Sensitive Photoacoustic IR Spectroscopy for the Characterization of Amino/Azido Mixed-Linker Metal-Organic Frameworks.

Photoacoustic Fourier-transform infrared spectroscopy makes it possible to determine the organic composition of mixed-linker metal-organic frameworks. The sound produced upon IR irradiation enables the discrimination of azido and amino linkers in three different MOF platforms with a sensitivity that is two orders of magnitude higher than that achieved using classic IR analysis.

Sequential Monte Carlo Instant Radiosity.

Instant Radiosity and its derivatives are interactive methods for efficiently estimating global (indirect) illumination. They represent the last indirect bounce of illumination before the camera as the composite radiance field emitted by a set of virtual point light sources (VPLs). In complex scenes, current algorithms suffer from a difficult combination of two issues: it remains a challenge to distribute VPLs in a manner that simultaneously gives a high-quality indirect illumination solution for each frame, and to do so in a temporally coherent manner. We address both issues by building, and maintaining over time, an adaptive and temporally coherent distribution of VPLs in locations where they bring indirect light to the image. We introduce a novel heuristic sampling method that strives to only move as few of the VPLs between frames as possible. The result is, to the best of our knowledge, the first interactive global illumination algorithm that works in complex, highly-occluded scenes, suffers little from temporal flickering, supports moving cameras and light sources, and is output-sensitive in the sense that it places VPLs in locations that matter most to the final result.

Human hair in the identification of cocaine abuse with cantilever-enhanced photoacoustic spectroscopy and principal component analysis.

In this study, a novel approach combining different techniques, including Fourier transform infrared (FT-IR) spectroscopy, photoacoustic spectroscopy (PAS) with an interferometric cantilever microphone, and principal component analysis (PCA) along with a proper data preprocessing procedure, have been used in the investigation of hair samples for cocaine abuse. Hair fibers from cocaine-overdose patients have been measured using a simple procedure involving cantilever-enhanced photoacoustic Fourier transform infrared spectroscopy. In addition, a reference group of hair samples from subjects with no cocaine abuse has been measured. We present a first approach to discriminate the cocaine users from the reference group with the photoacoustic method and PCA. With proper data preprocessing methods, the two groups were successfully separated according to their spectra. The results were confirmed with two different classification methods independent of the principal component data analysis.

Cardiac MRI: accuracy of simultaneous measurement of left and right ventricular parameters using three different sequences.

BACKGROUND AND AIM: We evaluated a value of Qp/Qs (left-to-right shunt measurement) using volumetric cardiac magnetic resonance (CMR) cardiac output (CO) measurements. We defined intraobserver, interobserver variability and reproducibility of left and right ventricular parameters by CMR. Furthermore, we studied whether shortened acquisition time has an effect on the accuracy of left and right ventricular parameters both in healthy volunteers and in patients with cardiovascular disease. METHODS: Sixteen subjects were enrolled in this study. Group A (n = 8, five males) consisted of healthy volunteers with a mean age of 25.9 years (range 24-30). Group B (n = 8, four males) was heterogenic consisting of patients with left ventricular (LV) hypertrophy, hypertension or coronary artery disease with their mean age of 56.3 years (range 38-70). RESULTS: The measured Qp/Qs as calculated from the right and LV CO was 0.87 +/- 0.13. Overall variability [as presented with the lowest coefficient of variation (CV)%- the highest CV % of intraobserver, interobserver variability or reproducibility] of LV parameters were for ejection fraction (EF) 1.5-2.8%, stroke volume (SV) 1.3-3.2%, CO 1.4-3.2%, end-diastolic volume 0.5-3.0%, end-systolic volume 1.8-6.2% and LV mass 1.1-2.6%. Corresponding values for right ventricular parameters were for EF 1.1-4.2%, SV 1.9-8.2%, CO 1.9-7.6%, end-diastolic volume 2.1-7.6%, end-systolic volume 2.8-10.2% and right ventricle mass 2.9-8.3%. There was no statistically significant difference between the results of different sequences. CONCLUSIONS: The CMR allows accurate Qp/Qs observation but the absolute value is at slightly different level compared with reference methods. Both left and right ventricular parameters are highly reproducible and even small clinically relevant changes can be measured with CMR. The shortened acquisition does not affect significantly to the accuracy of CMR-derived parameters.