We used a pulsed Doppler technique to examine the flow velocity pattern in the right ventricular outflow tract in 33 adults. In the patients with normal pulmonary artery pressure (mean pressure < 20 mm Hg, 16 patients), ejection flow reached a peak level at midsystole (137 + 24 msec, mean + SD), producing a domelike contour of the flow velocity pattern during systole. In contrast, the flow velocity pattern in patients with pulmonary hypertension (mean pressure ¢ 20 mm Hg,17 patients) was demonstrated to accelerate rapidly and to reach a peak level sooner (97 + 20 msec, p < .01); in 10 of the pulmonary hypertensive patients a secondary slower rise in flow velocity was observed during a deceleration, resulting in the midsystolic notching. The time to peak flow (acceleration time, AcT) and right ventricular ejection time (RVET) were measured from the flow velocity pattern. Either AcT or AcT/RVET decreased with increase in mean pulmonary artery pressure, and a very high correlation (r = -.90) was found between AcT/RVET and log,0 (mean pulmonary artery pressure). The use of this technique permitted the noninvasive estimation of the pulmonary artery pressure. Circulation 68, No. 2, 302-309, 1983. NONINVASIVE evaluation of pulmonary hypertension has been an important clinical problem for many years. The presence of pulmonary hypertension has been assessed by abnormalities in heart sounds,' in electrocardiographic tracings, or in chest x-rays,2 but to date, the accurate measurement of the pulmonary artery pressure requires the use of cardiac catheterization procedures. The development of echocardiographic techniques has allowed the investigation of pulmonic valve motion,3 which represents some characteristic abnormalities associated with pulmonary hypertension, such as rapid opening slope in systole,j5 attenuation or absence of the "a" dip,' prolongation of the ratio of right ventricular preejection period (RPEP) to right ventricular ejection time (RVET),57 and midsystolic semiclosure of pulmonic valve.)6 A recent experimental study8 emphasized that these abnormalities of the pulmonic valve motion were determined by abnormal flow changes in the pulmonary artery. However, flow characteristics with regard to pulmonary artery pressure either in the pulmonary artery or in the right ventricular outflow tract have not been successfully studied in man. Our objectives were to study the blood flow characteristics in the right ventricular outflow tract in patients with pulmonary hypertension by a pulsed Doppler technique9-I and to develop an index that would permit quantitative evaluation of pulmonary hypertension by noninvasive methods. Materials and methodsPatient selection. Thirty-eight patients admitted for diagnostic catheterization were examined by a pulsed Doppler technique. Five patients were excluded in whom Doppler recordings of flow velocity in the right ventricular outflow tract were not satisfactorily obtained because of poor penetration of ultrasound through the chest wall. Doppler examination was perfor...

Spacetime geometries dual to arbitrary fluid flows in strongly coupled N = 4 super Yang Mills theory have recently been constructed perturbatively in the long wavelength limit. We demonstrate that these geometries all have regular event horizons, and determine the location of the horizon order by order in a boundary derivative expansion. Intriguingly, the derivative expansion allows us to determine the location of the event horizon in the bulk as a local function of the fluid dynamical variables. We define a natural map from the boundary to the horizon using ingoing null geodesics. The area-form on spatial sections of the horizon can then be pulled back to the boundary to define a local entropy current for the dual field theory in the hydrodynamic limit. The area theorem of general relativity guarantees the positivity of the divergence of the entropy current thus constructed.

We consider large N Yang Mills theory with D adjoint scalar fields in d dimensions for d = 0 or 1. We show the existence of a non-trivial saddle point of the functional integral at large D which is characterized by a mass gap for the adjoint scalars. We integrate out the adjoint scalars in a 1/D expansion around the saddle point. In case of one dimension which is regarded as a circle, this procedure leads to an effective action for the Wilson line. We find an analogue of the confinement/deconfinement transition which consists of a second order phase transition from a uniform to a non-uniform eigenvalue distribution of the Wilson line, closely followed by a Gross-Witten-Wadia transition where a gap develops in the eigenvalue distribution. The phase transition can be regarded as a continuation of a Gregory-Laflamme transition. Our methods involve large values of the dimensionless 'tHooft coupling. The analysis in this paper is quantitatively supported by earlier numerical work for D = 9.

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