Addendum to "Equation of state of classical Coulomb plasma mixtures".

Recently developed analytic approximation for the equation of state of fully ionized nonideal electron-ion plasma mixtures [A. Y. Potekhin, G. Chabrier, and F. J. Rogers, Phys. Rev. E 79, 016411 (2009)], which covers the transition between the weak and strong Coulomb coupling regimes and reproduces numerical results obtained in the hypernetted-chain (HNC) approximation, is modified in order to fit the small deviations from the linear mixing in the strong-coupling regime, revealed by recent Monte Carlo simulations. In addition, a mixing rule is proposed for the regime of weak coupling, which generalizes post-Debye density corrections to the case of mixtures and numerically agrees with the HNC approximation in that regime.

Improved convergence for two-component activity expansions.

It is well known that an activity expansion of the grand canonical partition function works well for attractive interactions, but poorly for repulsive interactions, such as occur between atoms and molecules. The virial expansion of the canonical partition function shows just the opposite behavior. This poses a problem for applications that involve both types of interactions, such as occur in the outer layers of low-mass stars. We show that it is possible to obtain expansions for repulsive systems that convert the poorly performing Mayer activity expansion into a series of rational polynomials that converge uniformly to the virial expansion. In the current work we limit our discussion to the second virial approximation. In contrast to the Mayer activity expansion, the activity expansion presented herein converges for both attractive and repulsive systems.

Demonstration of spectrally resolved x-ray scattering in dense plasmas.

We present the first spectrally resolved x-ray scattering measurements from solid-density plasmas. The scattering spectra show the broadened Compton down-shifted feature allowing us to determine the electron temperature and density with high accuracy. In the low temperature limit, our data indicate that the ionization balance reflects the electrons in the conduction band consistent with calculations that include quantum mechanical corrections to the interaction potential.

The muscle hypothesis: a model of chronic heart failure appropriate for osteopathic medicine.

Chronic heart failure is one of the most serious medical problems in the United States, affecting some 4 million persons. In spite of its common occurrence, and comprehensive literature regarding this condition, no unifying hypothesis has been accepted to explain the signs and symptoms of chronic heart failure. The cardiocirculatory and neurohormonal models place an emphasis on left ventricular ejection fraction and cardiac output and do not provide appropriate explanations for the symptoms of breathlessness and fatigue. The muscle hypothesis supplements these conventional models. It proposes that abnormal skeletal muscle in heart failure results in activation of muscle ergoreceptors, leading to an increase in ventilation and sensation of breathlessness, the perception of fatigue, and sympathetic activation. At least one fourth of patients with chronic heart failure are limited by skeletal muscle abnormalities rather than cardiac output. Cardiac rehabilitation exercise can lead to an increase in exercise capacity that is superior to that gained from digitalis or angiotensin-converting enzyme inhibitors. Exercise tends to reverse the skeletal muscle myopathy of chronic heart failure and reduces the abnormal ergoreflex. Other interventions that have been shown to have a favorable outcome include localized muscle group training, respiratory muscle training, and dietary approaches. The possibility that osteopathic manipulative treatment might be of benefit is an attractive, but untested, possibility.

The clinical spectrum of acute coronary syndromes.

More than 5 million Americans visit hospital emergency departments each year with the complaint of chest pain. Two million patients are admitted to hospitals because of chest pain, but the diagnosis of coronary heart disease is confirmed in only one fourth of them. Acute coronary syndrome represents a clinical syndrome that includes unstable angina, non-Q-wave myocardial infarction and Q-wave myocardial infarction. The goal of management of patients with acute coronary syndrome is to rapidly recognize and manage their cardiac ischemic event, define the risk of myocardial ischemia and recurrent cardiac events, and minimize unnecessary risk to the patient. These decisions can all be made by the use of standard clinical descriptors that include chest pain, the electrocardiogram, and biochemical markers of myocardial injury during and after an acute ischemic episode.

Effects of exercise training on chronotropic incompetence in patients with heart failure.

OBJECTIVE: To describe the effects of exercise training on chronotropic incompetence in patients with stable heart failure, as measured by their inability to achieve a peak exercise heart rate greater than 85% of maximum. BACKGROUND: Exercise intolerance and chronotropic incompetence are characteristic of patients with heart failure. Exercise training improves exercise capacity in these patients; however, to what extent reversal of chronotropic incompetence contributes to such a response remains uncertain. METHODS: Fifty-one patients undergoing standard medical therapy were randomly assigned to a 24-week exercise training program or a no exercise control group. Twenty-one of 26 patients assigned to the exercise group and 22 of 25 control patients completed the study. Peak oxygen consumption, resting and exercise plasma norepinephrine level, and quality of life (Living With Heart Failure Questionnaire) were assessed. RESULTS: A significant (P <.05) increase in peak heart rate was observed in the exercise group (9 +/- 3 beats/min) when compared with the control group (1 +/- 3 beats/min). Among exercise-trained patients with chronotropic incompetence at baseline (n = 14), the increase in peak heart rate at week 24 was 12 +/- 3 beats/min. Peak oxygen consumption was significantly (P <.05) increased in the exercise group (204 +/- 57 mL/min) versus the control group (72 +/- 33 mL/min). Health-related quality of life was not significantly changed with exercise training. Twenty-four weeks of exercise training induced a greater (P <.05) reduction in plasma norepinephrine at rest and during exercise in patients with a nonischemic cardiomyopathy versus those with ischemic cardiomyopathy. CONCLUSIONS: Exercise training results in an increase in peak heart rate and partial reversal of chronotropic incompetence among patients with stable heart failure. These responses contribute, in part, to the exercise training-induced increase in exercise capacity that occurs in these patients.

Exercise training in patients with heart failure. A randomized, controlled trial.

OBJECTIVE: To assess the benefit of exercise training in patients with heart failure caused by left ventricular systolic dysfunction and to further describe the physiologic changes associated with exercise training in these patients. DESIGN: Randomized, controlled trial. SETTING: Urban outpatient clinic. PATIENTS: 40 men with compensated heart failure who were receiving standard medical therapy were randomly assigned to an exercise-training group or to a control group that did not exercise. Fifteen of the 21 patients assigned to exercise training and 14 of the 19 patients assigned to the control group completed the study. INTERVENTION: Patients assigned to exercise training participated in a program of three exercise sessions per week for 24 weeks. MEASUREMENTS: Symptom-limited exercise tests with gas exchange analysis done just before randomization, at week 12, and at week 24. RESULTS: At week 24, the following changes (mean +/- SE) were seen in patients in the exercise group and patients in the control group, respectively; exercise duration, 2.8 +/- 0.6 minutes and 0.5 +/- 0.5 minutes; peak oxygen consumption (VO2), 231 +/- 54 L/min and 58 +/- 38 L/min; peak ventilation, 12 +/- 3 L/min and -4 +/- 3 L/min; peak heart rate, 10 +/- 4 beats/min and -2 +/- 4 beats/min; and peak power output, 20 +/- 6 W and 2 +/- 5 W. Differences between the increases occurring in the exercise group and the changes occurring in the control group were significant (P < 0.05). Among patients in the exercise group, 85% of the increase in peak VO2 occurred by week 12, and 46% of the increase in peak VO2 was caused by the increase in peak heart rate. CONCLUSION: Exercise training does not appear to be contraindicated in patients with compensated heart failure. Exercise training improved exercise tolerance, as measured by increases in peak VO2, exercise duration, and power output. This improved exercise tolerance was caused in part by an increase in peak heart rate.

Astrophysical opacity.

An array of problems in astronomy, cosmology, and particle physics is dependent on our understanding of the evolution and structure of stars. Stellar structure and evolution, in turn, depend on how the nuclear energy generated in the stellar center is transported to the surface. Energy transport by photons is a primary transfer mechanism. Recent improvements in the calculation of the radiative properties of stellar matter have helped resolve several long-standing discrepancies between observations and the predictions of theoretical models.

Circuit weight training in early cardiac rehabilitation.

A prospective, randomized study evaluated the feasibility, safety, and efficacy of upper body circuit weight training (CWT) in 25 stable male cardiac patients entering the initial out-of-hospital phase of cardiac rehabilitation. Both groups performed 30 minutes of aerobic exercise only for 6 weeks. The aerobic exercise group (N = 13) continued this regimen for 6 more weeks, during which time the CWT group (N = 12) performed 15 minutes of aerobic exercise followed by CWT (two loops, eight upper body exercises). The only adverse response was in one CWT patient in whom restenosis developed. Peak heart rate during aerobic exercise and CWT was similar, but peak systolic blood pressure during aerobic exercise was significantly greater than during CWT. Peak rate pressure product during aerobic exercise and CWT was similar. Treadmill time increased significantly in both groups. Upper body strength (cumulative pounds lifted) increased significantly only in the CWT group. A coordinated program of CWT and aerobic exercise can be performed safely in stable cardiac patients during phase 2 cardiac rehabilitation, resulting in improved upper body strength and aerobic capacity.

Sinoatrial and atrioventricular dysfunction associated with the use of guanabenz acetate.

Guanabenz acetate is an antihypertensive drug that is closely related to clonidine hydrochloride. Clonidine is well known to potentiate atrioventricular (AV) node conduction disturbances, but to date that effect has not been attributed to guanabenz. A case of electrocardiographic and electrophysiologic studies in a patient with both sinus and AV node conduction disturbances associated with the use of guanabenz acetate is reported. The sinus cycle length was increased by 50% after guanabenz and the sinus node recovery time was prolonged by 42%. AV block occurred proximal to the His bundle and His-ventricular prolongation of 42% also occurred. This drug should be used cautiously in patients with evidence of sinus or AV node dysfunction.

Cardiac rehabilitation: developing a successful program.

The Downriver Treadmill Team, a Phase II and Phase III outpatient cardiac rehabilitation program, is presented as a prototypical successful program. The qualities and attributes of this program are discussed as a means to actively promote cardiac rehabilitation directly to the consumer.

Early and late morphologic changes in major epicardial coronary arteries after percutaneous transluminal coronary angioplasty.

Certain clinical and morphologic observations are described in 4 men who had PTCA of the left anterior descending coronary artery early (4 hours) or late (80, 90 and 150 days) before sudden death. Histologically, each of the 4 patients had the site of PTCA narrowed 76 to 95% in cross-sectional area by atherosclerotic plaque. The early PTCA patient had coronary artery dissection at the site of PTCA. Each of the 3 late PTCA patients had a decrease in the mean transstenotic coronary gradient (17, 38 and 43 mm Hg) and an angiographic increase in the left anterior descending coronary artery luminal diameter (55, 60 and 65%) at the time of PTCA. At necropsy, 80, 90 and 150 days later, the LAD coronary artery in the area of the PTCA in each patient was narrowed 76 to 95% in cross-sectional area by plaques. No cracks in plaques or other lesions that may have resulted from PTCA were identified histologically in the left anterior descending coronary artery in any late PTCA patient.