• Journal of Environmental Science International
• /
• v.22 no.6
• /
• pp.651-666
• /
• 2013

This study introduces a novel approach to the differentiation of two phenomena, Asian Dust and haze, which are extremely difficult to distinguish based solely on comparisons of PM10 concentration, through use of the Optical Particle Counter (OPC), which simultaneously generates PM10, PM2.5 and PM1.0 concentration. In the case of Asian Dust, PM10 concentration rose to the exclusion of PM2.5 and PM1.0 concentration. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were below 40%, which is consistent with the conclusion that Asian Dust, as a prime example of the coarse-particle phenomenon, only impacts PM10 concentration, not PM2.5 and PM1.0 concentration. In contrast, PM10, PM2.5 and PM1.0 concentration simultaneously increased with haze. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were generally above 70%. In this case, PM1.0 concentration varies because a haze event consists of secondary aerosol in the fine-mode, and the relative ratios of PM10 and PM2.5 concentration remain intact as these values already subsume PM1.0 concentration. The sequential shift of the peaks in PM10, PM2.5 and PM1.0 concentrations also serve to individually track the transport of coarse-mode versus fine-mode aerosols. The distinction in the relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration in an Asian Dust versus a haze event, when collected on a national or global scale using OPC monitoring networks, provides realistic information on outbreaks and transport of Asian Dust and haze.

• Journal of Chest Surgery
• /
• v.26 no.8
• /
• pp.591-594
• /
• 1993

To clarify the apparent hypoplasia of the descending aorta in infants with atrioventricular septal defect[AVSD] patients, we reviewed the catheterization data and angiograms of 34 consecutive patients with AVSD less than 1 year of age who underwent repair at our institution since 1985. We compared them to 10 patients with Atrial Septal Defect[ASD] and 10 patients with Ventricular Septal Defect[VSD] who were matched for age, size and Qp/Qs. The Descending Aorta Index [DAI] of the AVSD group was not different from the VSD or ASD groups, [147.9$\pm$ 34.8 mm2/m2 versus 158.6$\pm$ 31.5 mm2/m2 and 153.2$\pm$ 43.1 mm2/m2].However, the Pulmonary Artery Index [PAI] of the AVSD group was significantly larger than the other groups [684.3$\pm$ 170.7 mm2/m2 versus 454.1$\pm$ 109.1 mm2/m2 and 534.9$\pm$ 148.4 mm2/m2][p<0.05], as was the ratio of PAI/DAI in the AVSD group [4.99$\pm$ 1.77 versus 2.89$\pm$ 0.81 and 3.6$\pm$ 0.92][p<0.05]. Despite similar Qp/Qs ratios, both the mean PA pressure and the Rp/Rs in the AVSD group was higher than the VSD and ASD groups: 43.1$\pm$ 15.6 mmHg versus 29$\pm$ 11.6 mmHg and 24$\pm$ 18.1 mmHg [p<0.05], and 0.27$\pm$ 0.22 versus 0.14$\pm$ 0.03 and 0.11$\pm$ 0.05 [p<0.05] respectively. The apparent hypoplasia of the descending aorta in infants with AVSD is an illusion created by the abnormally large pulmonary arteries, which are significantly larger than in patients with ASDs or VSDs.

• Investigative Magnetic Resonance Imaging
• /
• v.20 no.2
• /
• pp.88-94
• /
• 2016

Purpose: Fluid-attenuated inversion recovery (FLAIR) imaging can be obtained faster with shorter repletion time (TR), but it gets noisier. We hypothesized that shorter-TR FLAIR obtained at 3 tesla (3T) with a 32-channel coil may be comparable to conventional FLAIR. The aim of this study was to compare the diagnostic value between conventional FLAIR (TR = 9000 ms, FLAIR9000) and shorter-TR FLAIR (TR = 6000 ms, FLAIR6000) at 3T in terms of diffusion-weighted imaging-FLAIR mismatch. Materials and Methods: We recruited 184 patients with acute ischemic stroke (28 patients < 4.5 hours) who had undergone 5-mm diffusion-weighted imaging (DWI) and two successive 5-mm FLAIR images (no gap; in-plane resolution, $0.9{\times}0.9mm$) at 3T with a 32-channel coil. The acquisition times for FLAIR9000 and FLAIR6000 were 108 seconds (generalized autocalibrating partially parallel acquisitions [GRAPPA] = 2) and 60 seconds (GRAPPA = 3), respectively. Two radiologists independently assessed the paired imaging sets (DWI-FLAIR9000 and DWI-FLAIR6000) for the presence of matched hyperintense lesions on each FLAIR imaging. The signal intensity ratios (area of DWI lesion to contralateral normal-appearing region) on both FLAIR imaging sets were compared. Results: DWI-FLAIR9000 mismatch was present in 39 of 184 (21.2%) patients, which was perfectly the same on FLAIR6000. Three of 145 patients (2%) with DWI-matched lesions on FLAIR9000 had discrepancy on FLAIR6000, showing no significant difference (P > 0.05). Interobserver agreement was excellent for both DWI-FLAIR9000 and DWI-FLAIR6000 (k = 0.904 and 0.883, respectively). Between the two FLAIR imaging sets, there was no significant difference of signal intensity ratio (mean, standard deviation; $1.25{\pm}0.20$; $1.24{\pm}0.20$, respectively) (P > 0.05). Conclusion: For the determination of mismatch or match between DWI and FLAIR imaging, there is no significant difference between FLAIR9000 and FLAIR6000 at 3T with a 32-channel coil.