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Improvement in the transport critical current density and microstructure of isotopic (MgB2)-B-11 monofilament wires by optimizing the sintering temperature
No full textSuperconducting wires are widely used in fabricating magnetic coils in fusion reactors. In consideration of the stability of B-11 against neutron irradiation and lower induced radio-activation properties, MgB2 superconductor with B-11 serving as boron source is an alternative candidate to be used in fusion reactor with severe irradiation environment. In present work, a batch of monofilament isotopic (MgB2)-B-11 wires with amorphous B-11 powder as precursor were fabricated using powder-in-tube (PIT) process at different sintering temperature, and the evolution of their microstructure and corresponding superconducting properties was systemically investigated. Accordingly, the best transport critical current density (J(c)) = 2 x 10(4) A/cm(2) was obtained at 4.2 K and 5 T, which is even comparable to multi-filament (MgB2)-B-11 isotope wires reported in other work. Surprisingly, transport Jc vanished in our wire which was heat-treated at excessively high temperature (800 degrees C). Combined with microstructure observation, it was found that lots of big interconnected microcracks and voids that can isolate the MgB2 grains formed in this whole sample, resulting in significant deterioration in inter-grain connectivity. The results can be a constructive guide in fabricating (MgB2)-B-11 wires to be used as magnet coils in fusion reactor systems such as ITER-type tokamak magnet
Widely tunable continuous-wave solid-state red laser source using periodically-poled lithium niobate
No full textIn this work we have generated widely-tunable continuous-wave (CW) red light by second-harmonic generation (SHG) of the output of a Cr4+:forsterite laser, tunable from 1.206 to 1.320 mu m, using quasi-phasermatching (QPM) in periodically-poled lithium niobate (PPLN). For a given grating period in the PPLN, a combination of Cr4+:forsterite pump wavelength tuning and PPLN temperature tuning up to 200 degrees C provided continuous SHG tuning over a wavelength range of approximately 14 nm in the red. By translating the PPLN crystal to other periods, we have demonstrated SHG over the entire tuning range of the pump laser, yielding tunable CW output from 603 to 660 mu with maximum output powers of approximately 5 mW for a typical Cr4+:forsterite pump power of 500 mW
Novel distributed feedback lightwave circuit elements
No full textThe devices that are variations of inter-and intracoupled meandering optical waveguides are proposed as the lightwave circuit elements that exhibit distributed feedback. A preliminary transfer matrix method analysis is applied in frequency domain, taking the coupling purely directional and with constant coefficient on geometrically symmetric and anti-symmetric devices. The meandering loop mirror is the building block of all meandering waveguide based lightwave circuit elements. The simplest uncoupled meandering distributed feedback structure exhibits Rabi splitting in the transmittance spectrum. The symmetric and antisymmetric coupled meandering distributed feedback geometries can be utilized as band-pass, Fano, or Lorentzian filters or Rabi splitters. Meandering waveguide distributed feedback structures with a variety of spectral responses can be designed for a variety of lightwave circuit element functions and can be implemented with generality due to the analytic approach taken
Pension benefit insurance and pension plan portfolio choice
No full textPension benefit guarantees have been introduced in several countries to protect private plan members from the loss of income associated with the termination of an underfunded plan. Most such schemes face financial difficulty. Consequently, policy reforms are being contemplated. Economic theory suggests that such schemes will suffer moral hazard problems. We test a specific theoretical prediction: insured plans will invest more heavily in risky assets. Our test exploits policy differences across Canadian jurisdictions. We find that insured plans invest about 5% more in equities than do similar plans without benefit guarantees
Mitigation of 50-60 Hz power line interference in geophysical data
No full textThe analysis of ELF/VLF radio data has broad applications for ionospheric and magnetospheric phenomena, lightning activity, long-range communications, and geophysical prospecting. However, recordings of ELF/VLF data on the ground are adversely affected by the presence of electromagnetic fields from 50-60 Hz power lines, whose harmonics can extend to many kilohertz and interfere with the detection of natural and man-made signals. Removal of this interference is complicated by the time-varying fundamental frequency of power lines and strongly varying characteristics across different power grids. We discuss two methods for isolation and then subtraction of this interference, by an adaptive filtering technique and with least squares matrix analysis. Methods for estimating the time-varying frequency are also discussed. A few variants of these techniques are applied both to simulated data and then to real data. It is found that least squares isolation gives superior results, although the adaptive filter is potentially more effective for poorly behaved power line interference with rapidly changing fundamental frequencies as well as being computationally more efficient
Isolated blunt submandibular gland injury after a fall from a bicycle
No full textIntroduction: Injury to deep neck structures should be considered during emergency room (ER) admissions in patients with a chief complaint of swelling in the neck, particularly when there is a history of trauma to the neck. Life-threatening conditions should be assessed, diagnosis should be made using appropriate imaging modalities, and treatment should be planned accordingly. Case Report: A 30-year-old male presented to the ER with the chief complaint of a swollen neck 2 h after he fell off a bicycle. Based on the ultrasound and computed tomography analysis, he was diagnosed with isolated submandibular injury. Conclusion: Isolated submandibular injury following a blunt trauma is a rare condition. Obtaining appropriate imaging modalities is helpful in confirming the diagnosis. Patients with blunt trauma should also be carefully assessed for other, nonapparent injuries
Relapsing polychondritis
No full textRelapsing polychondritis (RPC) is a unique and rarely observed autoimmune condition regarded as recurrent extensive chondritis of the auricular, nasal, and tracheal cartilages. Moreover, heart, main arteries, skin, and eyes may be involved. Several forms of clinical manifestations may be seen, and the pathogenesis still remains anonymous. A concomitant disease, particularly myelodysplasia or other systemic autoimmune disease can be detected in one-third of the patients with RPC. The treatment of RPC should be considered on personal basis and classified according to disease activity and severity. This study reviews the available data on clinical manifestations, pathogenesis, diagnosis, and therapeutics of the RPC
Predictors of atrial fibrillation recurrence after cryoballoon ablation
No full textObjective: Cryoballoon ablation (CA) is a safe and efficient method for pulmonary vein isolation in the treatment of paroxysmal atrial fibrillation (AF). There are conflicting results about the predictors of AF recurrence. The aim of this study is to evaluate the role of hematological indices to predict AF recurrence after CA. Methods: A total of 49 patients (mean age 58.3±12.2 years, 51.02% female) with symptomatic paroxysmal AF underwent CA procedure. One hundred and sixty-eight pulmonary veins were used for pulmonary vein isolation with the second-generation cryoballoon. The hematological samples were obtained before and 24 hours after ablation. Results: At a mean follow-up of 10.2±2.4 months, the probability of being arrhythmia-free after a single procedure was 86%. Patients with AF recurrence had higher red cell distribution width levels (16.10%±1.44% vs 14.87%±0.48%, P=0.035). The neutrophil/lymphocyte ratio, erythrocyte sedimentation rate, and C-reactive protein levels were detected in the patients with or without recurrence. Left atrial diameter (46.28±4.30 mm vs 41.02±4.10 mm, P=0.002), duration of AF (6.71±4.57 years vs 3.59±1.72 years, P=0.003), and age (65.01±15.39 years vs 54.29±11.32 years, P=0.033) were the other independent predictors of clinical recurrence after CA. Multiple regression analysis revealed that left atrial diameter was the only independent predictor for AF recurrence (P=0.012). Conclusion: In this study of patients with paroxysmal AF undergoing cryoablation, increased preablation red cell distribution width levels, and not C-reactive protein or erythrocyte sedimentation rate, was associated with a higher rate of AF recurrence. Our results support the role of a preablation, proinflammatory, and pro-oxidant environment in the development of AF recurrence after ablation therapy but suggest that other factors are also important
Correcting for solvent-solvent electrostatic cutoffs considerably improves the ion-pair potential of mean force
No full textA recently developed algorithm based on the continuum treatment of the solvent molecules beyond the electrostatic cutoff sphere is applied to the potential of mean force results between sodium and chloride ions to study the effects of the solute-solvent and solvent-solvent cutoff errors. The results show that although the solute-solvent correction improves the thermodynamic results slightly, physically realistic results are obtained only when the solvent-solvent correction is applied. This further supports past findings that proper treatment of solvent-solvent interactions is as important as that of the solute interactions, and should not be ignored