Search for gravitational-wave bursts from soft gamma repeaters

We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

Intravascular effect in velocity-selective arterial spin labeling

Arterial spin labeling (ASL) has been developed into a useful tool for measuring local tissue perfusion with magnetic resonance imaging (MRI). Velocity-selective ASL (VS-ASL) tags spins on a basis of flow velocity, instead of the spatial distribution that is commonly used by conventional ASL techniques. Using a 90 degrees-180 degrees-90 degrees radiofrequency pulse train in combination with flow-sensitive gradients, VS-ASL can potentially generate tags that are very close to the imaging plane and whereby avoid the main error source of conventional ASL techniques coming from T1 relaxation during inflow time (TI). In practice, however, TI of VS-ASL should still be chosen with caution with respect to intravascular signal and cutoff velocity (Vc). With higher Vc, the maximum of VS-ASL signal was observed at shorter TI, which is due to intravacular signal in large vessels. For perfusion measurement in human brain, small Vc (=<2cm/s) is recommended. In contrast to the previous studies that suggested CSF suppression for Vc < 5cm/s, this study used lower amplitude and longer separation of diffusion gradients in the VS pulse train, which reduced b-value and eliminated the necessity of CSF suppression for Vc down to 2 cm/s.

Guar Gum as Potential Film Coating Material for Colon-specific Delivery of Fluorouracil

The potential of guar gum as a film coating material for colon-specific delivery of 5-fluorouracil is evaluated in this study. The guar gum-based multi-unit pellet system is prepared by coating guar gum and pH-sensitive polymer Eudragit FS30D sequentially around drug-loaded non-pareil cores in a fluid-bed coater. The outer Eudragit FS coating protects the system against gastrointestinal environment and dissolves rapidly in distal small intestine, where a lumen pH of over 7 triggers the dissolution of the enteric polymer. The inner guar gum coating works as a time-controlled retardant and offers additional protection of the pellets until it is degraded by microbial enzymes at the proximal colon. In vitro results indicate that guar gum is a feasible coating material to achieve timed and enzyme-triggered fluorouracil release. Pharmacokinetic study in beagle dogs shows delayed absorption of about 5 h and limited absorption fraction as a result of guar gum and Eudragit FS coating.

Effect of mode of birth on purine and malondialdehyde in umbilical arterial plasma in normal term newborns

OBJECTIVE

To examine the effect of mode of birth on plasma purine and malondialdehyde levels in normal term infants.

STUDY DESIGN

Umbilical arterial cord blood was obtained immediately after birth from a convenience sample of 119 normal term newborns born by vaginal delivery, with or without oxytocin augmentation or by elective cesarean delivery. Plasma was analyzed for purine and/or malondialdehyde levels. Numeric data were analyzed utilizing independent samples t-test and ordinal data were analyzed using Mann-Whitney test. Correlation coefficients were obtained using Spearman's rho.

RESULT

Uric acid levels were significantly elevated (P<0.001) in neonates undergoing vaginal birth, compared to neonates born by elective cesarean delivery. When the effect of oxytocin and length of labor was analyzed, neonates born to mothers on oxytocin had lower hypoxanthine, significantly lower xanthine (P=0.05) and higher uric acid levels. In addition, malondialdehyde levels were significantly higher (P<0.006) in neonates born to mothers who received oxytocin compared to neonates born to mothers without oxytocin augmentation. We also found significant correlations between malondialdehyde (MDA) and hypoxanthine (r=-0.465, P<0.039) and between MDA and xanthine (r=-0.753, P=0.003) in neonates born via oxytocin-augmented birth. Mode of birth had no statistically significant effect on clinical outcomes, although infants born by elective cesarean had higher incidence of acute respiratory distress and transient tachypnea of the newborn compared to those born vaginally.

CONCLUSION

Neonates born by elective cesarean had the lowest purine levels in cord blood compared to neonates born vaginally. Oxytocin augmentation is associated with some degree of uterine hyperstimulation which may enhance the ATP degradation pathway resulting in the rapid conversion of hypoxanthine to xanthine and xanthine to uric acid. Significantly higher MDA levels in neonates whose mothers received oxytocin as well as significant correlation between MDA and the purines hypoxanthine and xanthine, suggest free-radical production, most likely due to xanthine oxidase activation. However, despite differences in plasma purine and malondialdehyde levels, no significant differences were seen in neonatal outcome. Further studies are required to fully characterize the effect of mode of birth on purine metabolism and free-radical production.

Effect of V(2)O(5) on the sintering behavior, microstructure, and electrical properties of (Na(0.5)K(0.5))NbO(3) ceramics

Well-sintered (Na(0.5)K(0.5))NbO(3)-x mol% V(2)O(5) ceramics (abbreviated as NKN-V) with fine electrical properties were successfully prepared by conventional solid-state reaction through the careful control of processing conditions. The sintering behavior, phase structure, and electrical properties of the V(2)O(5)-doped NKN ceramics were investigated. Results show that when the V(2)O(5) content is 0.6 mol%, the NKN ceramics attained the maximum density of 4.46 g/cm(3) (about 98.9% of the theoretical density) at 1060 degrees C, and therefore possessed enhanced electrical properties. But when the V(2)O(5) content continued increasing, the density decreased. The secondary phase (Na(2)V (6)O(16)) could be detected by XRD analysis in all samples except x = 0 mol%. The Curie temperature of the NKN-based materials was found to decrease with the increase of V(2)O(5). The dielectric properties of NKN ceramics doped with 0.6 and 0.9 mol% V(2)O(5) were better than that of pure NKN ceramics. In addition, annealing treatment was proved to be an effective technique for improving dielectric properties and reducing the leakage current density.

Effects of the sol-concentration on the structural and dielectric properties of Pb(0.3)Sr(0.7)TiO(3) thin films derived by the sol-gel method

Pb(0.3)Sr(0.7)TiO(3)(PST) thin films were deposited on Pt coated Si(100) substrates by sol-gel techniques using different sol-concentrations. The structural and dielectric characteristics of lead strontium titanate (PST) thin films as a function of the sol concentration were investigated. PST thin films reveal a columnar texture through the thickness when the sol-concentration is lower than 0.30 M. PST thin films derived from 0.35 M sol show better dielectric characteristics with the dielectric constant, dielectric loss, tunability, and field of motion (FOM) (tunability/ dissipation) of 200, 0.01, 47% and 47, respectively. The temperature dependence of the dielectric constant, dielectric loss and tunability of PST thin films were investigated in the temperature range of -140 to 120 degrees C exhibiting a dielectric peak of about -45 degrees C.

Primary chemoprevention of endometrial hyperplasia with the peroxisome proliferator-activated receptor gamma agonist rosiglitazone in the PTEN heterozygote murine model

PTEN mutations have been implicated in the development of endometrial hyperplasia and subsequent cancer. Peroxisome proliferator-activated receptor gamma (PPAR-gamma) agonists have demonstrated antineoplastic and chemopreventive effects. The purpose of this study was to evaluate the effects of the PPAR-gamma agonist rosiglitazone on both PTEN wild type and PTEN null cell lines and in the PTEN heterozygote((+/-)) murine model. Hec-1-A (PTEN wild type) and Ishikawa (PTEN null) cells were treated with rosiglitazone. Thirty-five female PTEN(+/-) mice were genotyped and placed into one of four groups for treatment for 18 weeks: A) PTEN wild type with 4 mg/kg rosiglitazone, B) PTEN(+/-) mice with vehicle, C) PTEN(+/-) mice with 4 mg/kg rosiglitazone, and D) PTEN(+/-) mice with 8 mg/kg rosiglitazone. Proliferation and apoptosis were measured by bromodeoxyuridine (BrdU) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling of DNA fragmentation sites assay. Rosiglitazone caused cell growth inhibition in both Hec-1-A and Ishikawa in a dose-dependent manner (P < 0.02 and P < 0.03, respectively). Rosiglitazone also induced apoptosis in both Hec-1-A (P < .001) and Ishikawa (P < .001) cells in a dose-dependent manner. In the murine model, rosiglitazone decreased proliferation of the endometrial hyperplastic lesions (B vs C; 39.7% vs 9.3% and B vs D; 39.7% vs 4.2%; P < 0.0001) and increased apoptosis of glandular endometrial epithelial cells (B vs C; 2.8% vs 22.4%; P < 0.0001 and B vs D; 2.8% vs 30.2%; P = 0.003). PPAR-gamma agonist rosiglitazone inhibits proliferation and induces apoptosis in both PTEN intact and PTEN null cancer cell lines and in hyperplastic endometrial lesions in the PTEN(+/)(-)murine model.