Vapor pressures and calculated heats of vaporization of concentrated nitric acid solutions in the composition range 71 to 89 percent nitrogen dioxide, 1 to 10 percent water, and in the temperature range 10 to 60 degrees C

Total vapor pressures were measured for 16 acid mixtures of the ternary system nitric acid, nitrogen dioxide, and water within the temperature range 10 degrees to 60 degrees Celsius, and with the composition range 71 to 89 weight percent nitric acid, 7 to 20 weight percent nitrogen dioxide, and 1 to 10 weight percent water. Heats of vaporization were calculated from the vapor pressure measurements for each sample for the temperatures 25, 40, and 60 degrees Celsius. The ullage of the apparatus used for the measurements was 0.46. Ternary diagrams showing isobars as a function of composition of the system were constructed from experimental and interpolated data for the temperatures 25, 40, 45, and 60 degrees C and are presented herein

Synthetic Event Reconstruction Experiments for Defining Sensor Network Characteristics

An event reconstruction technology system has been designed and implemented at Lawrence Livermore National Laboratory (LLNL). This system integrates sensor observations, which may be sparse and/or conflicting, with transport and dispersion models via Bayesian stochastic sampling methodologies to characterize the sources of atmospheric releases of hazardous materials. We demonstrate the application of this event reconstruction technology system to designing sensor networks for detecting and responding to atmospheric releases of hazardous materials. The quantitative measure of the reduction in uncertainty, or benefit of a given network, can be utilized by policy makers to determine the cost/benefit of certain networks. Herein we present two numerical experiments demonstrating the utility of the event reconstruction methodology for sensor network design. In the first set of experiments, only the time resolution of the sensors varies between three candidate networks. The most ''expensive'' sensor network offers few advantages over the moderately-priced network for reconstructing the release examined here. The second set of experiments explores the significance of the sensors detection limit, which can have a significant impact on sensor cost. In this experiment, the expensive network can most clearly define the source location and source release rate. The other networks provide data insufficient for distinguishing between two possible clusters of source locations. When the reconstructions from all networks are aggregated into a composite plume, a decision-maker can distinguish the utility of the expensive sensor network

Editor's Choice - Assessment of International Outcomes of Intact Abdominal Aortic Aneurysm Repair over 9 Years

Background: Case mix and outcomes of complex surgical procedures vary over time and between regions. This study analyses peri-operative mortality after intact abdominal aortic aneurysm (AAA) repair in 11 countries over 9 years. Methods: Data on primary AAA repair from vascular surgery registries in 11 countries for the years 2005-2009 and 2010-2013 were analysed. Multivariate adjusted logistic regression analyses were carried out to adjust for variations in case mix. Results: A total of 83,253 patients were included. Over the two periods, the proportion of patients >= 80 years old increased (18.5% vs. 23.1%; p <.0001) as did the proportion of endovascular repair (EVAR) (44.3% vs. 60.6; p <.0001). In the latter period, 25.8% of AAAs were less than 5.5 cm. The mean annual volume of open repairs per centre decreased from 12.9 to 10.6 between the two periods (p <.0001), and it increased for EVAR from 10.0 to 17.1 (p <.0001). Overall, peri-operative mortality fell from 3.0% to 2.4% (p <.0001). Mortality for EVAR decreased from 1.5% to 1.1% (p <.0001), but the outcome worsened for open repair from 3.9% to 4.4% (p = .008). The peri-operative risk was greater for octogenarians (overall, 3.6% vs. 2.1%, p <.0001; open, 9.5% vs. 3.6%, p <.0001; EVAR, 1.8% vs. 0.7%, p <.0001), and women (overall, 3.8% vs. 2.2%, p <.0001; open, 6.0% vs. 4.0%, p <.0001; EVAR, 1.9% vs. 0.9%, p <.0001). Peri-operative mortality after repair of AAAs Conclusions: In this large international cohort, total peri-operative mortality continues to fall for the treatment of intact AAAs. The number of EVAR procedures now exceeds open procedures. Mortality after EVAR has decreased, but mortality for open operations has increased. The peri-operative mortality for small AM treatment, particularly open surgical repair, is still considerable and should be weighed against the risk of rupture. (C) 2017 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Precursors to potential severe core damage accidents: 1994, a status report. Volume 22: Appendix I

Nine operational events that affected eleven commercial light-water reactors (LWRs) during 1994 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 {times} 10{sup {minus}6}. These events were identified by computer-screening the 1994 licensee event reports from commercial LWRs to identify those that could be potential precursors. Candidate precursors were then selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters and regional offices to ensure that the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969--1981 and 1984--1993 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for events. This document is bound in two volumes: Vol. 21 contains the main report and Appendices A--H; Vol. 22 contains Appendix 1

Precursors to potential severe core damage accidents: 1994, a status report. Volume 21: Main report and appendices A--H

Nine operational events that affected eleven commercial light-water reactors (LWRs) during 1994 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 {times} 10{sup {minus}6}. These events were identified by computer-screening the 1994 licensee event reports from commercial LWRs to identify those that could be potential precursors. Candidate precursors were then selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters and regional offices to ensure that the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969--1981 and 1984--1993 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for events. This document is bound in two volumes: Vol. 21 contains the main report and Appendices A--H; Vol. 22 contains Appendix 1

Differential regulation of Knotted1-like genes during establishment of the shoot apical meristem in Norway spruce (Picea abies)

Establishment of the shoot apical meristem (SAM) in Arabidopsis embryos requires the KNOXI transcription factor SHOOT MERISTEMLESS. In Norway spruce (Picea abies), four KNOXI family members (HBK1, HBK2, HBK3 and HBK4) have been identified, but a corresponding role in SAM development has not been demonstrated. As a first step to differentiate between the functions of the four Norway spruce HBK genes, we have here analyzed their expression profiles during the process of somatic embryo development. This was made both under normal embryo development and under conditions of reduced SAM formation by treatment with the polar auxin transport inhibitor NPA. Concomitantly with the formation of an embryonic SAM, the HBK2 and HBK4 genes displayed a significant up-regulation that was delayed by NPA treatment. In contrast, HBK1 and HBK3 were up-regulated prior to SAM formation, and their temporal expression was not affected by NPA. Ectopic expression of the four HBK genes in transgenic Arabidopsis plants further supported similar functions of HBK2 and HBK4, distinct from those of HBK1 and HBK3. Together, the results suggest that HBK2 and HBK4 exert similar functions related to the SAM differentiation and somatic embryo development in Norway spruce, while HBK1 and HBK3 have more general functions during embryo development

Common and Distinct Roles of Juvenile Hormone Signaling Genes in Metamorphosis of Holometabolous and Hemimetabolous Insects

Insect larvae metamorphose to winged and reproductive adults either directly (hemimetaboly) or through an intermediary pupal stage (holometaboly). In either case juvenile hormone (JH) prevents metamorphosis until a larva has attained an appropriate phase of development. In holometabolous insects, JH acts through its putative receptor Methoprene-tolerant (Met) to regulate Krüppel-homolog 1 (Kr-h1) and Broad-Complex (BR-C) genes. While Met and Kr-h1 prevent precocious metamorphosis in pre-final larval instars, BR-C specifies the pupal stage. How JH signaling operates in hemimetabolous insects is poorly understood. Here, we compare the function of Met, Kr-h1 and BR-C genes in the two types of insects. Using systemic RNAi in the hemimetabolous true bug, Pyrrhocoris apterus, we show that Met conveys the JH signal to prevent premature metamorphosis by maintaining high expression of Kr-h1. Knockdown of either Met or Kr-h1 (but not of BR-C) in penultimate-instar Pyrrhocoris larvae causes precocious development of adult color pattern, wings and genitalia. A natural fall of Kr-h1 expression in the last larval instar normally permits adult development, and treatment with an exogenous JH mimic methoprene at this time requires both Met and Kr-h1 to block the adult program and induce an extra larval instar. Met and Kr-h1 therefore serve as JH-dependent repressors of deleterious precocious metamorphic changes in both hemimetabolous and holometabolous juveniles, whereas BR-C has been recruited for a new role in specifying the holometabolous pupa. These results show that despite considerable evolutionary distance, insects with diverse developmental strategies employ a common-core JH signaling pathway to commit to adult morphogenesis

Immune cell counts and risks of respiratory infections among infants exposed pre- and postnatally to organochlorine compounds: a prospective study

<p>Abstract</p> <p>Background</p> <p>Early-life chemical exposure may influence immune system development, subsequently affecting child health. We investigated immunomodulatory potentials of polychlorinated biphenyls (PCBs) and <it>p,p'</it>-DDE in infants.</p> <p>Methods</p> <p>Prenatal exposure to PCBs and <it>p,p'</it>-DDE was estimated from maternal serum concentrations during pregnancy. Postnatal exposure was calculated from concentrations of the compounds in mother's milk, total number of nursing days, and percentage of full nursing each week during the 3 month nursing period. Number and types of infections among infants were registered by the mothers (N = 190). White blood cell counts (N = 86) and lymphocyte subsets (N = 52) were analyzed in a subgroup of infants at 3 months of age.</p> <p>Results</p> <p>Infants with the highest prenatal exposure to PCB congeners CB-28, CB-52 and CB-101 had an increased risk of respiratory infection during the study period. In contrast, the infection odds ratios (ORs) were highest among infants with the lowest prenatal mono-<it>ortho </it>PCB (CB-105, CB-118, CB-156, CB-167) and di-<it>ortho </it>PCB (CB-138, CB-153, CB-180) exposure, and postnatal mono- and di-<it>ortho </it>PCB, and <it>p,p'</it>-DDE exposure. Similar results were found for pre- and postnatal CB-153 exposure, a good marker for total PCB exposure. Altogether, a negative relationship was indicated between infections and total organochlorine compound exposure during the whole pre- and postnatal period. Prenatal exposure to CB-28, CB-52 and CB-101 was positively associated with numbers of lymphocytes and monocytes in infants 3 months after delivery. Prenatal exposure to <it>p,p'</it>-DDE was negatively associated with the percentage of eosinophils. No significant associations were found between PCB and <it>p,p'</it>-DDE exposure and numbers/percentages of lymphocyte subsets, after adjustment for potential confounders.</p> <p>Conclusion</p> <p>This hypothesis generating study suggests that background exposure to PCBs and <it>p,p'</it>-DDE early in life modulate immune system development. Strong correlations between mono- and di-<it>ortho </it>PCBs, and <it>p,p'</it>-DDE exposures make it difficult to identify the most important contributor to the suggested immunomodulation, and to separate effects due to pre- and postnatal exposure. The suggested PCB and <it>p,p'</it>-DDE modulation of infection risks may have consequences for the health development during childhood, since respiratory infections early in life may be risk factors for asthma and middle ear infections.</p

Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

Accidental or terrorist releases of hazardous materials into the atmosphere can impact large populations and cause significant loss of life or property damage. Plume predictions have been shown to be extremely valuable in guiding an effective and timely response. The two greatest sources of uncertainty in the prediction of the consequences of hazardous atmospheric releases result from poorly characterized source terms and lack of knowledge about the state of the atmosphere as reflected in the available meteorological data. In this report, we discuss the development of a new event reconstruction methodology that provides probabilistic source term estimates from field measurement data for both accidental and clandestine releases. Accurate plume dispersion prediction requires the following questions to be answered: What was released? When was it released? How much material was released? Where was it released? We have developed a dynamic data-driven event reconstruction capability which couples data and predictive models through Bayesian inference to obtain a solution to this inverse problem. The solution consists of a probability distribution of unknown source term parameters. For consequence assessment, we then use this probability distribution to construct a ''''composite'' forward plume prediction which accounts for the uncertainties in the source term. Since in most cases of practical significance it is impossible to find a closed form solution, Bayesian inference is accomplished by utilizing stochastic sampling methods. This approach takes into consideration both measurement and forward model errors and thus incorporates all the sources of uncertainty in the solution to the inverse problem. Stochastic sampling methods have the additional advantage of being suitable for problems characterized by a non-Gaussian distribution of source term parameters and for cases in which the underlying dynamical system is non-linear. We initially developed a Markov Chain Monte Carlo (MCMC) stochastic methodology and demonstrated its effectiveness by reconstructing a wide range of release scenarios, using synthetic as well as real-world data. Data for evaluation of our event reconstruction capability were drawn from the short-range Prairie Grass, Copenhagen, and Joint Urban 2003 field experiments and a continental-scale real-world accidental release in Algeciras, Spain. The method was tested using a variety of forward models, including a Gaussian puff dispersion model INPUFF, the regional-to-continental scale Lagrangian dispersion model LODI (the work-horse real-time operational dispersion model used by the National Atmospheric Release Advisory Center), the empirical urban model UDM, and the building-scale computational computational fluid dynamics code FEM3MP. The robustness of the Bayesian methodology was demonstrated via the use of subsets of the available concentration data and by introducing error into some of the measurements. These tests showed that the Bayesian approach is capable of providing reliable estimates of source characteristics even in cases of limited or significantly corrupted data. For more effective treatment of strongly time-dependent problems, we developed a Sequential Monte Carlo (SMC) approach. To achieve the best performance under a wide range of conditions we combined SMC and MCMC sampling into a hybrid methodology. We compared the effectiveness and advantages of this approach relative to MCMC using a set of synthetic data examples. Our dynamic data-driven event reconstruction capability seamlessly integrates observational data streams with predictive models, in order to provide the best possible estimates of unknown source term parameters, as well as optimal and timely situation analyses consistent with both models and data