaturated environment, such as may be expected in the proposed repository at Yucca Mountain. In these tests, simulated groundwater is periodically injected onto a sample at 90 C in a steel vessel. The solids react with the dripping groundwater and water condensed on surfaces to form a suite of U(VI) alteration phases. Solution chemistry is determined from leachate at the bottom of each vessel after the leachate stops interacting with the solids. A more detailed knowledge of the compositional evolution of the leachate is desirable. By providing just enough water to maintain a thin film of water on a small quantity of fuel in batch experiments, we can more closely monitor the compositional changes to the water as it reacts to form alteration phases

    IgG4-related kidney disease: a rare cause of tubulointerstitial nephritis

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    A 42-year-old black female was referred with unexplained renal failure. Initial radiological examination revealed a right adnexal inflammatory mass and bilateral hydronephrosis. The renal failure persisted despite the insertion of double J stents. A kidney biopsy showed a lymphoplasmacytic interstitial infiltrate that stained positive for IgG4. A diagnosis of IgG4-related tubulointerstitial nephritis (TIN) with pelvic-limited retroperitoneal fibrosis (RPF) was made and immunosuppressive treatment was initiated, with a good initial response to therapy. This report highlights the importance of considering RPF in cases of unexplained obstructive uropathy and of considering the diagnosis of IgG4-related disease when TIN is found in combination with other organ involvement. 

    Adhesion of Polymer Vesicles

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    The adhesion and bending modulus of polybutadiene-poly(ethylene oxide) block copolymer vesicles made from a bidisperse mixture of polymers is measured using micropipette aspiration. The adhesion energy between biotinylated vesicles and avidin beads is modeled by incorporating the extension of the adhesive ligands above the surface brush of the vesicle according to the blob model of bidisperse polymer mixtures of Komura and Safran assuming the polymer brush at the surface of the vesicle is compact. The same model accurately reproduces the scaling of the bending modulus with polymer composition

    A Special Homotopy Continuation Method For A Class of Polynomial Systems

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    A special homotopy continuation method, as a combination of the polyhedral homotopy and the linear product homotopy, is proposed for computing all the isolated solutions to a special class of polynomial systems. The root number bound of this method is between the total degree bound and the mixed volume bound and can be easily computed. The new algorithm has been implemented as a program called LPH using C++. Our experiments show its efficiency compared to the polyhedral or other homotopies on such systems. As an application, the algorithm can be used to find witness points on each connected component of a real variety

    Primordial helium recombination III: Thomson scattering, isotope shifts, and cumulative results

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    Upcoming precision measurements of the temperature anisotropy of the cosmic microwave background (CMB) at high multipoles will need to be complemented by a more complete understanding of recombination, which determines the damping of anisotropies on these scales. This is the third in a series of papers describing an accurate theory of HeI and HeII recombination. Here we describe the effect of Thomson scattering, the 3^3He isotope shift, the contribution of rare decays, collisional processes, and peculiar motion. These effects are found to be negligible: Thomson and 3^3He scattering modify the free electron fraction xex_e at the level of several ×104\times 10^{-4}. The uncertainty in the 23Po11S2^3P^o-1^1S rate is significant, and for conservative estimates gives uncertainties in xex_e of order 10310^{-3}. We describe several convergence tests for the atomic level code and its inputs, derive an overall CC_\ell error budget, and relate shifts in xe(z)x_e(z) to the changes in CC_\ell, which are at the level of 0.5% at =3000\ell =3000. Finally, we summarize the main corrections developed thus far. The remaining uncertainty from known effects is 0.3\sim 0.3% in xex_e.Comment: 19 pages, 15 figures, to be submitted to PR

    AVIAN SPECIATION IN THE PANTEPUI: THE CASE OF THE RORAIMAN ANTBIRD (PERCNOSTOLA [SCHISTOCICHLA] ‘‘LEUCOSTIGMA’’ SATURATA)

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    This is the published version. Copyright Central Ornithology Publication OfficeWe document the first records for Guyana of Roraiman Antbird (Percnostola [Schistocichla] “leucostigma” saturata), an endemic of the tepui highlands of southeastern Venezuela, northern Brazil and western Guyana. This form is well differentiated from nominate leucostigma (Spot-winged Antbird) of the Guianan lowlands in morphology, vocalizations, and genetics, and replaces it both altitudinally and ecologically. The two taxa are distributed parapatrically on the continuously forested northeastern slopes of the eastern tepuis, and they almost certainly come into contact, yet there is no evidence of intermediacy. We recommend that saturata be treated as a distinct species of Percnostola, and consider its' origin in the light of various models of speciation in the tepuis

    Playing with social and emotional game companions

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    This paper presents the findings of an empirical study that explores player game experience by implementing the ERiSA Framework in games. A study with Action Role-Playing Game (RPG) was designed to evaluate player interactions with game companions, who were imbued with social and emotional skill by the ERiSA Framework. Players had to complete a quest in the Skyrim game, in which players had to use social and emotional skills to obtain a sword. The results clearly show that game companions who are capable of perceiving and exhibit emotions, are perceived to have personality and can forge relationships with the players, enhancing the player experience during the game
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