Preliminary results of the 105 GHz collective Thomson scattering system on HL-2A

A 105 GHz collective Thomson scattering (CTS) diagnostic has been successfully developed for fast-ion measurements on the HL-2A tokamak, and it has been deployed during an experimental campaign. Enhanced signals exhibiting synchronous modulation characteristics have been observed across all CTS channels upon the launch of a modulated probe wave. Results show that the intensity of the CTS signal increases with Neutral Beam Injection (NBI) power and is proportional to neutron count, indicating that the scattering signal contains a contribution from fast ions. Compared with the signal without NBI, the enhanced scattering spectrum due to NBI is slightly wider than the predicted fast ion range. Such broadening might be attributed to the heating effects of the gyrotron.

Plasma position measurements by O-mode and X-mode reflectometry systems in tokamak plasmas

Plasma Position Reflectometry (PPR) is planned to provide plasma position and shape information for plasma operation in future fusion reactors. Its primary function is to calibrate the drift of the magnetic signals due to the integral nature of magnetic measurement. Here, we attempt to measure plasma position using ordinary mode (O-mode) and extraordinary mode (X-mode) reflectometry systems on two tokamaks. A new physical model based on the phase shift is proposed to deduce the relative movement of the cut-off layer without density inversion. We demonstrate the plasma position measurements by absolute measurement from density profile inversion and relative measurement from phase shift. The combination of X-mode and O-mode reflectometers can minimize the limitations of single polarization reflectometry and further increase the accuracy of plasma position measurement. These results could provide an important technical basis for the further development of a real-time control system based on PPR.

A gamma ray spectrometer with Compton suppression on the HL-2A tokamak

A new broad-energy, high-resolution gamma ray spectrometer (GRS) with Compton suppression function has been developed recently in the HL-2A tokamak to obtain the gamma ray information in the energy range of 0.1-10 MeV. This is the first time to develop an anti-Compton GRS for a magnetic confinement fusion device. The anticoincidence detector consists of a large-volume high purity germanium (HPGe) crystal (Φ63 × 63 mm²) as the primary detector and eight trapezoidal bismuth germinate (BGO) scintillators (trapezoid crystal with 30 mm thickness) as the secondary detector. The anti-coincidence data processing is implemented by a digital-based data acquisition system with fast digitization and software signal processing technology. Using radioisotope gamma ray sources and Monte Carlo N-Particle code, the energy and efficiency of the spectrometer have been calibrated and quantitatively tested. The Compton continuum suppression factor reaches 4.2, and the energy resolution (Full Width at Half Maximum) of the 1.332 MeV full energy peak for ⁶⁰Co is 2.1 keV. Measurements of gamma ray spectra with Compton suppression using the spectrometer have been successfully performed during HL-2A discharges with different conditions. The performance of the spectrometer and the first experimental results are presented in this paper.

Development of solid state terahertz interferometer for the first plasma on HL-2M tokamak

A solid state terahertz interferometer has been developed on the recent commissioned HL-2M tokamak. It can work in a wide frequency region of 220-325 GHz, and the terahertz wave is generated from a low frequency phase locked voltage controlled oscillator with the frequency multiplying technique. A phase processor based on field programmable gate array (FPGA) technology is designed for the heterodyne interferometer, and it contributes to real-time display of electron density. To extract phase information, a novel numerical algorithm related to fast Fourier transform is written on the FPGA chip and enables one to obtain phase shift without being affected by amplitude variation induced by plasma absorption or frequency modulation from the outer electromagnetic environment. The interferometer achieves minimum measurable electron density in the order of 10¹⁶ m^-3. With the plasma diagnosis, electron density and low frequency tearing mode have been measured during the first experimental campaign.

A remote gain controlled and polarization angle tunable Doppler backward scattering reflectometer

Remote control of the diagnostic systems is the basic requirement for the high performance plasma operation in a fusion device. This work presents the development of the remote control system for the multichannel Doppler backward scattering (DBS) reflectometers. It includes a remote controlled quasi-optical system and a remote intermediate frequency (IF) amplifier gain control system. The quasi-optical system contains a rotational polarizer, its polarization angle is tunable through a remote controlled motor, and it could combine the microwave beams with a wide frequency range into one focused beam. The remote IF gain control system utilizes the digital microcontroller (MCU) technique to regulate the signal amplitude for each signal channel. The gain parameters of amplifiers are adjustable, and the feedback of working status in the IF system will be sent to MCU in real time for safe operation. The gain parameters could be controlled either by the Ethernet remote way or directly through the local control interface on the system. Preliminary experimental results show the effectiveness of the remote controlled multichannel DBS system.

[Application of artificial intelligence-assisted diagnosis for cervical liquid-based thin-layer cytology]

Objective: To explore the application value of artificial intelligence-assisted diagnosis system for TBS report in cervical cancer screening. Methods: A total of 16 317 clinical samples and related data of cervical liquid-based thin-layer cell smears, which were obtained from July 2020 to September 2020, were collected from Southern Hospital, Guangzhou Huayin Medical Inspection Center, Shenzhen Bao'an People's Hospital(Group) and Changsha Yuan'an Biotechnology Co., Ltd. The TBS report artificial intelligence-assisted diagnosis system of cervical liquid-based thin-layer cytology jointly developed by Southern Medical University and Guangzhou F. Q. PATHOTECH Co., Ltd. based on deep learning convolution neural network was used to diagnose all clinical samples. The sensitivity,specificity and accuracy of both artificial intelligence-assisted diagnosis system and cytologists using artificial intelligence-assisted diagnosis system were analyzed based on the evaluation standard(2014 TBS). The time spent by the two methods was also compared. Results: The sensitivity of artificial intelligence-assisted diagnosis system in predicting cervical intraepithelial lesions and other lesions (including endometrial cells detected in women over 45 years old and infectious lesions) under different production methods, different cytoplasmic staining and different scanning instruments was 92.90% and 83.55% respectively, and the specificity of negative samples was 87.02%, while that of cytologists using artificial intelligence-assisted diagnosis system was 99.34%, 97.79% and 99.10%, respectively. Moreover, cytologists using artificial intelligence-assisted diagnosis system could save about 6 times of reading time than manual. Conclusions: Artificial intelligence-assisted diagnosis system for TBS report of cervical liquid-based thin-layer cytology has the advantages of high sensitivity, high specificity and strong generalization. Cytologists can significantly improve the accuracy and work efficiency of reading smears by using artificial intelligence-assisted diagnosis system.

[Blood pressure control and influencing factors in hypertension patients with metabolic syndrome]

Objective: To investigate the blood pressure control and its influencing factors in hypertension patients with MS. Methods: Between January 2017 and December 2018, more than 78 000 residents aged 35-75 years selected through convenient sampling were invited to participant in China Patient-Centered Evaluative Assessment of Cardiac Event Million Persons Project in Fujian province, physical and laboratory tests were conducted for them, and their basic information were recorded. A total of 5 281 hypertension patients with MS were included in the study. Results: The treatment rate of hypertension patients with MS was 55.5%, and the control rate was 7.2%. The control rate was higher in patients who were older, women, had advanced education level, had history or family history of cardiovascular disease. The results of multivariate analysis indicated that living area (urban or rural), cardiovascular history, diabetes, urine protein, BMI had impacts on both treatment and control of hypertension. Family history of cardiovascular disease, age, self-management of hypertension, dyslipidemia, waist circumference and drinking had impacts on the treatments, and gender had effects on the control. Conclusions: The treatment rate of hypertension patients with MS was unsatisfactory and the control rate was low. Intervention should be strengthened in rural area, males and young age groups, and activity of self-management group of hypertension should be conducted regularly.

An eight-channel correlation electron cyclotron emission diagnostic for turbulent electron temperature fluctuation measurement in HL-2A tokamak

A new correlation electron cyclotron emission (CECE) diagnostic has recently been installed on the HL-2A tokamak in order to study electron temperature fluctuations. Eight radial locations are measured simultaneously through eight pairs of correlated channels. Multiplexers are employed in the intermediate frequency section instead of the conventional separated filter banks to meet strict cross-isolation specifications and lower insertion loss. Relative electron temperature fluctuations are observed by CECE for the first time on the HL-2A by using the spectral decorrelation method. The achieved minimum detectable fluctuation level is up to (T̃_e/T_e)_min∼0.5%. When studying electron temperature fluctuations in the core region with gas puffing, the cross-power spectra show that the amplitude of the electron temperature fluctuation increases in a high temperature and low density plasma. Further analysis demonstrates that the electron temperature gradient ∇T_e drives the electron temperature fluctuations together with electron heat transport.

Aryl hydrocarbon receptor polymorphisms are associated with dry skin phenotypes in Chinese patients with atopic dermatitis

BACKGROUND

Epidermal barrier dysfunction is the initial event in the development of atopic dermatitis (AD). Recent studies have identified a crucial role for the aryl hydrocarbon receptor (AHR) in controlling the gene expression of filaggrin and other skin barrier proteins, suggesting an underlying association between AHR and AD pathogenesis.

AIM

To investigate the role of AHR gene polymorphisms in the susceptibility to AD and in AD-associated phenotypes.

METHODS

We enrolled 487 patients with AD, 210 patients with psoriasis and 226 healthy controls (HCs) from the Han Chinese population, and genotyped two AHR single-nucleotide polymorphisms (rs10249788 and rs2066853) by PCR and subsequent DNA sequencing.

RESULTS

The AHR rs10249788 and rs2066853 polymorphisms were found in both sets of patients (AD and psoriasis) and in HCs, but no significant differences were detected in genotype or allele frequencies between the three groups. However, patients with AD with the rs10249788 (CT/TT) or rs2066853 (AG + AA) genotype were more likely to have severe dry skin scores. In the stratification analysis, the AHR rs2066853 (AG + AA) and rs10249788 (CT + TT) genotypes could predict a higher risk of severe dry skin phenotypes in the male, early-onset and allergic rhinitis subgroups. Furthermore, the combined rs10249788 (CT + TT) and rs2066853 (AG + AA) genotypes led to a higher risk for severe dry skin in patients with AD.

CONCLUSION

AHR polymorphisms are not associated with the risk of AD; however, they may predict a dry skin phenotype in patients with AD.

[Estimation of underreporting rate of death cases in disease surveillance system of Fujian province using propensity score weighting method, 2012-2014]

Objective: To understand the underreporting of death cases and related factors in disease surveillance system of Fujian province. Methods: We carried out a field underreporting survey in 20 disease surveillance sites selected through stratified cluster random sampling during 2012-2014. The related factors of underreporting were analyzed by using logistic regression method. Propensity score weighting method was used to calculate the underreporting rate in different groups classified by year, urban/rural areas, gender, age and death cause variables. Results: The overall underreporting rate was 9.21%(95%CI: 9.06%-9.39%) after adjusting by propensity score weighting method. The underreporting rate was higher in rural area (11.55%, 95%CI: 11.30%-11.81%) than in urban area (6.64%, 95%CI: 6.50%-6.78%). The underreporting rate was highest in age group 0-14 years (36.29%, 95% CI: 34.23%-38.67%) and lowest in age group ≥65 years (7.91%, 95% CI: 7.78%-8.03%). The underreporting rate was higher in people died of perinatal disease, congenital anomalies and injury. Conclusion: The underreporting rates were different between different groups classified by urban/rural areas, age and death cause variables. Propensity score weighting method can be used to adjust underreporting rate of death cases in mortality surveillance in Fujian.

Limits on Active to Sterile Neutrino Oscillations from Disappearance Searches in the MINOS, Daya Bay, and Bugey-3 Experiments

Searches for a light sterile neutrino have been performed independently by the MINOS and the Daya Bay experiments using the muon (anti)neutrino and electron antineutrino disappearance channels, respectively. In this Letter, results from both experiments are combined with those from the Bugey-3 reactor neutrino experiment to constrain oscillations into light sterile neutrinos. The three experiments are sensitive to complementary regions of parameter space, enabling the combined analysis to probe regions allowed by the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE experiments in a minimally extended four-neutrino flavor framework. Stringent limits on sin^{2}2θ_{μe} are set over 6 orders of magnitude in the sterile mass-squared splitting Δm_{41}^{2}. The sterile-neutrino mixing phase space allowed by the LSND and MiniBooNE experiments is excluded for Δm_{41}^{2}<0.8  eV^{2} at 95%  CL_{s}.

Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the 2×10^{-4}≲|Δm_{41}^{2}|≲0.3  eV^{2} mass range. The resulting limits on sin^{2}2θ_{14} are improved by approx imately a factor of 2 over previous results and constitute the most stringent constraints to date in the |Δm_{41}^{2}|≲0.2  eV^{2} region.

[Retroperitoneoscopic renal pedicle lymphatic disconnection for chyluria via extra-adipose capsule]

OBJECTIVE

To evaluate the clinical effect of retroperitoneoscopic renal pedicle lymphatic disconnection via extra-adipose capsule in the management of chyluria and to discuss the management of its complications.

METHODS

From August 2013 to June 2008, five patients with chyluria were admitted. All the patients were female, aged from 26 to 73 years, and disease course from 1 to 10 years. All the five patients had complained of intermittently voiding milky urine with varying degrees of weight loss, and fatigue, of whom two presented with flank pain and one with anemia. Their urine chyle tests were confirmed to be positive. Preoperative cystoscopy found that chyluria was from the left side in 3 cases,and from the right side in 2 cases. Their proteinuria ranged from + to ++++. All the cases had been treated with the modified procedure by which lymphatic ligation was performed to hilar vessels and proximalureter via extra-adipose capsule without disconnection of perirenal fat tissues. The operation time, intraoperative blood loss, postoperative intestinal function recovery, catheter time, drainage tube removal time and complications during operation were collected.

RESULTS

All the five cases were performed successfully. The operation time ranged from 75 to 170 minutes, mean (126.0±39.6) minutes, with the intraoperative blood loss 20 to 60 mL, mean (38.0±16.4) mL, and the postoperative intestinal function recovery time 1 to 3 days, mean (1.9±0.4) days. The catheter time was 1 to 4 days, mean (2.1±0.3) days and the drainage tube removal time ranged from 3 to 15 days, mean (9.3±1.8) days. Postoperatively lymphorrhagia was found in two cases. No renal vessels injury occurred during operation. Chyluria of all the patients disappeared on the operation day with negative chyluria test after surgery. Furthermore, urine test revealed that proteinuria was totally negative. No recurrence was detected in our patients in the 9 to 31 months' follow-up.

CONCLUSION

This modified procedure does not have to disconnect perirenal fat tissues and nephropexy during operation. It was characterized with shorter operation time, definitive effect and fewer complications.

Observation of Double Impurity Critical Gradients for Electromagnetic Turbulence Excitation in Tokamak Plasmas

The impact of impurity ions on a pedestal has been investigated in the HL-2A Tokamak, at the Southwestern Institute of Physics, Chengdu, China. Experimental results have clearly shown that during the H-mode phase, an electromagnetic turbulence was excited in the edge plasma region, where the impurity ions exhibited a peaked profile. It has been found that double impurity critical gradients are responsible for triggering the turbulence. Strong stiffness of the impurity profile has been observed during cyclic transitions between the I-phase and H-mode regime. The results suggest that the underlying physics of the self-regulated edge impurity profile offers the possibility for an active control of the pedestal dynamics via pedestal turbulence.

[Retroperitoneoscopic renal pedicle lymphatic disconnection for chyluria via extra-adipose capsule]

OBJECTIVE

To evaluate the clinical effect of retroperitoneoscopic renal pedicle lymphatic disconnection via extra-adipose capsule in the management of chyluria and to discuss the management of its complications.

METHODS

From August 2013 to June 2008, five patients with chyluria were admitted. All the patients were female, aged from 26 to 73 years, and disease course from 1 to 10 years. All the five patients had complained of intermittently voiding milky urine with varying degrees of weight loss, and fatigue, of whom two presented with flank pain and one with anemia. Their urine chyle tests were confirmed to be positive. Preoperative cystoscopy found that chyluria was from the left side in 3 cases,and from the right side in 2 cases. Their proteinuria ranged from + to ++++. All the cases had been treated with the modified procedure by which lymphatic ligation was performed to hilar vessels and proximalureter via extra-adipose capsule without disconnection of perirenal fat tissues. The operation time, intraoperative blood loss, postoperative intestinal function recovery, catheter time, drainage tube removal time and complications during operation were collected.

RESULTS

All the five cases were performed successfully. The operation time ranged from 75 to 170 minutes, mean (126.0±39.6) minutes, with the intraoperative blood loss 20 to 60 mL, mean (38.0±16.4) mL, and the postoperative intestinal function recovery time 1 to 3 days, mean (1.9±0.4) days. The catheter time was 1 to 4 days, mean (2.1±0.3) days and the drainage tube removal time ranged from 3 to 15 days, mean (9.3±1.8) days. Postoperatively lymphorrhagia was found in two cases. No renal vessels injury occurred during operation. Chyluria of all the patients disappeared on the operation day with negative chyluria test after surgery. Furthermore, urine test revealed that proteinuria was totally negative. No recurrence was detected in our patients in the 9 to 31 months' follow-up.

CONCLUSION

This modified procedure does not have to disconnect perirenal fat tissues and nephropexy during operation. It was characterized with shorter operation time, definitive effect and fewer complications.

Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18)  cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43)  cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

New measurement of antineutrino oscillation with the full detector configuration at Daya Bay

We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th}  ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3}  eV^{2} in the three-neutrino framework.

Note: Upgrade of electron cyclotron emission imaging system and preliminary results on HL-2A tokamak

The electron cyclotron emission imaging system on the HL-2A tokamak has been upgraded to 24 (poloidally) × 16 (radially) channels based on the previous 24 × 8 array. The measurement region can be flexibly shifted due to the independence of the two local oscillator sources, and the field of view can be adjusted easily by changing the position of the zoom lenses. The temporal resolution is about 2.5 μs and the achievable spatial resolution is 1 cm. After laboratory calibration, it was installed on HL-2A tokamak in 2014, and the local 2D mode structures of MHD activities were obtained for the first time.

Search for a light sterile neutrino at Daya Bay

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Calibration of a 32 channel electron cyclotron emission radiometer on the HL-2A tokamak

A novel 32-channel electron cyclotron emission radiometer has been designed and tested for the measurement of electron temperature profiles on the HL-2A tokamak. This system is based on the intermediate frequency filter detection technique, and has the features of wide working frequency range and high spatial resolution. Two relative calibration methods have been investigated: sweeping the toroidal magnetic field and hopping the output frequency of the local oscillator. Preliminary results show that both methods can ensure reasonable profiles.

Development of frequency modulated continuous wave reflectometer for electron density profile measurement on the HL-2A tokamak

The frequency modulated continuous wave reflectometer was developed for the first time on the HL-2A tokamak. The system utilizes a voltage controlled oscillator and an active multiplier for broadband coverage and detects as heterodyne mode. Three reflectometers have been installed and operated in extraordinary mode polarization on HL-2A to measure density profiles at low field side, covering the Q-band (33-50 GHz), V-band (50-75 GHz), and W-band (75-110 GHz). For density profile reconstruction from the phase shift of the probing wave, a corrected phase unwrapping method is introduced in this article. The effectiveness of the method is demonstrated. The density profile behavior of a fast plasma event is presented and it demonstrates the capability of the reflectometer. These diagnostics will be contributed to the routine density profile measurements and the plasma physics study on HL-2A.

Convective velocity reversal caused by turbulence transition in tokamak plasma

Particle transport has been studied in the Tore Supra tokamak by using modulated ion cyclotron resonance heating to generate perturbations of density and temperature. For the first time, a reversal of the particle convective velocity and a strong increase in the turbulent particle flux have been clearly observed. When the mixed critical gradient ζc=R/L(T)+4(R/L(n))=22 is exceeded, the particle flux increases sharply and the convective velocity reverses from inward to outward. These observations are in agreement with quasilinear, gyrokinetic calculations. The critical gradient corresponds to a transition from an instability driven by the ion temperature gradient to the onset of another instability caused by trapped electrons.

Development of electron cyclotron emission imaging system on the HL-2A tokamak

A 2D electron cyclotron emission imaging (ECEI) system has been developed for measurement of electron temperature fluctuations in the HL-2A tokamak. It is comprised of a front-end 24 channel heterodyne imaging array with a tunable RF range spanning 75-110 GHz, and a set of back-end ECEI electronics that together generate 24 × 8 = 192 channel images of the 2nd harmonic X-mode electron cyclotron emission from the HL-2A plasma. The simulated performance of the local oscillator (LO) optics and radio frequency (RF) optics is presented, together with the laboratory characterization results. The Gaussian beams from the LO optics are observed to properly cover the entire detector array. The ECE signals from the plasma are mixed with the LO signal in the array box, then delivered to the electronics system by low-loss microwave cables, and finally to the digitizers. The ECEI system can achieve temporal resolutions of ~μs, and spatial resolutions of 1 cm (radially) and 2 cm (poloidally).

Dynamics of low-intermediate-high-confinement transitions in toroidal plasmas

The dynamic features of the low-intermediate-high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type-Y and type-J), which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-Y, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-J. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types-Y and -J is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-J.

Frequency-resolved nonlinear turbulent energy transfer into zonal flows in strongly heated L-mode plasmas in the HL-2A tokamak

The absolute rate of nonlinear energy transfer among broadband turbulence, low-frequency zonal flows (ZFs) and geodesic acoustic modes (GAMs) was measured for the first time in fusion-grade plasmas using two independent methods across a range of heating powers. The results show that turbulent kinetic energy from intermediate frequencies (20-80 kHz) was transferred into ZFs and GAMs, as well as into fluctuations at higher frequencies (>80  kHz). As the heating power was increased, the energy transfer from turbulence into GAMs and the GAM amplitudes increased, peaked and then decreased, while the energy transfer into the ZFs and the ZFs themselves increased monotonically with heating power. Thus there exists a competition between ZFs and GAMs for the transfer of turbulent energy, and the transfer into ZFs becomes dominant as the heating power is increased. The poloidal-radial Reynolds stress and the mean radial electric field profiles were also measured at different heating powers and found to be consistent with the energy transfer measurement. The results suggest that ZFs play an important role in the low-to-high (L-H) plasma confinement transition.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

Time-frequency analysis for microwave reflectometry data processing in the HL-2A tokamak

The Choi-Williams distribution (CWD) technique is introduced as a time-frequency tool for processing data measured from the new developed homodyne and the fixed frequency reflectometry in the HL-2A tokamak. The comparison between spectrogram and CWD for the simulated signal is presented. It indicates that the CWD can greatly improve the representation of the time-frequency content of the multi-components signal. Its effectiveness is demonstrated through two applications in HL-2A, which are the extraction of beat frequencies from the frequency modulated-continuous wave reflectometry (FM-CW) and the characterizing of the fluctuations. The density profile inversed from the group delay of the FM-CW and the density fluctuations deduced from the fixed-frequency reflectometry would be more reliable and accurate by using the CWD technique.

First-Principles Study of the (001) Surface of Cubic SrHfO3 and SrTiO3

We have performed first-principles calculations on the (001) surface of cubic SrHfO(3) and SrTiO(3) with SrO and BO(2) (B = Ti or Hf) terminations. Surface structure, partial density of states, band structure, and surface energy have been obtained. For the BO(2)-terminated surface, the largest relaxation appears on the second-layer atoms but not on the first-layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the (001) surface for SrHfO(3) with SrO termination is stronger than that for SrTiO(3). For the HfO(2)-terminated surface of SrHfO(3), the surface state appears near the M point of its band structure.