Developement of real time diagnostics and feedback algorithms for JET in view of the next step

Real time control of many plasma parameters will be an essential aspect in the development of reliable high performance operation of Next Step Tokamaks. The main prerequisites for any feedback scheme are the precise real-time determination of the quantities to be controlled, requiring top quality and highly reliable diagnostics, and the availability of robust control algorithms. A new set of real time diagnostics was recently implemented on JET to prove the feasibility of determining, with high accuracy and time resolution, the most important plasma quantities. With regard to feedback algorithms, new model–based controllers were developed to allow a more robust control of several plasma parameters. Both diagnostics and algorithms were successfully used in several experiments, ranging from H-mode plasmas to configuration with ITBs. Since elaboration of computationally heavy measurements is often required, significant attention was devoted to non-algorithmic methods like Digital or Cellular Neural/Nonlinear Networks. The real time hardware and software adopted architectures are also described with particular attention to their relevance to ITER.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Cost Analysis In A Multi-Mission Operations Environment

Spacecraft control centers have evolved from dedicated, single-mission or single missiontype support to multi-mission, service-oriented support for operating a variety of mission types. At the same time, available money for projects is shrinking and competition for new missions is increasing. These factors drive the need for an accurate and flexible model to support estimating service costs for new or extended missions; the cost model in turn drives the need for an accurate and efficient approach to service cost analysis. The National Aeronautics and Space Administration (NASA) Huntsville Operations Support Center (HOSC) at Marshall Space Flight Center (MSFC) provides operations services to a variety of customers around the world. HOSC customers range from launch vehicle test flights; to International Space Station (ISS) payloads; to small, short duration missions; and has included long duration flagship missions. The HOSC recently completed a detailed analysis of service costs as part of the development of a complete service cost model. The cost analysis process required the team to address a number of issues. One of the primary issues involves the difficulty of reverse engineering individual mission costs in a highly efficient multimission environment, along with a related issue of the value of detailed metrics or data to the cost model versus the cost of obtaining accurate data. Another concern is the difficulty of balancing costs between missions of different types and size and extrapolating costs to different mission types. The cost analysis also had to address issues relating to providing shared, cloud-like services in a government environment, and then assigning an uncertainty or risk factor to cost estimates that are based on current technology, but will be executed using future technology. Finally the cost analysis needed to consider how to validate the resulting cost models taking into account the non-homogeneous nature of the available cost data and the decreasing flight rate. This paper presents the issues encountered during the HOSC cost analysis process, and the associated lessons learned. These lessons can be used when planning for a new multi-mission operations center or in the transformation from a dedicated control center to multi-center operations, as an aid in defining processes that support future cost analysis and estimation. The lessons can also be used by mature serviceoriented, multi-mission control centers to streamline or refine their cost analysis process

Magnetic reversal and pinning in a perpendicular zero-moment half-metal

Compensated ferrimagnets are promising materials for fast spintronic applications based on domain-wall motion as they combine the favorable properties of ferromagnets and antiferromagnets. They inherit from antiferromagnets immunity to external fields, fast spin dynamics, and rapid domain-wall motion. From ferromagnets they inherit straightforward ways to read out the magnetic state, especially in compensated half metals, where electrons flow in only one spin channel. Here, we investigate domain structure in compensated half-metallic Mn2Ru0.5Ga films and assess their potential in domain-wall motion-based spin-electronic devices. Our focus is on understanding and reducing domain-wall pinning in unpatterned epitaxial thin films. Two modes of magnetic reversal, driven by nucleation or domain-wall motion, are identified for different thin film deposition temperatures (Tdep). The magnetic aftereffect is analyzed to extract activation volumes (V∗), activation energies (EA), and their variation (ΔEA). The latter is decisive for the magnetic reversal regime, where domain-wall motion dominated reversal (weak pinning) is found for ΔEA0.5eV. A minimum ΔEA=28meV is found for Tdep=290∘C. Prominent pinning sites are visualized by analyzing virgin domain patterns after thermal demagnetization. In the sample investigated they have spacings of order 300 nm, which gives an upper limit of the track width of spin-torque domain-wall motion-based devices.This project has received funding from Science Foundation Ireland through Contracts No. 16/IA/4534 ZEMS and No. 12/RC/2278 AMBER and from the European Union’s FET-Open research programme under Grant Agreement No. 737038. N.T. acknowledges funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie EDGE Grant agreement No. 713567. We also gratefully acknowledge funding from Northern Ireland’s Department for Economy through USIreland Grant No. USI 108

Minority and mode conversion heating in (3He)-H JET plasma

Radio frequency (RF) heating experiments have recently been conducted in JET (He-3)-H plasmas. This type of plasmas will be used in ITER's non-activated operation phase. Whereas a companion paper in this same PPCF issue will discuss the RF heating scenario's at half the nominal magnetic field, this paper documents the heating performance in (He-3)-H plasmas at full field, with fundamental cyclotron heating of He-3 as the only possible ion heating scheme in view of the foreseen ITER antenna frequency bandwidth. Dominant electron heating with global heating efficiencies between 30% and 70% depending on the He-3 concentration were observed and mode conversion (MC) heating proved to be as efficient as He-3 minority heating. The unwanted presence of both He-4 and D in the discharges gave rise to 2 MC layers rather than a single one. This together with the fact that the location of the high-field side fast wave (FW) cutoff is a sensitive function of the parallel wave number and that one of the locations of the wave confluences critically depends on the He-3 concentration made the interpretation of the results, although more complex, very interesting: three regimes could be distinguished as a function of X[He-3]: (i) a regime at low concentration (X[He-3] < 1.8%) at which ion cyclotron resonance frequency (ICRF) heating is efficient, (ii) a regime at intermediate concentrations (1.8 < X[He-3] < 5%) in which the RF performance is degrading and ultimately becoming very poor, and finally (iii) a good heating regime at He-3 concentrations beyond 6%. In this latter regime, the heating efficiency did not critically depend on the actual concentration while at lower concentrations (X[He-3] < 4%) a bigger excursion in heating efficiency is observed and the estimates differ somewhat from shot to shot, also depending on whether local or global signals are chosen for the analysis. The different dynamics at the various concentrations can be traced back to the presence of 2 MC layers and their associated FW cutoffs residing inside the plasma at low He-3 concentration. One of these layers is approaching and crossing the low-field side plasma edge when 1.8 < X[He-3] < 5%. Adopting a minimization procedure to correlate the MC positions with the plasma composition reveals that the different behaviors observed are due to contamination of the plasma. Wave modeling not only supports this interpretation but also shows that moderate concentrations of D-like species significantly alter the overall wave behavior in He-3-H plasmas. Whereas numerical modeling yields quantitative information on the heating efficiency, analytical work gives a good description of the dominant underlying wave interaction physics

Analytic frameworks for assessing dialogic argumentation in online learning environments

Over the last decade, researchers have developed sophisticated online learning environments to support students engaging in argumentation. This review first considers the range of functionalities incorporated within these online environments. The review then presents five categories of analytic frameworks focusing on (1) formal argumentation structure, (2) normative quality, (3) nature and function of contributions within the dialog, (4) epistemic nature of reasoning, and (5) patterns and trajectories of participant interaction. Example analytic frameworks from each category are presented in detail rich enough to illustrate their nature and structure. This rich detail is intended to facilitate researchers’ identification of possible frameworks to draw upon in developing or adopting analytic methods for their own work. Each framework is applied to a shared segment of student dialog to facilitate this illustration and comparison process. Synthetic discussions of each category consider the frameworks in light of the underlying theoretical perspectives on argumentation, pedagogical goals, and online environmental structures. Ultimately the review underscores the diversity of perspectives represented in this research, the importance of clearly specifying theoretical and environmental commitments throughout the process of developing or adopting an analytic framework, and the role of analytic frameworks in the future development of online learning environments for argumentation

Chemical and biological differentiation of three human breast cancer cell types using time-of-flight secondary ion mass spectrometry (TOF-SIMS)

We use Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) to image and classify individual cells based on their characteristic mass spectra. Using statistical data reduction on the large data sets generated during TOF-SIMS analysis, similar biological materials can be differentiated based on a combination of small changes in protein expression, metabolic activity and cell structure. We apply this powerful technique to image and differentiate three carcinoma-derived human breast cancer cell lines (MCF-7, T47D and MDA-MB-231). In homogenized cells, we show the ability to differentiate the cell types as well as cellular compartments (cytosol, nuclear and membrane). These studies illustrate the capacity of TOF-SIMS to characterize individual cells by chemical composition, which could ultimately be applied to detect and identify single aberrant cells within a normal cell population. Ultimately, we anticipate characterizing rare chemical changes that may provide clues to single cell progression within carcinogenic and metastatic pathways

Effect and Safety of Meropenem\u2013Vaborbactam versus Best-Available Therapy in Patients with Carbapenem-Resistant Enterobacteriaceae Infections: The TANGO II Randomized Clinical Trial

Introduction: Treatment options for carbapenem-resistant Enterobacteriaceae (CRE) infections are limited and CRE infections remain associated with high clinical failure and mortality rates, particularly in vulnerable patient populations. A Phase 3, multinational, open-label, randomized controlled trial (TANGO II) was conducted from 2014 to 2017 to evaluate the efficacy/safety of meropenem\u2013vaborbactam monotherapy versus best available therapy (BAT) for CRE. Methods: A total of 77 patients with confirmed/suspected CRE infection (bacteremia, hospital-acquired/ventilator-associated bacterial pneumonia, complicated intra-abdominal infection, complicated urinary tract infection/acute pyelonephritis) were randomized, and 47 with confirmed CRE infection formed the primary analysis population (microbiologic-CRE-modified intent-to-treat, mCRE-MITT). Eligible patients were randomized 2:1 to meropenem\u2013vaborbactam (2&nbsp;g/2&nbsp;g over 3&nbsp;h, q8h for 7\u201314&nbsp;days) or BAT (mono/combination therapy with polymyxins, carbapenems, aminoglycosides, tigecycline; or ceftazidime-avibactam alone). Efficacy endpoints included clinical cure, Day-28 all-cause mortality, microbiologic cure, and overall success (clinical cure + microbiologic eradication). Safety endpoints included adverse events (AEs) and laboratory findings. Results: Within the mCRE-MITT population, cure rates were 65.6% (21/32) and 33.3% (5/15) [95% confidence interval (CI) of difference, 3.3% to 61.3%; P = 0.03)] at End of Treatment and 59.4% (19/32) and 26.7% (4/15) (95% CI of difference, 4.6% to 60.8%; P = 0.02) at Test of Cure;.Day-28 all-cause mortality was 15.6% (5/32) and 33.3% (5/15) (95% CI of difference, 12 44.7% to 9.3%) for meropenem\u2013vaborbactam versus BAT, respectively. Treatment-related AEs and renal-related AEs were 24.0% (12/50) and 4.0% (2/50) for meropenem\u2013vaborbactam versus 44.0% (11/25) and 24.0% (6/25) for BAT. Exploratory risk\u2013benefit analyses of composite clinical failure or nephrotoxicity favored meropenem\u2013vaborbactam versus BAT (31.3% [10/32] versus 80.0% [12/15]; 95% CI of difference, 12 74.6% to 12 22.9%; P &lt; 0.001). Conclusions: Monotherapy with meropenem\u2013vaborbactam for CRE infection was associated with increased clinical cure, decreased mortality, and reduced nephrotoxicity compared with BAT. Clinical Trials Registration: NCT02168946. Funding: The Medicines Company