Note: Internal diamagnetic flux measurements on ASDEX Upgrade.

Internal diamagnetic flux measurements, with measurement loops and compensation magnetic probes inside the vacuum vessel, are now available on the ASDEX Upgrade tokamak. The measured diamagnetic flux is compared to that predicted by simulations and calculated from equilibrium reconstruction. The diamagnetic flux measured at 2 positions separated toroidally by 180° in the vacuum vessel is compared.

Real-time diamagnetic flux measurements on ASDEX Upgrade.

Real-time diamagnetic flux measurements are now available on ASDEX Upgrade. In contrast to the majority of diamagnetic flux measurements on other tokamaks, no analog summation of signals is necessary for measuring the change in toroidal flux or for removing contributions arising from unwanted coupling to the plasma and poloidal field coil currents. To achieve the highest possible sensitivity, the diamagnetic measurement and compensation coil integrators are triggered shortly before plasma initiation when the toroidal field coil current is close to its maximum. In this way, the integration time can be chosen to measure only the small changes in flux due to the presence of plasma. Two identical plasma discharges with positive and negative magnetic field have shown that the alignment error with respect to the plasma current is negligible. The measured diamagnetic flux is compared to that predicted by TRANSP simulations. The poloidal beta inferred from the diamagnetic flux measurement is compared to the values calculated from magnetic equilibrium reconstruction codes. The diamagnetic flux measurement and TRANSP simulation can be used together to estimate the coupled power in discharges with dominant ion cyclotron resonance heating.

Application of AXUV diode detectors at ASDEX Upgrade.

In the ASDEX Upgrade tokamak, a radiation measurement for a wide spectral range, based on semiconductor detectors, with 256 lines of sight and a time resolution of 5 µs was recently installed. In combination with the foil based bolometry, it is now possible to estimate the absolutely calibrated radiated power of the plasma on fast timescales. This work introduces this diagnostic based on AXUV (Absolute eXtended UltraViolet) n-on-p diodes made by International Radiation Detectors, Inc. The measurement and the degradation of the diodes in a tokamak environment is shown. Even though the AXUV diodes are developed to have a constant sensitivity for all photon energies (1 eV-8 keV), degradation leads to a photon energy dependence of the sensitivity. The foil bolometry, which is restricted to a time resolution of less than 1 kHz, offers a basis for a time dependent calibration of the diodes. The measurements of the quasi-calibrated diodes are compared with the foil bolometry and found to be accurate on the kHz time scale. Therefore, it is assumed, that the corrected values are also valid for the highest time resolution (200 kHz). With this improved diagnostic setup, the radiation induced by edge localized modes is analyzed on fast timescales.

First observation of edge localized modes mitigation with resonant and nonresonant magnetic perturbations in ASDEX Upgrade.

First experiments with nonaxisymmetric magnetic perturbations, toroidal mode number n=2, produced by newly installed in-vessel saddle coils in the ASDEX Upgrade tokamak show significant reduction of plasma energy loss and peak divertor power load associated with type-I edge localized modes (ELMs) in high-confinement mode plasmas. ELM mitigation is observed above an edge density threshold and is obtained both with magnetic perturbations that are resonant and not resonant with the edge safety factor profile. Compared with unperturbed type-I ELMy reference plasmas, plasmas with mitigated ELMs show similar confinement, similar plasma density, and lower tungsten impurity concentration.

The pathology of upper-extremity arterial disease.

The arteries to the upper extremities can be involved at multiple levels by a variety of diseases. Because of the critical sensitivity of motor function and sensation in the arms and hands, minor degrees of ischemia can have major clinical significance. It is essential to understand the exact pathologic process and the sites of involvement to provide proper therapy.

Percutaneous transluminal angioplasty. The radiologist's contribution to the treatment of vascular disease.

Percutaneous transluminal angioplasty is a nonsurgical treatment for vascular disease. It is relatively safe and economical and may be an alternative, or an adjunct, to surgery, or may be helpful where no surgical alternative exists. Percutaneous transluminal angioplasty is applicable to nearly every system, except the carotid bifurcation plaque.

The emerging role of epidural anesthesia in arteriography and in vascular operations.

Continuous epidural anesthesia offers special advantages for patients with vascular disease. In 193 patients who had this technique employed for aortofemoral arteriography, profound pain relief was provided and the accompanying vasodilation produced superior demonstration of collateral and small distal vessels. Eleven of these patients had epidural anesthesia for major vascular reconstruction operations. This caused minimal depression of pulmonary and myocardial performance during the procedure. Postoperative epidural analgesics improved the pulmonary performance by allowing normal pain-free breathing. No epidural complications were seen. Special precautions are described for the safe use of these techniques.

Surgical management of aortic abdominal aneurysms in patients with severe pulmonary insufficiency.

In view of the poor prognosis associated with the natural history of aortic abdominal aneurysms, this disorder is being surgically corrected in an increasing number of patients. There remains a group of patients with serious coexisting disease in whom careful consideration must be given concerning the risk of operation. One such group of patients is those with severe respiratory insufficiency. The records of ten patients with clinical and physiologic evidence of severe pulmonary insufficiency and concomitant aortic abdominal aneurysms were reviewed. While some patients were refused operation for severe cardiovascular disease, malignant disease and obesity, none was denied operation on the basis of severe respiratory insufficiency alone. With detailed respiratory assessment, appropriate preoperative preparation and careful attention to pulmonary function in the postoperative course, these patients can now undergo aortic abdominal aneurysm resection and grafting with a high expectation of success. In the ten patients, no operative deaths occurred, and all were discharged from the hospital having undergone a favorable postoperative course.

Aspirin and dipyridamole decrease intimal hyperplasia in experimental vein grafts.

Release from platelets of a factor mitogenic for smooth muscle cells is a postulated mechanism for the pathogenesis of vascular intimal hyperplasia. In this study the effect of antiplatelet therapy was evaluated. Aspirin (165 mg twice daily) and dipyridamole (25 mg twice daily) were administered to six rhesus monkeys and six were given placebo only. Bilateral vein bypass grafts were placed in the iliac arteries. In addition, to evaluate the relative contribution of adventitial dissection and intimal injury, on one side the carotid artery and femoral vein were stripped of adventitia and on the other side the intima of these vessels were injured by the single passage of an inflated balloon tipped catheter. Animals were killed after 16 weeks. In grafts relative luminal area was determined by a photographic gravimetric method at three standard locations. Femoral veins and carotid arteries were classified as histologically normal or as exhibiting hyperplasia. All vessels with adventitial stripping were normal. All vessels with intimal injury in the placebo group except one exhibited intimal hyperplasia compared to the drug treated group in which over half were normal. Relative intimal area was significantly less in grafts from drug treated animals at all three locations and luminal area greater in two. These data suggest that vascular intimal hyperplasia can be reduced by treatment with antiplatelet agents.

Intimal thickening and hyperlipidemia in experimental primate vascular autografts.

Intimal thickening is a significant cause of late failure of aorto-coronary vein grafts. The microscopic appearance of this thickening has some similarities to the microscopic appearance of arterial atherosclerosis, and it has been suggested that hyperlipidemia may play a role in its pathogenesis. This study examines the morphology and lipid composition of autologous vein and artery grafts in normal and hyperlipidemic rhesus monkeys. Grafts were examined six months after insertion by light and electron microscopy and tissue lipids were determined quantitatively. Intimal thickening occurred in all grafts. Specific morphological and lipid compositional features of the grafts were influenced by the type of tissue used for grafting and the presence or absence of hyperlipidemia. However, the degree of intimal thickening per se could not be related to either of these two factors. It is concluded that surgical transplantation in this model provides the most powerful stimulus for intimal thickening and any additional effect on this process by hyperlipidemia is small.

Effects of experimental hypertension and hypercholesterolemia on the lipid composition of the aorta.

This study evaluates alterations in canine aortic lipid composition under conditions of hypertension, hypercholesterolemia, or a combination of these factors. Hypertension was produced in the proximal thoracic aorta by creation of an aortic coarctation, whereas hypercholesterolemia was brought about by a lard-cholesterol diet in combination with thyroidectomy. Hypertension alone produced only minor changes in the lipid content of the arterial wall, but hypercholesterolemia yielded modest increases. The combination of hypertension and hypercholesterolemia, however, produced a striking increase in the total lipid content in the arterial wall. This change was most marked in the cholesteryl ester fraction, and a shift in cholesteryl ester fatty acids from linoleate to oleate was found. These data indicate that the interaction of hypertension and hypercholesterolemia produces alterations in lipid composition in a relationship which appears to be more geometric than arithmetic in nature.

Digoxin kinetics during furosemide administration.

The urinary excretion of a 0.75-mg oral dose of digoxin was assessed in 8 healthy men during a control 5-day period and then, after a washout period of at least 2 wk, during a 5-day period when the subjects also took oral furosemide, 40 mg daily. Analysis of the raw data by a paired Student's test and analysis of variance of log-transformed urinary digoxin excretion data revealed no significant difference attributable to the addition of furosemide (F = 1.16; df = 1,21). The treatment by day interaction showed the slopes to be consistent between the two treatments. It seems that in the presence of normal renal function there is no need to alter loading or maintenance doses of digoxin when furosemide is also given. Analysis of variance with log transformation of data is suggested as a practical approach to handling digoxin urinary excretion results when the transformation linearizes the data through examination by the method of orthogonal polynomials.