Atherogenic index of plasma and triglyceride-glucose index to predict more advanced coronary artery diseases in patients with the first diagnosis of acute coronary syndrome.

OBJECTIVE: Coronary heart disease (CHD) is the most common cause of mortality and morbidity. Acute coronary syndrome (ACS) is the most advanced form of the CHD spectrum. The triglyceride-glucose index (TGI) and atherogenic plasma index (AIP) are associated with future cardiovascular events. This study investigated the association of these parameters with the severity of CAD and prognosis in the first-diagnosed ACS patients. PATIENTS AND METHODS: Our study was designed retrospectively, including 558 patients. Patients were divided into four subgroups: high and low TGI and high and low AIP. SYNTAX scores, in-hospital mortality, major adverse cardiac events (MACE), and survival were compared at 12-month follow-up. RESULTS: More three-vessel disease and higher SYNTAX scores have been detected in the high AIP and TGI groups. More MACEs have been observed in high AIP and TGI groups than low groups. AIP and TGI were found to be independent predictors for SYNTAX ≥23. While AIP has been found to be an independent risk factor for MACE, TGI has not been detected as an independent risk factor. In addition to AIP, age, three-vessel disease, and lower EF were the independent risk factors for MACE. Survival was lower in high TGP and AIP groups. CONCLUSIONS: AIP and TGI are costless bedside parameters that can be easily calculated. These parameters can predict the severity of CAD in first-diagnosed ACS patients. Besides, AIP is an independent risk factor for MACE. AIP and TGI parameters can guide our treatment in this patient population.

Experimental comparison of a Shack-Hartmann sensor and a phase-shifting interferometer for large-optics metrology applications.

We performed a direct side-by-side comparison of a Shack-Hartmann wave-front sensor and a phase-shifting interferometer for the purpose of characterizing large optics. An expansion telescope of our own design allowed us to measure the surface figure of a 400-mm-square mirror with both instruments simultaneously. The Shack-Hartmann sensor produced data that closely matched the interferometer data over spatial scales appropriate for the lenslet spacing, and much of the <20-nm rms systematic difference between the two measurements was due to diffraction artifacts that were present in the interferometer data but not in the Shack-Hartmann sensor data. The results suggest that Shack-Hartmann sensors could replace phase-shifting interferometers for many applications, with particular advantages for large-optic metrology.

Absolute concentration measurements of atomic hydrogen in subatmospheric premixed H(2)/O(2)/N(2) flat flames with photoionization controlled-loss spectroscopy.

An experimental protocol, using photoionization controlled-loss spectroscopy (PICLS), has been developed for obtaining absolute number densities of atomic hydrogen from laser-induced fluorescence measurements in flames. Two laser beams are employed, the first to excite hydrogen atoms from the ground state to the second excited state via two-photon absorption and the second to strongly photoionize the excited atoms. The resulting fluorescence measurements are independent of quenching. A model is presented that assures the viability of PICLS as long as the photoionization rate is greater than or equal to the quenching rate. The model is verified in fuel-lean, stoichiometric, and fuel-rich flat premixed H(2)/O(2)/N(2) flames at pressures of 20 and 72 Torr. Over this range in pressure, the ratio of number densities obtained from PICLS to those calculated from partial equilibrium is constant to within 20%. Most of the error arises from the sensitivity of the partial equilibrium calculat ions to small uncertainties in both the fuel-oxidizer ratio and the measured OH concentration. Because of the quenching-independent nature of PICLS, quantitative fluorescence measurements can be made by calibrating at a single favorable flame condition.

Feasibility of hydroxyl concentration measurements by laser-saturated fluorescence in high-pressure flames.

A feasibility study has been performed on the application of laser-saturated fluoresence (LSF) to the measurement of OH concentration in high-pressure flames. Using a numerical model for the collisional dynamics of the OH molecule under nonuniform laser excitation, we have investigated the effect of pressure on the balanced cross-rate model and determined the sensitivity of the depopulation of the laser-coupled levels to the ratio of rate coefficients describing (1) electronic quenching of the vibrational levels for which upsilon'' > 0 and (2) vibrational relaxation from upsilon'' > 0 to upsilon'' = 0. At sufficiently high pressures in near-saturated conditions, the total population of the laser-coupled levels reaches an asymptotic value, which is insensitive to the degree of saturation. When the ratio of electronic quenching is vibrational relaxation is small and the rate coefficients for rotational transfer in the ground and excited electronic states are nearly the same, the balanced cross-rate model remains a good approximation for all pressures. When the above ratio is large, depopulation of the laser-coupled levels becomes significant at high pressures, and thus the balanced crossrate model no longer holds. In these conditions, however, knowledge of the asymptotic value achieved by the laser-coupled levels could be used to correct the balanced cross-rate model and thus allow LSF measurements at sufficiently high pressures.

Quenching-independent fluorescence measurements of atomic hydrogen with photoionization controlled-loss spectroscopy.

Quenching-independent fluorescence by atomic hydrogen has been measured with photoionization controlled-loss spectroscopy (PICLS) in stoichiometric and fuel-rich premixed H(2)/O(2)/N(2) flames at a pressure of 20 Torr. These measurements are compared with conventional fluorescence measurements in the same flames. When matched in the postflame zone, the two sets of measurements diverge in the preheat zone between the burner surface and the peak of the fluorescence profiles. This divergence, caused by changes in the local quenching rate coefficient, shows the utility of PICLS for determining the kinetics of atomic hydrogen in the preheat zone.

Calibration of laser-saturated fluorescence measurements using Rayleigh scattering.

Calibration of laser-saturated fluorescence measurements using Rayleigh scattering is presented as an alternative to absorption. This new procedure is advantageous when measuring radical species at concentrations well below the corresponding detection limit for absorption. The calibration accounts for nonuniform laser irradiation by extracting the local fluorescence emission along the laser axis and works equally well for both saturated and near-saturated center-line conditions. The predicted error due to misfocusing of the collection optics is nearly negligible when the measured fluorescence is within 10% of its peak value. Number densities obtained using this method are within 15% of those obtained from absorption measurements.

Two-photon-excited fluorescence measurement of hydrogen atoms in flames.

We report the first two-photon-excited hydrogen-atom fluorescence measurements in flames made to our knowledge. The n = 3 level of the H atom was excited by 205.1-nm radiation generated by Raman shifting a 224-nm beam produced by frequency mixing. Fluorescence was observed at 656.3 nm as a result of radiative decay from n = 3 to n = 2, the Balmer-alpha transition. A novel technique, photoionization-controlled loss spectroscopy, is proposed to eliminate the quenching dependence of the fluorescence signal.