Outer Vessel Research Articles

Diagnostic Abilities of the Optical Microangiography Parameters of the 3×3 mm and 6×6 mm Macular Scans in Glaucoma.

To evaluate the diagnostic abilities of macular vessel length and perfusion densities measured with optical microangiography (OMAG) over a 3×3 mm and a 6×6 mm region, and to compare these with macular ganglion cell-inner plexiform layer (GCIPL) thickness in eyes with primary open-angle glaucoma (POAG). In a cross-sectional study, 96 eyes of 57 control subjects and 88 eyes of 57 POAG patients underwent macular imaging with optical coherence tomography. Area under receiver operating characteristic curves (AUC) and sensitivities at 90% specificity of OMAG and GCIPL parameters were evaluated. Most OMAG parameters of the 3×3 mm macular scan and all inner sector parameters of the 6×6 mm scan were similar (P>0.05) in the POAG and control eyes. All outer sector OMAG parameters of the 6×6 mm scan were significantly less (P<0.05) in the POAG eyes. AUC and sensitivity at 90% specificity of the best parameter of the 3×3 mm OMAG scan (inner temporal vessel length density; 0.65% and 26%, respectively) were statistically similar (P>0.05) to that of the 6×6 mm scan (outer inferior vessel length density; 0.72% and 30%, respectively). AUC and sensitivity of the best GCIPL thickness parameter (inferotemporal GCIPL thickness, 0.84% and 67%) were significantly better (P<0.05) than that of the vessel length densities. The outer sector measurements of the 6×6 mm macular OMAG scans seem to be better than the inner sector measurements in diagnosing glaucoma. The GCIPL thickness measurements were significantly better than all macular OMAG parameters in diagnosing glaucoma.

Experimental Study on Melt Coolability Capability of Calandria Vault Water During Severe Accident in Indian PHWRs for Prolonged Duration

The present experimental investigation in a scaled facility of an Indian pressurized heavy water reactors (PHWRs) is focused on the heat transfer behavior from the calandria vessel (CV) to the calandria vault during a prolonged severe accident condition in the presence of decay heat. The transient heat transfer simulates the conditions from single phase to boiling in the calandria vault water, partial uncovery of the CV due to boil off of water in the vault, and refill of calandria vault. Molten borosilicate glass was used as the simulant due to its comparable heat transfer characteristics similar to prototypic material. About 60 kg of the molten material was poured into the test section at about 1100 °C. Decay heat in the melt pool was simulated by using high watt cartridge type heaters. The temperature distributions inside the molten pool across the CV wall thickness and vault water were measured for prolonged period which can be divided into various phases, viz., single phase natural convection heat transfer in calandria vault, boiling heat transfer in calandria vault, partial uncovery of CV, and refilling calandria vault. Experimental results showed that once the crust formed, the inner vessel temperature remained very low and vessel integrity maintained. Even boiling of calandria vault water and uncovery of CV had negligible effect on melt, CV, and vault water temperature. The heat transfer coefficients on outer vessel surface were obtained and compared with various conditions.

Recent Improvement of the Design of the ITER Steady-State Magnetic Sensors

A recent improvement of the design of the ITER outer vessel steady-state magnetic field sensors (OVSS) is presented. OVSS features a pair of Hall sensors with a sensing layer made of bismuth. Sixty OVSS will be installed on the ITER vacuum vessel outer skin to perform an absolute measurement of magnetic field. The bismuth Hall sensor measurement is temperature dependent, and the maximum allowed OVSS error of 4-mT limits the error of the measurement of the Hall sensor temperature by an on-board thermocouple to be less than 0.28 °C. This error consists of the temperature difference between the thermocouple and Hall sensors, thermocouple calibration error, and thermocouple measurement error. The improved design of the sensor housing reduces the temperature difference between the thermocouple and the Hall sensors bellow 0.04 °C. Procedures of the calibration prior installation and in situ calibration will allow calibrating the on-board thermocouple with the error less than 0.06 °C. The thermocouple measurement error limit was determined as 0.27 °C in which case OVSS meets the maximum allowed error.

Step-by-step design of a single phase 3.3 kV/200 a resistive type superconducting fault current limiter (R-SFCL) and cryostat

In our first attempt to design a single phase R-SFCL in India, we have chosen the typical rating of a medium voltage level (3.3 kVrms, 200 Arms, 1Φ) R-SFCL. The step-by-step design procedure for the R-SFCL involves conductor selection, time dependent electro-thermal simulations and recovery time optimization after fault removal. In the numerical analysis, effective fault limitation for a fault current of 5 kA for the medium voltage level R-SFCL are simulated. Maximum normal state resistance and maximum temperature rise in the SFCL coil during current limitation are estimated using one-dimensional energy balance equation. Further, a cryogenic system is conceptually designed for aforesaid MV level R-SFCL by considering inner and outer vessel materials, wall-thickness and thermal insulation which can be used for R-SFCL system. Finally, the total thermal load is calculated for the designed R-SFCL cryostat to select a suitable cryo-refrigerator for LN2 re-condensation.

Comparison of Inter‐Observer Bias between Low Resolution and High Resolution Scans using 3T and 7T Scanners

IntroductionMRI can be used to assess atherosclerotic disease severity and to identify plaque components noninvasively. Vessel wall thickening can be measured with MRI and is associated with atherosclerosis. However, there are observer biases when measuring the vessel wall. We investigate whether there is a difference in inter‐observer bias between low resolution and high resolution imaging in both 3T and 7T field strengths.MethodsAtherosclerosis was induced in 5 male New Zealand White rabbits. The rabbits were placed on a high fat diet for 4 months and then imaged. Animals were each imaged twice, once on a 7T clinical scanner (Magnetom, Siemens Healthineers), and once on a 3T clinical scanner (mMR, Siemens Healthineers). The 7T scanner utilized a custom rabbit coil consisting of a transmit‐only quadrature‐driven high‐pass birdcage and 12‐channel receive‐only loop elements. The 3T scanner used a product Tx/Rx15‐ channel knee coil. On both scanners, localizer scans and time‐of‐flight (TOF) angiography were used to identify the rabbit aorta. A 3D T2 weighted SPACE (Sampling Perfection with Application optimized Contrasts using different flip angle Evolution) sequence was acquired using 0.6 mm3 (Low Resolution) and 0.4mm3 (High Resolution). The sequence was acquired in the sagittal plane, covering the rabbit abdominal aorta. Imaging data was analyzed with Osirix software. All images were reformatted in the axial plane, and axial slices from the left renal artery to the aortic bifurcation were analyzed. Vessel wall area was measured by tracing and subtracting the inner and outer vessel wall contours. Two independent observers traced each data set. Inter‐observer reliability was evaluated using Bland‐Altman analysis.ResultsFor the 3T low resolution scans, the percent bias was 37.41, the percent limit of agreement was from −5.868 to 80.69, the absolute bias was 0.05566, and the absolute limit of agreement was from −0.01227 to 0.1236. For the 3T high resolution scans, the percent bias was 34.31, the percent limit of agreement was from −5.987 to 74.62, the absolute bias was 0.03818, and the absolute limit of agreement was from −0.01884 to 0.0952. For the 7T low resolution scans, the percent bias was 42.85, the percent limit of agreement was from −1.001 to 86.70, the absolute bias was 0.06657, and the absolute limit of agreement was from −0.002535 to 0.1375. For the 7T high resolution scans, the percent bias was 41.35, the percent limit of agreement was from −6.707 to 89.4, the absolute bias was 0.04268, and the absolute limit of agreement was from −0.01173 to 0.0970.ConclusionBland‐Altman analysis revealed a bias for all imaging sequences analyzed between two observers. For both 3T and 7T field strengths, percent and absolute bias were smaller for the high resolution scans. Furthermore, the absolute and percent biases were lower for images acquired at 3T. Overall, these data indicate that a significant percent and absolute bias in vessel wall area measurements can be observed among different analysts. These findings underscore the importance of analysis standardization among observers when calculating absolute measures of plaque burden in animal studies or clinical trials. Furthermore, increasing imaging spatial resolution may help to reduce bias between observers and allow for more robust quantitative analysis.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Variable impact of CSF flow suppression on quantitative 3.0T intracranial vessel wall measurements.

Flow suppression techniques have been developed for intracranial (IC) vessel wall imaging (VWI) and optimized using simulations; however, simulation results may not translate in vivo. To evaluate experimentally how IC vessel wall and lumen measurements change in identical subjects when evaluated using the most commonly available blood and cerebrospinal fluid (CSF) flow suppression modules and VWI sequences. Prospective. Healthy adults (n = 13; age = 37 ± 15 years) were enrolled. A 3.0T 3D T1 /proton density (PD)-weighted turbo-spin-echo (TSE) acquisition with post-readout anti-driven equilibrium module, with and without Delay-Alternating-with-Nutation-for-Tailored-Excitation (DANTE) was applied. DANTE flip angle (8-12°) and TSE refocusing angle (sweep = 40-120° or 50-120°) were varied. Basilar artery and internal carotid artery (ICA) wall thicknesses, CSF signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal ratio (SR) were assessed. Measurements were made by two readers (radiology resident and board-certified neuroradiologist). A Wilcoxon signed-rank test was applied with corrected two-sided P < 0.05 required for significance (critical P = 0.008, 0.005, and 0.05 for SNR/CNR, SR, and wall thickness, respectively). A TSE pulse sweep = 40-120° and sweep = 50-120° provided similar (P = 0.55) CSF suppression. Addition of the DANTE preparation reduced CSF SNR from 17.4 to 6.7, thereby providing significant (P < 0.008) improvement in CSF suppression. The DANTE preparation also resulted in a significant (P < 0.008) reduction in vessel wall SNR, but variable vessel wall to CSF CNR improvement (P = 0.87). There was a trend for a difference in blood SNR with vs. without DANTE (P = 0.05). The outer vessel wall diameter and wall thickness values were lower (P < 0.05) with (basilar artery 4.45 mm, 0.81 mm, respectively) vs. without (basilar artery 4.88 mm, 0.97 mm, respectively) DANTE 8°. IC VWI with TSE sweep = 40-120° and with DANTE flip angle = 8° provides the best CSF suppression and CNR of the approaches evaluated. However, improvements are heterogeneous, likely owing to intersubject vessel pulsatility and CSF flow variations, which can lead to variable flow suppression efficacy in these velocity-dependent modules. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;48:1120-1128.

Combining Ultrasound-Guided Vascular Access With Ultrasound-Guided Analgesia for Single Skin and Vessel Puncture

Purpose: To describe a single skin puncture technique combining subcutaneous injection of anesthetic to the depth of the vessel wall with venipuncture in the same movement. Technique: Using ultrasound guidance, controlled anesthetic instillation along the needle tract and outer vessel wall with a 21-G vascular access needle can be combined with vessel puncture. This technique reduces the number of skin punctures and ensures accurate anesthetic instillation. The maximum inadvertent intravascular dose of commercial local anesthetic preparations that can be delivered with a small syringe is far below toxicity thresholds. Conclusion: A technique for combining anesthetic administration and vascular access with a 21-G needle and ultrasound guidance is feasible.

Choroidal Changes After Suprachoroidal Injection of Triamcinolone Acetonide in Eyes With Macular Edema Secondary to Retinal Vein Occlusion

To evaluate choroidal and suprachoroidal changes following suprachoroidal injection of triamcinolone acetonide injectable suspension (CLS-TA), in eyes with macular edema due to retinal vein occlusion (RVO). Prospective cohort study within a randomized, controlled phase 2 clinical trial. Enhanced depth imaging optical coherence tomography (EDI-OCT) images were analyzed from 38 eyes of 38 treatment-naïve patients with macular edema due to RVO, enrolled in the prospective Suprachoroidal Injection of Triamcinolone Acetonide with Intravitreal Aflibercept in Subjects with Macular Edema Due to Retinal Vein Occlusion (TANZANITE) study who received either a suprachoroidal injection of CLS-TA with an intravitreal injection of aflibercept (combination arm) or only an intravitreal injection of aflibercept (monotherapy arm), followed by monthly intravitreal aflibercept injections in both arms based on pro re nata criteria. Macular choroidal thickness measured to the outer choroidal vessel lumen (vascular choroidal thickness, VCT), outer choroid stroma (stromal choroidal thickness, SCT), or inner scleral border (total choroidal thickness, TCT) showed no significant changes over 3months in both study arms (P= .231-.342). Eyes that received combination therapy showed a trend toward thickening of the suprachoroidal space (SCS) compared with monotherapy alone (13.4μm vs 5.3μm at 3months; P= .077). In the 15 eyes that demonstrated a visible SCS at baseline, the SCS expanded significantly after suprachoroidal CLS-TA injection (16.2μm to 27.8μm at 3months; P= .033). Suprachoroidal injection of CLS-TA does not alter choroidal thickness in eyes with macular edema due to RVO, but may result in expansion of the SCS.

Electro-Magnetic Analysis of the ITER Upper Visible Infrared Wide Angle Viewing System

The Upper Visible Infrared Wide Angle Viewing System (UWAVS) is a diagnostic used in five upper ports of ITER. Each UWAVS provides visible and infrared views of various sections of the divertor. A single UWAVS is designed in three main sections: in-vessel, interspace and port cell assemblies. Each assembly utilizes multiple steering and relay mirrors to direct the in-vessel light out of the tokamak to the port cell camera sensors.For the in-vessel components, the transient electro-magnetic (EM) environment resulting from the ITER magnet operation and plasma events induces design driving Lorentz forces. As such, all in-vessel systems require detailed electro-magnetic finite element analysis (FEA) to derive the resulting time dependent Lorentz loads.ANSYS Maxwell software was used to perform transient electro-magnetic simulations of the UWAVS in ITER upper port 14. A 20 degree sector, cyclic symmetric model was employed and included, inner and outer vacuum vessel, blanket shield modules, diagnostic fist wall (DFW) and shield module (DSM), upper port plug structure, DSM shield blocks, and a detailed model of the UWAVS in-vessel assembly.The resulting data includes eddy current density and vector plots along with force and moment summation for various UWAVS components. Front end optical components are specifically reported as these components have significant EM loads.

A Novel Evaluation for Predicting Aortic Complicated Lesions Using Calcification on Chest X-ray

Background: The aorta is a significant source of cerebral thromboembolisms. Aortic complicated lesions (ACLs) are key findings on transesophageal echocardiography (TEE) for assessing aortic sources of emboli to the brain. TEE is sometimes avoided due to its invasiveness. However, few reports have examined alternative methods for predicting ACLs. We investigated relationships between aortic arch calcification (AAC) on chest X-ray and ACLs. Methods: Participants comprised 300 patients with acute ischemic stroke or transient ischemic attack who underwent TEE for the evaluation of the aortic arch and heart. A postero-anterior plain chest X-ray in the recumbent position was evaluated on admission for each patient. AAC was evaluated using 4 grades (0-3) and “AAC thickness” defined as the distance from the inner margin of the most distant AAC to the outer margin of the aortic vessel wall. ACLs were defined by intima-media thickness (IMT) ≥4.0 mm or presence of ulcerated or mobile plaques. Carotid maximum IMT on ultrasonography was also evaluated. Comparison of the diagnostic ability to predict ACL was performed between AAC grades and AAC thickness or AAC thickness and carotid maximum IMT using the Delong method. Results: ACLs were identified in 71 patients (23.7%), including ACLs with ulcerated plaques in 24 (8.0%) and ACLs with mobile plaques in 9 (3.0%). Plaque thickness was greater in higher AAC grades or higher quartiles of AAC thickness (p for trend <0.001 each). The Cochran-Armitage test showed that both higher AAC grade and higher quartile of AAC thickness were significantly associated with the presence of ACLs, as well as the presence of ulcerated or mobile plaques (p for trend < 0.001 each). Receiver-operating characteristic (ROC) analysis showed optimal cut-off values for AAC thickness of 5.6 mm for ACLs and 6.0 mm for ulcerated or mobile plaques. Multivariate logistic regression revealed a higher grade of AAC (grades 2-3) and AAC thickness (≥6 mm) as significantly associated with ACLs and ulcerated or mobile plaques (p < 0.001 each). ROC curve comparisons showed that AAC thickness offered a better marker of ACLs than AAC grade (p = 0.019), although no significant difference was evident between AAC thickness and carotid maximum IMT (p = 0.567). Conclusions: AAC on chest X-ray, evaluated by both AAC grade and AAC thickness to the outer aortic vessel wall, was significantly associated with ACLs on TEE. AAC thickness was suggested as more useful than AAC grade and equivalent to carotid IMT in predicting ACLs.

Investigation of linearity of the ITER outer vessel steady-state magnetic field sensors at high temperature

Three vacuum vessel sectors in ITER will be instrumented by the outer vessel steady-state magnetic field sensors. Each sensor unit features a pair of metallic Hall sensors with a sensing layer made of bismuth to measure tangential and normal components of the local magnetic field. The influence of temperature and magnetic field on the Hall coefficient was tested for the temperature range from 25 to 250 ̂C and the magnetic field range from 0 to 0.5 T. A fit of the Hall coefficient normalized temperature function independent of magnetic field was found, and a model of the Hall coefficient functional dependence at a wide range of temperature and magnetic field was built with the purpose to simplify the calibration procedure.

Process Design and Operation of a Wood Charcoal Retort

An efficient approach for the development of a compact integrated wood charcoal retort was designed. The key fundamental requirements to guarantee efficiency and productivity are initially investigated via CFD simulations to identify the temperature and velocity profiles inside the unit. The final compact design is comprised of a double vessel arrangement where the wood to be carbonized is placed in the central vessel (i.e. carbonizer). A flue-gas recycle line leaves the outer vessel (i.e. combustion furnace) to preheat the wood in the carbonizer during startup. This design allows the syngas/methane leaving the carbonizer to be re-circulated into the combustion furnace to provide the necessary energy. The integrated compact retort system is further tested experimentally; only 2–3 h were needed to achieve complete carbonization of oak wood. Various temperatures are achieved during operation, the maximum of which is at 900 °C. The charcoal yield ranged between 37 and 46% on a dry basis, and the charcoal carbon contents were between 73 and 87%.

Final Assembly and Factory Testing of the Jefferson Lab SHMS Spectrometer Quadrupole and Dipole Superconducting Magnets

Jefferson Lab is constructing an 11-Gev/c electron spectrometer called the super high momentum spectrometer (SHMS) as part of the 12-GeV JLAB upgrade for experimental Hall C. Three of the five superconducting SHMS magnets are under construction at SigmaPhi in Vannes, France, as a result of an international competition for design and fabrication. The three magnets Q2 and Q3 60 cm bore quadrupoles and the 60 cm warm bore dipole are complete or near complete and have many design features in common. All three magnets share a common superconductor, collaring system, cryostat design, cold to warm support, cryogenic interface, burnout resistant current leads, dc power supply, quench protection, and instrumentation and controls. The three magnets are collared, installed in cryostats and welded up, and in various stages of final testing. The Q2 quadrupole is due to ship from France to America in August arriving during this ASC conference and has passed all final hipot, leak, and pressure tests. The dipole is in leak and pressure testing as of July 2016, whereas the Q3 quadrupole requires some outer vacuum vessel assembly. Delivery of the Q3 and dipole magnets will follow the Q2 at about one month intervals. Factory testing has included hipot and electrical tests, magnetic tests at low field, mechanical alignments to center the coils, leak tests, and ASME code required pressure tests. Upon installation in Hall C at JLAB cold testing will commence.

Effect of Rotation on Scaffold Motion and Cell Growth in Rotating Bioreactors.

Efficient use of different bioreactor designs to improve cell growth in three-dimensional scaffolds requires an understanding of their mechanism of action. To address this for rotating wall vessel bioreactors, fluid and scaffold motion were investigated experimentally at different rotation speeds and vessel fill volumes. Low cost bioreactors with single and dual axis rotation were developed to investigate the effect of these systems on human osteoblast proliferation in free floating and constrained collagen-glycosaminoglycan porous scaffolds. A range of scaffold motions (free fall, periodic oscillation, and orbital motion) were observed at the rotation speeds and vessel fluid/air ratios used, with 85% fluid fill and an outer vessel wall velocity of ∼14 mm s−1 producing a scaffold in a free fall state. The cell proliferation results showed that after 14 and 21 days of culture, this combination of fluid fill and speed of rotation produced significantly greater cell numbers in the scaffolds than when lower or higher rotation speeds (p < 0.002) or when the chamber was 60% or 100% full (p < 0.01). The fluid flow and scaffold motion experiments show that biaxial rotation would not improve the mass transfer of medium into the scaffold as the second axis of rotation can only transition the scaffold toward oscillatory or orbital motion and, hence, reduce mass transport to the scaffold. The cell culture results confirmed that there was no benefit to the second axis of rotation with no significant difference in cell proliferation either when the scaffolds were free floating or constrained (p > 0.05).

Monitoring of W7-X cryostat commissioning with cryostat system FE model

The Wendelstein 7-X stellarator started its first operational phase in October 2015 at the Max-Planck-Institute for Plasma Physics in Greifswald with the goal to verify that a stellarator magnetic confinement concept is a viable option for a fusion power plant.The main components of the W7-X cryostat system are the plasma vessel (PV), outer vessel (OV), 254 ports, thermal insulation, vessel supports and the machine base. The main task of the cryostat system is to provide an insulating vacuum for the cryogenic magnet system, UHV conditions within the PV and to provide external access to the PV through ports for diagnostic-, supply- and heating systems.The updated finite element (FE) Global Model of the Cryostat System (GMCS) has continued to be used for predicting and assessing the behavior of W7-X as measured during its commissioning and operational phase. The measurements with strain, temperature and displacement sensors as positioned on the OV, Ports, PV and its supports form the basis of the cryostat system monitoring. After successful evacuation of the OV [1] commissioning continued and in 2015 the PV has been evacuated and baked for the first time. The measurements show good correspondence with the predictions of the GMCS and allowed for continuation of the commissioning. This paper gives an overview of analyses performed with the GMCS in support of cryostat commissioning and operation. In addition, the assessment performed for optional PV position adjustment is presented. A PV adjustment might be required in case plasma operation reveals problems with the plasma heat load distribution on critical in-vessel components.

Segmentation of lumen and outer wall of abdominal aortic aneurysms from 3D black-blood MRI with a registration based geodesic active contour model.

Segmentation of the geometric morphology of abdominal aortic aneurysm is important for interventional planning. However, the segmentation of both the lumen and the outer wall of aneurysm in magnetic resonance (MR) image remains challenging. This study proposes a registration based segmentation methodology for efficiently segmenting MR images of abdominal aortic aneurysms. The proposed methodology first registers the contrast enhanced MR angiography (CE-MRA) and black-blood MR images, and then uses the Hough transform and geometric active contours to extract the vessel lumen by delineating the inner vessel wall directly from the CE-MRA. The proposed registration based geometric active contour is applied to black-blood MR images to generate the outer wall contour. The inner and outer vessel wall are then fused presenting the complete vessel lumen and wall segmentation. The results obtained from 19 cases showed that the proposed registration based geometric active contour model was efficient and comparable to manual segmentation and provided a high segmentation accuracy with an average Dice value reaching 89.79%.

Signal conditioning and processing for metallic Hall sensors

Two electronics prototypes for the ITER outer vessel steady-state magnetic field Hall sensors based on a lock-in signal processing and current spinning technique were developed. The prototypes, the first using a rectangular lock-in signal processing with sensor offset cancellation and the second employing advanced lock-in signal processing with sensor and electronics offset cancellation, were compared with a DC technique and commercial lock-in amplifier. The influence of long interconnection cables, white noise, and interfering planar Hall effect to a measurement accuracy was evaluated. The planar Hall voltage suppression by the current spinning technique was investigated. Whilst the rectangular lock-in amplifier prototype failed to meet the ITER accuracy requirement, the advanced lock-in amplifier prototype demonstrated required functionality and accuracy.

Final design of the ITER outer vessel steady-state magnetic sensors

The outer vessel steady-state sensors (OVSS) – a subsystem of the ITER magnetic diagnostics – will contribute to the measurement of the plasma current, plasma-wall clearance, and local perturbations of the magnetic flux surfaces near the wall. The diagnostic consists of a poloidal array of sixty sensors welded to the vacuum vessel outer surface. Each OVSS contains a pair of bismuth Hall sensors with the measurement axes parallel (in the poloidal plane) and normal to the vacuum vessel. These Hall sensors were successfully tested in environmental conditions corresponding to those in ITER (neutron irradiation, vacuum vessel bakeout, etc.) and have proven to be capable of measuring the magnetic field up to at least ±7T. An AC analogue lock-in current spinning signal processing electronics has been developed for the OVSS to eliminate the spurious voltage due to Hall sensor manufacturing imperfections and the planar Hall effect. This paper presents the final design of the OVSS diagnostic, developed jointly by the ITER Organization and the Institute of Plasma Physics in Prague.

Compressed sensing based simultaneous black- and gray-blood carotid vessel wall MR imaging

ObjectiveIn this study, we sought to demonstrate the blood suppression performance, image quality and morphological measurements for compressed sensing (CS) based simultaneous 3D black- and gray-blood imaging sequence (CS-siBLAG) in carotid vessel wall MR imaging. Materials and methodsSeven healthy volunteers and five patients were recruited. Healthy subjects underwent five CS-siBLAG scans with 1, 2, 3, 4 and 5-fold accelerations. Signal-to-tissue ratio (STR) and contrast-to-tissue ratio (CTR) were computed as the measures of flowing signal suppression performance and the image quality for black-blood imaging of the technique. Vessel lumen area (LA) and wall area (WA) were compared between fully sampled acquisition and each accelerated acquisition. Patients underwent three CS-siBLAG scans with 1, 3 and 5-fold accelerations as well as a 3D time of flight (3D TOF) scan. Two radiologists reviewed the under-sampled black- and gray-blood image quality. ResultsSTR and CTR values obtained with 2 to 5-fold accelerations were not significantly different from those with full acquisition. LA and WA measured at 2×, 3×, 4× and 5× were all highly correlated to the corresponding values at 1×. For patients imaging, two radiologists both found that the dual-contrast images at 3× acceleration exhibited comparable image quality to that of the fully sampled acquisition, and that the images at 5× exhibited slightly blurred vessel wall and outer vessel wall boundaries. ConclusionBy combining the CS under-sampling pattern and reconstruction, pseudo-centric phase encoding order and dual blood contrast sequences, this technique provides spatially registered black- and gray-blood images and excellent visualization for vessel wall imaging and gray-blood imaging in a short scan time.

Methods for Evaluation of Radiation View Factor: A Review

Evaluation of radiation view factor is animportant task for calculating exact radiation heat load.The shape factor is a function of the spatial orientation between surfaces. Shape factor is mainly depending on thegeometry of body, incident and leaving radiation on the body. View factor is a purely geometric parameter and is independent of the surface properties and temperature.In the present work, different analytical methods for calculating the view factor are discussed with their parametric comparison in detail.In any cryogenics system, two wall vessels configuration is generally adopted. The inner vessel always kept at the cryogenic temperature as per the cryogenic fluid and outer vessel is generally at the atmospheric temperature. These vessels are separated with the vacuum insulation. Hence radiation heat load impinges on the inner cryogenic vessel. The general configuration of both the vessels is cylindrical in nature. The length of outer cylindrical vessel can be equal to or more than the length of inner cylindrical vessel.A special case of cryopump has been considered as a case study in which the inner vessel cylindrical length is less than the outer vessel length. The calculation of shape factor between two concentric finite cylinders with different length becomes important to calculate the exact radiation heat load. In the present work matrix method, Howell’s method and cross string methods were implemented for this problem and comparison of the different shape factor value is obtained.