32 research outputs found
Autoantibodies against type I IFNs in patients with life-threatening COVID-19
Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-w (IFN-w) (13 patients), against the 13 types of IFN-a (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men
Low Energy Spin Dynamics In The Spin Ice Ho 2sn 2o 7
The magnetic properties of Ho 2Sn 2O 7have been investigated and compared to other spin ice compounds. Although the lattice has expanded by 3% relative to the better studied Ho 2Ti 2O 7spin ice, no significant changes were observed in the high temperature properties, T20K. As the temperature is lowered and correlations develop, Ho 2Sn 2O 7enters its quantum phase at a slightly higher temperature than Ho 2Ti 2O 7and is more antiferromagnetic in character. Below 80K a weak inelastic mode associated with the holmium nuclear spin system has been measured. The hyperfine field at the holmium nucleus was found to be 700T. © 2012 IOP Publishing Ltd.247Gardner, J.S., Gingras, M.J.P., Greedan, J.E., Magnetic pyrochlore oxides (2010) Rev. Mod. Phys., 82 (1), pp. 53-107Subramanian, M.A., Aravamudan, G., Subba Rao, G.V., Oxide pyrochloresa review (1983) Prog. Solid State Chem., 15 (2), pp. 55-143Ramirez, A.P., Hayashi, A., Cava, R.J., Siddharthan, R., Shastry, B.S., Zero-point entropy in spin ice (1999) Nature, 399 (6734), pp. 333-335Den Hertog, B.C., Gingras, M.J.P., Dipolar interactions and origin of spin ice in Ising pyrochlore magnets (2000) Phys. Rev. Lett., 84 (15), pp. 3430-3433Bramwell, S.T., Gingras, M.J.P., Spin ice state in frustrated magnetic pyrochlore materials (2001) Science, 294 (5546), pp. 1495-1501. , DOI 10.1126/science.1064761Bramwell, S.T., Spin correlations in Ho 2Ti 2O 7: A dipolar spin ice system (2001) Phys. Rev. Lett., 87 (4)Fennell, T., Petrenko, O.A., Fak, B., Bramwell, S.T., Enjalran, M., Yavorskii, T., Gingras, M.J.P., Balakrishnan, G., Neutron scattering investigation of the spin ice state in Dy(2)Ti(2)O(7) (2004) Phys. 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Rev., 64 (14)Stewart, J.R., Ehlers, G., Wills, A.S., Bramwell, S.T., Gardner, J.S., Phase transitions, partial disorder and multi-k structures in Gd 2Ti 2O 7 (2004) J. Phys.: Condens. Matter, 16 (28), pp. 321-L326Bondah-Jagalu, V., Bramwell, S.T., Magnetic susceptibility study of the heavy rare-earth stannate pyrochlores (2001) Canadian Journal of Physics, 79 (11-12), pp. 1381-1385. , DOI 10.1139/cjp-79-11-12-1381Matsuhira, K., Hinatsu, Y., Tenya, K., Amitsuka, H., Sakakibara, T., Low-temperature magnetic properties of pyrochlore stannates (2002) J. Phys. Soc. Japan, 71 (6), pp. 1576-1582Wills, A.S., Zhitomirsky, M.E., Canals, B., Sanchez, J.P., Bonville, P., De Ŕotier, P.D., Yaouanc, A., Magnetic ordering in Gd(2)Sn(2)O(7): The archetypal Heisenberg pyrochlore antiferromagnet (2006) J. Phys.: Condens. Matter, 18 (3), pp. 37-L42Quilliam, J.A., Ross, K.A., Del Maestro, A.G., Gingras, M.J.P., Corruccini, L.R., Kycia, J.B., Evidence for gapped spin-wave excitations in the frustrated Gd 2Sn 2O 7 pyrochlore antiferromagnet from low-temperature specific heat measurements (2007) Phys. Rev. Lett., 99 (9)Stewart, J.R., Gardner, J.S., Qiu, Y., Ehlers, G., Collective dynamics in the heisenberg pyrochlore antiferromagnet Gd 2Sn 2O 7 (2008) Phys. Rev., 78 (13)Mirebeau, I., Apetrei, A., Rodrguez-Carvajal, J., Bonville, P., Forget, A., Colson, D., Glazkov, V., Suard, E., Ordered spin ice state and magnetic fluctuations in Tb 2Sn 2O 7 (2005) Phys. Rev. Lett., 94 (24)Rule, K.C., Polarized inelastic neutron scattering of the partially ordered Tb 2Sn 2O 7 (2007) Phys. 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Injected mass deposition thresholds for lithium granule instigated triggering of edge localized modes on EAST
The ability of an injected lithium granule to promptly trigger an edge localized mode (ELM) has been established in multiple experiments. By horizontally injecting granules ranging in diameter from 200 microns to 1mm in diameter into the low field side of EAST H-mode discharges we have determined that granules with diameter > 600 microns are successful in triggering ELMs more than 95% of the time. It was also demonstrated that below 600 microns the triggering efficiency decreased roughly with granule size. Granules were radially injected from the outer midplane with velocities ~ 80 m/s into EAST upper single null discharges with an ITER like tungsten monoblock divertor. These granules were individually tracked throughout their injection cycle in order to determine their efficacy at triggering an ELM. For those granules of sufficient size, ELM triggering was a prompt response to granule injection. By simulating the granule injection with an experimentally benchmarked neutral gas shielding (NGS) model, the ablatant mass deposition required to promptly trigger an ELM is calculated and the fractional mass deposition is determined.readme, digital data file
ELM elimination with Li powder injection in EAST discharges using the tungsten upper divertor
We report the first successful use of lithium (Li) to eliminate edge-localized modes (ELMs) with tungsten divertor plasma-facing components in the EAST device. Li powder injected into the scrape-off layer of the tungsten upper divertor successfully eliminated ELMs for 3-5 sec in EAST. The ELM elimination became progressively more effective in consecutive discharges at constant lithium delivery rates, and the divertor D-alpha baseline emission was reduced, both signatures of improved wall conditioning. A modest decrease in stored energy and normalized energy confinement was also observed, but the confinement relative to H98 remained well above 1, extending the previous ELM elimination results via Li injection into the lower carbon divertor in EAST [J.S. Hu et al., Phys. Rev. Lett. 114 (2015) 055001]. These results can be compared with recent observations with lithium pellets in ASDEX-Upgrade that failed to mitigate ELMs [P.T. Lang et al., Nucl. Fusion 57 (2017) 016030], highlighting one comparative advantage of continuous powder injection for real-time ELM elimination.readme, digital data file
ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes
The injection of impurity granules into fusion research discharges can serve
as a catalyst for ELM events. For sufficiently low ELM frequencies, and granule
sizes above a threshold, this can result in full control of the ELM cycle,
referred to as ELM pacing. For this research, we extend the investigation
to conditions where the natural ELM frequency is too high for ELM pacing to
be realized. Utilizing multiple sizes of lithium granules and classifying their
effects by granule size, we demonstrate that ELM mitigation through frequency
multiplication can be used at ELM triggering rates that nominally make ELM pacing
unrealizable. We find that above a size threshold, injected granules promptly
trigger ELMs and commensurately enhance the ELM frequency . Below this threshold
size, injection of an individual granule does not always lead to the prompt
triggering of an ELM; however, collective ablation in the edge pedestal region
does enhance the ELM frequency. Specifically, Li granules too small to individually
trigger ELMs were injected into EAST H-mode discharges at frequencies up to 2.3 kHz;
collectively the granules were observed to enhance the natural ELM frequency up to
620 Hz, resulting in a ~2.4x multiplication of the natural ELM frequency and a 50%
decrease of the ELM size.readme and digitial data file