139 research outputs found

    RESULTS OF RESEARCH TO EVALUATE SOLID PLUTONIUM NITRATE AS A SAFE SHIPPING FORM

    Full text link
    The three compounds chosen for evaluation were Pu (NO{sub 3}){sub 4}*XH{sub 20}O, K{sub 2}Pu (NO{sub 3}){sub 6} and (NH{sub 4}){sub 2}Pu(NO{sub 3}){sub 6}. The nitrates were selected since they would not add an extraneous anion to the process streams. The halides were ruled out since they would not be compatible with stainless steel, and organics were not felt to be sufficiently stable for use. A systematic study of the radiolytic and thermal stability, solubility, and ease of preparation of each of the three nitrate compounds selected was then accomplished. These results allowed each compound to be evaluated as a potential solid shipping form as a guide to shipping package requirements. This report presents the results of the chemical development on a laboratory scale

    The Waldschmidt constant for squarefree monomial ideals

    Get PDF
    Given a squarefree monomial ideal IR=k[x1,,xn]I \subseteq R =k[x_1,\ldots,x_n], we show that α^(I)\widehat\alpha(I), the Waldschmidt constant of II, can be expressed as the optimal solution to a linear program constructed from the primary decomposition of II. By applying results from fractional graph theory, we can then express α^(I)\widehat\alpha(I) in terms of the fractional chromatic number of a hypergraph also constructed from the primary decomposition of II. Moreover, expressing α^(I)\widehat\alpha(I) as the solution to a linear program enables us to prove a Chudnovsky-like lower bound on α^(I)\widehat\alpha(I), thus verifying a conjecture of Cooper-Embree-H\`a-Hoefel for monomial ideals in the squarefree case. As an application, we compute the Waldschmidt constant and the resurgence for some families of squarefree monomial ideals. For example, we determine both constants for unions of general linear subspaces of Pn\mathbb{P}^n with few components compared to nn, and we find the Waldschmidt constant for the Stanley-Reisner ideal of a uniform matroid.Comment: 26 pages. This project was started at the Mathematisches Forschungsinstitut Oberwolfach (MFO) as part of the mini-workshop "Ideals of Linear Subspaces, Their Symbolic Powers and Waring Problems" held in February 2015. Comments are welcome. Revised version corrects some typos, updates the references, and clarifies some hypotheses. To appear in the Journal of Algebraic Combinatoric

    Applying science in practice: the optimization of biological therapy in rheumatoid arthritis

    Get PDF
    Most authorities recommend starting biological agents upon failure of at least one disease-modifying agent in patients with rheumatoid arthritis. However, owing to the absence of head-to-head studies, there is little guidance about which biological to select. Still, the practicing clinician has to decide. This review explores the application of published evidence to practice, discussing the goals of treatment, the (in) ability to predict individual responses to therapy, and the potential value of indirect comparisons. We suggest that cycling of biological agents, until remission is achieved or until the most effective agent for that individual patient is determined, deserves consideration in the current stage of knowledge

    Decreased surfactant phosphatidylcholine synthesis in neonates with congenital diaphragmatic hernia during extracorporeal membrane oxygenation

    Get PDF
    Purpose: Congenital diaphragmatic hernia (CDH) may result in severe respiratory insufficiency with a high morbidity. The role of a disturbed surfactant metabolism in the pathogenesis of CDH is unclear. We therefore studied endogenous surfactant metabolism in the most severe CDH patients who required extracorporeal membrane oxygenation (ECMO). Methods: Eleven neonates with CDH who required ECMO and ten ventilated neonates without significant lung disease received a 24-h infusion of the stable isotope [U-13C] glucose. The13C-incorporation into palmitic acid in surfactant phosphatidylcholine (PC) isolated from serial tracheal aspirates was measured. Mean PC concentration in epithelial lining fluid (ELF) was measured during the first 4 days of the study. Results: Fractional surfactant PC synthesis was decreased in CDH-ECMO patients compared to controls (2.4 ± 0.33 vs. 8.0 ± 2.4%/day, p = 0.04). The control group had a higher maximal enrichment (0.18 ± 0.03 vs. 0.09 ± 0.02 APE, p = 0.04) and reached this maximal enrichment earlier (46.7 ± 3.0 vs. 69.4 ± 6.6 h, p = 0.004) compared to the CDH-ECMO group, which reflects higher and faster precursor incorporation in the control group. Surfactant PC concentration in ELF was similar in both groups. Conclusion: These results show that CDH patients who require ECMO have a decreased surfactant PC synthesis, which may be part of the pathogenesis of severe pulmonary insufficiency and has a negative impact on weaning from ECMO

    Decreased surfactant phosphatidylcholine synthesis in neonates with congenital diaphragmatic hernia during extracorporeal membrane oxygenation

    Get PDF
    Purpose: Congenital diaphragmatic hernia (CDH) may result in severe respiratory insufficiency with a high morbidity. The role of a disturbed surfactant metabolism in the pathogenesis of CDH is unclear. We therefore studied endogenous surfactant metabolism in the most severe CDH patients who required extracorporeal membrane oxygenation (ECMO). Methods: Eleven neonates with CDH who required ECMO and ten ventilated neonates without significant lung disease received a 24-h infusion of the stable isotope [U-13C] glucose. The13C-incorporation into palmitic acid in surfactant phosphatidylcholine (PC) isolated from serial tracheal aspirates was measured. Mean PC concentration in epithelial lining fluid (ELF) was measured during the first 4 days of the study. Results: Fractional surfactant PC synthesis was decreased in CDH-ECMO patients compared to controls (2.4 ± 0.33 vs. 8.0 ± 2.4%/day, p = 0.04). The control group had a higher maximal enrichment (0.18 ± 0.03 vs. 0.09 ± 0.02 APE, p = 0.04) and reached this maximal enrichment earlier (46.7 ± 3.0 vs. 69.4 ± 6.6 h, p = 0.004) compared to the CDH-ECMO group, which reflects higher and faster precursor incorporation in the control group. Surfactant PC concentration in ELF was similar in both groups. Conclusion: These results show that CDH patients who require ECMO have a decreased surfactant PC synthesis, which may be part of the pathogenesis of severe pulmonary insufficiency and has a negative impact on weaning from ECMO
    corecore