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Characterization of a retroreflector array for 320-GHz interferometer system in Heliotron J. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:093501. [PMID: 37671952 DOI: 10.1063/5.0162649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/16/2023] [Indexed: 09/07/2023]
Abstract
A retroreflector array, composed of a cluster of small retroreflectors, is experimentally studied for application to a Michelson-type interferometer system in the fusion plasma experiment. Such a new-type reflector has the potential to be a vital and effective tool at a spatially limited location, such as on the vacuum chamber wall of plasma experimental devices. To investigate the effect of retroreflector array on the reflected beam properties, a tabletop experiment is performed with the retroreflector array composed of 4 mm corner-cube retroreflectors and with a 320-GHz (λ ∼ 0.937 mm) submillimeter wave source. An imaging camera is utilized to measure the submillimeter wave beam profile and is scanned perpendicularly to the beam propagation direction if necessary. The experimental result exhibits a diffraction effect on the reflected beam, resulting in the emergence of discrete peaks on the reflected beam profile, as predicted in the past numerical study; however, the most reflected beam power converges on the one reflected into the incident direction, resulting from a property as a retroreflector. Furthermore, the dependence of the reflected beam on the incident beam angle is characterized while fixing the detector position, and the retroreflection beam intensity is found to vary due to the diffraction effect. Such an undesired variation of beam intensity induced by the diffraction can be suppressed with a focusing lens placed in front of the detector in the practical application to an interferometer.
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Development and initial results of 320 GHz interferometer system in Heliotron J. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113519. [PMID: 36461432 DOI: 10.1063/5.0101808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 10/02/2022] [Indexed: 06/17/2023]
Abstract
A new 320 GHz solid-state source interferometer is installed in the Heliotron J helical device to explore the physics of high-density plasmas (ne > 2-3 × 1019 m-3, typically) realized with advanced fueling techniques. This interferometry system is of the Michelson type and is based on the heterodyne principle, with two independent solid-state sources that can deliver an output power of up to 50 mW. A high time resolution measurement of <1 µs can be derived by tuning the frequency of one source in the frequency range of 312-324 GHz on the new system, which can realize the fluctuation measurement. We successfully measured the line-averaged electron density in high-density plasma experiments. The measured density agreed well with a microwave interferometer measurement using a different viewing chord, demonstrating that the new system can be used for routine diagnostics of electron density in Heliotron J.
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3D metal powder additive manufacturing phased array antenna for multichannel Doppler reflectometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113535. [PMID: 36461436 DOI: 10.1063/5.0101723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/07/2022] [Indexed: 06/17/2023]
Abstract
Measuring the time variation of the wavenumber spectrum of turbulence is important for understanding the characteristics of high-temperature plasmas, and the application of a Doppler reflectometer with simultaneous multi-frequency sources is expected. To implement this diagnostic in future fusion devices, the use of a phased array antenna (PAA) that can scan microwave beams without moving antennas is recommended. Since the frequency-scanning waveguide leaky-wave antenna-type PAA has a complex structure, we have investigated its characteristics by modeling it with 3D metal powder additive manufacturing (AM). First, a single waveguide is fabricated to understand the characteristics of 3D AM techniques, and it is clear that there are differences in performance depending on the direction of manufacture and surface treatment. Then, a PAA is made, and it is confirmed that the beam can be emitted in any direction by frequency scanning. The plasma flow velocity can be measured by applying the 3D manufacturing PAA to plasma measurement.
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Receiver circuit improvement of dual frequency-comb ka-band Doppler backscattering system in the large helical device (LHD). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113518. [PMID: 36461466 DOI: 10.1063/5.0101588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/04/2022] [Indexed: 06/17/2023]
Abstract
Doppler-backscattering (DBS) has been used in several fusion plasma devices because it can measure the perpendicular velocity of electron density perturbation v⊥, the radial electric field Er, and the perpendicular wavenumber spectrum S(k⊥) with high wavenumber and spatial resolution. In particular, recently constructed frequency comb DBS systems enable observation of turbulent phenomena at multiple observation points in the radial direction. A dual-comb microwave DBS system has been developed for the large helical device plasma measurement. Since it is desirable to control the gain of each frequency-comb separately, a frequency-comb DBS system was developed with a function to adjust the gain of the scattered signal intensity of each channel separately. A correction processing method was also developed to correct the amplitude ratio and the phase difference between the in-phase and quadrature-phase signals of the scattered signals. As a result, the error in Doppler-shift estimation required to observe vertical velocity and the radial electric field was reduced, which enables more precise measurements.
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Characterization of Diarrhetic Shellfish Toxins in the Mizuhopecten yessoensis (Scallop) Midgut Gland by High-Performance Liquid Chromatography – Tandem Mass Spectrometry (HPLC-MS/MS). ANAL LETT 2022. [DOI: 10.1080/00032719.2022.2092633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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6
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Bayesian inference of ion velocity distribution function from laser-induced fluorescence spectra. Sci Rep 2021; 11:20810. [PMID: 34675232 PMCID: PMC8531337 DOI: 10.1038/s41598-021-00138-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 10/06/2021] [Indexed: 11/21/2022] Open
Abstract
The velocity distribution function is a statistical description that connects particle kinetics and macroscopic parameters in many-body systems. Laser-induced fluorescence (LIF) spectroscopy is utilized to measure the local velocity distribution function in spatially inhomogeneous plasmas. However, the analytic form of such a function for the system of interest is not always clear under the intricate factors in non-equilibrium states. Here, we propose a novel approach to select the valid form of the velocity distribution function based on Bayesian statistics. We formulate the Bayesian inference of ion velocity distribution function and apply it to LIF spectra locally observed at several positions in a linear magnetized plasma. We demonstrate evaluating the spatial inhomogeneity by verifying each analytic form of the local velocity distribution function. Our approach is widely applicable to experimentally establish the velocity distribution function in plasmas and fluids, including gases and liquids.
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Conceptual design of heavy ion beam probes on the PLATO tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053553. [PMID: 34243249 DOI: 10.1063/5.0041814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 05/05/2021] [Indexed: 06/13/2023]
Abstract
Heavy ion beam probe (HIBP) systems have been designed for the new tokamak, PLATO [A. Fujisawa, AIP Conf. Proc. 1993, 020011 (2018)]. The designs have been completed, and the installations are in progress. Two HIBPs are being installed in toroidal sections 180° apart to investigate long-range correlations in the toroidal direction. Each HIBP consists of an injection beamline and a detection beamline as usual. Yet, one of the HIBPs is equipped with an additional detection beamline; the measurement positions of its two detection beamlines can be placed on almost the same magnetic surface yet at poloidal angles that differ by ∼180°. The use of three detection beamlines allows us to investigate spatial asymmetry and long-range correlations in both the toroidal and poloidal directions, simultaneously. The detected beam intensity is expected to be enough for turbulence measurements in almost the entire plasma region when the electron density is up to 1 × 1019 m-3 by selecting appropriate ion species for the probe beam. Each detector has three channels 10 mm apart, allowing measurement of local structures of micro-scale turbulence. Therefore, using the HIBPs on the PLATO tokamak will enable both local and global properties of plasma turbulence to be investigated, simultaneously.
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W-band millimeter-wave back-scattering system for high wavenumber turbulence measurements in LHD. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043536. [PMID: 34243406 DOI: 10.1063/5.0043474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/01/2021] [Indexed: 06/13/2023]
Abstract
A 90 GHz W-band millimeter-wave back-scattering system is designed and installed for measuring electron scale turbulence (k⊥ρs ∼ 40). A metal lens relay antenna is used for in-vessel beam focusing, and a beam diameter of less than 40 mm is achieved in the plasma core region. This antenna can be steered at an angle of 159° ± 6°, which almost covers the plasma radius. The estimated size of the scattering volume is ∼105 mm at the edge and 135 mm at the core, respectively. A 60 m corrugated waveguide is used to achieve a low transmission loss of ∼8 dB. A heterodyne detection system for millimeter-wave circuits with probing power modulation can distinguish the scattered signal from background noise.
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Prostaglandin D 2 metabolite is not a useful clinical indicator for assessing atopic dermatitis. Clin Exp Dermatol 2020; 46:130-134. [PMID: 32705704 DOI: 10.1111/ced.14393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/17/2020] [Accepted: 07/10/2020] [Indexed: 11/29/2022]
Abstract
Prostaglandin D2 (PGD2 ) plays an important role in atopic dermatitis (AD), and 11,15-dioxo-9α-hydroxy-2,3,4,5-tetranorprostan-1,20-dioicacid (PGDM) is a major metabolite of PGD2 . We investigated the relationship between urinary PGDM levels and severity of paediatric AD. In total, 31 patients with AD and 21 healthy controls (HCs) without AD were recruited, and urinary PGDM levels were measured. Of the 31 patients with AD, 14 were reassessed for urinary PGDM after topical steroid therapy. There was no difference in urinary PGDM levels between patients with AD and HCs. Although there was a significant positive correlation between the SCORing Atopic Dermatitis (SCORAD) index and the serum level of thymus and activation-regulated chemokine (TARC), the urinary PGDM levels did not correlate with either SCORAD or serum TARC. Moreover, both SCORAD and serum TARC were significantly improved by topical steroid therapy; however, urinary PGDM levels were not changed. In conclusion, the level of urinary PGD2 metabolites in children with AD is substantially the same as that in HCs even if the disease is severe.
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Tomography system for two-dimensional observation of fluctuation in magnetized plasma. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:033502. [PMID: 32259999 DOI: 10.1063/1.5144480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
A tomography system is developed for observing local fluctuations, pursuing higher spatial resolution, over the entire plasma of a linear cylindrical plasma. The system is equipped with totally 126 lines-of-sight that are distributed equally to six sets of light guide arrays placed around the plasma. The system has succeeded in measuring the two-dimensional structure of plasma emission and resolving coherent fluctuation structures, with spatial resolution comparable to the ion Larmor radius.
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11
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Characterization of scallop midgut gland certified reference material for quantification of diarrhetic shellfish toxins. Food Chem 2019; 298:125011. [PMID: 31261011 DOI: 10.1016/j.foodchem.2019.125011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 05/23/2019] [Accepted: 06/13/2019] [Indexed: 10/26/2022]
Abstract
A scallop midgut gland certified reference material, NMIJ CRM 7520-a, was developed for validation and quality assurance during the inspection of shellfish for diarrhetic shellfish toxins. The candidate material was prepared by using naturally-toxic and nontoxic boiled midgut glands spiked with okadaic acid (OA). The homogeneity and stability of the material were found to be appropriate. For the characterization of OA and dinophysistoxin-1 (DTX1), nine participants were involved in a co-laboratory study based on the Japanese Official Testing Method, where the compounds were assayed by liquid chromatography-tandem mass spectrometry following alkaline hydrolysis. The analytical values were obtained by the standard addition method with a standard spiking solution calibrated using the standard-solution certified reference materials OA and DTX1. The certified concentrations with expanded uncertainties (coverage factor k = 2, approximate 95% confidence interval) were determined to be (0.205 ± 0.061) mg/kg for OA and (0.45 ± 0.11) mg/kg for DTX1.
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12
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Microwave frequency comb Doppler reflectometer applying fast digital data acquisition system in LHD. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H118. [PMID: 30399698 DOI: 10.1063/1.5035118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
We succeeded in increasing the radial observation points of the microwave frequency comb Doppler reflectometer system from 8 to 20 (or especially up to 45) using the high sampling rate of 40 GS/s digital signal processing. For a new acquisition system, the estimation scheme of the Doppler shifted frequency is constructed and compared with the conventional technique. Also, the fine radial profile of perpendicular velocity is obtained, and it is found that the perpendicular velocity profile is consistent with the E × B drift velocity one.
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13
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Interlaboratory comparison of liquid chromatography-tandem mass spectrometry quantification of diarrhetic shellfish toxins in scallop midgut glands. Food Chem 2018; 252:366-372. [DOI: 10.1016/j.foodchem.2018.01.105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 01/04/2018] [Accepted: 01/14/2018] [Indexed: 11/25/2022]
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14
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Quantification of Turbulent Driving Forces for the Geodesic Acoustic Mode in the JFT-2M Tokamak. PHYSICAL REVIEW LETTERS 2018; 120:045002. [PMID: 29437414 DOI: 10.1103/physrevlett.120.045002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/29/2017] [Indexed: 06/08/2023]
Abstract
We investigate spatial structures of turbulence and turbulent transport modulated by the geodesic acoustic mode (GAM), from which the excitation mechanism of the GAM is discussed. The GAM is found to be predominantly excited through a localized Reynolds stress force, rather than the dynamic shearing force. The evaluated growth rate is larger than the linear damping coefficients and is on the same order of magnitude as the effective growth rate evaluated from time evolution in the GAM kinetic energy.
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15
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Turbulent transport reduction induced by transition on radial electric field shear and curvature through amplitude and cross-phase in torus plasma. Sci Rep 2017; 7:14971. [PMID: 29097702 PMCID: PMC5668279 DOI: 10.1038/s41598-017-14821-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/16/2017] [Indexed: 11/23/2022] Open
Abstract
Spatiotemporal evolutions of radial electric field and turbulence are measured simultaneously in the H-mode transition, which is a prototypical example of turbulence structure formation in high-temperature plasmas. In the dynamical phase where transport barrier is established abruptly, the time-space-frequency-resolved turbulent particle flux is obtained. Here we report the validation of the mechanism of transport barrier formation quantitatively. It is found that the particle flux is suppressed predominantly by reducing density fluctuation amplitude and cross phase between density fluctuation and potential fluctuation. Both radial electric field shear and curvature are responsible for the amplitude suppression as was predicted by theory. Turbulence amplitude reduction immediately responds to the growth of the radial electric field non-uniformity and saturates, while cross phase continuously approaches zero.
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16
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Potential and Density Fluctuation Characteristics of the Hot-Cathode-Biased Supersonic Plasma in TU-Heliac. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst07-a1370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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17
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18
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Developments of Electron Cyclotron Emission Spectroscopy and Microwave Reflectometry on LHD. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst10-a10822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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19
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Configuration Effect on Energy Confinement and Local Transport in LHD and Contribution to the International Stellarator Database. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst04-a543] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Improvement of Plasma Core Confinement Via Electron-Root Realization by Strongly Focused ECRH in LHD: Core Electron-Root Confinement. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst10-a10791] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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21
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Experimental Study on Nonlocality of Heat Transport in LHD. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst10-a10799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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22
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Effects of Rational Surfaces and Magnetic Islands on Radial Electric Fields and Ion Viscosity in Tohoku University Heliac. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst06-a1236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Characteristics of the Global Energy Confinement and Central Pressure in LHD. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst10-a10790] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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25
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Electron Cyclotron Heating Applied to the JT-60U Tokamak. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst08-a1659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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26
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Synchronization of Geodesic Acoustic Modes and Magnetic Fluctuations in Toroidal Plasmas. PHYSICAL REVIEW LETTERS 2016; 117:145002. [PMID: 27740841 DOI: 10.1103/physrevlett.117.145002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 06/06/2023]
Abstract
The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a dominant GAM, and m/n=6/2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m/n=6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n=6/2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. Such nonlinear synchronization may also contribute to low-frequency zonal flow formation, reduction of turbulence level, and thus confinement regime transitions.
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Experimental Identification of Electric Field Excitation Mechanisms in a Structural Transition of Tokamak Plasmas. Sci Rep 2016; 6:30720. [PMID: 27489128 PMCID: PMC4973265 DOI: 10.1038/srep30720] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 07/06/2016] [Indexed: 11/09/2022] Open
Abstract
Self-regulation between structure and turbulence, which is a fundamental process in the complex system, has been widely regarded as one of the central issues in modern physics. A typical example of that in magnetically confined plasmas is the Low confinement mode to High confinement mode (L-H) transition, which is intensely studied for more than thirty years since it provides a confinement improvement necessary for the realization of the fusion reactor. An essential issue in the L-H transition physics is the mechanism of the abrupt "radial" electric field generation in toroidal plasmas. To date, several models for the L-H transition have been proposed but the systematic experimental validation is still challenging. Here we report the systematic and quantitative model validations of the radial electric field excitation mechanism for the first time, using a data set of the turbulence and the radial electric field having a high spatiotemporal resolution. Examining time derivative of Poisson's equation, the sum of the loss-cone loss current and the neoclassical bulk viscosity current is found to behave as the experimentally observed radial current that excites the radial electric field within a few factors of magnitude.
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Reconstruction of high temporal resolution Thomson scattering data during a modulated electron cyclotron resonance heating using conditional averaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:043505. [PMID: 27131672 DOI: 10.1063/1.4945258] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This paper provides a software application of the sampling scope concept for fusion research. The time evolution of Thomson scattering data is reconstructed with a high temporal resolution during a modulated electron cyclotron resonance heating (MECH) phase. The amplitude profile and the delay time profile of the heat pulse propagation are obtained from the reconstructed signal for discharges having on-axis and off-axis MECH depositions. The results are found to be consistent with the MECH deposition.
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Abstract
The variety of scalar and vector fields in laboratory and nature plasmas is formed by plasma turbulence. Drift-wave fluctuations, driven by density gradients in magnetized plasmas, are known to relax the density gradient while they can generate flows. On the other hand, the sheared flow in the direction of magnetic fields causes Kelvin-Helmholtz type instabilities, which mix particle and momentum. These different types of fluctuations coexist in laboratory and nature, so that the multiple mechanisms for structural formation exist in extremely non-equilibrium plasmas. Here we report the discovery of a new order in plasma turbulence, in which chained structure formation is realized by cross-interaction between inhomogeneities of scalar and vector fields. The concept of cross-ferroic turbulence is developed, and the causal relation in the multiple mechanisms behind structural formation is identified, by measuring the relaxation rate and dissipation power caused by the complex turbulence-driven flux.
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Nonlinear Excitation of Subcritical Instabilities in a Toroidal Plasma. PHYSICAL REVIEW LETTERS 2016; 116:015003. [PMID: 26799024 DOI: 10.1103/physrevlett.116.015003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Indexed: 06/05/2023]
Abstract
In a collisionless plasma, it is known that linearly stable modes can be destabilized (subcritically) by the presence of structures in phase space. However, nonlinear growth requires the presence of a seed structure with a relatively large threshold in amplitude. We demonstrate that, in the presence of another, linearly unstable (supercritical) mode, wave-wave coupling can provide a seed, which is significantly below the threshold, but can still grow by (and only by) the collaboration of fluid and kinetic nonlinearities. By modeling the subcritical mode kinetically, and the impact of the supercritical mode by simple wave-wave coupling equations, it is shown that this new kind of subcritical instability can be triggered, even when the frequency of the supercritical mode is rapidly sweeping. The model is applied to the bursty onset of geodesic acoustic modes in a LHD experiment. The model recovers several key features such as relative amplitude, time scales, and phase relations. It suggests that the strongest bursts are subcritical instabilities, driven by this mechanism of combined fluid and kinetic nonlinearities.
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Strong Destabilization of Stable Modes with a Half-Frequency Associated with Chirping Geodesic Acoustic Modes in the Large Helical Device. PHYSICAL REVIEW LETTERS 2016; 116:015002. [PMID: 26799023 DOI: 10.1103/physrevlett.116.015002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 06/05/2023]
Abstract
Abrupt and strong excitation of a mode has been observed when the frequency of a chirping energetic-particle driven geodesic acoustic mode (EGAM) reaches twice the geodesic acoustic mode (GAM) frequency. The frequency of the secondary mode is the GAM frequency, which is a half-frequency of the primary EGAM. Based on the analysis of spatial structures, the secondary mode is identified as a GAM. The phase relation between the secondary mode and the primary EGAM is locked, and the evolution of the growth rate of the secondary mode indicates nonlinear excitation. The results suggest that the primary mode (EGAM) contributes to nonlinear destabilization of a subcritical mode.
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Method for estimating the propagation direction of a coherent plasma structure using a one-dimensional diagnostic array. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:083507. [PMID: 25173269 DOI: 10.1063/1.4893482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This article proposes a new method to evaluate basic characteristics of the dynamics of a coherent plasma structure (blob). With this method, one can evaluate the propagation angle of a blob in a two-dimensional plasma cross section as well as the blob velocity, size, and amplitude from one-dimensional data. The method is applied to blob measurements from the Lithium beam emission spectroscopy system in ASDEX-Upgrade. Statistical features of the observed blob velocities, angles of propagation, blob sizes, and amplitudes are discussed. The validity of the method is examined by comparing two values of the propagation angle that are evaluated in an independent manner.
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Spatiotemporal structures of edge limit-cycle oscillation before L-to-H transition in the JFT-2M tokamak. PHYSICAL REVIEW LETTERS 2013; 111:035002. [PMID: 23909334 DOI: 10.1103/physrevlett.111.035002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 06/02/2023]
Abstract
In this Letter, we report analyses of spatiotemporal dynamics of turbulence and structure in the limit-cycle oscillation (LCO) that precedes an L-to-H transition. Zonal flows are not observed during LCO, and the oscillation is the periodic generations or decays of barrier with edge-localized mean flow. Oscillatory Reynolds stress is found to be too small to accelerate the LCO flow, by considering the dielectric constant in magnetized toroidal plasmas. Propagation of changes of the density gradient and turbulence amplitude into the core is also observed.
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A novel derivatization reagent possessing a bromoquinolinium structure for biological carboxylic acids in HPLC-ESI-MS/MS. J Sep Sci 2013; 36:1883-9. [DOI: 10.1002/jssc.201300083] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/25/2013] [Accepted: 03/27/2013] [Indexed: 11/08/2022]
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What triggers differential DNA methylation of genes and TEs: contribution of body methylation? COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2013; 77:155-60. [PMID: 23302809 DOI: 10.1101/sqb.2013.77.016212] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Transposable elements (TEs) are epigenetically silenced with extensive DNA methylation. The silent epigenetic marks should, however, be excluded from active genes. By genetic approaches, we study mechanisms to remove the heterochromatin marks from transcribed genes. Based on our observations on control of TE transcription, we propose a possible trigger for the TE-specific accumulation of DNA methylation. A critical difference between TEs and genes could be their responses to the DNA methylation in the internal part of transcribed regions. When their internal region is methylated, genes are still transcribed, but TEs could be silenced, which may reflect the obligatory position of every critical cis-acting element within the TE itself. This initial difference of TEs and genes will be amplified by positive feedback loops to stabilize active or silent states. Thus, the mechanisms to accumulate heterochromatin marks within transcribed regions could provide a trigger to induce differential DNA methylation between genes and TEs.
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Potential involvement of collagen-binding proteins of Streptococcus mutans in infective endocarditis. Oral Dis 2012; 19:387-93. [PMID: 22998492 DOI: 10.1111/odi.12016] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/13/2012] [Accepted: 08/20/2012] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Streptococcus mutans, a major pathogen of dental caries, is considered to be one of the causative agents of infective endocarditis (IE). Two types of cell surface collagen-binding proteins, Cnm and Cbm, have been identified in the organism. The aim of the present study was to analyze these proteins as possible etiologic factors for IE. MATERIALS AND METHODS The binding activities of S. mutans strains to collagen types I, III, and IV were analyzed relative to the presence of Cnm and Cbm, as were their adhesion and invasion properties with human umbilical vein endothelial cells (HUVEC). In addition, distributions of the genes encoding Cnm and Cbm in S. mutans-positive heart valve specimens extirpated from IE and non-IE patients were analyzed by PCR. RESULTS Most of the Cbm-positive strains showed higher levels of binding to type I collagen as well as higher rates of adhesion and invasion with HUVEC as compared to the Cnm-positive strains. Furthermore, the gene encoding Cbm was detected significantly more frequently in heart valve specimens from IE patients than from non-IE patients. CONCLUSIONS These results suggest that the collagen-binding protein Cbm of S. mutans may be one of the potential important factor associated with the pathogenesis of IE.
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Enhanced translational diffusion of confined water under electric field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:021506. [PMID: 23005768 DOI: 10.1103/physreve.86.021506] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/09/2012] [Indexed: 06/01/2023]
Abstract
High resolution quasielastic neutron scattering measurements have been used to study the effects of applied electric field on the dynamics of water molecules confined in the pores of folded silica sheet material FSM-12 with an average pore diameter (apd) of 16 Å. In the absence of field, there is a significant slowing down of the water molecule diffusion as the temperature is lowered, in agreement with previous observations. The application of a moderate electric field of 2.5 kV/mm remarkably enhances the translational diffusion of water molecules. We interpret this as being due to a disruption of the hydrogen bonding by the electric field. This new observation suggests that existing theories valid at large electric field strengths may have to be corrected at moderate fields.
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Rapid enantiomeric separation and simultaneous determination of phenethylamines by ultra high performance liquid chromatography with fluorescence and mass spectrometric detection: application to the analysis of illicit drugs distributed in the Japanese ma. Drug Test Anal 2012; 4:1001-8. [DOI: 10.1002/dta.1327] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 01/11/2012] [Accepted: 01/13/2012] [Indexed: 11/11/2022]
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Progress of ECRH by EBW in over-dense plasmas and controlling the confinement regime by ECCD with high power launching in LHD. EPJ WEB OF CONFERENCES 2012. [DOI: 10.1051/epjconf/20123202006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Protocol dependence of mechanical properties in granular systems. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2011; 34:124. [PMID: 22113399 DOI: 10.1140/epje/i2011-11124-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 10/28/2011] [Indexed: 05/31/2023]
Abstract
We study the protocol dependence of the mechanical properties of granular media by means of computer simulations. We control a protocol of realizing disk packings in a systematic manner. In 2D, by keeping material properties of the constituents identical, we carry out compaction with various strain rates. The disk packings exhibit the strain rate dependence of the critical packing fraction above which the pressure becomes non-zero. The observed behavior contrasts with the well-studied jamming transitions for frictionless disk packings. We also observe that the elastic moduli of the disk packings depend on the strain rate logarithmically. Our results suggest that there exists a time-dependent state variable to describe macroscopic material properties of disk packings, which depend on its protocol.
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Observation of long-distance radial correlation in toroidal plasma turbulence. PHYSICAL REVIEW LETTERS 2011; 107:115001. [PMID: 22026678 DOI: 10.1103/physrevlett.107.115001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Indexed: 05/31/2023]
Abstract
This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ∼1-3 kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ∼2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.
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Stable isotope-dilution liquid chromatography/tandem mass spectrometry method for determination of thyroxine in saliva. J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:1013-7. [DOI: 10.1016/j.jchromb.2011.02.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 10/18/2022]
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A specific LC/ESI-MS/MS method for determination of 25-hydroxyvitamin D3 in neonatal dried blood spots containing a potential interfering metabolite, 3-epi-25-hydroxyvitamin D3. J Sep Sci 2011; 34:725-32. [PMID: 21328697 DOI: 10.1002/jssc.201000911] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 01/13/2011] [Accepted: 01/15/2011] [Indexed: 11/06/2022]
Abstract
Vitamin D deficiency in an infant is associated with a wide range of adverse health outcomes in later life. A method for the quantification of 25-hydroxyvitamin D(3) [25(OH)D(3), the best-established indicator of vitamin D status] in neonatal dried blood spots (DBSs) using LC/ESI-MS/MS has been developed and validated. The method employed two steps of derivatization, a Diels-Alder reaction with 4-phenyl-1,2,4-triazoline-3,5-dione followed by acetylation, to enhance the detectability of 25(OH)D(3) in ESI-MS/MS and to separate 25(OH)D(3) from 3-epi-25-hydroxyvitamin D(3) [3-epi-25(OH)D(3)], a potent interfering metabolite. 25(OH)D(3) was extracted from two DBS punches (3 mm in diameter, equivalent to 5.3 μL of whole blood), purified using an Oasis HLB(®) cartridge, and subjected to derivatization prior to analysis with LC/ESI-MS/MS. 25-Hydroxyvitamin D(4) was used as the internal standard. This method was reproducible (intra- and inter-assay RSDs, <6.9%) and accurate (analytical recovery, 95.2-102.7%), and the LOQ was 3.0 ng/mL. The developed method enabled specific quantification of 25(OH)D(3) in neonatal DBSs and detection of vitamin D deficiency without interference from 3-epi-25(OH)D(3).
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Inhibitory effects of Oenothera biennis (evening primrose) seed extract on Streptococcus mutans and S. mutans-induced dental caries in rats. Caries Res 2011; 45:56-63. [PMID: 21311187 DOI: 10.1159/000323376] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 11/29/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Oenothera biennis (evening primrose) seed extract (OBSE) is known to contain polyphenols, which may possess antioxidant activities. Polyphenols extracted from several plants are reported to exhibit cariostatic activities by inhibiting mutans streptococcus growth and glucosyltransferase activities. The purpose of the present study was to examine the inhibitory effects of OBSE on the development of dental caries, both in vitro and in vivo. METHODS OBSE was investigated for its inhibitory effects on cellular aggregation, hydrophobicity, sucrose-dependent adherence and insoluble glucan synthesis. Furthermore, biofilm formation was examined in the presence of OBSE, using confocal microscopic imaging. An animal experiment was also performed to examine the in vivo effects. RESULTS OBSE induced a strong aggregation of Streptococcus mutans MT8148 cells, while cell surface hydrophobicity was decreased by approximately 90% at a concentration of 0.25 mg/ml. The sucrose-dependent adherence of the MT8148 cells was also reduced by addition of OBSE, with a reduction rate of 73% seen at a concentration of 1.00 mg/ml. Additionally, confocal microscopic observations revealed the biofilm development phase to be remarkably changed in the presence of OBSE. Furthermore, insoluble glucan synthesis was significantly reduced when OBSE was present at concentrations greater than 0.03 mg/ml. In an animal experiment, the caries scores in rats given OBSE (0.05 mg/ml in drinking water) were significantly lower than those in rats given water without OBSE. CONCLUSION Our results indicate that OBSE has inhibitory activity on dental caries.
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Development and validation of stable-isotope dilution liquid chromatography-tandem mass spectrometric method for determination of salivary progesterone. Biomed Chromatogr 2011; 25:1175-80. [DOI: 10.1002/bmc.1586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 11/09/2010] [Accepted: 11/09/2010] [Indexed: 11/06/2022]
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Simultaneous determination of polyamines in human nail as 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole derivatives by nano-flow chip LC coupled with quadrupole time-of-flight tandem mass spectrometry. Clin Chim Acta 2011; 412:98-106. [DOI: 10.1016/j.cca.2010.09.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2010] [Revised: 09/15/2010] [Accepted: 09/16/2010] [Indexed: 12/01/2022]
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Biomarker discovery in biological specimens (plasma, hair, liver and kidney) of diabetic mice based upon metabolite profiling using ultra-performance liquid chromatography with electrospray ionization time-of-flight mass spectrometry. Clin Chim Acta 2010; 412:861-72. [PMID: 21185819 DOI: 10.1016/j.cca.2010.12.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 12/16/2010] [Accepted: 12/17/2010] [Indexed: 01/02/2023]
Abstract
BACKGROUND The number of diabetic patients has recently been increasing worldwide. Diabetes is a multifactorial disorder based on environmental factors and genetic background. In many cases, diabetes is asymptomatic for a long period and the patient is not aware of the disease. Therefore, the potential biomarker(s), leading to the early detection and/or prevention of diabetes mellitus, are strongly required. However, the diagnosis of the prediabetic state in humans is a very difficult issue, because the lifestyle is variable in each person. Although the development of a diagnosis method in humans is the goal of our research, the extraction and structural identification of biomarker candidates in several biological specimens (i.e., plasma, hair, liver and kidney) of ddY strain mice, which undergo naturally occurring diabetes along with aging, were carried out based upon a metabolite profiling study. METHODS The low-molecular-mass compounds including metabolites in the biological specimens of diabetic mice (ddY-H) and normal mice (ddY-L) were globally separated by ultra-performance liquid chromatography (UPLC) using different reversed-phase columns (i.e., T3-C18 and HS-F5) and detected by electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). The biomarker candidates related to diabetes mellitus were extracted from a multivariate statistical analysis, such as an orthogonal partial least-squares-discriminant analysis (OPLS-DA), followed by a database search, such as ChemSpider, KEGG and HMDB. RESULTS Many metabolites and unknown compounds in each biological specimen were detected as the biomarker candidates related to diabetic mellitus. Among them, the elucidation of the chemical structures of several possible metabolites, including more than two biological specimens, was carried out along with the comparison of the tandem MS/MS analyses using authentic compounds. One metabolite was clearly identified as N-acetyl-L-leucine based upon the MS/MS spectra and the retention time on the chromatograms. CONCLUSIONS N-acetyl-L-leucine is an endogenous compound included in all biological specimens (plasma, hair, liver and kidney). Therefore, this metabolite appears to be a potential biomarker candidate related to diabetes. Although the structures of other biomarker candidates have still not yet determined, the present approach based upon a metabolite profiling study using UPLC-ESI-TOF-MS could be helpful for understanding the abnormal state of various diseases.
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Practical analytical approach for the identification of biomarker candidates in prediabetic state based upon metabonomic study by ultraperformance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry. J Proteome Res 2010; 9:3912-22. [PMID: 20557141 DOI: 10.1021/pr100121k] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The number of diabetic patients has recently been increasing worldwide. Thus, the discovery of potential diabetic biomarker(s), leading to the early detection and/or prevention of diabetes mellitus, is strongly required. The diagnosis of the prediabetic state in humans is a very difficult issue because of the lifestyle differences in each person and ethical consideration. Upon the basis of these considerations, animal experiments using ddY strain mice (ddY-H), which undergo naturally occurring diabetes along with age, were carried out in this study. Biomarker discovery based upon a metabonome study is now quite common, the same as that in the proteome analysis. Reversed-phase liquid chromatography-mass spectrometry (LC-MS) has mainly been used for the extensive analysis of low-molecular mass compounds including metabolites. The metabolites in the plasma of diabetic mice (ddY-H) and normal mice (ddY-L) were exhaustively separated and detected by ultraperformance liquid chromatography along with electrospray ionization time-of-flight mass spectrometry (UPLC-ESI-TOF-MS) using T3-C18 and HS-F5 columns. The biomarker candidates related to diabetes mellitus were extracted from the metabolite profiling of ddY-H and ddY-L at 5, 9 13, and 20 weeks old using a multivariate statistical analysis such as orthogonal partial least-squares-discriminant analysis (OPLS-DA). Various metabolites and unknown compounds were detected as biomarker candidates related to diabetic mellitus. Furthermore, the concentration of several metabolites on Lysine biosynthesis and Lysine degradation pathways were remarkably changed between the 9-week old ddY-H and ddY-L mice. Because a couple of biomarker candidates related to the prediabetic state were identified using the present approach, the metabolite profiling study could be helpful for understanding the abnormal state of various diseases.
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