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New experiments have been conducted at DIII-D to improve the physics understanding of plasma initiation assisted by electron cyclotron (EC) wave injection, allowing better extrapolation to ITER. This has been achieved by applying an EC pulse prior to start of the inductive plasma initiation (i.e. the generation of a loop voltage). A pre-plasma was formed during the EC pulse that was characterized in terms of the maximum density and temperature. Parametric scans were performed to study the influence of the EC injected power, EC injection angle, and pre-fill gas pressure on the pre-plasma creation process. These experiments showed that pre-ionized plasma of good quality can have a significant effect on the subsequent V loop induced plasma initiation process, i.e. a high density pre-plasma, increases the plasma current rise and speed at which ionization is achieved when the V loop is applied. A good quality pre-plasma is one that achieved a significant degree of ionization, mainly obtained by providing sufficient ECH power in DIII-D of the order of 1Â MW. It was found that a minimum EC power of 0.5Â MW was required in DIII-D to create ionization, and this would scale to a minimum power of roughly 6.5Â MW for ITER. [ABSTRACT FROM AUTHOR]

Focused gas migration through the gas hydrate stability zone in vertical gas conduits is a global phenomenon. The process can lead to concentrated gas hydrate formation and seafloor gas seepage, which influences seafloor biodiversity and ocean biogeochemistry. However, much is unknown about how gas and gas hydrate co‐exist within and around gas conduits. We present seismic imaging of the gas hydrate system beneath a four‐way closure anticlinal ridge at New Zealand's southern Hikurangi subduction margin. Gas has accumulated beneath the base of gas hydrate stability to a thickness of up to ∼240 m, which has ultimately led to hydraulic fracturing and propagation of a vertical gas conduit to the seafloor. Despite the existence of an array of normal faults beneath the ridge, these structures are not exploited as long‐range gas flow conduits. Directly beneath the conduit, and extending upward from the regional base of gas hydrate stability, is a broad zone characterized by both negative‐ and positive‐polarity reflections. We interpret this zone as a volume of sediment hosting both gas hydrate and free gas, that developed due to partial gas trapping beneath a mass transport deposit. Similar highly reflective zones have been identified at the bases of other gas conduits, but they are not intrinsic to all gas conduits through gas hydrate systems. We suggest that pronounced intervening sealing units within the gas hydrate stability zone determine whether or not they form. Plain Language Summary: Gas hydrates are ice‐like substances composed of natural gas and water. They form between sediment grains underneath large regions of the Earth's seafloor. An important reason to study gas hydrates is that they partly control the way that methane gas flows through sediments and out of the seafloor. It is this flow of methane that sustains some diverse biological communities on the seafloor and affects the chemistry of the oceans. In this study, we use reflected sound waves to explore how gas flow beneath the seafloor depends on the way in which sedimentary layers are folded and fractured. Our data reveal a 240‐m thick reservoir of gas that is trapped in a large sedimentary fold, ∼500 m beneath the seafloor. The buoyancy of the gas has caused a vertical fracture zone to propagate upward to the seafloor, where gas bubbles are venting into the ocean. Further, our data suggest that a broad accumulation of gas hydrates (together with gas) has formed beneath the vertical fracture zone. This gas hydrate deposit may grow larger with time, and it will continue to influence the way that gas flows through the sediments. Key Points: 240 m thick free gas column accumulated beneath the base of hydrate stability, which led to hydraulic fracturing and gas chimney formationBroad zone of free gas and gas hydrate formed beneath the gas chimney, extending upward from the regional base of hydrate stabilitySuch zones of hydrate and free gas likely form due to pronounced lithological contrasts (sealing layers) within the hydrate stability zone [ABSTRACT FROM AUTHOR]

Measurements of the plasma response to applied n = 1 perturbations from DIII-D ITER baseline scenario (IBS) demonstration discharges exhibit increasing amplitude prior to disruption inducing mode locking events. Simulations reveal that changes in ideal and resistive stability impact the response in the DIII-D IBS regime, well below the pressure limit of the external kink mode. The dependencies of the response measurements on the plasma normalized internal inductance ℓ i and beta β N are qualitatively consistent with ideal MHD, although in most cases the amplitude of the measurements exceeds predictions, indicating that the experimental discharges are less stable than expected. Resistive MHD simulations of the response show improved compatibility with the measurements, and the closest agreement is obtained by including the experimental plasma rotation in the simulations. Although the input neutral beam torque is near zero, the simulations show that the corresponding level of rotation can lead to nearly complete screening of the pitch-resonant field component at the q = 2 surface. However, the simulation results exhibit a significant weakening of this screening effect at the lowest rotation levels in the dataset, concurrent with predictions of elevated response amplitudes that are consistent with measurements. These comparisons with DIII-D data provide a qualitative validation of a linear, resistive MHD response model. [ABSTRACT FROM AUTHOR]

The thermal and fast-ion transport properties of DIII-D steady-state hybrid discharges with normalized beta βN ≳ 3 are studied at low injected torque and an increased electron to ion temperature ratio Te/Ti. Linear stability analysis performed with the TGLF turbulent code indicates that a high-k mode is usually dominant at smaller radii, whereas a low-k mode is usually dominant at larger radii in these plasmas. A reduction in the net injected torque from 8.6 to 4.3 N-m leads to reduced E × B shear and hence, an enhanced turbulence that was observed on the Doppler backscattering diagnostic and was also computed with TGLF. As Te/Ti in the core was increased from 0.57 to 0.66 by adding electron cyclotron current drive (ECCD) to these plasmas, higher levels of transport are observed with increased high-k modes indicated by TGLF. The fast-ion transport level varied over an order of magnitude in these discharges depending on whether Alfvén eigenmodes, fishbones, or no instabilities were observed. Hybrid plasmas with fishbones have decreased fast-ion transport, compared to plasmas with Alfvén eigenmodes, since they are resonant with a smaller portion of phase space and their resonance is farther from the wall. This reduction in fast-ion transport with ECCD mitigates the increase in turbulent transport, resulting in higher performance than expected during strong electron heating. Similarly, the lowest fast-ion transport was observed in the low torque plasma, which also led to better than expected performance at this torque value. The thermal and fast-ion transport changes observed as the torque/rotation and Te/Ti are varied indicate possible methods for transferring this scenario to a reactor. [ABSTRACT FROM AUTHOR]

Spontaneous mitigation of giant ELMs and appearance of grassy ELMs have been observed repeatedly at low pedestal collisionality () in the high-power (Pinj > 13 MW) hybrid scenario in DIII-D. Higher βp and higher q95 appear to be beneficial to achieving the grassy ELM regime. The grassy ELM H-mode plasma shows high energy confinement performance (H98y2 up to over 1.5) under the conditions of high neutral beam torque and high core rotation. The pedestal width appears to exceed the EPED1.0 model prediction by more than 50%. Pedestal stability analysis performed with the ELITE code indicates that the stability against low-n kink/peeling modes is improved with increased auxiliary heating power and the operational point in the grassy ELM regime is located near the ballooning boundary. The pedestal stability characteristics during the grassy ELM crashes have been investigated in comparison with the giant ELM crashes based on plasma profiles experimentally measured with high resolution and accuracy. It has been found that the underlying mechanism for the observed small-amplitude ELM crashes is mainly the expansion of the ballooning stability boundary induced by an initial radially localized collapse in the pedestal, which helps to stop the growth of instabilities and further collapse of the pedestal. The effect of electron density pedestal on mitigating edge localized instabilities has been analyzed by numerical simulation, suggesting that the electron density pedestal characterized by high ne,sep/ne,ped and low density gradient helps to stabilize peeling-ballooning modes because of a low pressure pedestal gradient and to lower the ballooning boundary mainly because of a low ion diamagnetic frequency in the pedestal region, thus triggering ballooning instabilities and producing the intrinsic grassy ELMs. Numerical simulation of the Chinese fusion engineering test reactor (CFETR) with the SOLPS code indicates that the separatrix density might be insensitive to the electron diffusivity in the pedestal region and increase with the power flowing from the core region to the edge region. Pedestal stability analysis suggests that the flat density pedestal with high separatrix density obtained in the high-power plasma in CFETR would make the operational point close to the ballooning boundary, which is considered to help destabilize ballooning instabilities and facilitate the access to the grassy ELM regime. [ABSTRACT FROM AUTHOR]

Significant variations in MHD activity and fast-ion transport are observed in the DIII-D high-beta, steady-state hybrid discharges with a mixture of electron cyclotron (EC) waves and neutral beam injection (NBI). When electron cyclotron heating (ECH) or current drive (ECCD) is applied, Alfvén eigenmodes (AEs) are usually suppressed and replaced by low-frequency bursting modes. The analysis of a recently compiled database of hybrid discharges suggests that the change of the fast-ion pressure especially the perpendicular pressure is the main factor responsible for the instability transition although the transition in some discharges can also be explained by a slight drop of the safety factor. The lower ratio of fast-ion injection speed vinj to Alfvén speed valfven and slight drop of during ECCD also facilitate the transition. The database shows that AEs mainly occur when the fast-ion fraction is less than 0.53 and is greater than 0.50, while low-frequency bursting modes appear in the opposite regime. Here, Pf and Ptotal are the central fast-ion pressure from classical prediction and total plasma pressure, respectively. The correlation with is weaker, and is around unity in all the cases. The reason why the instability transition correlates with and is that they can significantly modify the drive of low-frequency bursting modes and AEs. The explanation is supported by the observation that low-frequency bursting modes are rarely seen in the hybrids with NBI only, with EC waves and counter-NBI, or with high plasma density. A careful check of the low-frequency bursting modes suggests that they are mainly chirping (neoclassical) tearing modes (referred to as chirping (N)TMs), i.e. the mode frequency firstly jumps up from the steady (N)TM frequency, then chirps down, and finally returns to the steady (N)TM frequency. Occasionally, the (N)TMs are fully stabilized and replaced with pure fishbones. The resonance condition calculation and 'Kick' model simulations suggest that (N)TMs and fishbones can interact through modification of the fast ion distribution in phase space, which influences the drive. [ABSTRACT FROM AUTHOR]

Thirty fragments of red slip, glazed, common and cooking ware from Hellenistic and Parthian tombs at Kal‐e Chendar in Shami (Iran) were investigated. Petrographic assemblage and chemometric evaluation of chemical data collected most samples in a large cluster, suggesting a common provenance, even in a quite wide area which includes Izeh plain and lowland Susiana, and underlining the presence of smaller very distinguished groupings. Surface finishing layers (both glazes and red slips) showed a high degree of alteration of their morphological features. Blue glazes are typical plant‐ash, with copper as a colouring agent. [ABSTRACT FROM AUTHOR]

A new SEM‐EDS procedure for ancient ceramic classification, based on the automated acquisition and the semiautomated processing of multi‐elemental X‐ray maps, is described. Based on the detection of each aplastic inclusion, the procedure allows to simultaneously obtain a quantitative evaluation of both the inclusion mineral–chemical composition and the ceramic matrix chemical composition. The two data sets can individually or jointly be subjected to statistical methods. The proposed protocol was applied on a set of 22 samples of black glaze pottery from Adrano (north‐eastern Sicily), Hellenistic age (4th to 2nd centuries B.C.). Two main groups emerged from the application of the procedure, mainly distinguished for their quartz–feldspars versus calcium–aluminosilicate relative abundance as the inclusion mineral–chemical composition is concerned and for their matrix SiO2 versus CaO. The classification based on the inclusion mineral–chemical data obtained with the proposed method mirrors the results from the traditional OM observation, but when the two data sets are simultaneously considered, a subtler differentiation is observed with the separation of one of the groups in two subgroups, allowing to refine the partition. [ABSTRACT FROM AUTHOR]

Presents a model of a nearly optimal inspection policy suitable for production plant equipment. Rates of wear of the equipment; Different stages of the failure process.

Investigates the factors determining the interface quality in II-VI and III-V compound semiconductors such as zinc selenide and gallium arsenide (GaAs). Issue on polar heteroepitaxy between compound semiconductors; Polar heteroepitaxial configuration of GaAs surface; GaAs growth on zinc selenide.

Presents a study which examined high-quality molecular-beam epitaxial (MBE) regrowth of (Al[sub5]Ga)As on gallium arsenide (GaAs). Method used in high-quality MBE regrowth; Experiment on the regrowth of gallium arsenide surface; Summary of the surface reconstruction observed by reflection high-energy electron diffraction during the regrowth of GaAs.

Investigates the growth of III-V materials by molecular-beam epitaxy using reflection high-energy electron diffraction intensity oscillations. Influence of the three main growth parameters on the zinc selenide growth rate; Overview of zinc sticking coefficient versus growth temperature.

In DIII-D hybrid discharges, the intense Alfvén eigenmode (AE) activity driven by Neutral Beam Injection that is typically observed can be suppressed and replaced by fishbone modes when Electron Cyclotron Current Drive (ECCD) is centrally applied. Simulations have been carried out with the kinetic-magnetohydrodynamic hybrid code M3D-K based on DIII-D discharges #161401 without ECCD and #161403 with ECCD, respectively. In both cases, unstable modes are found—the mode frequency and the mode structure indicate that the instability excited in #161403 is of fishbone type, while that in #161401 is identified as the beta-induced Alfvén eigenmode-like mode. Moreover, we find that the calculated mode frequencies of these two shots are consistent with experimental observations. A systematic scan has been performed to study the instability region of n = 1 , 2 , 3 modes in (q 0 , β h o t) parameter space, where n is the toroidal mode number, q 0 is the safety factor value at the magnetic axis, and β h o t is the energetic particle beta. It is found that the transition between AEs and fishbone modes can occur when q 0 is changed. In addition, the modes of n = 1 , 2 , 3 are stable or weakly unstable in the region of P h o t / P total ≤ 0.5 and 1.2 < q 0 < 1.3 , where P h o t is the central energetic particle pressure and P total is the central total pressure. These results provide useful guidance for future experiments for minimizing energetic particle-driven instabilities and associated transport. [ABSTRACT FROM AUTHOR]

Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufactures (Piedmont, Italy) from the Palazzo Madama Museum collection were analysed by means of an X-ray fluorescence portable detector. The present study represents the first chemical characterization of these early (1737-1825) European porcelains. Chemical composition data were submitted to multivariate clustering techniques that underscored a complete classification of the three manufactures and the presence of three subgroups for the Vinovo production. These resulting subgroups did not mirror the classification expected on the basis of the historiographic literature. The overall data pointed to technological continuity not only through all the Vinovo phases but even continuing from the earlier Vische manufacture. [ABSTRACT FROM AUTHOR]

Several plasters and mortars from the Middle Bronze Age site of Erimi - Laonin tou Porakou (Cyprus) were analysed in order to perform a technological characterization. Morphological (SEM), elemental (EDX), mineralogical (XRPD), petrographic (polarized OM, SEM-EDX), thermal (TGA) and spectroscopic (FT-IR) techniques were applied. Plasters and mortars were identified as pyrotechnological lime products, obtained using local raw materials and containing a moderate amount of spathic calcite fragments. The use of organic fibres was ascertained and a seminal use of a crumbled ceramic as additive was evidenced. [ABSTRACT FROM AUTHOR]

New experiments on DIII-D have demonstrated the steady-state potential of the hybrid scenario, with 1 MA of plasma current driven fully non-inductively and βN up to 3.7 sustained for ~3 s (~1.5 current diffusion time, τR, in DIII-D), providing the basis for an attractive option for steady-state operation in ITER and FNSF. Excellent confinement is achieved (H98y2 ~ 1.6) without performance limiting tearing modes. The hybrid regime overcomes the need for off-axis current drive efficiency, taking advantage of poloidal magnetic flux pumping that is believed to be the result of a saturated 3/2 tearing mode. This allows for efficient current drive close to the axis, without deleterious sawtooth instabilities. In these experiments, the edge surface loop voltage is driven down to zero for >1 τR when the poloidal β is increased above 1.9 at a plasma current of 1.0 MA and the ECH power is increased to 3.2 MW. Stationary operation of hybrid plasmas with all on-axis current drive is sustained at pressures slightly above the ideal no-wall limit, while the calculated ideal with-wall MHD limit is βN ~ 4–4.5. Off-axis Neutral Beam Injection (NBI) power has been used to broaden the pressure and current profiles in this scenario, seeking to take advantage of higher predicted kink stability limits and lower values of the tearing stability index Δ′, as calculated by the DCON and PEST3 codes. Results based on measured profiles predict ideal limits at βN > 4.5, 10% higher than the cases with on-axis NBI. A 0-D model, based on the present confinement, βN and shape values of the DIII-D hybrid scenario, shows that these plasmas are consistent with the ITER 9 MA, Q = 5 mission and the FNSF 6.7 MA scenario with Q = 3.5. With collisionality and edge safety factor values comparable to those envisioned for ITER and FNSF, the high-βN hybrid represents an attractive high performance option for the steady-state missions of these devices. [ABSTRACT FROM AUTHOR]

Results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high-qmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin>2 that target the typical range of q95= 5-7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable βN. In contrast, similar plasmas except with qmin just above 1 have approximately classical fast-ion transport. Experiments that take qmin>3 plasmas to higher βP with q95= 11-12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-qmin scenario, the high βP cases have shorter slowing-down time and lower ∇βfast, and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q95, high-qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes. [ABSTRACT FROM AUTHOR]

Experiments conducted at DIII-D investigate the role of drift kinetic damping and fast neutral beam injection (NBI)-ions in the approach to the no-wall βN limit. Modelling results show that the drift kinetic effects are significant and necessary to reproduce the measured plasma response at the ideal no-wall limit. Fast neutral-beam ions and rotation play important roles and are crucial to quantitatively match the experiment. In this paper, we report on the model validation of a series of plasmas with increasing βN, where the plasma stability is probed by active magnetohydrodynamic (MHD) spectroscopy. The response of the plasma to an externally applied field is used to probe the stable side of the resistive wall mode and obtain an indication of the proximity of the equilibrium to an instability limit. We describe the comparison between the measured plasma response and that calculated by means of the drift kinetic MARS-K code [Liu et al., Phys. Plasmas 15, 112503 (2008)], which includes the toroidal rotation, the electron and ion drift-kinetic resonances, and the presence of fast particles for the modelled plasmas. The inclusion of kinetic effects allows the code to reproduce the experimental results within ~13% for both the amplitude and phase of the plasma response, which is a significant improvement with respect to the undamped MHD-only model. The presence of fast NBI-generated ions is necessary to obtain the low response at the highest βN levels (~90% of the ideal no-wall limit). The toroidal rotation has an impact on the results, and a sensitivity study shows that a large variation in the predicted response is caused by the details of the rotation profiles at high βN . [ABSTRACT FROM AUTHOR]

The system for controlling neoclassical tearing modes (NTMs) in DIII-D now catches the NTM the moment it becomes unstable by turning on the stabilizing electron cyclotron current drive (ECCD) and promptly bringing it back to stable before it has grown to a large size. Between NTMs, the ECCD can be turned off to save power, which will improve the fusion gain, Q, when used in ITER. This technique, named ‘catch and subdue’ (C&S), has been made possible by several advancements over the years at DIII-D. Firstly, ECCD must be very accurately aligned to the NTM; this is achieved by algorithms that probe how the NTM responds to changes in the alignment. Secondly, the alignment must be maintained even when the NTM is gone so that the ECCD will immediately stabilize when turned on in response to a new NTM. This is made possible by real-time equilibrium reconstructions that include measurements of the motional Stark effect and by a refraction estimator. Thirdly, real-time steerable mirrors are now fast and accurate actuators for the alignment adjustments. Fourthly, early NTM detection is made possible by a real-time mode analysis that filters noise to minimize false positives. These various control elements will be described and followed by a discussion of the further development needed for NTM control on ITER. [ABSTRACT FROM AUTHOR]

The initial experiments on off-axis neutral beam injection into high noninductive current fraction (fNI), high normalized pressure (βN) discharges in DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] have demonstrated changes in the plasma profiles that increase the limits to plasma pressure from ideal low-n instabilities. The current profile is broadened and the minimum value of the safety factor (qmin) can be maintained above 2 where the profile of the thermal component of the plasma pressure is found to be broader. The off-axis neutral beam injection results in a broadening of the fast-ion pressure profile. Confinement of the thermal component of the plasma is consistent with the IPB98(y,2) scaling, but global confinement with qmin>2 is below the ITER-89P scaling, apparently as a result of enhanced transport of fast ions. A 0-D model is used to examine the parameter space for fNI=1 operation and project the requirements for high performance steady-state discharges. Fully noninductive solutions are found with 4<βN<5 and bootstrap current fraction near 0.5 for a weak shear safety factor profile. A 1-D model is used to show that a fNI=1 discharge at the top of this range of βN that is predicted stable to n=1, 2, and 3 ideal MHD instabilities is accessible through further broadening of the current and pressure profiles with off-axis neutral beam injection and electron cyclotron current drive. [ABSTRACT FROM AUTHOR]

The seven Australasian genera of blister beetles (Coleoptera : Meloidae : Nemognathinae) are reviewed. Included are a key to genera, generic synopses and descriptions of two new genera of Nemognathini, Australozonitis and Pulchrazonitis, as well as a new monotypic tribe Palaestrini, which features a bauplan of male genitalia unique not only to the subfamily Nemognathinae but to the entire family. The genus Palaestra is redefined to include several Australasian, Asian and African species previously assigned to Zonitis. Exceptional variation of male genitalia encountered in the Palaestrini challenges current subfamily definitions, which are partly based on male genitalic structure and correlated sexual behaviour. Generic synopses include synonyms, type species, number of species, geographic distribution, significant references on taxonomy, life history and morphology, and additional notes. Forty-six new combinations are proposed for species previously in Zonitis. Distribution and relationship of tribes within the Nemognathinae, as well as the biogeography of the Australasian Meloidae are outlined and discussed. Blister beetles (Meloidae) are an outstanding and diverse component of Australasian fauna, still virtually ignored by entomologists. This study focusses on the identification and characterisation of higher taxa occurring in the area, relating them to the worldwide blister beetle fauna. The morphological uniqueness of some groups led to the redefinition of genera and the description of new taxa, including a new tribe. [ABSTRACT FROM AUTHOR]

Tokamaks with weak to moderate reversed central shear in which the minimum inverse rotational transform (safety factor) qmin is in the neighbourhood of unity can trigger bifurcated magnetohydrodynamic equilibrium states, one of which is similar to a saturated ideal internal kink mode. Peaked prescribed pressure profiles reproduce the 'snake' structures observed in many tokamaks which has led to a novel explanation of the snake as a bifurcated equilibrium state. Snake equilibrium structures are computed in simulations of the tokamak `a configuration variable (TCV), DIII-D and mega amp spherical torus (MAST) tokamaks. The internal helical deformations only weakly modulate the plasma-vacuum interface which is more sensitive to ripple and resonant magnetic perturbations. On the other hand, the external perturbations do not alter the helical core deformation in a significant manner. The confinement of fast particles in MAST simulations deteriorate with the amplitude of the helical core distortion. These threedimensional bifurcated solutions constitute a paradigm shift that motivates the applications of tools developed for stellarator research in tokamak physics investigations. [ABSTRACT FROM AUTHOR]

With the installation of non-axisymmetric coil systems on major tokamaks for the purpose of studying the prospects of ELM-free operation, understanding the plasma response to the applied fields is a crucial issue. Application of different response models, using standard tools, to DIII-D discharges with applied non-axisymmetric fields from internal coils, is shown to yield qualitatively different results. The plasma response can be treated as an initial value problem, following the system dynamically from an initial unperturbed state, or from a nearby perturbed equilibrium approach, and using both linear and nonlinear models [A. D. Turnbull, Nucl. Fusion 52, 054016 (2012)]. Criteria are discussed under which each of the approaches can yield a valid response. In the DIII-D cases studied, these criteria show a breakdown in the linear theory despite the small 10-3 relative magnitude of the applied magnetic field perturbations in this case. For nonlinear dynamical evolution simulations to reach a saturated nonlinear steady state, appropriate damping mechanisms need to be provided for each normal mode comprising the response. Other issues arise in the technical construction of perturbed flux surfaces from a displacement and from the presence of near nullspace normal modes. For the nearby equilibrium approach, in the absence of a full 3D equilibrium reconstruction with a controlled comparison, constraints relating the 2D system profiles to the final profiles in the 3D system also need to be imposed to assure accessibility. The magnetic helicity profile has been proposed as an appropriate input to a 3D equilibrium calculation and tests of this show the anticipated qualitative behavior. [ABSTRACT FROM AUTHOR]

Background Mental stress (MS) may alter gastric sensory-motor function. The aim of the study was to assess postprandial autonomic nervous system activity and stress hormones in response to acute mental stress in dyspeptic patients. Methods A total of 25 patients with postprandial distress syndrome (PDS; 11 mol L−1, age 35.9 ± 9.3 years) and 12 healthy controls (5 mol L−1, age 25.8 ± 4.6 years) underwent electrogastrography and 13C-octanoate gastric emptying study using a 480 kcal solid meal. Heart rate variability (LF/HF ratio) and corticotrophin-releasing factor, adrenocorticotropic hormone (ACTH), and cortisol serum levels were also evaluated. Dyspeptic symptoms were scored by analogue visual scale and expressed as symptoms total score (TS). The protocol was repeated twice in each subject, with and without a mental stress test before the meal. Key Results Mental stress significantly increased postprandial symptoms severity in patients (TS: stress 111 ± 18 vs basal 50 ± 10; P < 0.05). Low-/high-frequency component ratio was significantly higher in patients after MS at 120 min (stress 5.46 ± 0.41 vs basal 3.41 ± 0.64; P < 0.01) and 180 min (stress 5.29 ± 0.2 vs basal 3.58 ± 0.19; P < 0.05). During stress session, in patients we found a significantly higher ACTH level than baseline at 30, 60, 90, 150, 210, 240, and 270 min and a significantly higher cortisol level at 30, 60, 90, 120, 210, and 270 min. Gastric emptying rate and electrical activity were not influenced by MS. Conclusions & Inferences In PDS patients, administration of MS before meal increases symptoms severity by inducing sympathetic hyperactivity and increased stress hormones levels. As the gastric emptying looks not altered, we conclude that these neurohormonal responses mainly affect sensitive function. [ABSTRACT FROM AUTHOR]

Sawtooth control using electron cyclotron current drive (ECCD) has been demonstrated in ITER-like plasmas with a large fast ion fraction, wide q = 1 radius and long uncontrolled sawtooth period in DIII-D. The sawtooth period is minimized when the ECCD resonance is just inside the q = 1 surface. Sawtooth destabilization using driven current inside q = 1 avoids the triggering of performance-degrading neoclassical tearing modes (NTMs), even at much higher pressure than required in the ITER baseline scenario. Operation at βN = 3 without 3/2 or 2/1 NTMs has been achieved in ITER demonstration plasmas when sawtooth control is applied using only modest ECCD power. Numerical modelling qualitatively confirms that the achieved driven current changes the local magnetic shear sufficiently to compensate for the stabilizing influence of the energetic particles in the plasma core. [ABSTRACT FROM AUTHOR]

An analysis of the dependence of transport on the safety factor profile in high-performance, steady-state scenario discharges is presented. This is based on experimental scans of q95 and qmin taken with fixed βN, toroidal field, double-null plasma shape, divertor pumping, and electron cyclotron current drive input. The temperature and thermal diffusivity profiles were found to vary considerably with the q-profile, and these variations were significantly different for electrons and ions. With fixed q95, both temperature profiles increase and broaden as qmin is increased and the magnetic shear becomes low or negative in the inner half radius, but these temperature profile changes are stronger for the electrons. Power balance calculations show the peak in the ion thermal diffusivity (χi) at ρ=0.6-0.8 increases with q95 or qmin. In contrast, the peak in the electron diffusivity (χe) decreases as qmin is raised from ∼1 to 1.5, and it is insensitive to q95. This is important for fully non-inductive scenario development because it demonstrates that elevated qmin and weak or reversed shear allow larger electron temperature gradients and, therefore, increased bootstrap current density to exist at ρ=0.6-0.8. Chord-averaged measurements of long wavelength density fluctuation amplitudes (ñ) are shown, and these have roughly the same dependence on q-profile as χi. This data set provides an opportunity for testing whether theory based transport models can provide insight into the underlying transport physics of high performance scenarios and if they can reproduce observed experimental trends. To this end, we applied the trapped gyro-Landau fluid (TGLF) code to calculate the linear stability of drift waves and found that the resulting variation of growth rates with q-profile are mostly inconsistent with the observed trends of χi, χe, and ñ with q-profile. TGLF simulations of the temperature profiles consistent with heating sources also have mixed agreement with the measured profiles, such that the simulated electron and ion heat flux in low qmin discharges are too low and heat fluxes in high qmin discharges are too high. [ABSTRACT FROM AUTHOR]

Background Enteric glial cells (EGCs) have been recently indicated as key regulators of intestinal inflammation in animals. Whether or not this is true and how these cells participate to inflammatory responses in humans is unknown. Methods We isolated primary EGCs from human small bowel and then, we purified and characterized those using specific glial markers, such as S100B and glial fibrillary acidic protein (GFAP). To mimic an inflammatory scenario, we exposed EGCs to exogenous stimuli, such as lipopolysaccharide and interferon-gamma (LPS and IFN-γ), alone or in combination, to evaluate glial activation [measuring GFAP, S100B level together with c-fos, major histocompatibility complex (MHC) class II, inducible nitric oxide (iNOS) proteins expression and nitric oxide (NO) production] and proliferation, respectively. Key Results We showed that, when challenged with a combination of LPS and IFN-γ, EGCs are significantly activated, as indicated by their positivity to c-fos and MHC class II. Similarly, pro-inflammatory stimuli significantly increase the cell proliferation rate, the expression of both S100B and GFAP, and the NO production consequent to the induction of EGCs-derived iNOS protein, with the last being dependent on S100B-RAGE (receptor for advanced glycation endproducts) interaction. Conclusions & Inferences Our data provide the first evidence that human EGCs directly respond to pro-inflammatory stimuli by changing their expression profile and by proliferating. The finding that stimulated EGCs are able to produce NO points to a role of this cell population in the scenario of intestinal inflammation. [ABSTRACT FROM AUTHOR]

Accurate measurement of internal magnetic field direction using motional Stark effect (MSE) polarimetry in the edge pedestal is desired for nearly all tokamak scenario work. A newly installed 500 kHz 32-channel digitizer on the MSE diagnostic of DIII-D allows full spectral information of the polarimeter signal to be recovered for the first time. Fourier analysis of this data has revealed magnetohydrodynamic (MHD) fluctuations in the plasma edge pedestal at ρ >= 0.92. By correlating edge localized mode fluctuations seen on lock-in amplifier outputs with MSE spectrograms, it has been shown that edge pedestal tearing mode fluctuations cause interference with MSE second harmonic instrument frequencies. This interference results in unrecoverable errors in the real-time polarization angle measurement that are more than an order of magnitude larger than typical polarimeter uncertainties. These errors can cause as much as a 38% difference in local q. By using a redundant measure of the linear polarization found at the fourth harmonic photo-elastic modulator (PEM) frequency, MHD interference can be avoided. However, because of poorer signal-to-noise the fourth harmonic signal computed polarization angle shows no improvement over the MHD polluted second harmonics. MHD interference could be avoided in future edge pedestal tokamak polarimeters by utilizing PEMs with higher fundamental frequencies and a greater separation between their frequencies. [ABSTRACT FROM AUTHOR]

Copyright of La Radiologia Medica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The regime of nonlinear temperature oscillations (O-regime), characteristic of noninductive discharges on Tore Supra [Équipe Tore Supra, Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Nice, France, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 1, p. 9], is investigated in its triggering and suppressing mechanism. This regime can be described by two nonlinearly coupled equations for the current density j(r) and the electron temperature Te(r) where the equation coefficients are functions of j and Te themselves. Both the integrated modeling code CRONOS [V. Basiuk et al., Nucl. Fusion 43, 822 (2003)] and a two-patch predator-prey system with diffusion and noise have been used and results have been compared to the experimental observations of the O-regime. A database of discharges is analyzed which features monotonic, flat, and reversed safety factor (q) profiles in order to characterize the action of external actuators on the regime dynamics with the widest generality. Electron cyclotron current drive and neutral beam injections have been used in order to induce localized perturbations in the total current profile j(r) as well as to change the plasma confinement conditions in the central region. Magnetic shear perturbations and modifications of the heat transport turn out to be the central parameters governing the dynamics of the O-regime. [ABSTRACT FROM AUTHOR]

This study aims at contributing to the development of a method to be used for analysing and measuring parameters such as production throughput, production capacity and productivity; the approach is strictly targeted for diagnostic purposes and potentially proves useful during the implementation of improvement projects. In an explicit attempt to provide production managers with useful hints and suggestions, this paper focuses its quantitative analysis on systems dominated by one machine, where the performance achieved strongly depends on the plant management. The paper starts with a detailed analysis of the causes leading to an inefficient or poor plant performance; this will lead to a representation of different plant status conditions together with their throughput time; a picture of the major performance parameters to be monitored within the system will then be outlined through a theoretical description of performance deployments. The work focuses on the calculation of these parameters in order to define the different production capacity concepts and to provide an interpretation of their meaning for management purposes. Finally managerial implications are reported and a summary of the whole model highlighting its working method is given through a numeric example. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento della Societa Italiana di Fisica: D is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have grown InGaAs/InAlAs quantum wells and InGaAs, InAlAs single layers over InP nonplanar substrates. Photoluminescence, transmission electron microscopy, and energy-dispersive x-ray analysis give evidence for large lateral thickness and compositional variations, which lead to in situ modification of the growth profile. These effects, which differ for InGaAs and InAlAs, reveal the importance of surface migration in (Al,Ga)InAs. Our results demonstrate a tool for in situ lateral patterning of this material system. [ABSTRACT FROM AUTHOR]

The reported experimental results demonstrate the influence of the substrate-induced strain on the In incorporation coefficient in the growth of AlInAs by molecular beam epitaxy. AlInAs has either been grown lattice matched to InP or with a 2.3% lattice mismatch with GaAs. The In incorporation coefficient has been determined through reflection high-energy electron diffraction intensity oscillations. The strain effect on the In incorporation coefficient is supported by a thermodynamic analysis applied to the more simple but similar case of strained InAs growth. [ABSTRACT FROM AUTHOR]

Real-time steerable electron cyclotron current drive (ECCD) has been demonstrated to reduce the power requirements and time needed to remove 3/2 and 2/1 neoclassical tearing modes (NTMs) in the DIII-D tokamak. In a world first demonstration of the techniques required in ITER, the island formation onset is detected automatically, gyrotrons are turned on and the real-time steerable ECCD launcher mirrors are moved promptly to drive current at the location of the islands. This shrinks and suppresses the modes well before saturation using real-time motional Stark effect constrained equilibria reconstruction with advanced feedback and search algorithms to target the deposition. In ITER, this method will reduce the ECCD energy requirement and so raise Q by keeping the EC system off when the NTM is not present. Further, in the experiments with accurate tracking of pre-emptive ECCD to resonant surfaces, both 3/2 and 2/1 modes are prevented from appearing with much lower ECCD peak power than required for removal of a saturated mode. [ABSTRACT FROM AUTHOR]

Recent experiments on DIII-D have provided the first systematic data on the impact of the current profile on the transport and stability properties of high-performance, steady-state scenario plasmas. In a future tokamak, to achieve 100% noninductive conditions and produce net power, the current profile J must be sustained by a large fraction of bootstrap current JBS, which is nonlinearly coupled with the kinetic profiles. Systematic scans of qmin and q95 were performed to determine empirically the best alignment of the noninductive currents with J and the variation of the transport properties with q. Transport analysis indicates that χe and χi are sensitive to the details of J in a way that makes the pressure profile peaking and JBS scale nonlinearly with both q and β in the experiment. Drift wave stability analysis yields linear growth rates that do not reproduce experimental trends in χ with qmin and q95. At high beta, necessary to maximize fBS, the plasma duration is often limited by n=1 tearing modes, whose stability also depends on the J profile. Broadly deposited electron cyclotron (EC) current at mid-radius was found to supply part of the required noninductive current and to positively affect the tearing stability. The modes appear when JEC is turned off for stable cases and always appear when the EC deposition is shifted outwards. The variation in the EC scan results is consistent with PEST3 calculations, showing that the tearing stability becomes extremely sensitive to small perturbations of the equilibrium in wall-stabilized plasmas run close to the ideal MHD limit. These modeling results are being used to design new experiments with higher ideal and tearing limits. A new capability for off-axis neutral beam injection system will be used to explore higher qmin scenarios and different current alignments. [ABSTRACT FROM AUTHOR]