Fabry-Perot interferometry with fractional charges

Resistance oscillations in electronic Fabry-Perot interferometers near fractional quantum Hall (FQH) filling factors 1/3, 2/3, 4/3, and 5/3 in the constrictions are compared to those near integer quantum Hall (IQH) filling factors in the same devices and at the same gate voltages. Two-dimensional plots of resistance versus gate voltage and magnetic field indicate that all oscillations are Coulomb dominated. A charging-model analysis of gate-voltage periods yields an effective tunneling charge e* ≈ e/3 for all FQH states and e* ≈ e for IQH states. Temperature decay of the oscillations appears exponential, qualitatively consistent with a recent prediction, and the surprising filling-factor dependence of the associated energy scale may shed light on edge structure.

Hemodynamic changes in patients with arteriovenous malformations assessed using high-resolution 3D radial phase-contrast MR angiography

BACKGROUND AND PURPOSE

Arteriovenous malformations have a high lifetime risk of hemorrhage; however, treatment carries a significant risk of morbidity and mortality, including permanent neurologic sequelae. WSS and other hemodynamic parameters are altered in patients with symptomatic AVMs, and analysis of hemodynamics may have value in stratifying patients into different risk groups. In this study, we examined hemodynamic data from patients with stable symptoms and those who presented with acute symptoms to identify trends which may help in risk stratification.

MATERIALS AND METHODS

Phase-contrast MRA using a radial readout (PC-VIPR) is a fast, high-resolution technique that can acquire whole-brain velocity-encoded angiograms with scan times of approximately 5 minutes. Ten patients with AVMs were scanned using PC-VIPR; velocity, area, flow, and WSS in vessels feeding the AVMs and normal contralateral vessels were calculated using velocity data from the phase-contrast acquisition.

RESULTS

Patients with an asymptomatic presentation or mild symptoms (n = 4) had no significant difference in WSS in feeding vessels compared with normal contralateral vessels, whereas patients presenting with hemorrhage, severe headaches/seizures, or focal neurologic deficits (n = 6) had significantly higher WSS in feeding vessels compared with contralateral vessels.

CONCLUSIONS

In this study, we demonstrate that estimates of WSS and other hemodynamic parameters can be obtained noninvasively in patients with AVMs in clinically useful imaging times. Variation in WSS between feeders and normal vessels appears to relate to the clinical presentation of the patient. Further analysis of hemodynamic changes may improve characterization and staging of AVM patients, when combined with existing risk factors.

Femtosecond nonlinear fiber optics in the ionization regime

By using a gas-filled kagome-style photonic crystal fiber, nonlinear fiber optics is studied in the regime of optically induced ionization. The fiber offers low anomalous dispersion over a broad bandwidth and low loss. Sequences of blueshifted pulses are emitted when 65 fs, few-microjoule pulses, corresponding to high-order solitons, are launched into the fiber and undergo self-compression. The experimental results are confirmed by numerical simulations which suggest that free-electron densities of ∼10(17) cm(-3) are achieved at peak intensities of 10(14) W/cm(2) over length scales of several centimeters.

Influence of ionization on ultrafast gas-based nonlinear fiber optics

We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

Bright spatially coherent wavelength-tunable deep-UV laser source using an Ar-filled photonic crystal fiber

We report on the spectral broadening of ~1 μJ 30 fs pulses propagating in an Ar-filled hollow-core photonic crystal fiber. In contrast with supercontinuum generation in a solid-core photonic crystal fiber, the absence of Raman and unique pressure-controlled dispersion results in efficient emission of dispersive waves in the deep-UV region. The UV light emerges in the single-lobed fundamental mode and is tunable from 200 to 320 nm by varying the pulse energy and gas pressure. The setup is extremely simple, involving <1 m of a gas-filled photonic crystal fiber, and the UV signal is stable and bright, with experimental IR to deep-UV conversion efficiencies as high as 8%. The source is of immediate interest in applications demanding high spatial coherence, such as laser lithography or confocal microscopy.

The effect of spatial resolution on wall shear stress measurements acquired using radial phase contrast magnetic resonance angiography in the middle cerebral arteries of healthy volunteers. Preliminary results

We have recently implemented radial phase-contrast techniques that allow high resolution angiograms with velocity information to be acquired within clinically-useful imaging times. 10 healthy volunteers were scanned using PC-VIPR and PC-SOS, two high resolution phase-contrast techniques at spatial resolutions of 0.67×0.67×0.67 mm(3) and 0.4×0.4×1 mm(3) respectively. The velocity measurements from the two acquisitions were imported into a custom Matlab runtime environment that automatically calculated WSS values using Green's Theorem and B-spline interpolation. Time average axial WSS was 1.069 N/m(2) (95% confidence interval: 0.8628< x < 1.276) in the left and right middle cerebral arteries of the 10 healthy volunteers (n=20) when scanned by PC-VIPR, and 1.670 N/m(2) when scanned by PC-SOS (95% confidence interval: 1.395 < x < 1.946). This difference in means was statistically significant (p < 0.002). Previous investigators have found that higher spatial resolution results in higher WSS measurements because smaller voxel size results in fewer partial volume effects. This was true in our study as well. In this study, we found that PC-SOS has significantly higher spatial resolution than PC-VIPR and this followed in the WSS measurements. Higher in-plane spatial resolution allows WSS calculations to be performed more accurately because of increased precision near the vessel boundary.

Examination of the possibility of negative capacitance using ferroelectric materials in solid state electronic devices

We show here, using fundamental energy storage relationships for capacitors, that there are severe constraints upon what can be realized utilizing ferroelectric materials as FET dielectrics. A basic equation governing all small signal behavior is derived, a negative capacitance quality factor is defined based upon it, and thousands of carefully measured devices are evaluated. We show that no instance of negative capacitance occurs within our huge database. Furthermore, we demonstrate that highly nonlinear biasing behavior in a series stack could be misinterpreted as giving a negative capacitance.

Frequency Agile Microwave Applications Using (Ba,Sr)TiO3/Y3Fe5O12 Multilayer Grown by Pulsed Laser Deposition

(Ba,Sr)TiO3 (BST) thin films have been deposited by pulsed laser deposition (PLD) onto single crystal Y3Fe5O12 (YIG) substrates with/without an MgO buffer layer. The structure and microwave properties of BST films have been investigated as function of substrate orientation and O2 deposition pressures (5-800m Torr). The orientation of BST film is varies with the deposition conditions. The dielectric constant, loss tangent, and change in dielectric constant with an applied electric field have been measured at room temperature using interdigitated capacitors at 0.1 – 20 GHz. Polycrystalline BST films have a high tunability (∼40%) with a dc bias field of 67kV/cm and a dielectric Q (=l/tanδ) between 30 and 40, while (001) oriented BST films have a lower tunability (∼20%) but higher dielectric Q (∼50). A coplanar waveguide transmission line was fabricated from a (001) oriented BST film on (111)YIG which exhibited a 17° differential phase shift with an applied dc bias of 21 kV/cm. An equivalent differential phase shift was achieved with a magnetic field of 160Guass.

Velocity measurements in the middle cerebral arteries of healthy volunteers using 3D radial phase-contrast HYPRFlow: comparison with transcranial Doppler sonography and 2D phase-contrast MR imaging

BACKGROUND AND PURPOSE

We have developed PC HYPRFlow, a comprehensive MRA technique that includes a whole-brain CE dynamic series followed by PC velocity-encoding, yielding a time series of high-resolution morphologic angiograms with associated velocity information. In this study, we present velocity data acquired by using the PC component of PC HYPRFlow (PC-VIPR).

MATERIALS AND METHODS

Ten healthy volunteers (6 women, 4 men) were scanned by using PC HYPRFlow and 2D-PC imaging, immediately followed by velocity measurements by using TCD. Velocity measurements were made in the M1 segments of the MCAs from the PC-VIPR, 2D-PC, and TCD examinations.

RESULTS

PC-VIPR showed approximately 30% lower mean velocity compared with TCD, consistent with other comparisons of TCD with PC-MRA. The correlation with TCD was r = 0.793, and the correlation of PC-VIPR with 2D-PC was r = 0.723.

CONCLUSIONS

PC-VIPR is a technique capable of acquiring high-resolution MRA of diagnostic quality with velocity data comparable with TCD and 2D-PC. The combination of velocity information and fast high-resolution whole-brain morphologic angiograms makes PC HYPRFlow an attractive alternative to current MRA methods.

Myocardial protection in cardiac surgery patients requiring prolonged aortic cross-clamp times: a single-center evaluation of clinical outcomes comparing two blood cardioplegic strategies

AIM

The aim of this study was to evaluate the impact of intermittent warm (IWC) versus intermittent cold blood cardioplegia (ICC) in high-risk patients that require prolonged periods of aortic cross-clamping during on-pump cardiac surgery.

METHODS

From 3527 consecutive patients undergoing on-pump cardiac surgery, 520 patients were retrospectively identified that required prolonged aortic cross-clamp ≥ 75 min. Myocardial protection was performed with ICC (N.=280) or IWC (N.=240). Groups were compared regarding clinical outcomes, myocardial injury (CK-MB, cTnT) and multivariate analysis was performed to assess the impact of applied cardioplegia on 30-day all-cause mortality, cardiac death, perioperative myocardial injury (PM) and major adverse cardiac events (MACE).

RESULTS

Demographic data, mean logistic Euroscore, aortic-cross-clamping and CPB time were comparable between groups. Patients with ICC needed more intraoperative defibrillations, had more postoperative blood transfusions and a prolonged hospital stay when compared to the IWC-group (P < 0.05). Thirty-day all-cause mortality tended to be higher in IWC (11% vs. 6%; P = 0.083) with significantly higher cardiac mortality (9% vs. 4%; P=0.015) compared to ICC. Myocardial injury was more pronounced in the IWC-group with a higher incidence of PMI (IWC: 17% vs. ICC:6%; P < 0.05) and MACE (IWC:37% vs. ICC:25%; P < 0.05). Groups did not differ regarding other postoperative clinical outcomes. Multivariate analysis revealed IWC to be independently predictive (P < 0.05) for 30-day all-cause mortality (OR:2.42; 95% CI:1.04-5.05), cardiac death (OR:3.57; 95% CI:1.49-8.85), MACE (OR:1.87; 95% CI:1.22-2.87) and PMI (OR:3.46; 95% CI:1.86-6.41).

CONCLUSION

ICC results in less myocardial damage and reduced postoperative cardiac mortality and morbidity in patients requiring extended periods of aortic-cross-clamping during on-pump cardiac surgery, suggesting superior cardioprotection when compared to IWC.

Fast whole-brain 4D contrast-enhanced MR angiography with velocity encoding using undersampled radial acquisition and highly constrained projection reconstruction: image-quality assessment in volunteer subjects

We report on the image quality obtained by using fast contrast-enhanced whole-brain 4D radial MRA with 0.75-second temporal resolution, isotropic submillimeter spatial resolution, and velocity encoding (HYPRFlow). Images generated by HYPR-LR by using the velocity-encoded data as the constraining image were of diagnostic quality. In addition, we demonstrate that measurements of shear stress within the middle cerebral artery can be derived from the high-resolution 3D velocity data.

Circulating interleukin 17 is increased in the acute stage of Kawasaki disease

OBJECTIVES

During the acute phase, patients with Kawasaki disease (KD), an acute systemic vasculitis, demonstrate a drastic increase in serum interleukin-6 (IL-6), which parallels the duration of the fever. Recently, IL-17 has been reported to induce IL-6 production. The aim of this study was to elucidate the involvement of IL-17 in the pathogenesis of KD.

METHODS

Serum samples were obtained from patients with KD (n=30) and normal controls (n=20), and the concentrations of IL-17 and IL-6 measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with the normal controls (2.08 +/- 2.14 pg/mL), serum IL-17 was markedly elevated in patients with acute KD (25.47 +/- 5.05 pg/mL): levels gradually decreased in the subacute phase (5.94 +/- 2.83 pg/mL). In the acute phase, levels of IL-6 were 83.52 +/- 19.12 pg/L, which correlated well with the serum levels of IL-17.

CONCLUSION

These results suggest that IL-17 may be involved in the development of, or the effects of inflammation in KD.

A prediction model for type 2 diabetes risk among Chinese people

AIMS/HYPOTHESIS

A range of prediction rules for the onset of type 2 diabetes have been proposed. However, most studies have been conducted in white groups and it is not clear whether these models apply to Asian populations. The purpose of this study was to construct a simple points model for predicting incident diabetes among Chinese people.

METHODS

We estimated the 10 year risk of diabetes in a cohort study of middle-aged and elderly participants who were free from diabetes at baseline. Cox regression coefficients were used to construct the simple points model and the discriminatory ability of the resulting prediction rule was determined using AUC and net reclassification improvement and integrated discrimination improvement statistics. Fivefold random splitting was used to test the internal validity and obtain bootstrap estimates of the AUC.

RESULTS

Of the 2,960 participants without diabetes at the baseline examination, 548 developed type 2 diabetes during a median 10 year follow-up period. Age (four points), elevated fasting glucose (11 points), body mass index (eight points), triacylglycerol (five points), white blood cell count (four points) and a higher HDL-cholesterol (negative four points) were found to strongly predict diabetes incidence in a multivariate model. The estimated AUC for the model was 0.702 (95% CI 0.676-0.727). This model performed better than existing prediction models developed in other populations, including the Prospective Cardiovascular Münster, Cambridge, San Antonia and Framingham models for diabetes risk.

CONCLUSIONS/INTERPRETATION

We have constructed a model for predicting the 10 year incidence of diabetes in Chinese people that could be useful for identifying individuals at high risk of diabetes in the Chinese population.

Molecular replacement studies on crystal structure of allophycocyanin from red algaePorphyra yezoensis

Using the crystal structure of allophycocyanin from cyanobacteriumSpirulina platensis (APC-SP) as a search model, the crystal structure of allophycocyanin from red algaePorphyra yezoensis (APC-PY) has been studied by molecular replacement methods. The APC-PY crystals (Form 3) belong to the space group of R32, cell dimensions a =b = 10.53 nm,c = 18.94 nm, alpha= beta = 90 degrees , gamma= 120 degrees ; there is one alphabeta monomer in each crystallographic asymmetric unit in the cell. The translation function search gave a unique peak with a correlation coefficient (Cc) of 67.0% and an R-factor of 36.1 % for reflection data from 1.0 to 0.4 nm. Using the results by molecular replacement, the initial model of APC-PY was built, and the coincidence of the chromophore in APC-PY initial model with its2F (o)- F(c) OMIT map further confirms the results by molecular replacement.

Bim mediates mitochondria-regulated particulate matter-induced apoptosis in alveolar epithelial cells

We studied the role of Bim, a pro-apoptotic BCL-2 family member in Airborne particulate matter (PM 2.5 microm)-induced apoptosis in alveolar epithelial cells (AEC). PM induced AEC apoptosis by causing significant reduction of mitochondrial membrane potential and increase in caspase-9, caspase-3 and PARP-1 activation. PM upregulated pro-apoptotic protein Bim and enhanced translocation of Bim to the mitochondria. ShRNABim blocked PM-induced apoptosis by preventing activation of the mitochondrial death pathway suggesting a role of Bim in the regulation of mitochondrial pathway in AEC. Accordingly, we provide the evidence that Bim mediates PM-induced apoptosis via mitochondrial pathway.

41 TRANSMISSION OF A PARASITE-RESISTANT PHENOTYPE FROM A DONOR RAM TO ITS CLONED OFFSPRING

A 9-year-old parasite-resistant superfine Merino ram was cloned to study the inherited phenotype in cloned offspring. This donor ram was &gt;3 standard deviations below the mean for internal parasite fecal egg counts in a 10 000 sheep flock. Two viable rams were produced from 3 days of NT. Their health status was studied from birth to maturity and their fertility and progeny via an AI program. Their mucosal immune system was indirectly assessed through their ability to cope with high internal parasite challenges. Oocytes were extracted from abattoir ovaries in late autumn. Serum-starved fibroblasts were combined with enucleated oocytes and fused; the couplets wereactivated at 25–26 h postmaturation with ionomycin and then DMAP. Embryos were cultured in a 2-stage bovine embryo culture medium (Cook) for 6 days in 5% oxygen. From 3 days of NT, all 37 embryos reaching blastocyst or compact morula stages were transferred into 14 ewes. At Day 30, 6/14 ewes were pregnant with single fetuses and 1 fetus died by Day 60. Each of the 5 lambs had breathing difficulties at birth and 3 died. For 2 weeks prior to term, maternal serum levels (collected every other day) of progesterone and estradiol were not different between viable and non-viable pregnancies. In the 2 viable pregnancies, cortisol levels peaked (&gt;10 ng mL–1), then dropped sharply (&lt;2 ng mL–1 for 4 days), and then rose to the time of birth (&gt;7 ng mL–1). This cortisol profile may help explain why the 2 viable lambs acquired sufficient lung capacity by the time of birth to survive. Samples for fecal egg counts and complete blood counts were collected monthly for 12 months on the 2 surviving ram lambs. Fecal egg counts were 2–5 times higher than for 2 control animals, with peak counts reaching 3000–4000 eggs per gram. Larval culture showed the eggs were predominantly Hemonchus. Clone 2 had consistently higher egg counts than clone 1. Both clones had persistent loose feces for the first 6 months and Clone 2 continues to have diarrhea. Red blood cell counts were consistently low normal (8–11 million/�L). White cell counts were normal, other than when high counts (16 000 per �L) corresponded with high fecal egg counts. Body weight, wool quantity, and fiber diameter at 1 year of age were slightly different between clones (59 kg; 5.3 kg; 16.4 �m vs. 54 kg; 4 kg; 16 �m, respectively). Scrotal circumference was larger for clone 1 than for clone 2 (29 cm vs. 24.5 cm). Semen from the rams was cryopreserved for use in an AI program (50 ewes per sire) to progeny-test lambs produced by the 2 rams, the original donor ram, and a link ram, with lambing due in October 06. Overall, clone 1 has remained consistently healthier than clone 2. High fecal egg counts indicated significant internal parasite challenge during their first year of life, which resulted in elevated white blood cell responses. The obvious clinical effect of high egg counts was diarrhea, which may indicate a beneficial response to parasite infection. Continued studies will further document their parasite resistance, immune responses, and progeny characteristics.