The proximity and duration of the tidal disruption event (TDE) ASASSN-14li led to the discovery of narrow, blue-shifted absorption lines in X-rays and UV. The gas seen in X-ray absorption is ...consistent with bound material close to the apocenter of elliptical orbital paths, or with a disk wind similar to those seen in Seyfert-1 active galactic nuclei. We present a new analysis of the deepest high-resolution XMM-Newton and Chandra spectra of ASASSN-14li. Driven by the relative strengths of He-like and H-like charge states, the data require N/C > 2.4, in qualitative agreement with UV spectral results. Flows of the kind seen in the X-ray spectrum of ASASSN-14li were not clearly predicted in simulations of TDEs; this left open the possibility that the observed absorption might be tied to gas released in prior AGN activity. However, the abundance pattern revealed in this analysis points to a single star rather than a standard AGN accretion flow comprised of myriad gas contributions. The simplest explanation of the data is likely that a moderately massive star (M ~ 3 Msun) with significant CNO processing was disrupted. An alternative explanation is that a lower mass star was disrupted that had previously been stripped of its envelope. We discuss the strengths and limitations of our analysis and these interpretations.
Doppler echocardiography enables noninvasive determination of blood velocity and flow area through which quantitation of blood flow in vessels and across valvular orifices can be achieved. The stroke ...volume is rendered as the product of the flow area and the area beneath the velocity curve; on taking the heart rate into consideration, the cardiac output can be calculated. Essentially, this method can be used in the region of all four cardiac valves, the ascending aorta and the pulmonary artery. For calculation of the mitral and tricuspid velocity, the sample volume is positioned in the region of the tips of the leaflets or in the valve anulus. The flow area is most frequently calculated from the diameter of the valve anulus under the assumption of a circular cross-section. Additionally, in some studies, with respect to correction for area changes during diastole, separation of the leaflets in the M-mode echocardiogram has been employed. Determination of the right ventricular output is accomplished through the combination of the blood flow velocity in the pulmonary artery and the cross-sectional area of this vessel, the right ventricular outflow tract or the pulmonic anulus. To calculate flow in the ascending aorta, both pulsed and continuous-wave Doppler techniques have been employed and the diameter of the ascending aorta or the aortic root is derived echocardiographically. Comparative studies of the various methods show that measurement of flow in the region of the aortic anulus yields results somewhat superior to that of the other methods. Possible sources of error in these methods result from simplifying assumptions with respect to calculation of the area of flow, that is, equating the anatomical area with the area of flow, circular or elliptical cross-sectional models, temporal constancy of the areas as well as the velocities, that is, constant position of the sample volume, flat velocity profile and neglect of angle deviations.
Although two-dimensional echocardiography has provided accurate measurements of left ventricular ejection fraction, the technique has been limited in the evaluation of diastolic function. First ...half-filling fraction, representing the difference between mid-diastolic and end-systolic volumes divided by stroke volume, is a recently introduced index of diastolic function. We developed a method for determining half-filling fraction by two-dimensional echocardiography with the use of the average of left ventricular internal diameters measured at the base, middle, and apical third of the ventricular cavity in multiple longitudinal planes. In 27 patients with a wide range of ventricular function, we compared angiographic measurements of half-filling fraction to results obtained by two-dimensional echocardiography. Half-filling fraction measured angiographically averaged (mean +/- SD) 0.58 +/- 0.15 (range 0.26 to 0.77) and measured by two-dimensional echocardiography averaged 0.58 +/- 0.15 (range 0.35 to 0.90). A significant correlation was found between angiographic and echocardiographic half-filling fractions (r = 0.84, SEE = 0.08). Results were similar in the presence or absence of segmental wall motion abnormalities. All seven patients with half-filling fractions below 0.50 by echocardiography had depressed half-filling fractions by angiography; three of these patients had ejection fractions of greater than or equal to 0.55. Thus half-filling fraction can be derived with two-dimensional echocardiography providing a noninvasive assessment of diastolic function.
The Future of Cardiac Imaging Douglas, Pamela S., MD; Cerqueira, Manuel D., MD; Berman, Daniel S., MD ...
JACC. Cardiovascular imaging,
October 2016, Volume:
9, Issue:
10
Journal Article
Peer reviewed
Open access
Abstract The American College of Cardiology’s Executive Committee and Cardiovascular Imaging Section Leadership Council convened a discussion regarding the future of cardiac imaging among thought ...leaders in the field during a 2 day Think Tank. Participants were charged with thinking broadly about the future of imaging and developing a roadmap to address critical challenges. Key areas of discussion included: 1) how can cardiac imaging services thrive in our new world of value-based health care? 2) Who is the cardiac imager of the future and what is the role of the multimodality imager? 3) How can we nurture innovation and research in imaging? And 4) how can we maximize imaging information and optimize outcomes? This document describes the proceedings of this Think Tank.
A simple and sensitive high performance liquid chromatographic (HPLC) method for glimepiride determination in human serum is described. The assay involves one-step liquid-liquid extraction with ...dichloromethane in acidified serum. Glibenclamide is used as the internal standard. Detection is done at 228 nm and limit of quantification is less than 10 ng/mL for glimepiride. The calibration curves are linear over the concentration range tested (10-1000 ng/mL). Accuracy, precision, and stability studies are performed.
This method is applied to the analysis of glimepiride serum samples of 41 Lebanese male volunteers after oral administration of a single glimepiride 3 mg tablet. Pharmacokinetic analysis of the data is done using a noncompartmental approach with WinNonlin software (WinNonlin
®
Professional, version 4.1).
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