Spectroscopic observation of super-Alfvénic field-reversed configuration merging process by mixing of tracer ions.

Visualization of the collisional merging formation process of field-reversed configuration (FRC) has been attempted. In the collisional merging formation process, two initial FRC-like plasmoids are accelerated toward each other by a magnetic pressure gradient. The relative speed of the collision reaches several times the typical ion sonic speed and Alfvénic speed. The magnetic structure of the initial-FRCs is disrupted in the collision process, but the FRC-like magnetic structure is reformed in ∼30 µs after the collision. Magnetic reconnection should occur in this process; however, general theoretical models in magnetohydrodynamics approximation cannot be applied to this process because of the high-beta nature of FRC and super-Alfvénic/sonic relative speed. In this work, the spectroscopic observation of the collisional merging FRC formation was conducted to evaluate the timescale and geometry of merging. A slight amount of tracer element (e.g., helium) was mixed into one of two initial-FRCs. Mixing of the tracer did not cause serious adverse effects on the performance of the initial-FRC in the collision and merging processes. The collision and merging processes were visualized successfully and observed using a fast-framing camera with a bandpass filter. The timescale of merging and the outflow speed in the collisional merging process of FRCs were optically evaluated for the first time.

Development of new experimental setup focusing on long-pulse magnetic reconnection by using rotating magnetic field technique.

A new closed-type experimental setup to achieve a long-pulse magnetic reconnection in weakly ionized plasmas was developed by using a rotating magnetic field (RMF) technique. The experimental setup has a cylindrical vacuum vessel in which two sets of four antennas are equipped to generate RMF which drives steady azimuthal electron current in two torus plasmas. This device provided a quasi-steady magnetic reconnection condition in weakly ionized plasmas with ionization fraction of less than 1%. The proposed experimental setup will extend the research area of laboratory reconnection experiments and be helpful to comprehend the reconnection process in weakly ionized plasmas such as solar chromosphere.

Electron and Ion Heating Characteristics during Magnetic Reconnection in the MAST Spherical Tokamak.

Electron and ion heating characteristics during merging reconnection start-up on the MAST spherical tokamak have been revealed in detail using a 130 channel yttrium aluminum garnet (YAG) and a 300 channel Ruby-Thomson scattering system and a new 32 chord ion Doppler tomography diagnostic. Detailed 2D profile measurements of electron and ion temperature together with electron density have been achieved for the first time and it is found that electron temperature forms a highly localized hot spot at the X point and ion temperature globally increases downstream. For the push merging experiment when the guide field is more than 3 times the reconnecting field, a thick layer of a closed flux surface form by the reconnected field sustains the temperature profile for longer than the electron and ion energy relaxation time ~4-10 ms, both characteristic profiles finally forming a triple peak structure at the X point and downstream. An increase in the toroidal guide field results in a more peaked electron temperature profile at the X point, and also produces higher ion temperatures at this point, but the ion temperature profile in the downstream region is unaffected.

Development of multi-channel Doppler spectroscopic measurement system using 8 × 8 multianode photomultiplier tube assembly.

Using an 8 × 8 channel photomultiplier tube assembly and a single Czerny-Turner monochromator, we have developed a novel Doppler spectroscopic system which can measure the time evolutions of spectral distribution of plasma emission from eight different lines of sight simultaneously. An optical lens system is employed to couple the output of the monochromator with the detector assembly, resulting in small cross-talks less than 5% in spatial distribution together with large magnification of up to 50 in wavelength direction. The suggested system yields cost-effective polychromatic measurements of eight spatial channels with uniform optical and electrical characteristics.

Ion and electron heating characteristics of magnetic reconnection in a two flux loop merging experiment.

Characteristics of the high-power reconnection heating were measured for the first time directly by two-dimensional measurements of ion and electron temperatures. While electrons are heated mainly inside the current sheet by the Ohmic heating power, ions are heated mainly by fast shock or viscosity damping of the reconnection outflow in the two downstream areas. The magnetic reconnection converts the energy of reconnecting magnetic field B(p) mostly to the ion thermal energy, indicating that the reconnection heating energy is proportional to B(p)(2).

Development of effective power supply using electric double layer capacitor for static magnetic field coils in fusion plasma experiments.

A cost-effective power supply for static magnetic field coils used in fusion plasma experiments has been developed by application of an electric double layer capacitor (EDLC). A prototype EDLC power supply system was constructed in the form of a series LCR circuit. Coil current of 100 A with flat-top longer than 1 s was successfully supplied to an equilibrium field coil of a fusion plasma experimental apparatus by a single EDLC module with capacitance of 30 F. The present EDLC power supply has revealed sufficient performance for plasma confinement experiments whose discharge duration times are an order of several seconds.

Host Status of Graminaceous Cover Crops for Pratylenchus brachyurus.

Taking into account that information about the host status of cover crops for Pratylenchus brachyurus is scarce or contradictory, this study was undertaken to assess the host status of selected graminaceous cover crops by estimating nematode reproduction and their ability to decrease the nematode density in glasshouse conditions. Furthermore, the reproductive fitness of three P. brachyurus populations was assessed for Brachiaria grasses. Silage and forage sorghum proved to be good hosts for P. brachyurus; consequently, they should be avoided in fields infested with this lesion nematode, mainly before susceptible crop such as soybean, common bean, cowpea, and cotton. Dictyoneura grass, the pearl millet cv. ADR 300, and black oat were poor hosts for P. brachyurus but may increase densities of this nematode over time. Consequently, these cover crops might be used in infested fields for only short periods, because they could increase the P. brachyurus population density slowly but progressively.

Inductive sustainment of a field-reversed configuration stabilized by shaping, magnetic diffusion, and finite-Larmor-radius effects.

Oblate field-reversed configuration (FRC) plasmas are sustained for up to 350 micros, or approximately 15 poloidal flux-confinement times, in the magnetic reconnection experiment. The diamagnetic equilibrium is maintained in argon plasmas as a balance of an inward pinch and outward diffusion. Numerical and analytic models show that the observed stability is provided by a combination of plasma shaping, magnetic diffusion, and finite-Larmor radius effects. FRCs formed with lighter ions, which benefit less from these stabilizing effects, succumb to rapid instability and cannot be sustained.

Host-range characterization of two Pratylenchus coffeae isolates from Brazil.

Two isolates of Pratylenchus coffeae were collected from coffee roots (in Marília, São Paulo State, Brazil) and Aglaonema (in Rio de Janeiro City, Rio de Janeiro State, Brazil) and maintained in the laboratory on alfalfa callus. Twenty-four plants were tested in the greenhouse to characterize the host preference of these isolates. The host ranges of the isolates differed from each other and, interestingly, coffee, banana, and citrus were not among the better hosts of either isolate. Rather, sorghum, maize, rice, millet, okra, melon, eggplant, and lettuce were the best hosts of the Marília isolate. Poor hosts included French marigold, Rangpur lime, banana, sesame, peanut, sunflower, cotton, French bean, onion, and small onion. The best hosts of the Rio de Janeiro isolate were sesame, soybean, sorghum, castor oil plant, watermelon, squash, eggplant, and melon; the poorest hosts were French marigold, coffee, Rangpur lime, banana, sunflower, peanut, maize, millet, French bean, cotton, onion, sweet pepper, lettuce, okra, and small onion. These isolates have important molecular and morphological differences, suggesting host preference is linked to these characteristics.

Elevated interleukin-12 in pseudosynovial fluid in patients with aseptic loosening of hip prosthesis.

Loosening of a prosthesis is a major problem in total joint arthroplasty. To assess levels of cytokines in patients with such loosening, we measured the pseudosynovial fluid concentration of the following cytokines; tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12, matrix metalloproteinase (MMP)-1, and MMP-3. We examined the pseudosynovial fluid in patients with a loose hip prosthesis (group A; n = 8) and the synovial fluid in patients with osteoarthritis (OA) of the hip (group B; n = 18) using enzyme-linked immunosorbent assays. The mean concentration of IL-12 was significantly higher in group A than in group B (P < 0.01). Also, we found a significant (P < 0.05) correlation between the concentration of IL-12 and the concentration of MMP-1 in the patients with prosthesis loosening. The concentrations of TNF-alpha, IL-1beta, IL-4, IL-6, IL-10, IFN-gamma, MMP-1, and MMP-3 appeared to be similar in the two groups, although the small number of samples available precluded us from determining that there was no significant difference. The present study is the first to report elevated IL-12 levels in the pseudosynovial fluid of patients with a loose prosthesis. The immunoregulatory effect of IL-12 against wear particles could play an important role in causing loosening of the prosthesis.

[Identification of PKC isozymes and effect of knockdown of PKC alpha by antisense oligodeoxynucleotide on iNOS expression via interleukin-1 receptor in vascular smooth muscle cells].

Protein kinase C (PKC) family, is now classified into three groups; conventional (cPKC), novel (nPKC) and atypical (aPKC), and to date, 10 members of isozymes have been identified. We have suggested that PKC is essential to interleukin-1 (IL-1)-triggered expression of inducible NO synthase (iNOS), and that by pharmacological analysis, cPKC is not involved in iNOS induction in rat vascular smooth muscle cells (VSMC). In the present study, we identified some PKC isozymes and investigated the effect of PKC alpha knockdown by antisense oligodeoxynucleotide (AS-ODN) strategy on iNOS expression and nuclear translocation of NF-kappa B in RASMC. Western blot analysis revealed the presence of cPKC (alpha), nPKCs (delta and epsilon) and aPKCs (tau and lambda). Short-time (10-20 min) treatment with phorbol 12-myristate 13-acetate (PMA) induced translocation of PKC alpha from cytosolic to particulate fraction. PKC alpha was completely downregulated by treatment with 100 nM PMA for 24 hours. Treatment with AS-ODN against PKC alpha mRNA depleted PKC alpha specifically, and had no detectable effect on the other PKCs. The production of iNOS mRNA, but not nuclear translocation of NF-kappa B, stimulated by IL-1 beta was decreased by PKC alpha knockdown. These results suggest that there are 5 PKC isozymes in RASMC, and that PKC alpha is involved in iNOS expression triggered by IL-1 beta, supporting our previous pharmacological conclusion.

Effects of Pratylenchus brachyurus and P. coffeae on Seedlings of Coffea arabica.

Two experiments were carried out to evaluate the effects of Pratylenchus brachyurus and P. coffeae on Coffea arabica. The first experiment was conducted in a greenhouse to determine the effects of Pratylenchus brachyurus and P. coffeae on seedlings of Coffea arabica cv. Mundo Novo. Both Pratylenchus spp. reduced the growth of coffee seedlings. Higher contents of soluble sugars were detected in the leaves of infected plants. The reproduction rate of P. brachyurus was very low on cv. Mundo Novo, indicating an intolerance to this nematode. In a second experiment, C. arabica cultivars Mundo Novo and Catuaf both were intolerant hosts of P. brachyurus.