On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

State of the world’s plants and fungi 2020

Kew’s State of the World’s Plants and Fungi project provides assessments of our current knowledge of the diversity of plants and fungi on Earth, the global threats that they face, and the policies to safeguard them. Produced in conjunction with an international scientific symposium, Kew’s State of the World’s Plants and Fungi sets an important international standard from which we can annually track trends in the global status of plant and fungal diversity

Li/Li/sub 2/ supersonic nozzle beam

The characterization of a lithium supersonic nozzle beam was made using spectroscopic techniques. It is found that at a stagnation pressure of 5.3 kPa (40 torr) and a nozzle throat diameter of 0.4 mm the ground state vibrational population of Li/sub 2/ can be described by a Boltzmann distribution with T/sub v/ = 195 +- 30/sup 0/K. The rotational temperature is found to be T/sub r/ = 70 +- 20/sup 0/K by band shape analysis. Measurements by quadrupole mass spectrometer indicates that approximately 10 mole per cent Li/sub 2/ dimers are formed at an oven body temperature of 1370/sup 0/K n the supersonic nozzle expansion. This measured mole fraction is in good agreement with the existing dimerization theory

Photon and positive ion production from collisions of superthermal hydrogen atoms with lithium atoms and molecules. [1 to 10 eV, cross sections, emission spectra]

Photon and positive ion production from superthermal collisions of hydrogen atoms with lithium atoms and molecules is reported. These are the first results in the difficult 1 to 10 eV collision regime obtained with recently developed high intensity plasma-arc source of H atoms. These superthermal H atoms (approximately 5 eV average kinetic energy but not velocity selected in these experiments) have been collided with an intense supersonic lithium beam (approximately 10 percent Li/sub 2/; Li/sub 3/ undetectable) with cold internal degrees of freedom (T/sub vib/ = 195/sup 0/K, T/sub rot/ = 70/sup 0/K). The other aspects of the apparatus have been given previously. Low resolution photon and positive ion production in the collision chamber scattering center and also medium resolution; photon production in the magnet chamber between the skimmer and the magnet were detected

(-)-Epigallocatechin Gallate Induces Fas/CD95-Mediated Apoptosis through Inhibiting Constitutive and IL-6-Induced JAK/STAT3 Signaling in Head and Neck Squamous Cell Carcinoma Cells

In this study, we examined the effects of several plant-derived natural compounds on head and neck squamous cell carcinoma (HNSCC) cells. The results revealed that (-)-epigallocatechin gallate (EGCG) demonstrated the most efficient cytotoxic effects on HNSCC cells. We then investigated the underlying molecular mechanism for the potent proapoptotic effect of EGCG on HNSCC. Cell apoptosis was observed in the EGCG-treated SAS and Cal-27 cells in a time- and dose-dependent manner. In concert with the caspase-8 activation by EGCG, an enhanced expression in functional Fas/CD95 was identified. Consistent with the increased Fas/CD95 expression, a drastic decrease in the Tyr705 phosphorylation of STAT3, a known negative regulator of Fas/CD95 transcription, was shown within 15 min in the EGCG-treated cells, leading to downregulation of the target gene products of STAT3, such as bcl-2, vascular endothelial growth factor (VEGF), mcl-1, and cyclin D1. An overexpression in STAT3 led to resistance to EGCG, suggesting that STAT3 was a critical target of EGCG. Besides inhibiting constitutive expression, EGCG also abrogated the interleukin-6 (IL-6)-induced JAK/STAT3 signaling and further inhibited IL-6-induced proliferation on HNSCC cells. In comparison with apigenin, curcumin, and AG490, EGCG was a more effective inhibitor of IL-6-induced proliferation on HNSCC cells. Overall, our results strongly suggest that EGCG induces Fas/CD95-mediated apoptosis through inhibiting constitutive and IL-6-induced JAK/STAT3 signaling. This mechanism may be partially responsible for EGCG's ability to suppress proliferation of HNSCC cells. These findings provide that EGCG may be useful in the chemoprevention and/or treatment of HNSCC