Effects of magnetic shear on toroidal rotation in tokamak plasmas with lower hybrid current drive.

Application of lower hybrid (LH) current drive in tokamak plasmas can induce both co- and countercurrent directed changes in toroidal rotation, depending on the core q profile. For discharges with q(0) <1, rotation increments in the countercurrent direction are observed. If the LH-driven current is sufficient to suppress sawteeth and increase q(0) above unity, the core toroidal rotation change is in the cocurrent direction. This change in sign of the rotation increment is consistent with a change in sign of the residual stress (the divergence of which constitutes an intrinsic torque that drives the flow) through its dependence on magnetic shear.

Rotation reversal bifurcation and energy confinement saturation in tokamak Ohmic L-mode plasmas.

Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-mode plasmas following electron density ramps. For low density discharges, the core rotation is directed cocurrent, and reverses to countercurrent following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm(-1)≤k(θ)≤11 cm(-1) and frequencies above 70 kHz. There is a strong correlation between the reversal density and the density at which the Ohmic L-mode energy confinement changes from the linear to the saturated regime.

Thrombin-induced increase in intracellular cyclic 3',5'-adenosine monophosphate in human platelets.

The present data disagree with earlier suggestions that thrombin's effect on platelets is to cause a decrease in intracellular cyclic 3',5'-adenosine monophosphate. Washed human platelets or platelet-rich plasma were incubated at 37 degrees C with human thrombin. After centrifugation, the supernates were assayed for nucleotides and calcium released. The platelet pellets, and in some experiments the supernates as well, were assayed by radioimmunoassay for intracellular cyclic AMP. In the washed platelet system, increasing doses of thrombin to 0.5 U/cc induced increasing release of nucleotides and calcium. This was accompanied by an average twofold increase in intracellular cyclic AMP levels. Prostaglandin E(1), which inhibited 30-50% of release, induced a four- to fivefold increase in cyclic AMP levels that was additive to the cyclic AMP-stimulatory effect of thrombin. Theophylline, which inhibited only 20-40% of nucleotide release, was synergistic with thrombin in the intracellular accumulation of cyclic AMP. The time-course of cyclic AMP accumulation in response to thrombin was slower than thrombin-induced nucleotide release. Similar findings were made in the platelet-rich plasma system where thrombin stimulation of nucleotide release also resulted in a marked accumulation of intracellular cyclic AMP. Thrombin did not appear to stimulate the release of intracellular cyclic AMP. The mechanism underlying these observations was not apparent. The thrombin had no measurable inhibitory effect on platelet phosphodiesterase activity in either intact washed cells or the platelet homogenate supernates. Furthermore, thrombin inhibited, rather than stimulated, platelet adenyl cyclase activity in both intact washed cells and washed platelet particulate fractions. Of note, however, was the finding that thrombin did not completely inhibit the adenyl cyclase activity of prostaglandin-stimulated cells. Further work is needed to clarify the significance of this observation.Nonetheless, the accumulation of intracellular cyclic AMP in response to thrombin observed in the present study suggests that the antagonistic actions of various agents on the platelet release reaction, thought to underlie platelet function, may depend upon a mechanism more intricate than a straightforward mediation through directly opposite effects on platelet cyclic AMP.

Temperature gradient scale length measurement: A high accuracy application of electron cyclotron emission without calibration.

Calibration is a crucial procedure in electron temperature (Te) inference from a typical electron cyclotron emission (ECE) diagnostic on tokamaks. Although the calibration provides an important multiplying factor for an individual ECE channel, the parameter ΔTe/Te is independent of any calibration. Since an ECE channel measures the cyclotron emission for a particular flux surface, a non-perturbing change in toroidal magnetic field changes the view of that channel. Hence the calibration-free parameter is a measure of Te gradient. BT-jog technique is presented here which employs the parameter and the raw ECE signals for direct measurement of electron temperature gradient scale length.

Oxygen consumption of human blood platelets. I. Effect of thrombin.

The effect of thrombin on the oxygen consumption of washed human platelets was measured polarographically with the Clark oxygen electrode. The average basal respiratory rate was 18 plus or minus 1.6 (mean plus or minus S.E.) natoms oxygen per min per 10-9 platelets. Thrombin (1.9 units/ml) caused a 4-13-fold increase in the rate of oxygen consumption (138 plus or minus 14 (mean plus or minus S.E.) natoms oxygen per min per 10-9 platelets). The thrombin-stimulated increase of oxygen consumption was transient, lasting from 1 to 1.5 min before returning to the respiratory rate observed before the thrombin addition. Release of platelet constituents appeared to precede the stimulation of oxygen consumption. These results may provide a basis for explaining the discrepancy in the literature concerning the effects of thrombin on platelet respiration.

Oxygen consumption of human blood platelets. II. Effect of inhibitors on thrombin-induced oxygen burst.

The effect of selected inhibitors on the thrombin-stimulated burst and the basal oxygen consumption of washed human platelets were investigated and compared with inhibition of the release reaction. Cyanide (0.2 mM) caused complete inhibition of the basal respiration, but only 15% inhibition of the thrombin-stimulated burst of oxygen consumption. Similar differential inhibitory effects were observed with oligomycin, antimycin, rotenone and N-ethylmaleimide. Prostaglandin E1 (0.03 mM) and acetylsalicylic acid (0.8 mM) had little effect on basal respiration, but inhibited the thrombin-stimulated burst of oxygen consumption. N-Ethylmaleimide (0.4 mM) inhibited the release of calcium from platelets by 90%, while prostaglandin E1, acetylsalicylic acid and the above mitochondrial inhibitors caused no more than 30% inhibition of the release reaction. Our results provide evidence that basal respiration and a portion of the thrombin-stimulated burst of oxygen consumption are involved in respiratory chain phosphorylation, and that this component of the thrombin-stimulated burst may be coupled to the maintenance of the release reaction.

Myopathy in sarcoidosis: clinical and pathologic study of four cases and review of the literature.

The clinical course and muscle biopsy findings of four adults with sarcoidosis who developed a myopathy are described. Three patients had evidence of an inflammatory myopathy and elevated CPK. Two patients had no detectable granulomas at muscle biopsy and may represent a separate autoimmune disorder (polymyositis) concurrent with sarcoidosis. Asymptomatic muscle disease in sarcoidosis probably occurs with a much greater frequency than symptomatic disease. Isolated sarcoid myopathy without prior or concurrent organ involvement has been described, but comprehensive autopsy studies to confirm this are lacking. The origin of symptoms associated with granulomas is obscure and may be mediated through the effects of lymphokines and monokines. Corticosteroids seem to play a useful role in therapy, but treatment over a prolonged period may be necessary. The use of cytotoxic agents is largely untested.

Recertification. A continuing debate.

Recertification, like taxes, will never draw many supporters from the targeted group. Why should physicians who have had to survive the stiffest of scholastic labors in order to obtain the privilege of a medical education again be asked to prove their continuing worth long after graduation? Apparently because health consumers feel that physicians occupy a critical role and want more tangible evidence that they are keeping up with the explosion of medical knowledge. Dr. Trobe has sought the opinion of Dr. Melvin Rubin, who challenges the assumption that a recertification test will offer a sufficient guarantee of clinical excellence to warrant the expense to the public and the "mental anguish" to physicians, and the opinion of Dr. Sidney Wolfe, who argues that examination is a necessary (though perhaps not sufficient) protection against flagging knowledge and skill.

Nurse-midwifery. The beneficial alternative.

The number of nurse-midwife-attended births in U.S. hospitals has jumped ten-fold in the last 20 years, rising from just 19,686 in 1975 to 196,977 in 1994. Certified nurse-midwives (CNMs) focus on childbirth as a normal event, emphasizing the educational and psychosocial aspects of care and the judicious use of technological interventions. CNM care appears particularly well suited to help solve two difficult problems in U.S. obstetric care--our country's slow progress in improving the health status of newborns and the excessive use of medical interventions during childbirth. Despite the fact that CNM care has been found to be safe and cost-effective, only a small fraction of those pregnant women who could benefit from CNM care use midwifery services. Lack of consumer awareness is part of the problem, but barriers also exist to accessing CNM services. Sixty-four percent of CNM practices responding to a survey reported practice restrictions, most commonly due to state laws, hospital policies, and inappropriately restrictive physician back-up. One state, Florida, is aggressively promoting the use of CNM care as the standard of practice for healthy pregnant women.

Requesting organ donation: an interview study of donor and nondonor families.

BACKGROUND: Approximately half of the families asked to consider donation of a relative's organs decline to give consent. Understanding the difference between stated public support of organ donation and actual behavior is key to decreasing the shortage of donor organs. OBJECTIVES: To gain insight into the experiences of potential donor families and to define features of the donation-request process and other factors that are associated with consent for organ donation. METHODS: A structured telephone interview was conducted with the immediate next of kin of 164 medically suitable potential organ donors. Interviews 30 to 60 minutes long were held with members of both donor and nondonor families 4 to 6 months after the death of the study participant's relative. RESULTS: Several factors were associated with consent for organ donation: characteristics of the patient and the patient's family, beliefs and attitudes about organ donation and transplantation, whether the family knew the deceased's wishes about donation, the family's satisfaction with the hospital care that their relative received, specific aspects of the donation-request process, and the family's understanding of brain death. CONCLUSIONS: Organ donation rates could be increased by enhancing the quality of hospital care and ensuring that the request for donation is handled in a way that meets the families' informational and emotional needs.

The vanishing health care safety net: new data on uninsured Americans.

New data obtained from the Census Bureau shows that the number of Americans without any health insurance increased by 1.3 million between 1989 and 1990, bringing the total number of uninsured to 34.7 million, more than at any time since the passage of Medicare and Medicaid 25 years ago. This increase coincided with a 10.5 percent increase in health spending, the second largest in the past three decades. The number of people covered by Medicaid grew by 3.1 million, due to a one-time expansion of eligibility mandated by Congress, but this was more than counter-balanced by a population growth of 3 million and a decrease of 1.3 million in people covered by private insurance. Had Medicaid not been expanded, the number of uninsured would have increased by 4.4 million. The increase in the uninsured affected virtually all parts of the nation. Seven states had increases of more than 100,000 persons each. Only Texas experienced a decrease of that magnitude, but still had the second highest rate of uninsurance of any state. Of the 1.3 million additional uninsured in 1990, 77 percent were male, 32 percent had family incomes in excess of $50,000 per year, and 74 percent had annual family incomes above $25,000. Fewer than 9 percent had incomes below the poverty line. The numbers of uninsured children and senior citizens fell slightly (but not significantly), while the number of uninsured working-age adults rose by 1.4 million. The number of uninsured workers in each of four of 20 major industry groups increased by more than 100,000 in 1990. None of the industry groups showed a significant decline in the number of uninsured. Among professionals, there were substantial numbers of uninsured doctors, engineers, teachers, college professors, clergy, and others, but all legislators and judges were insured. The data presented here largely predate the recession and understate current problems. In 1991 the number of uninsured will likely reach nearly 40 million. Also, these estimates are based on the number of people uninsured at a single time during 1990; a far higher number were temporarily uninsured at some point during the year. Moreover the Census Bureau survey ignores the problem of the underinsurance of at least 50 million insured Americans. Patchwork public programs are grossly inadequate to plug the holes. A national health program covering all Americans could assure access to care and contain costs.

The growing epidemic of uninsurance: new data on the health insurance coverage of Americans.

Despite a massive expansion of Medicaid and an upswing in the economy, the total number of Americans uninsured in 1993 was 39.7 million, more than at any time since the passage of Medicaid and Medicare in the 1960s. Since 1989, the ranks of the uninsured have swelled by 6.3 million. Millions more would be uninsured if Medicaid enrollment had not risen dramatically, by 10.5 million people since 1989. Loss of health coverage is a growing problem for middle-income families, women, and children, as it has long been for low-income families. Even in Hawaii, whose employer mandate program is often cited as a model of universal coverage, there was a large increase in uninsurance. Nationwide, the sharp upswing in the number of Americans who are uninsured has coincided with government and corporate policies to encourage medical competition and push people into managed care plans. Republican proposals to limit AFDC benefits threaten to further increase uninsurance, particularly among women and children. Only a Canadian-style single-payer reform can assure universal coverage and simultaneously contain costs.

Takayasu's arteritis.

Takayasu's arteritis, an inflammatory and obliterative disease of medium and large arteries, is classified as a giant cell arteritis. It has a predilection for the aortic arch and its branches and the pulmonary arteries. Unlike atherosclerotic vascular diseases, Takayasu's arteritis affects young women primarily. Early symptoms may be mainly systemic and may resemble polymyalgia rheumatica. The etiology is unknown, but infectious agents and autoimmunity have been suggested to play a role. Diagnosis is based on symptoms, physical findings, and angiographic findings, because tissue diagnosis rarely is feasible. The two cases reported here represent contrasting phases of Takayasu's arteritis.

Energetic ion loss detector on the Alcator C-Mod tokamak.

A scintillator-based energetic ion loss detector has been successfully commissioned on the Alcator C-Mod tokamak. This probe is located just below the outer midplane, where it captures ions of energies up to 2 MeV resulting from ion cyclotron resonance heating. After passing through a collimating aperture, ions impact different regions of the scintillator according to their gyroradius (energy) and pitch angle. The probe geometry and installation location are determined based on modeling of expected lost ions. The resulting probe is compact and resembles a standard plasma facing tile. Four separate fiber optic cables view different regions of the scintillator to provide phase space resolution. Evolving loss levels are measured during ion cyclotron resonance heating, including variation dependent upon individual antennae.

X-ray imaging crystal spectroscopy for use in plasma transport research.

This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain particle, momentum, and heat transport studies in a tokamak for the first time. Doppler tomography techniques have been extended to include propagation of statistical uncertainty due to photon noise, the effect of non-uniform instrumental broadening as well as flux surface variations in impurity density. These methods have been deployed as a suite of modeling and analysis tools, written in interactive data language (IDL) and designed for general use on tokamaks. Its application to the Alcator C-Mod XICS is discussed, along with novel spectral and spatial calibration techniques. Example ion temperature and radial electric field profiles from recent I-mode plasmas are shown, and the impact of poloidally asymmetric impurity density and natural line broadening is discussed in the context of the planned ITER x-ray crystal spectrometer.