RESUMEN

Eu(2+)-activated phosphors are being widely used in illuminations and displays. Some of these phosphors feature an extremely broad and red-shifted Eu(2+) emission band; however, convincing explanation of this phenomenon is lacking. Here we report a new localized/delocalized emitting state of Eu(2+) ions in a new hexagonal EuAl(2)O(4) phosphor whose Eu(2+) luminescence exhibits a very large bandwidth and an extremely large Stokes shift. At 77 K, two luminescent sites responsible for 550 nm and 645 nm broadband emissions are recognized, while at room temperature only the 645 nm emission band emits. The 645 nm emission exhibits a typical radiative lifetime of 1.27 µs and an unusually large Stokes shift of 0.92 eV. We identify the 645 nm emission as originating from a new type of emitting state whose composition is predominantly that of localized 4f(6)5d character but which also contains a complementary component with delocalized conduction-band-like character. This investigation provides new insights into a unique type of Eu(2+) luminescence in solids whose emission exhibits both a very large bandwidth and an extremely large Stokes shift.

RESUMEN

In the United States, smoking is the leading cause of death - having a mortality rate of approximately 435,000 people in 2000-accounting for 8.1% of all US deaths recorded that year. Consequently, we analyzed the Delaware Hospital Discharge Database, and identified state and non-state residents discharged with AMI or asthma for the years 1999 to 2004. Statistical data analysis compared the incidence of AMI or asthma for each group before (1999-2002) and after (2003-2004) the amendment. As a result, we found that pre-ordinance and post-ordinance quarterly rates of AMI for Delaware residents were 451 (se = 21) and 430 (se = 21) respectively, representing a 4.7% reduction. Over the same time period, there was negligible change in the incidence of AMI for non-Delaware residents. After adjusting for population growth, the Risk Ratio (RR) for asthma in Delaware residents post-ordinance was 0.95 (95% CI, 0.90 to 0.999), which represented a significant reduction (P = 0.046). By comparison, non-Delaware residents had an increased RR for asthma post-ordinance of 1.62 (95% CI, 1.46 to 1.86; P < 0.0001).The results suggest that Delaware's comprehensive non-smoking ordinance effectively was associated with a statistically significant decrease in the incidence of AMI and asthma in Delaware residents when compared to non-Delaware residents.

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RESUMEN

Optical dephasing of Pr3+ and Tm3+ ions doped in transparent oxyfluoride glass ceramics was studied with the two-pulse photon echo technique. It was found that the dephasing time of rare earth ions is dramatically less in nanocrystals embedded in a glass matrix than in bulk crystals. A quasi-linear temperature dependence obtained at low temperatures proved that the long-range interaction of the ions inside the nanocrystals with the two level systems of the glass matrix dominates the optical dephasing. The local thermal effect in glass ceramics containing nanocrystals elevates the local temperature, which results in the reduction of optical dephasing time. For Tm(3+)-doped glass ceramics, the elevation of local temperature induced by the irradiation of excitation laser even quenched the photon echo signals in the experimental study.

RESUMEN

Aortic arch atherosclerosis is associated with an increased risk of stroke or TIA. Up to now, transesophageal echocardiography has been the standard method for diagnosing protruding and/or mobile aortic arch atherosclerosis. We report a case where a mobile aortic arch atheroma was diagnosed using transthoracic echo in a patient with a recent stroke.

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RESUMEN

Echocardiographic left ventricular mass (LVM) estimates are strong predictors of subsequent mortality and cardiovascular events. It is known that blood pressure (BP), weight (WT), and age are significantly correlated with LVM. We hypothesized that stroke volume (SV) measured by Doppler echocardiography would also be correlated with LVM. Two hundred and thirteen patients referred for routine echocardiography had determination of LVM, cuff BP, and Doppler SV. Those with localized LV disease, valvular disease, or cor pulmonale were excluded. In both men and women, systolic BP (SBP) was more closely correlated with LVM than was diastolic blood pressure or mean arterial pressure, and SV was more closely correlated with LVM than cardiac output or cardiac index. Stepwise regression, followed by multiple regression showed that four variables (WT, SV, SBP, and AGE) explained 32.3% of the variability in LVM in men and 48.5% of the variability in LVM in women. WT and SV were significant determinants of LVM in both men and women. Age was also significant in men and SBP was also significant in women. For both men and women, SV was more significantly correlated with LVM than was SBP. The changes in LVM associated with 1 SD increments of SV and SBP, respectively, were 8 and 5 g for men and 13 and 11 g for women. We conclude that men and women have different patterns of variables influencing LVM. Doppler echocardiographic SV is a newly described determinant of LVM that has a greater correlation with LVM than does SBP. This study reemphasizes the importance of WT as the major determinant of LVM. (ECHOCARDIOGRAPHY, Volume 13, January 1996)

RESUMEN

To test the hypothesis that the full extent of in vitro cell lysis due to ultrasound becomes evident with time lapse following insonation, human erythrocytes (2% hematocrit) in autologous plasma were mixed with Albunex(R), a pulse echo contrast agent, and exposed to 1-MHz, continuous-wave ultrasound (US) (5 W/cm(2) SPTA intensity) for 60 seconds while in a rotating (200 rpm) dialysis membrane vessel. Exposed and sham-exposed samples were subsequently assayed for hemolysis colorimetrically, either immediately or after a delay of 3 hours. Hemolysis was dependent on the interval between US exposure and assay, with significantly greater lysis evident with delayed assay. There was also temporality in lytic yield with sample number, i.e., with time postpreparation of the blood sample, US-induced cell lysis decreased. The temporality of lytic yield was eliminated by maintenance at ice water temperatures, or by waiting about 1 hour before beginning treatments. The collective data indicate that the full extent of US-induced cell lysis is not evident upon assay immediately after insonation, and that with time postpreparation and preinsonation, erythrocytes may undergo changes in sensitivity to US. (ECHOCARDIOGRAPHY, Volume 13, January 1996)