882 research outputs found
Global turbulence simulations of the tokamak edge region with GRILLIX
Turbulent dynamics in the scrape-off layer (SOL) of magnetic fusion devices
is intermittent with large fluctuations in density and pressure. Therefore, a
model is required that allows perturbations of similar or even larger magnitude
to the time-averaged background value. The fluid-turbulence code GRILLIX is
extended to such a global model, which consistently accounts for large
variation in plasma parameters. Derived from the drift reduced Braginskii
equations, the new GRILLIX model includes electromagnetic and electron-thermal
dynamics, retains global parametric dependencies and the Boussinesq
approximation is not applied. The penalisation technique is combined with the
flux-coordinate independent (FCI) approach [F. Hariri and M. Ottaviani,
Comput.Phys.Commun. 184:2419, (2013); A. Stegmeir et al., Comput.Phys.Commun.
198:139, (2016)], which allows to study realistic diverted geometries with
X-point(s) and general boundary contours. We characterise results from
turbulence simulations and investigate the effect of geometry by comparing
simulations in circular geometry with toroidal limiter against realistic
diverted geometry at otherwise comparable parameters. Turbulence is found to be
intermittent with relative fluctuation levels of up to 40% showing that a
global description is indeed important. At the same time via direct comparison,
we find that the Boussinesq approximation has only a small quantitative impact
in a turbulent environment. In comparison to circular geometry the fluctuations
are reduced in diverted geometry, which is related to a different zonal flow
structure. Moreover, the fluctuation level has a more complex spatial
distribution in diverted geometry. Due to local magnetic shear, which differs
fundamentally in circular and diverted geometry, turbulent structures become
strongly distorted in the perpendicular direction and are eventually damped
away towards the X-point
Reduced model for H-mode sustainment in unfavorable drift configuration in ASDEX Upgrade
A recently developed reduced model of H-mode sustainment based on
interchange-drift-Alfv\'en turbulence description in the vicinity of the
separatrix matching experimental observations in ASDEX Upgrade has been
extended to experiments with the unfavorable drift. The combination
with the theory of the magnetic-shear-induced Reynolds stress offers a
possibility to quantitatively explain the phenomena. The extension of the
Reynolds stress estimate in the reduced model via the magnetic shear
contribution is able to reproduce the strong asymmetry in the access conditions
depending on the ion drift orientation in agreement with
experimental observations. The Reynolds stress profile asymmetry predicted by
the magnetic shear model is further extended by comparison with GRILLIX and
GENE-X simulations matched with comparable experiments in realistic X-point
geometry. The predictions of the radial electric field well depth and its
difference between the favorable and unfavorable configurations at the same
heating power from the extended model also show consistency with experimental
measurements.Comment: Submitted to Nuclear Fusio
Oral ibandronate reduces the risk of skeletal complications in breast cancer patients with metastatic bone disease: results from two randomised, placebo-controlled phase III studies
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Lexical retrieval after Arabic aphasia: Syntactic access and predictors of spoken naming
Research into anomia has been carried out in English and many Indo-European languages extensively, but not in Arabic. Previous studies have investigated predictors of successful lexical retrieval after anomia, and access to syntax during lexical retrieval. The aim of the current study is to examine impaired lexical retrieval in Arabic at two levels: predictors of lexical retrieval, and access to syntax during lexical retrieval, via checking whether syntactic cueing (using the definite article/əl-/'the' prior to nouns) facilitates noun retrieval in Arabic aphasia, with regard to naming speed and accuracy, and establishing the determinants of aphasic noun retrieval in Arabic. Three participants with anomia following CVA named 186 pictures from a published Arabic database in two conditions: bare noun condition, and determiner + noun condition. Participants' accuracy and reaction times were compared in both conditions. Furthermore, a multiple regression analysis was carried out to test the effect of psycholinguistic variables (visual complexity, name agreement, age of acquisition, imageability and other intrinsic variables) on successful lexical retrieval to determine predictors of Arabic noun retrieval after anomia. The production of the determiner + noun in picture naming facilitated spoken naming in all three participants. Nouns produced with the determiner were produced faster and more accurately than their counterparts produced without the determiner. The two participants with agrammatism produced morpho-syntactic errors in the bare noun condition, but not in the determiner + noun condition, suggesting that the determiner sets up a noun phrase frame with a slot for the noun to be filled, resulting in responses that are faster and more accurate. Age of acquisition and imageability were the only two variables that had influence across the participants. These results have theoretical and clinical implications for lexical retrieval models
Global temperature definition affects achievement of long-term climate goals
The Paris Agreement on climate change aims to limit 'global average temperature' rise to 'well below 2 °C' but reported temperature depends on choices about how to blend air and water temperature data, handle changes in sea ice and account for regions with missing data. Here we use CMIP5 climate model simulations to estimate how these choices affect reported warming and carbon budgets consistent with the Paris Agreement. By the 2090s, under a low-emissions scenario, modelled global near-surface air temperature rise is 15% higher (5%-95% range 6%-21%) than that estimated by an approach similar to the HadCRUT4 observational record. The difference reduces to 8% with global data coverage, or 4% with additional removal of a bias associated with changing sea-ice cover. Comparison of observational datasets with different data sources or infilling techniques supports our model results regarding incomplete coverage. From high-emission simulations, we find that a HadCRUT4 like definition means higher carbon budgets and later exceedance of temperature thresholds, relative to global near-surface air temperature. 2 °C warming is delayed by seven years on average, to 2048 (2035-2060), and CO2 emissions budget for a >50% chance of <2 °C warming increases by 67 GtC (246 GtCO2)
On order and disorder during the COVID-19 pandemic
Funding: Canadian Institute for Advanced Research.In this paper, we analyse the conditions under which the COVID‐19 pandemic will lead either to social order (adherence to measures put in place by authorities to control the pandemic) or to social disorder (resistance to such measures and the emergence of open conflict). Using examples from different countries (principally the United Kingdom, the United States, and France), we first isolate three factors which determine whether people accept or reject control measures. These are the historical context of state‐public relations, the nature of leadership during the pandemic and procedural justice in the development and operation of these measures. Second, we analyse the way the crisis is policed and how forms of policing determine whether dissent will escalate into open conflict. We conclude by considering the prospects for order/disorder as the pandemic unfolds.Publisher PDFPeer reviewe
Additive growth inhibitory effects of ibandronate and antiestrogens in estrogen receptor-positive breast cancer cell lines
INTRODUCTION: Bisphosphonates are inhibitors of osteoclast-mediated tumor-stimulated osteolysis, and they have become standard therapy for the management of bone metastases from breast cancer. These drugs can also directly induce growth inhibition and apoptosis of osteotropic cancer cells, including estrogen receptor-positive (ER+) breast cancer cells. METHODS: We examined the anti-proliferative properties of ibandronate on two ER+ breast cancer cell lines (MCF-7 and IBEP-2), and on one ER negative (ER-) cell line (MDA-MB-231). Experiments were performed in steroid-free medium to assess ER regulation and the effect of ibandronate in combination with estrogen or antiestrogens. RESULTS: Ibandronate inhibited cancer cell growth in a dose- and time-dependent manner (approximate IC(50): 10(-4 )M for MCF-7 and IBEP-2 cells; 3 × 10(-4 )M for MDA-MB-231 cells), partly through apoptosis induction. It completely abolished the mitogenic effect induced by 17β-estradiol in ER+ breast cancer cells, but affected neither ER regulation nor estrogen-induced progesterone receptor expression, as documented in MCF-7 cells. Moreover, ibandronate enhanced the growth inhibitory action of partial (4-hydroxytamoxifen) and pure (ICI 182,780, now called fluvestrant or Faslodex™) antiestrogens in estrogen-sensitive breast cancer cells. Combination analysis identified additive interactions between ibandronate and ER antagonists. CONCLUSION: These data constitute the first in vitro evidence for additive effects between ibandronate and antiestrogens, supporting their combined use for the treatment of bone metastases from breast cancer
Validation of SOLPS-ITER Simulations against the TCV-X21 Reference Case
This paper presents a quantitative validation of SOLPS-ITER simulations
against the TCV-X21 reference case and provides insights into the neutral
dynamics and ionization source distribution in this scenario. TCV-X21 is a
well-diagnosed diverted L-mode sheath-limited plasma scenario in both toroidal
field directions, designed specifically for the validation of turbulence codes
[D.S. Oliveira, T. Body, et al 2022 Nucl. Fusion 62 096001]. Despite the
optimization to reduce the impact of the neutral dynamics, the absence of
neutrals in previous turbulence simulations of TCV-X21 was identified as a
possible explanation for the disagreements with the experimental data in the
divertor region. This motivates the present study with SOLPS-ITER that includes
kinetic neutral dynamics via EIRENE. Five new observables are added to the
extensive, publicly available TCV-X21 dataset. These are three deuterium Balmer
lines in the divertor and neutral pressure in the common and private flux
regions. The quantitative agreement metric is combined with the conjugate
gradient method to approach the SOLPS-ITER input parameters that return the
best overall agreement with the experiment. A proof-of-principle of this method
results in a modest improvement in the level-of-agreement; shortcomings of the
method and how to improve it are discussed. Alternatively, a scan of the
particle and heat diffusion coefficients shows an improvement of 10.4% beyond
the agreement level achieved by the gradient method. The result is found for an
increased transport coefficient compared to what is usually used for TCV L-mode
plasmas, suggesting the need for accurate self-consistent turbulence models for
predictive boundary simulations. The simulations indicate that ~65% of the
total ionization occurs in the SOL, motivating the inclusion of neutrals in
future turbulence simulations towards improved agreement with the experiment
The role of particle, energy and momentum losses in 1D simulations of divertor detachment
A new 1D divertor plasma code, SD1D, has been used to examine the role of recombination, radiation, and momentum exchange in detachment. Neither momentum or power losses by themselves are found to be sufficient to produce a reduction in target ion flux in detachment (flux rollover); radiative power losses are required to a) limit and reduce the ionization source and b) access low-target temperature, T_target, conditions for volumetric momentum losses. Recombination is found to play little role at flux rollover, but as T_target drops to temperatures around 1eV, it becomes a strong ion sink. In the case where radiative losses are dominated by hydrogen, the detachment threshold is identified as a minimum gradient of the energy cost per ionisation with respect to T_target. This is also linked to thresholds in T_target and in the ratio of upstream pressure to power flux. A system of determining the detached condition is developed such that the divertor solution at a given T_target (or lack of one) is determined by the simultaneous solution of two equations for target ion current - one dependent on power losses and the other on momentum. Depending on the detailed momentum and power loss dependence on temperature there are regions of T_target where there is no solution and the plasma 'jumps' from high to low T_target states. The novel analysis methods developed here provide an intuitive way to understand complex detachment phenomena, and can potentially be used to predict how changes in the seeding impurity used or recycling aspects of the divertor can be utilised to modify the development of detachment
The role of particle, energy and momentum losses in 1D simulations of divertor detachment
A new 1D divertor plasma code, SD1D, has been used to examine the role of recombination, radiation, and momentum exchange in detachment. Neither momentum or power losses by themselves are found to be sufficient to produce a reduction in target ion flux in detachment (flux rollover); radiative power losses are required to a) limit and reduce the ionization source and b) access low-target temperature, T_target, conditions for volumetric momentum losses. Recombination is found to play little role at flux rollover, but as T_target drops to temperatures around 1eV, it becomes a strong ion sink. In the case where radiative losses are dominated by hydrogen, the detachment threshold is identified as a minimum gradient of the energy cost per ionisation with respect to T_target. This is also linked to thresholds in T_target and in the ratio of upstream pressure to power flux. A system of determining the detached condition is developed such that the divertor solution at a given T_target (or lack of one) is determined by the simultaneous solution of two equations for target ion current - one dependent on power losses and the other on momentum. Depending on the detailed momentum and power loss dependence on temperature there are regions of T_target where there is no solution and the plasma 'jumps' from high to low T_target states. The novel analysis methods developed here provide an intuitive way to understand complex detachment phenomena, and can potentially be used to predict how changes in the seeding impurity used or recycling aspects of the divertor can be utilised to modify the development of detachment
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