Stratospheric age of air computed with trajectories based on various 3D-Var and 4D-Var data sets

International audienceThe age of stratospheric air is computed with a trajectory model, using ECMWF ERA-40 3D-Var and operational 4D-Var winds. Analysis as well as forecast data are used. In the latter case successive forecast segments are put together to get a time series of the wind fields. This is done for different forecast segment lengths. The sensitivity of the computed age to the forecast segment length and assimilation method are studied, and the results are compared with observations and with results from a chemistry transport model that uses the same data sets. A large number of backward trajectories are started in the stratosphere, and from the fraction of these trajectories that has passed the tropopause the age of air is computed. First, for ten different data sets 50-day backward trajectories starting in the tropical lower stratosphere are computed. The results show that in this region the computed cross-tropopause transport decreases with increasing forecast segment length. Next, for three selected data sets (3D-Var 24-h and 4D-Var 72-h forecast segments, and 4D-Var analyses) 5-year backward trajectories are computed that start all over the globe at an altitude of 20km. For all data sets the computed ages of air in the extratropics are smaller than the observation-based age. For 4D-Var forecast series they are closest to the observation-based values, but still 0.5-1.5 year too small. Compared to the difference in age between the results for the different data sets, the difference in age between the trajectory and the chemistry transport model results is small

Bradyrhizobium japonicum and soybean symbiotic response to glyphosate in glyphosate-tolerant soybeans

Soybean (Glycine max) grain contains approximately 40% protein and 6.5% nitrogen (N) on an elemental basis. Therefore, the plant requires an abundant N supply throughout its life cycle, and symbiotic N fixation of soybean with Bradyrhizobium japonicum provides 40 to 85% of the soybean N. Although soybean cultivars have been genetically engineered to withstand the herbicide glyphosate, B. japonicum grown in culture is sensitive to glyphosate. We hypothesized that glyphosate applied to glyphosate-tolerant soybean would inhibit nodulation by B. japonicum unless B. japonicum could also be selected for glyphosate tolerance. Cultures of B. japonicum were challenged with sublethal doses of glyphosate, and individual colonies were selected for growth in the presence of glyphosate. Of the 40 isolates that were originally selected for glyphosate tolerance, all isolates in subsequent experiments had similar sensitivity to glyphosate as wild-type B. japonicum. To determine if glyphosate affected B. japonicum in plants, soybean seeds were imbibed with differing levels of glyphosate and water and then planted and inoculated with B. japonicum. After several weeks of growth the plants were harvested and nodules were scanned and analyzed by digital imagery. Glyphosate application to glyphosate-tolerant soybean did not affect the ability of B. japonicum to form nodules and fix nitrogen. These data do not agree with previous responses of small soybean plants sprayed with glyphosate, which showed delayed nodulation and decreased nodule size. It may be that the dosage applied to plants and the timing of the application affect the response of glyphosate on symbiotic effectiveness

To Kick Against the Pricks: An Examination of the Oresteia and the Acts of the Apostles

The major themes found in the Oresteia and the books of Luke and Acts of the Apostles are compared. By focusing on the similarities found in the themes of Justice, Religion, and New versus Old, the reader may determine if the phrase in question is being used as a literary allusion in the book of Acts of the Apostles to the Oresteia trilogy. The author believes this to be the case and believes that to arrive at a full understanding of the literary meaning of the phrase in question, an understanding of the major themes of the Oresteia is necessary

How To Get Your Clinical Teaching Team Ready For Curriculum Change: A Practical Guide

Our health care system is constantly adapting to change at an increasingly rapid pace. Unavoidably, this also applies to the field of medical education. As a result, clinical teaching teams face the challenging task of successfully implementing the proposed changes in daily practice. It goes without saying that implementing change takes time and that you need to be patient. However, a successful change process needs more than that. Change models or strategies could offer a helping hand. The questionnaire Specialty training’s Organizational Readiness for curriculum Change (STORC) is a tool aiming to do just that. With a focus on readiness for change, this questionnaire tries to support implementation efforts in PGME. Additionally, since change is a team effort, it focusses on clinical teaching teams particularly. In this paper, we offer a practical guide for clinical teaching teams on how to deal with any concerns or hurdles detected in any of the core elements of readiness for change, in order to smoothen and support the educational change processes these teams are confronted with

Assessment of the Use of Nitrogen Trifluoride for Purifying Coolant and Heat Transfer Salts in the Fluoride Salt-Cooled High-Temperature Reactor

This report provides an assessment of the use of nitrogen trifluoride for removing oxide and water-caused contaminants in the fluoride salts that will be used as coolants in a molten salt cooled reactor

Thermoelectric properties of lead chalcogenide core-shell nanostructures

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials. On the basis of these results we propose suitable core-shell material combinations for future thermoelectric materials of large electric conductivities in combination with an increased thermopower by energy filtering.Comment: 12 pages, 8 figure

Determination of Ras-GTP and Ras-GDP in patients with acute myelogenous leukemia (AML), myeloproliferative syndrome (MPS), juvenile myelomonocytic leukemia (JMML), acute lymphocytic leukemia (ALL), and malignant lymphoma: assessment of mutational and indirect activation

The 21-kD protein Ras of the low-molecular-weight GTP-binding (LMWG) family plays an important role in transduction of extracellular signals. Ras functions as a ‘molecular switch’ in transduction of signals from the membrane receptors of many growth factors, cytokines, and other second messengers to the cell nucleus. Numerous studies have shown that in multiple malignant tumors and hematopoietic malignancies, faulty signal transduction via the Ras pathway plays a key role in tumorigenesis. In this work, a non-radioactive assay was used to quantify Ras activity in hematologic malignancies. Ras activation was measured in six different cell lines and 24 patient samples, and sequence analysis of N- and K-ras was performed. The 24 patient samples comprised of seven acute myelogenous leukemia (AML) samples, five acute lymphocytic leukemia (ALL) samples, four myeloproliferative disease (MPD) samples, four lymphoma samples, four juvenile myelomonocytic leukemia (JMML) samples, and WBC from a healthy donor. The purpose of this study was to compare Ras activity determined by percentage of Ras-GTP with the mutational status of the Ras gene in the hematopoietic cells of the patients. Mutation analysis revealed ras mutations in two of the seven AML samples, one in codon 12 and one in codon 61; ras mutations were also found in two of the four JMML samples, and in one of the four lymphoma samples (codon 12). We found a mean Ras activation of 23.1% in cell lines with known constitutively activating ras mutations, which was significantly different from cell lines with ras wildtype sequence (Ras activation of 4.8%). Two of the five activating ras mutations in the patient samples correlated with increased Ras activation. In the other three samples, Ras was probably activated through “upstream” or “downstream” mechanisms