Te Values Research Articles

H-mode power threshold reduction in a slot-divertor configuration on the Alcator C-Mod tokamak

H-mode power thresholds (Pth) are examined in Alcator C-Mod lower single null plasmas with standard vertical-plate and slot-type divertor configuration (BT = 5.4 T, Ip = 0.9 MA, q95 ∼ 4.0 and 〈ne〉 = (1.3–1.6) × 1020 m−3). The required power to access H-mode is found to be significantly reduced when the plasma is operated with a slot divertor. The lowest Pth achieved is ∼0.7 MW, about 1/3 of the normal level and 40% of the multi-machine scaling law prediction. Pth does not explicitly correlate with plasma shaping parameters (X-point locations, elongation, triangularities, etc), but somehow shows an overall inverse correlation with outer divertor leg length (the poloidal distance between X-point and outer strike point) and/or the outer divertor connection length. This implies that another, still unknown parameter hidden in the vicinity of the separatrix outer leg might be responsible for the observed difference in H-mode access power. Despite the large differences in Pth, the edge electron temperature (Te) and density (ne) profiles prior to L–H transition are not strongly affected by the divertor configuration. Values of Te,95 (i.e. Te at 95% normalized poloidal flux surface) at the L–H transition are similar for the two divertor configurations.

Reappraisal of effective elastic thickness in the south-west Indian Ocean, and its possible implications

<p>The bathymetry of the south-west Indian Ocean is dominated by three mid-oceanic ridge systems: the Chagos–Laccadives Ridge, the Central Indian Ridge, and the Mascarene Plateau. Although there have been a number of geophysical and geological investigations over the region, the genesis of these morphological features is still contradictory. Most of the estimations of effective elastic thickness in this region have been carried out in the spectral domain, either by transfer function analysis or by free-air admittance analysis. As these investigations were along some one-dimensional profiles or discrete blocks, spatial variation of the effective elastic thickness was not achieved. Here, we reappraise the estimation of effective elastic thickness in the south-west Indian Ocean by performing the computation in the spatial domain using flexure inversion. During this process, we also estimate the Moho depth throughout the region by two independent processes: gravity inversion, and flexural inversion. The Te values (effective elastic thickness) are estimated in the spatial domain, which match well with the results in the spectral domain obtained with the free-air admittance method. In addition, there is spatial variation of the Te values over the area analyzed. Our estimated Te values are low (1-6 km) along the Chagos-Laccadives ridge, implying its proximity to a spreading ridge at the time of creation. The Te values along the Mascarene Plateau show spatial variation with a seafloor age from north (Te, ca. 4 km) to south (Te, ca. 20 km). These findings substantiate earlier data and suggest that Réunion was created due to intraplate volcanism.</p>

A new assessment of the elastic thickness (Te) structure of the Indian shield, and its implications

<p>The elastic thickness (Te) of continents is a matter of much debate. Recent studies have shown that a number of factors control the continental Te, including age, heat flow, and lithospheric thickness. Here, we estimate the Te structure of the whole Indian shield using an improved isotropic fan wavelet land ocean deconvolution methodology, and we compare these results with the global published Te estimates in the Archean, Proterozoic and younger geological provinces. Our study reveals low (0-45 km/0-35 km), intermediate (45-70 km) and high (70-100 km) Te values in the Archean/Quaternary, the Proterozoic, and the Tertiary provinces, respectively, of the Indian shield. This is in contrast with global estimates of Te in similar geological provinces. In the absence of any correlation of Te with any controlling parameters, we propose that the mantle properties, rather than the tectonic history, are responsible for influences on the Te values within the Indian shield. The global positioning system horizontal velocity vectors yielded a locking depth of ca. 20 ±4 km, and the aseismic creep beyond correlates well with the high strength of ca. 70 km to 100 km in the central Himalayan foreland.</p>

Effective elastic thickness and mechanical anisotropy of South China and surrounding regions

South China and surrounding regions extend from the eastern Tibetan plateau, through the tectonically stable Sichuan basin and the broad Mesozoic magmatic and fold belt, to the trench-arc-basin system in the western Pacific which provide an ideal place to study deformation of the continental lithosphere under long-term magmatism and oceanic subduction. We obtained the effective elastic thickness (Te) and its anisotropy of South China and surrounding regions from the analysis of coherence between topography and satellite gravity using wavelet methods. The Te values of the study area vary from 2 to 75km, with relatively low Te values (≤30km) along the tectonic boundaries, the North–South Gravity Lineament (NSGL) and seismic zones, and in the regions with high surface heat flow. The evenly low Te values in the Lower Yangtze region and the Cathaysia block can be attributed to the long-lived subduction of the Paleo-Tethys and the Paleo-Pacific ocean basins beneath the South China block (SCB). The NSGL in the SCB may separate the unmodified (high Te) and thermally weakened (low Te) continental lithosphere due to oceanic subduction. Despite different distances to the tectonic boundaries, earthquakes occur more frequently in regions with Te values of 10–30km, implying strain concentration in the low-Te regions. A positive correlation between seismic activity and the magnitude of Te anisotropy suggests that a highly anisotropic mechanical structure will promote strain localization and brittle failure in the lithosphere. The poor correlation between the weak axis of Te anisotropy and the dynamic indicators of the present tectonic regime (the shear-wave splitting direction, the maximum horizontal compressive stress direction) confirms that Te anisotropy mainly reflects tectonic inheritance of the continental lithosphere.

Resonant features of energy and particle transport during application of resonant magnetic perturbation fields at TEXTOR and DIII-D**This is the paper of the IAEA contribution by Schmitz O. et al 2010 Key results from the DIII-D/TEXTOR Collaboration on the Physics of Stochastic Boundaries projected to ELM control at ITER, EXD/P3-30.

In this paper, results of a direct comparison of TEXTOR and DIII-D experiments with resonant magnetic perturbation (RMP) fields are presented. This comparison of resistive L-mode plasmas at TEXTOR with highly conductive H-mode plasmas at DIII-D is useful to identify generic physics mechanisms during application of RMP fields with a strong field line pitch angle alignment in the plasma edge.A reduction in the pedestal electron pressure pe with increasing extension of the vacuum modelled stochastic layer and pe recovery with decreasing layer width is found caused by a q95 resonant reduction in the edge (0.8 < ΨN < 0.95) electron temperature Te(q95) on both devices. For RMP edge-localized mode (ELM) suppressed H-mode plasmas at DIII-D, the gradients ∇Te and nominal values of Te are reduced in this edge region while increasing in the pedestal (0.95 < ΨN < 1.0) with RMP field applied and both are highly dependent on q95. In contrast, an increase in the central ion temperature with strong steepening of the ion temperature profile at mid-radius is found—again being highly dependent on q95. However, these resonant thermal transport effects are only seen in high triangularity plasmas revealing a strong shape dependence of the thermal transport. In contrast to the highly q95 dependent thermal transport features, the reduction of ne—known as density pump out—shows a much weaker dependence on q95. We show the potential to reduce the RMP induced particle pump out by fine tuning of the RMP spectral properties. At low resonant field amplitudes enhanced particle confinement is seen in high-field side limited L-mode discharges on both devices while higher resonant field amplitudes yield particle pumps out.

Characteristic features of a barrier discharge occurring on the zhukovskii aerofoil on variation of the surrounding air pressure

The results of measuring the jet thrust produced by a dielectric barrier discharge on the Zhukovskii aerofoil are presented. The measurements were made in the pressure range 40–1200 Torr. The maximum velocity of the ion wind attained 4–5 m/s. Based on the analysis of the plasma glow spectrum at a residual air pressure in the vacuum chamber of 40 Torr in the barrier discharge, the values of the temperature Te ~ 2.5⋅104 K and of electron concentration Ne ~ 2⋅1015 cm-3 were obtained.

Reprint of: Flexural controls on late Neogene basin evolution in southern McMurdo Sound, Antarctica

The basins of southern McMurdo Sound have evolved under the influence of lithospheric flexure induced by the loads of the Erebus Volcanic Province. To characterise these basins, it is important to investigate the lithosphere's flexural properties, and estimate their influence on basin architecture and evolution. Seismic and gravity data are used to constrain 3D forward modelling of the progressive development of accommodation space within the flexural basins. Elastic plate flexure was calculated for a range of effective elastic thicknesses (Te) from 0.5 to 25km using a spectral method. Models with low, but nonzero, Te values (2km<Te<5km) produce the best fit to the gravity data, although uncertainty is high due to inaccuracies in the Digital Elevation Model. The slopes of flexural horizons revealed in seismic reflection lines are consistent with this, indicating a Te of 2km to 5km, although the depths to these horizons are not consistent, perhaps due to a northwards slope, or step, in the pre-flexural surface. These results indicate that the lithospheric strength of southern McMurdo Sound is significantly less than estimates of the regional average (Te ~20km). This low strength may reflect the weakening effects of the Terror Rift, and perhaps also the Discovery Accommodation Zone, a region of major transverse faulting. A low Te model (Te=3) for southern McMurdo Sound predicts the development of two discrete flexural depressions, each 2–2.5km deep. The predicted stratigraphy of the northern basin reflects flexure due to Ross Island, predominantly erupted since ca. 1.8Ma. The predicted stratigraphy of the southern basin reflects more gradual flexure from ca. 10Ma to ca. 2Ma, due to the more dispersed volcanoes of the Discovery subprovince. Collectively, these two basins have the potential to preserve a remarkable stratigraphic record of Antarctic climate change through the late Neogene.

Two-dimensional Thomson scattering diagnostics of pulsed discharges produced at atmospheric pressure

Laser Thomson scattering (LTS) method has been applied to measure two dimensional distributions of electron density (ne) and electron temperature (Te) of a pulsed discharge in Ne gas at a pressure of 400 Torr. Such a discharge was produced with good reproducibility by using a set of electrodes composed of a needle and a hemisphere with a spacing gap of 0.5 mm. The values of ne and Te at t = 25 ns after the start of the discharge and at the center of the discharge were evaluated to be 4.6 × 1022 m−3 and 1.0 eV, respectively. Based on the observed signal intensity and noise components, signal-to-noise ratios were examined and the way to apply present diagnostic system to the discharge plasma with an electron density as low as 1018 m−3 was discussed.

Influence of ion current on plasma electron temperature and density determined by probe methods

It is established that the electron temperature (T e) of plasma as determined from the slope of the current-voltage (I-U) characteristic or from the second derivative of the probe current (Druyvesteyn method) is overstated. By taking into account the ion current contribution, it is possible to refine the T e value determined from the slope of the I-U curve. Analysis confirms that the concentration of ions determined from I-U curves for a collisional regime in the near-probe space-charge region is also overstated.

Populations of metastable and resonant argon atoms in radio frequency magnetron plasmas used for deposition of indium-zinc-oxide films

This work reports optical absorption spectroscopy measurements of the number density of Ar atoms in resonant (3P1, 1P1) and metastable (3P2, 3P0) states in rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the density of Ar 3P2 and 3P0 was fairly independent of pressure in the range of experimental conditions investigated, the density of Ar 3P1 and 1P1 first sharply increased with pressure and then reached a plateau at values close to those of the 3P2 and 3P0 levels at pressures above about 50 mTorr. At such pressures, ultraviolet radiation from resonant states becomes trapped such that these levels behave as metastable states. For a self-bias voltage of −115 V and pressures in the 5–100 mTorr range, similar number densities of Ar resonant and metastable atoms were obtained for Zn, ZnO, and In2O3 targets, suggesting that, over the range of experimental conditions investigated, collisions between these excited species and sputtered Zn, In, and O atoms played only a minor role on the discharge kinetics. The metastable-to-ground state number density ratios were also fitted to the predictions of a global model using the average electron temperature, Te, as the only adjustable parameter. For all targets examined, the values of Te deduced from this method were in excellent agreement with those obtained from Langmuir probe measurements.

A Multi-reference configuration interaction investigation of the X2+and A2 low-lying electronic states of AsO+ isotope ion

The potential energy curves (PECs) of AsO+(X2+) and AsO+(A2) are investigated using the full valence complete active space self-consistent field (CASSCF) method through the highly accurate valence internally contracted multireference configuration interaction approach including Davidson correction (MRCI+Q). In the present calculations, the basis sets for As and O are aug-cc-pV5Z and aug-cc-pV6Z respectively. The spectroscopic parameters of the isotopes 75As16O+ and 75As18O+ are determined. The present values of Re, e, exe, e and Be for 75As16O+ (X2+) are 0.15770 nm, 1091.07 cm-1, 5.02017 cm-1, 0.514826 cm-1 and 0.003123 cm-1, respectively; the present values of Te, Re, e, exe, e and Be for 75As16O+ (A2) are 5.248 eV, 0.16982 nm, 776.848 cm-1, 6.71941 cm-1, 0.443385 cm-1 and 0.003948 cm-1, respectively, which are compared with those reported by previous investigations in the literature. And the comparison shows that excellent agreement exists between the present results and the experimentsal ones. With the PECs of AsO+ (X2+) and AsO+ (A2) determined here, the first 20 vibrational states for each electronic state are determined when the rotational quantum number J equals zero (J =0). For each vibrational state, the vibrational level G(v ), inertial rotation constant Bv and centrifugal distortion constant Dv are evaluated when J=0, which are in good accord ance with the available experimental data.

Echo time에 따른 MR spectrum의 SNR: 1.5T와 3.0T비교

TE를 변화시킨 정상인 대뇌의 MR spectrum에서 주요 대사물질의 면적과 SNR을 측정하여 PRESS 펄스파형과 STEAM 펄스파형 그리고 1.5T와 3.0T간의 자장세기에 따른 spectrum 간의 차이를 알아보고자 하였다. Phantom 실험을 통하여 적절한 TR을 정한 후, 정상인 지원자 10명(3.0T 5명, 1.5T 5명 ; 남 22~30세 : 평균 26세)을 대상으로 단일용적기법의 STEAM과 PRESS 기법을 시행하였다. 사용된 장비는 3.0T MR scanner(Magnetom Trio, SIEMENS, Germany)와 1.5T MR scanner(Signa Twinspeed GE, USA)이였다. 영상변수는 TR은 2000ms, TE는 30ms, 40ms, 50ms, 60ms, 90ms, 144ms, 288ms, NA는 96, 용적 크기는 <TEX>$20{\times}20{\times}20mm3$</TEX>로 하였으며, spectrum 획득시간은 3분 20초였다. 획득한 데이터는 후처리과정을 통하여 PRESS와 STEAM, 그리고 1.5T와 3.0T system 간의 NAA, Cho, Cr 등의 단순면적값과 SNR을 비교하였다. 또한 육안적 관찰을 통하여 각 대사물질들의 관찰정도를 비교하였다. 1.5T와 3.0T MR spectrum을 분석한 결과, STEAM과 PRESS의 주요 대사물질의 단순 면적값과 SNR은 TE가 증가함에 따라 감소하는 경향을 보였으며, PRESS는 STEAM보다 1.5T에서 1.4배, 3.0T에서 1.3배 높은 SNR을 보였다. 자장의 세기에 따른 SNR 비교에서는 TE가 30ms에서 3.0T가 1.5T보다 약 2배 정도 높은 SNR을 보였으나 TE값이 증가함에 따라 3.0T에서의 SNR 감소율이 1.5T에서의 SNR 감소율보다 커서 TE가 90ms 이상부터는 큰 차이가 없었다. 반면 3.0T의 spectrum에서는 1.5T에서 구분할 수 없었던 <TEX>${\alpha}$</TEX>-Glx, <TEX>${\beta}{\cdot}{\gamma}$</TEX>-Glx, NAA complex등 작은 대사물질들을 보다 정확히 감별 할 수 있었고 short TE의 PRESS일 때 short TE의 STEAM보다 작은 대사물질들이 잘 관찰 되었다. 3.0T spectrum의 해상도와 SNR이 1.5T spectrum에 비하여 우수함을 알 수 있었다. 그러나 90ms이상의 long TE에서는 3.0T와 1.5T spectrum간의 SNR은 차이가 없었다. 따라서 고자장하에서의 자기공명분광법은 30ms 이하의 짧은 TE를 이용한 PRESS 펄스 파형을 사용하는 것이 임상적으로 유용하게 사용될 수 있을 것이라 사료된다. The purpose of this study is to know the differences of MR spectra, obtained from normal volunteers by variable TE value, through the quantitative analysis of brain metabolites by peak integral and SNR between 1.5T and 3.0T, together with PRESS and STEAM pulse sequence. Single-voxel MR proton spectra of the human brain obtained from normal volunteers at both 3.0T MR system (Magnetom Trio, SIEMENS, Germany) and 1.5T MR system (Signa Twinspeed, GE, USA) using the STEAM and PRESS pulse sequence. 10 healthy volunteers (3.0T:3 males, 2 females; 1.5T : 3 males, 2 females) with the range from 22 to 30 years old (mean 26 years) participated in our study. They had no personal or familial history of neurological diseases and had a normal neurological examination. Data acquisition parameters were closely matched between the two field strengths. Spectra were recorded in the white matter of the occipital lobe. Spectra were compared in terms of resolution and signal-to-noise ratio(SNR), and echo time(TE) were estimated at both field strengths. Imaging parameters was used for acquisition of the proton spectrum were as follow : TR 2000msec, TE 30ms, 40ms, 50ms, 60ms, 90ms, 144ms, 288ms, NA=96, VOI=<TEX>$20{\times}20{\times}20mm3$</TEX>. As the echo times were increased, the spectra obtained from 3.0T and 1.5T show decreased peak integral and SNR at both pulse sequence. PRESS pulse sequence shows higher SNR and signal intensity than those of STEAM. Especially, Spectra in normal volunteers at 3.0T demonstrated significantly improved overall SNR and spectral resolution compared to 1.5T(Fig1). The spectra acquired at short echo time, 3T MR system shows a twice improvement in SNR compared to 1.5T MR system(Table. 1). But, there was no significant difference between 3.0Tand 1.5T at long TE It is concluded that PRESS and short TE is useful for quantification of the brain metabolites at 3.0T MRS, our standardized protocol for quantification of the brain metabolites at 3.0T MRS is useful to evaluate the brain diseases by monitoring the systematic changes of biochemical metabolites concentration in vivo.

Application of Parametric and Non-parametric Method to Analyzing of Energy Consumption for Cucumber Production in Iran

This study applied a parametric (Cobb-Douglas production function) and non-parametric (Data Envelopment Analysis) method to examine the energy equivalents of inputs and output, analyze the efficiency of farmers, discriminate efficient farmers from inefficient ones and to identify wasteful uses of energy in order to optimize the energy inputs for cucumber greenhouse production in Esfahan province of Iran. Data were collected from 25 cucumber greenhouses in Esfahan province (Iran) by using a face-to-face questionnaire. Results showed that the cucumber production consumed a total 124447.5MJ ha-1 and diesel fuel is the major energy inputs in this cultivation. The CCR and BCC models indicated 6 and 9 greenhouses were efficient, respectively. The average values of TE, PTE and SE of greenhouses were found to be 0.90, 0.95 and 0.94, respectively. The results also revealed that about 8.12% of the total input resources could be saved if the farmers follow the input package recommended by the DEA. Econometric model evaluation showed that the impact of human power for cucumber production was significant at 1% levels and had the highest effect among the other inputs in this research, also the regression coefficient of fertilizer energy was found negative, indicating that power consumption for fertilizer is high in the surveyed greenhouses.

THE STRUCTURE OF NGC 1976 IN THE RADIO RANGE

High angular resolution radio continuum images of NGC 1976 (M42, Orion A) at frequency=330 MHz (wavelength=91 cm), 1.5 GHz (20 cm) and 10.6 GHz (2.8 cm), have been aligned, placed on a common grid, smoothed to common resolutions of 80" (=0.16 pc at 420 pc) and 90" (=0.18 pc) and compared on a position-by-position basis. The results are not consistent with a single value of Te. Rather, there is a significant variation, from Te =6000K in the low intensity, extended region to Te=8500K in the higher intensity, more compact region. The best fit to the data is a multi-layer model obtained from radio recombination line (RRL) data. An estimate of temperature fluctuations from the model yields t2=0.003. This is a factor of 10 lower than fluctuation values from optical O++ line data.

Energy use pattern and optimization of energy consumption for greenhouse cucumber production in Iran using data envelopment analysis (DEA)

In this study a non-parametric method of Data Envelopment Analysis (DEA) is used to estimate the energy efficiencies of cucumber producers based on eight energy inputs including human power, diesel fuel, machinery, fertilizers, chemicals, water for irrigation, electricity and seed energy and single output of production yield. Data were collected using face-to-face surveys from 25 greenhouses in Khuzestan province of Iran. Energy indices, technical, pure technical and scale efficiencies were calculated by using Data Envelopment Analysis (DEA) approach for 25 cucumber greenhouses. Total energy input and output were calculated as 163994 MJha -1 and 62496 MJha -1 , respectively, whereas diesel fuel consumption with 45.15% was the highest level between energy inputs. Energy output-input ratio, energy productivity and net energy gain were 0.38, 0.47 kg MJ ?1 , -101498 MJ ha ?1 , respectively. The average values of TE, PTE and SE were 88%, 91% and 96%, respectively.

Effect of Antioxidant Therapy On Hepatic Fibrosis and Liver Iron Concentrations In Beta-Thalassemia Major Patients

Abstract 5292 Objective:Repeated blood transfusion my lead to peroxidative tissue injury in thalassemia ptients due to secondary iron overload. The aim of the study was to assess the effects of antioxidant vitamins on the oxidative stress, antioxidant status, erythrocytes, hemoglobin derivatives. Also to demonstrate their effects on hepatic status in multitransfused beta-thalassemia major patients. Methods:The study was a prospective follow up study. It involved thirty β-thalassemia major patients aged 4–17 years (15 males and 15 females) recruited from Hematology Oncology Department, Ain Shams University. They were compared to a 20 healthy age and sex matched subjects served as controls. Patients were treated with oral dose of vitamin E (400 mg/day if patient weight < 20 kg and 600 mg/day in patient weight at least 20 kg), low dose of vitamin C (100 mg/day) and vitamin A (25000 IU/ week) for twelve months. Investigations were performed before and after 6 and twelve months of therapy: liver transaminases, serum ferrittin, hepatitis status for HBV, HCV, hepatic fibroscan elastography (TE) for assessment of liver fibrosis and hepatic MRI R2* to measure liver iron concentration (LIC). Assessment of the oxidant /antioxidant capacity by measuring: reduced glutathione, malondialdehyde, ascorbic acid, catalase enzyme, superoxide dismutase, glutathione reductase as well as glutathione peroxidase determination. Results:All patients were on iron chelation therapy: 12 patients received deferiprone (DFP) (75 mg/kg per day orally), 8 patients received deferoxamine (DFO) (30–50 mg/kg per day subcutaneously at least 5 times/week), and 10 patients received a combination of DFO (30–50 mg/kg per day, 2–3 days/week) and DFP (75 mg/kg per day, 7 days/week). In the studied thalassemics 40.0% and 54% were HCV RNA and hepatitis B surface antigen positive. The basal levels of vitamin A, E and C were 3.1, 4, and 2.6 times significantly lower in thalassemia patients compared to controls(p<0.001). Malondialdehyde concentration was 3.4 times higher while reduced glutathione level was 3.2 times lower in studied thalassemics compared to controls(p=0.02,p=0.04). Levels of vitamin A, C, E, reduced glutathione and hemoglobin were significantly elevated during the study period on antioxidant therapy(P=0.03, P=0.02, P<0.001)).This was paralleled by a significant decline in the oxidative-stress marker malondialdehyde (7.87±2.2,8.2±3,11.6±4.1nmol/L;at baseline, after 6 and 12 ms therapy respectively, p<0.001) and serum ferritin levels(2887±1009,2456±1122,2114±990 μg/L, p=0.05). After twelve months of vitamins treatment, there were highly significant improvements of enzymatic antioxidants parameters as compared with before treatment in thalassemia patients. Alanine transaminase, aspartate transaminase, superoxide dismutase and glutathione peroxidase were significantly decreased(p<0.001) while catalase and glutathione reductase activities were significantly elevated(p<0.005). The extent of hemolysis of erythrocytes in studied patients decreases markedly after treatment compared to baseline (p<0.001).There was significant improvement of hepatic fibrosis after 12ms of therapy as 20% of patients had high TE values (FibroScan>12kPa) at baseline compared to 16% after 12 ms therapy (P=0.04).And 56% of patients had value of (>6kPa) at baseline compared to 66%, 70% at 6 and 12months therapy respectively(p=0.03). Levels of liver iron concentration were progressively decreased during the study period compared to baseline (22.4±6.7, 19.4±4.8, 14.4±3.6 mg/gm) in MRI R2* at baseline, after 6 and 12 months therapy respectively<0.001. CONCLUSIONS:Antioxidants vitamins are effective in clinical practice for regulation of antioxidant status as well as improvement of liver iron concentration and hepatic fibrosis in multitransfused thalassemia major patients. Disclosures:No relevant conflicts of interest to declare.

Geophysical implications of the long-wavelength topography of the Saturnian satellites

[1] We use limb profiles to quantify the long‐wavelength topography of the Saturnian satellites. The degree 2 shapes of Mimas, Enceladus, and Tethys are not consistent with hydrostatic equilibrium. We derive 2‐D topographic maps out to spherical harmonic degree 8. There is a good correlation with topography derived from stereo techniques. If uncompensated, topography at degree 3 and higher is large enough to be detectable during close spacecraft flybys. If not properly accounted for, this topography may bias estimates of a satellite’s degree 2 gravity coefficients (which are used to determine the moment of inertia). We also derive a one‐dimensional variance spectrum (a measure of how roughness varies with wavelength) for each body. The short‐wavelength spectral slope is − 2t o−2.5, similar to silicate bodies. However, unlike the terrestrial planets, each satellite spectrum shows a reduction in slope at longer wavelengths. If this break in slope is due to a transition from flexural to isostatic support, the globally averaged elastic thickness Te of each satellite may be derived. We obtain Te values of ≥5 km, 1.5–5 km, ≈5 km, and ≥5 km for Tethys, Dione, Rhea, and Iapetus, respectively. For Europa, we obtain Te ≈ 1.5 km. These estimates are generally consistent with estimates made using other techniques. For Enceladus, intermediate wavelengths imply Te ≥ 0.5 km, but the variance spectrum at wavelengths greater than 150 km is probably influenced by long‐ wavelength processes such as convection or shell thickness variations. Impact cratering may also play a role in determining the variance spectra of some bodies. Citation: Nimmo, F., B. G. Bills, and P. C. Thomas (2011), Geophysical implications of the long‐wavelength topography of the Saturnian satellites, J. Geophys. Res., 116, E11001, doi:10.1029/2011JE003835.

L–H transition and pedestal studies on MAST

On MAST studies of the profile evolution of the electron temperature (Te), electron density (ne), radial electric field (Er) as well as novel measurements of the ion temperature (Ti) and toroidal current density (jϕ) in the pedestal region allow further insight into the processes forming and defining the pedestal such as the H-mode access conditions and MHD stability. This includes studies of fast evolution of Te, ne and Er with Δt = 0.2 ms time resolution and the evolution of pe and jϕ through an edge-localized mode (ELM) cycle. Measurements of the H-mode power threshold, PL−H revealed that about 40% more power is required to access H-mode in 4He than in D and that a change in the Z-position of the X-point can change PL−H significantly in single and double null configurations. The profile measurements in the L-mode phase prior to H-mode suggest that neither the gradient nor the value of the mean Te or Er at the plasma edge play a major role in triggering the L–H transition. After the transitions, first the fluctuations are suppressed, then the Er shear layer and the ne pedestal develops followed by the Te pedestal. In the banana regime at low collisionality (ν⋆) ∇Ti ≈ 0 leading to Ti > Te in the pedestal region with Ti ∼ 0.3 keV close to the separatrix. A clear correlation of ∇Ti with ν⋆ is observed. The measured jϕ (using the motional Stark effect) Te and ne are in broad agreement with the common peeling–ballooning stability picture for ELMs and neoclassical calculations of the bootstrap current. The jϕ and ∇pe evolution Δt ≈ 2 ms as well as profiles in discharges with counter current neutral beam injection raise questions with respect to this edge stability picture.

Echo-Time and Field Strength Dependence of BOLD Reactivity in Veins and Parenchyma Using Flow-Normalized Hypercapnic Manipulation

While the BOLD (Blood Oxygenation Level Dependent) contrast mechanism has demonstrated excellent sensitivity to neuronal activation, its specificity with regards to differentiating vascular and parenchymal responses has been an area of ongoing concern. By inducing a global increase in Cerebral Blood Flow (CBF), we examined the effect of magnetic field strength and echo-time (TE) on the gradient-echo BOLD response in areas of cortical gray matter and in resolvable veins. In order to define a quantitative index of BOLD reactivity, we measured the percent BOLD response per unit fractional change in global gray matter CBF induced by inhaling carbon dioxide (CO2). By normalizing the BOLD response to the underlying CBF change and determining the BOLD response as a function of TE, we calculated the change in R2 * (ΔR2 *) per unit fractional flow change; the Flow Relaxation Coefficient, (FRC) for 3T and 1.5T in parenchymal and large vein compartments. The FRC in parenchymal voxels was 1.76±0.54 fold higher at 3T than at 1.5T and was 2.96±0.66 and 3.12±0.76 fold higher for veins than parenchyma at 1.5T and 3T respectively, showing a quantitative measure of the increase in specificity to parenchymal sources at 3T compared to 1.5T. Additionally, the results allow optimization of the TE to prioritize either maximum parenchymal BOLD response or maximum parenchymal specificity. Parenchymal signals peaked at TE values of 62.0±11.5 ms and 41.5±7.5 ms for 1.5T and 3T, respectively, while the response in the major veins peaked at shorter TE values; 41.0±6.9 ms and 21.5±1.0 ms for 1.5T and 3T. These experiments showed that at 3T, the BOLD CNR in parenchymal voxels exceeded that of 1.5T by a factor of 1.9±0.4 at the optimal TE for each field.

Sulfur exchange capacity and thiophene hydrodesulfurization activity of sulfided molybdena-alumina catalysts promoted by nickel

The capacity of sulfur exchange (i.e. S TE—the total number of exchangeable sulfur atoms) has been determined at 673 K in a circulation system with H 2S (partial pressure ∼2.5 and 25 kPa) for five sulfided catalyst samples: molybdena-alumina (Mo12), NiO/Al 2O 3 (Ni12) and three Ni-promoted molybdena-alumina with different Ni:Mo ratios [NiMo(0.X)]. A linear correlation has been found between the S TE values and thiophene hydrodesulfurization activity of the catalyst samples, containing Mo. The S TE values have been determined also in exchange between catalyst sulfur and thiophene, for three samples: Mo12, Ni12, and NiMo(0.35) for comparison of the S-exchange affinity of S in thiophene with that in H 2S. The isotope exchange capacity of sulfur bound to the catalyst ( 35S cat) with sulfur in H 2S was substantially higher than that with sulfur in thiophene, but the sequence of the S TE values was similar for the three samples, i.e., NiMo(0.35) > Mo12 > Ni12.