GS-DeepNet: mastering tokamak plasma equilibria with deep neural networks and the Grad-Shafranov equation.

The force-balanced state of magnetically confined plasmas heated up to 100 million degrees Celsius must be sustained long enough to achieve a burning-plasma state, such as in the case of ITER, a fusion reactor that promises a net energy gain. This force balance between the Lorentz force and the pressure gradient force, known as a plasma equilibrium, can be theoretically portrayed together with Maxwell's equations as plasmas are collections of charged particles. Nevertheless, identifying the plasma equilibrium in real time is challenging owing to its free-boundary and ill-posed conditions, which conventionally involves iterative numerical approach with a certain degree of subjective human decisions such as including or excluding certain magnetic measurements to achieve numerical convergence on the solution as well as to avoid unphysical solutions. Here, we introduce GS-DeepNet, which learns plasma equilibria through solely unsupervised learning, without using traditional numerical algorithms. GS-DeepNet includes two neural networks and teaches itself. One neural network generates a possible candidate of an equilibrium following Maxwell's equations and is taught by the other network satisfying the force balance under the equilibrium. Measurements constrain both networks. Our GS-DeepNet achieves reliable equilibria with uncertainties in contrast with existing methods, leading to possible better control of fusion-grade plasmas.

A sustained high-temperature fusion plasma regime facilitated by fast ions.

Nuclear fusion is one of the most attractive alternatives to carbon-dependent energy sources1. Harnessing energy from nuclear fusion in a large reactor scale, however, still presents many scientific challenges despite the many years of research and steady advances in magnetic confinement approaches. State-of-the-art magnetic fusion devices cannot yet achieve a sustainable fusion performance, which requires a high temperature above 100 million kelvin and sufficient control of instabilities to ensure steady-state operation on the order of tens of seconds2,3. Here we report experiments at the Korea Superconducting Tokamak Advanced Research4 device producing a plasma fusion regime that satisfies most of the above requirements: thanks to abundant fast ions stabilizing the core plasma turbulence, we generate plasmas at a temperature of 100 million kelvin lasting up to 20 seconds without plasma edge instabilities or impurity accumulation. A low plasma density combined with a moderate input power for operation is key to establishing this regime by preserving a high fraction of fast ions. This regime is rarely subject to disruption and can be sustained reliably even without a sophisticated control, and thus represents a promising path towards commercial fusion reactors.

Fast-ion Dα spectroscopy diagnostic at KSTAR.

A fast-ion Dα (FIDA) diagnostics system was installed for core and edge measurements on KSTAR. This system has two tangential FIDA arrays that cover both blue- and redshifted Dα lines (cold: 656.09 nm) in active views along the neutral beam 1 A centerline. The spectral band is 647-662.5 nm, and it covers the Doppler shift of the emission from the maximum energy of the neutral beam (100 keV). A curved filter strip with a motorized stage adequately prevents saturation of the electron multiplying charge-coupled device signal by the cold Dα line from the plasma edge. From comparisons of the measured spectra and FIDASIM modeling code, the FIDA spectra are well matched quantitatively. Moreover, the first measurements show that the FIDA radiance agrees with the neutron rate in the time trace during external heating and perturbation. In addition, responses are observed in the core FIDA radiance during the edge-localized mode cycle.

Poor nutritional intake is a dominant factor for weight loss in chronic obstructive pulmonary disease.

Increase in energy expenditure and/or decrease in nutritional intake leads to low body mass index (BMI). The balance between energy expenditure and nutritional intake has rarely been evaluated in a large population of patients with chronic obstructive pulmonary disease (COPD). To evaluate BMI, nutritional intake and physical activity and the association of these factors with the severity of airflow obstruction in COPD patients. We analysed the Korean National Health and Nutrition Examination Survey (KNHANES) data set from 2012 to 2015. Among the 9682 individuals (1601 with COPD and 8081 without COPD) recruited, BMI was lower in COPD patients than in non-COPD participants (males, 23.86 ± 2.76 vs. 24.28 ± 2.80, P < 0.001; females, 23.63 ± 2.94 vs. 23.98 ± 3.10, P < 0.05). As the stage of COPD advanced, BMI, intake of nutrients (food, water and carbohydrates) and total energy levels declined in COPD patients. Total time spent walking in the preceding week decreased with advancing COPD stage in male patients with COPD. COPD severity was an important risk factor for the limitation of physical activity due to respiratory problems (OR 3.92, 95%CI 2.77∼5.34, P < 0.001). Patients with COPD had a low nutritional intake with little physical activity, which worsened with advancing COPD stage. In late-stage COPD, impaired nutritional intake outweighed the decrease in physical activity, resulting in weight loss. .

Detection of bovine coronavirus in nasal swab of non-captive wild water deer, Korea.

Bovine coronavirus (BCoV) is a causative agent of respiratory and enteric diseases in cattle and calves. BCoV infection was also evident in captive wild ruminants. Recently, water deer are recognized as the most common wildlife to approach farmhouses and livestock barns in Korea. Therefore, we investigated 77 nasal swab samples from non-captive wild water deer (Hydropotes inermis) between November 2016 and September 2017 and identified three samples positive for coronavirus, indicating potential for respiratory shedding. The full genomic sequences of the water deer coronavirus were closely related to BCoV (>98%). Therefore, effective biosecurity system in bovine farms would be necessary to prevent contact between farm ruminants and free-ranging wild water deer.

Propagation Dynamics Associated with Resonant Magnetic Perturbation Fields in High-Confinement Mode Plasmas inside the KSTAR Tokamak.

The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5 m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.

Experimental infection of clade 1.1.2 (H5N1), clade 2.3.2.1c (H5N1) and clade 2.3.4.4 (H5N6) highly pathogenic avian influenza viruses in dogs.

Since the emergence of highly pathogenic avian influenza (HPAI) H5N1 in Asia, the haemagglutinin (HA) gene of this virus lineage has continued to evolve in avian populations, and H5N1 lineage viruses now circulate concurrently worldwide. Dogs may act as an intermediate host, increasing the potential for zoonotic transmission of influenza viruses. Virus transmission and pathologic changes in HPAI clade 1.1.2 (H5N1)-, 2.3.2.1c (H5N1)- and 2.3.4.4 (H5N6)-infected dogs were investigated. Mild respiratory signs and antibody response were shown in dogs intranasally infected with the viruses. Lung histopathology showed lesions that were associated with moderate interstitial pneumonia in the infected dogs. In this study, HPAI H5N6 virus replication in dogs was demonstrated for the first time. Dogs have been suspected as a "mixing vessel" for reassortments between avian and human influenza viruses to occur. The replication of these three subtypes of the H5 lineage of HPAI viruses in dogs suggests that dogs could serve as intermediate hosts for avian-human influenza virus reassortment if they are also co-infected with human influenza viruses.

Comparing the meanings of living with advanced breast cancer between women resilient to distress and women with persistent distress: a qualitative study.

BACKGROUND: Most women with advanced breast cancer (ABC) show little distress, but about one in ten show persistent distress over time. It remains unclear if meanings ascribed by patients to ABC differentiate these distress trajectories. STUDY AIMS: This qualitative study (a) compared illness meanings of ABC between women with persistent psychological distress and those with low/transient distress, and (b) examined how illness meanings might influence coping strategies. METHODS: The sample was drawn from a prior quantitative study exploring psychological distress trajectories following ABC diagnosis. Overall, 42 Cantonese- or Mandarin-speaking Chinese women diagnosed with locally advanced or metastatic ABC were recruited based on their distress trajectory status (low-stable, transient, or persistent distress). Interviews were recorded, transcribed, and analyzed following grounded theory approach using simultaneous analysis. RESULTS: Women with persistent distress viewed their diagnosis as another blow in life, the illness was global, permeating every aspect of their life. Maladaptive rumination and thought suppression were common responses to illness demands. These women had poor social support. A sense of demoralization stood out in their narratives. In contrast, women with transient/low-stable distress encapsulated the illness, with minimum impacts of their life. They did not evidence dysfunctional repetitive thoughts. Living in a supportive environment, they were able to accept and/or live in the present-moment. CONCLUSIONS: Rumination, thought suppression, social constraints, and pre-existing exposure to life stress may be potential risks for chronic distress in response to advanced breast cancer. Persistent and transient distress responses to cancer may have different underpinnings. Copyright © 2016 John Wiley & Sons, Ltd.

Middle East respiratory syndrome in South Korea during 2015: Risk-related perceptions and quarantine attitudes.

A telephone survey involving 200 household members in and around Seoul, South Korea, was completed during the maturity stage of the outbreak of Middle East respiratory syndrome (MERS) in Korea during June 2015. The study found that respondents perceived low risk from contracting MERS, had low trust in government in controlling MERS, and generally held unfavorable attitudes toward quarantine.

Detection of Severe Acute Respiratory Syndrome-Like, Middle East Respiratory Syndrome-Like Bat Coronaviruses and Group H Rotavirus in Faeces of Korean Bats.

Bat species around the world have recently been recognized as major reservoirs of several zoonotic viruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), Nipah virus and Hendra virus. In this study, consensus primer-based reverse transcriptase polymerase chain reactions (RT-PCRs) and high-throughput sequencing were performed to investigate viruses in bat faecal samples collected at 11 natural bat habitat sites from July to December 2015 in Korea. Diverse coronaviruses were first detected in Korean bat faeces, including alphacoronaviruses, SARS-CoV-like and MERS-CoV-like betacoronaviruses. In addition, we identified a novel bat rotavirus belonging to group H rotavirus which has only been described in human and pigs until now. Therefore, our results suggest the need for continuing surveillance and additional virological studies in domestic bat.

Treatment Planning and Delivery of Whole Brain Irradiation with Hippocampal Avoidance in Rats.

BACKGROUND: Despite the clinical benefit of whole brain radiotherapy (WBRT), patients and physicians are concerned by the long-term impact on cognitive functioning. Many studies investigating the molecular and cellular impact of WBRT have used rodent models. However, there has not been a rodent protocol comparable to the recently reported Radiation Therapy Oncology Group (RTOG) protocol for WBRT with hippocampal avoidance (HA) which is intended to spare cognitive function. The aim of this study was to develop a hippocampal-sparing WBRT protocol in Wistar rats. METHODS: The technical and clinical challenges encountered in hippocampal sparing during rat WBRT are substantial. Three key challenges were identified: hippocampal localization, treatment planning, and treatment localization. Hippocampal localization was achieved with sophisticated imaging techniques requiring deformable registration of a rat MRI atlas with a high resolution MRI followed by fusion via rigid registration to a CBCT. Treatment planning employed a Monte Carlo dose calculation in SmART-Plan and creation of 0.5 cm thick lead blocks custom-shaped to match DRR projections. Treatment localization necessitated the on-board image-guidance capability of the XRAD C225Cx micro-CT/micro-irradiator (Precision X-Ray). Treatment was accomplished with opposed lateral fields with 225 KVp X-rays at a current of 13 mA filtered through 0.3 mm of copper using a 40x40 mm square collimator and the lead blocks. A single fraction of 4 Gy was delivered (2 Gy per lateral field) with a 41 second beam on time per field at a dose rate of 304.5 cGy/min. Dosimetric verification of hippocampal sparing was performed using radiochromic film. In vivo verification of HA was performed after delivery of a single 4 Gy fraction either with or without HA using γ-H2Ax staining of tissue sections from the brain to quantify the amount of DNA damage in rats treated with HA, WBRT, or sham-irradiated (negative controls). RESULTS: The mean dose delivered to radiochromic film beneath the hippocampal block was 0.52 Gy compared to 3.93 Gy without the block, indicating an 87% reduction in the dose delivered to the hippocampus. This difference was consistent with doses predicted by Monte Carlo dose calculation. The Dose Volume Histogram (DVH) generated via Monte Carlo simulation showed an underdose of the target volume (brain minus hippocampus) with 50% of the target volume receiving 100% of the prescription isodose as a result of the lateral blocking techniques sparing some midline thalamic and subcortical tissue. Staining of brain sections with anti-phospho-Histone H2A.X (reflecting double-strand DNA breaks) demonstrated that this treatment protocol limited radiation dose to the hippocampus in vivo. The mean signal intensity from γ-H2Ax staining in the cortex was not significantly different from the signal intensity in the cortex of rats treated with WBRT (5.40 v. 5.75, P = 0.32). In contrast, the signal intensity in the hippocampus of rats treated with HA was significantly lower than rats treated with WBRT (4.55 v. 6.93, P = 0.012). CONCLUSION: Despite the challenges of planning conformal treatments for small volumes in rodents, our dosimetric and in vivo data show that WBRT with HA is feasible in rats. This study provides a useful platform for further application and refinement of the technique.

Usefulness of the ratio of orbital fat to total orbit area in mild-to-moderate thyroid-associated ophthalmopathy.

OBJECTIVE: To identify a useful predictor of thyroid-associated ophthalmopathy (TAO) from orbital CT images; to evaluate the orbital fat and extraocular muscle area ratio as a CT-derived measure; and to investigate the correlations between this ratio and the clinical manifestations in mild-to-moderate TAO. METHODS: Between January 2012 and March 2013, 44 patients with TAO and 23 controls were studied prospectively. All of the patients underwent ophthalmic examinations, including clinical activity score, exophthalmometry, clinical photographs, alternate prism and cover test, duction and version test, Hess screen test, binocular single vision test, thyroid function tests and orbital CT. The cross-sectional areas of the four rectus muscles, superior oblique muscle, optic nerve and total orbit area were calculated in the coronal view 6 mm posterior from the posterior pole of globe. RESULTS: The cross-sectional area measured on orbital CT showed increased orbital fat in patients with TAO and an increased orbital fat to total orbit area ratio (fat/orbit) in TAO with retraction and proptosis. There were significant correlations between fat/orbit and margin reflex distance 1 (p = 0.022), margin reflex distance 2 (p = 0.013) and the exophthalmometric value (p = 0.007). CONCLUSION: The orbital fat to total orbit area ratio (fat/orbit) is a useful diagnostic index in mild-to-moderate TAO. ADVANCES IN KNOWLEDGE: The orbital CT offers a useful diagnostic index in TAO.

Edge profile measurements using Thomson scattering on the KSTAR tokamak.

In the KSTAR Tokamak, a "Tangential Thomson Scattering" (TTS) diagnostic system has been designed and installed to measure electron density and temperature profiles. In the edge system, TTS has 12 optical fiber bundles to measure the edge profiles with 10-15 mm spatial resolution. These 12 optical fibers and their spatial resolution are not enough to measure the pedestal width with a high accuracy but allow observations of L-H transition or H-L transitions at the edge. For these measurements, the prototype ITER edge Thomson Nd:YAG laser system manufactured by JAEA in Japan is installed. In this paper, the KSTAR TTS system is briefly described and some TTS edge profiles are presented and compared against the KSTAR Charge Exchange Spectroscopy and other diagnostics. The future upgrade plan of the system is also discussed in this paper.

Rotation characteristics during the resonant magnetic perturbation induced edge localized mode suppression on the KSTAR.

Measuring rotation profiles with a reliable spatial resolution is one of the critical diagnostics in understanding the plasma behavior especially for the edge transport. In the KSTAR experiments, it has been consistently observed from the charge exchange spectroscopy measurements that the magnetic perturbations not only suppresses edge localized modes (ELMs) but also reduces toroidal rotations. In this paper, toroidal velocities of the carbon impurity and their profile evolutions during ELMy and ELM-suppressed phases are presented. The rotation profiles are shown to collapse immediately after an ELM burst and continue to build up until the next burst that accompanies another collapse. Toroidal rotations following the resonant magnetic perturbations applications are observed to be reduced along with the ELMs suppressed.

Rotational resonance of nonaxisymmetric magnetic braking in the KSTAR tokamak.

One of the important rotational resonances in nonaxisymmetric neoclassical transport has been experimentally validated in the KSTAR tokamak by applying highly nonresonant n=1 magnetic perturbations to rapidly rotating plasmas. These so-called bounce-harmonic resonances are expected to occur in the presence of magnetic braking perturbations when the toroidal rotation is fast enough to resonate with periodic parallel motions of trapped particles. The predicted and observed resonant peak along with the toroidal rotation implies that the toroidal rotation in tokamaks can be controlled naturally in favorable conditions to stability, using nonaxisymmetric magnetic perturbations.

Infectivity, transmission, and pathology of human-isolated H7N9 influenza virus in ferrets and pigs.

The emergence of the H7N9 influenza virus in humans in Eastern China has raised concerns that a new influenza pandemic could occur. Here, we used a ferret model to evaluate the infectivity and transmissibility of A/Shanghai/2/2013 (SH2), a human H7N9 virus isolate. This virus replicated in the upper and lower respiratory tracts of the ferrets and was shed at high titers for 6 to 7 days, with ferrets showing relatively mild clinical signs. SH2 was efficiently transmitted between ferrets via direct contact, but less efficiently by airborne exposure. Pigs were productively infected by SH2 and shed virus for 6 days but were unable to transmit the virus to naïve pigs or ferrets. Under appropriate conditions, human-to-human transmission of the H7N9 virus may be possible.

Initial measurements of fast ion loss in KSTAR.

A fast ion loss detector (FILD) has been installed and tested in Korea Superconducting Tokamak Advanced Research (KSTAR). KSTAR FILD measures the energy and the pitch-angle of the escaping ions with the striking positions on the scintillator plane. Measurements of the fast ion loss have been performed for the neutral beam heated plasmas. Initial experimental results indicate the prompt losses from neutral beam are dominant and the effects of the resonant magnetic perturbation on the fast ion loss are investigated. In addition, further design change of the detector-head in order to avoid excessive heat load and to detect the fusion products or the fast ions having order of MeV of energy is also discussed.

Appearance and dynamics of helical flux tubes under electron cyclotron resonance heating in the core of KSTAR plasmas.

Dual (or sometimes multiple) flux tubes (DFTs) have been observed in the core of sawtoothing KSTAR tokamak plasmas with electron cyclotron resonance heating. The time evolution of the flux tubes visualized by a 2D electron cyclotron emission imaging diagnostic typically consists of four distinctive phases: (1) growth of one flux tube out of multiple small flux tubes during the initial buildup period following a sawtooth crash, resulting in a single dominant flux tube along the m/n=1/1 helical magnetic field lines, (2) sudden rapid growth of another flux tube via a fast heat transfer from the first one, resulting in approximately identical DFTs, (3) coalescence of the two flux tubes into a single m/n=1/1 flux tube resembling the internal kink mode in the normal sawteeth, which is explained by a model of two current-carrying wires confined on a flux surface, and (4) fast localized crash of the merged flux tube similar to the standard sawtooth crash. The dynamics of the DFTs implies that the internal kink mode is not a unique prerequisite to the sawtooth crash, providing a new insight on the control of the sawtooth.

Suppression of edge localized modes in high-confinement KSTAR plasmas by nonaxisymmetric magnetic perturbations.

Edge localized modes (ELMs) in high-confinement mode plasmas were completely suppressed in KSTAR by applying n=1 nonaxisymmetric magnetic perturbations. Initially, the ELMs were intensified with a reduction of frequency, but completely suppressed later. The electron density had an initial 10% decrease followed by a gradual increase as ELMs were suppressed. Interesting phenomena such as a saturated evolution of edge T(e) and broadband changes of magnetic fluctuations were observed, suggesting the change of edge transport by the applied magnetic perturbations.