Alternative optical concept for electron cyclotron emission imaging

The implementation of advanced electron cyclotron emission imaging (ECEI) systems on tokamak experiments has revolutionized the diagnosis of magnetohydrodynamic (MHD) activities and improved our understanding of instabilities, which lead to disruptions. It is therefore desirable to have an ECEI system on the ITER tokamak. However, the large size of optical components in presently used ECEI systems have, up to now, precluded the implementation of an ECEI system on ITER. This paper describes a new optical ECEI concept that employs a single spherical mirror as the only optical component and exploits the astigmatism of such a mirror to produce an image with one-dimensional spatial resolution on the detector. Since this alternative approach would only require a thin slit as the viewing port to the plasma, it would make the implementation of an ECEI system on ITER feasible. The results obtained from proof-of-principle experiments with a 125 GHz microwave system are presented.

Japanese strategies to maximize heart and lung availabilities: experience from 100 consecutive brain-dead donors

OBJECTIVE

Because the donor shortage is extremely severe in Japan because of a strict organ transplantation law, special strategies have been established to maximize heart and lung transplantations (HTs and LTs, respectively). We reviewed 100 consecutive brain-dead donors to evaluate our strategies to identify and manage heart and lung donors.

METHODS

We retrospectively reviewed all 100 consecutive brain-dead donors procured since the law was issued in 1997. There were 56 mens and the overall mean donor age was 43.5 years. The causes of death were cerebrovascular disease (n = 62), head trauma (n = 20), and asphyxia (n = 16): Since November 2002, special transplant management doctors were sent to donor hospitals to assess cardiac and lung functions, seeking to identify transplant opportunities. They stabilized donor hemodynamics and lung function by administering antidiuretic hormone intravenously and performing bronchofibroscopy for pulmonary toilet.

RESULTS

Seventy-nine HTs, 1 heart-lung transplantations, and 78 LTs (46 single and 32 bilateral) were performed. By applying these strategies organs per donor were increased from 4.5 to 6.8. Among heart donors, 61/80 were marginal: high inotrope requirement (n = 29), cardiopulmonary resuscitation (n = 28), and/or >55 years old (n = 20). None of the 80 HT recipients died of primary graft failure (PGF). Patient survival rate at 10 years after HT was 95.4%. Among lung donors, 48/65 were marginal: pneumonia (n = 41), chest trauma (n = 4), and >55 years old (n = 9). Only 2/78 LT recipients died of PGF. Patient survival rate at 3 years after LT was 72.2%. After inducing frequent pulmonary toilet, lung procurement and patient survival rates increased significantly after LT.

CONCLUSIONS

Although the number of cases was still small, the availability of organs has been greater and the outcomes of HT/LT acceptable.

Design of a millimeter-wave polarimeter for NSTX-Upgrade and initial test on DIII-D

Polarimetry is a powerful diagnostic technique to probe plasma equilibria and magnetic fluctuations in fusion plasmas. In a high beta plasma such as the National Spherical Torus eXperiment (NSTX), these measurements are important to understand plasma stability and anomalous transport. A 288 GHz polarimeter operating along a major radial chord in retroreflection geometry has been developed and is being tested on the DIII-D tokamak to prepare for future implementation on NSTX-Upgrade. The system launches a rotating linearly polarized beam and detects the phase shift directly related to the polarization change caused by the plasma. To accomplish this, a pair of orthogonal linearly polarized beams with a stable difference frequency is generated using a single sideband modulation technique, then combined and transformed to be counter-rotating circularly polarized. To improve phase resolution, quasi-optical isolation, using Faraday rotators and polarizers, is utilized to eliminate a multi-path feedback effect, which is found to be the primary source of phase error. The bench tests in the laboratory and DIII-D power supply test discharges indicate ≤1° phase resolution.

2D full wave modeling for a synthetic Doppler backscattering diagnostic

Doppler backscattering (DBS) is a plasma diagnostic used in tokamaks and other magnetic confinement devices to measure the fluctuation level of intermediate wavenumber (k(θ)ρ(s) ~ 1) density fluctuations and the lab frame propagation velocity of turbulence. Here, a synthetic DBS diagnostic is described, which has been used for comparisons between measurements in the DIII-D tokamak and predictions from nonlinear gyrokinetic simulations. To estimate the wavenumber range to which a Gaussian beam would be sensitive, a ray tracing code and a 2D finite difference, time domain full wave code are used. Experimental density profiles and magnetic geometry are used along with the experimental antenna and beam characteristics. An example of the effect of the synthetic diagnostic on the output of a nonlinear gyrokinetic simulation is presented.

Deletion of thyrotropin receptor residue Asp403 in a hyperfunctioning thyroid nodule provides insight into the role of the ectodomain in ligand-induced receptor activation

Somatic mutations of the TSH receptor (TSHR) gene are the main cause of autonomously functioning thyroid nodules. Except for mutations in ectodomain residue S281, all of the numerous reported activating mutations are in the TSHR membrane-spanning region. Here, we describe a patient with a toxic adenoma with a novel heterozygous somatic mutation caused by deletion of ectodomain residue Asp403 (Del-D403). Subsequent in vitro functional studies of the Del-D403 TSHR mutation demonstrated greatly increased ligand-independent constitutive activity, 8-fold above that of the wild-type TSHR. TSH stimulation had little further effect, indicating that the mutation produced near maximal activation of the receptor. In summary, we report only the second TSHR ectodomain activating mutation (and the first ectodomain deletion mutation) responsible for development of a thyroid toxic adenoma. Because Del-D403 causes near maximal activation, our finding provides novel insight into TSHR structure and function; residue D403 is more likely to be involved in the ligand-mediated activating pathway than in the ectodomain inverse agonist property.

InGaN Laser Diodes Grown on SiC Substrate Using Low-Pressure Metal-Organic Vapor Phase Epitaxy

We report the crystal growth and the characteristics of InGaN multiple quantum well (MQW) laser diodes grown on a 6H-SiC substrate using a low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). We discuss the buffer layer, the control of InGaN and AlGaN alloy composition, the magnesium doping of GaN and AlGaN, and the characteristics of the MQW structure. We also demonstrate the room-temperature pulsed operation of the laser diode. The threshold voltage was reduced to 15 V by improving the p-contact resistance. The threshold current was reduced to 500 mA by changing the MQW structure and employing high reflection coating.

Interaction between Faraday rotation and Cotton-Mouton effects in polarimetry modeling for NSTX

The evolution of electromagnetic wave polarization is modeled for propagation in the major radial direction in the National Spherical Torus Experiment with retroreflection from the center stack of the vacuum vessel. This modeling illustrates that the Cotton-Mouton effect-elliptization due to the magnetic field perpendicular to the propagation direction-is shown to be strongly weighted to the high-field region of the plasma. An interaction between the Faraday rotation and Cotton-Mouton effects is also clearly identified. Elliptization occurs when the wave polarization direction is neither parallel nor perpendicular to the local transverse magnetic field. Since Faraday rotation modifies the polarization direction during propagation, it must also affect the resultant elliptization. The Cotton-Mouton effect also intrinsically results in rotation of the polarization direction, but this effect is less significant in the plasma conditions modeled. The interaction increases at longer wavelength and complicates interpretation of polarimetry measurements.

A Ka-band tunable direct-conversion correlation reflectometer for NSTX

The recent availability of broadband microwave quadrature mixers in the Ka-band (28-40 GHz) of frequencies has allowed the fabrication of low-cost direct-conversion detection circuits for use in the variable-frequency correlation reflectometer on the National Spherical Torus eXperiment (NSTX). The quadrature receiver in this case can be implemented as a simple homodyne circuit, without the complication of a single-sideband modulator or a feedforward tracking circuit present in more typical designs. A pair of direct-conversion receivers is coupled with broadband microwave voltage-controlled oscillators to construct a flexible dual-channel radar system with a fast frequency settling time of ∼160 μs. A detailed description of the design and a full characterization of the hardware are provided. Examples of turbulence measurements from radial and poloidal correlation reflectometry on NSTX using a poloidal array of antennas (oriented normal to the magnetic flux surfaces for conventional reflectometry) are presented.

Whole-mount bone and cartilage staining of chick embryos with minimal decalcification

Whole-mount staining with Alcian blue for cartilage and alizarin red for bone has been widely used for visualizing the skeletal patterns of embryos and small adult vertebrates. The possibility of decalcification by the acidic Alcian blue solution is known, but standard staining protocols do not always avoid this issue. We investigated the effects of acidity on the stainability of developing bones in stage 36 chick embryos and developed an optimal procedure for obtaining reliable results with minimal decalcification. The diaphyses of long bone rudiments and the maxillofacial membranous bones progressively lost their stainability with alizarin red when the chick embryos were soaked for long periods in the preceding acidic Alcian blue staining solution for cartilage. Unless the acidity was neutralized with an alkaline solution, the remaining acidity in the specimens rendered the pH sufficiently low to prevent the subsequent alizarin red staining of the bones. These findings indicate that the mineralizing bones at the early stages of development are labile to acidity and become decalcified more substantially during the staining process than previously appreciated. The following points are important for visualizing such labile mineralizing bones in chick embryos: 1) fixing with formaldehyde followed by soaking in 70% ethanol, 2) minimizing the time that the specimens are exposed to the acidic Alcian blue solution, and 3) neutralizing and dehydrating the specimens by an alkaline-alcohol solution immediately after the cartilage staining. When the exact onset and/or an early phase of ossification are of interest, the current double-staining procedure should be accompanied by a control single-staining procedure directed only toward bone.

Neurodegenerative influence of oxidative stress in the retina of a murine model of diabetes

AIMS/HYPOTHESIS

Diabetic retinopathy is a progressive neurodegenerative disease, but the underlying mechanism is still obscure. Here, we focused on oxidative stress in the retina, and analysed its influence on retinal neurodegeneration, using an antioxidant, lutein.

METHODS

C57BL/6 mice with streptozotocin-induced diabetes were constantly fed either a lutein-supplemented diet or a control diet from the onset of diabetes, and their metabolic data were recorded. In 1-month-diabetic mice, reactive oxygen species (ROS) in the retina were measured using dihydroethidium and visual function was evaluated by electroretinograms. Levels of activated extracellular signal-regulated kinase (ERK), synaptophysin and brain-derived neurotrophic factor (BDNF) were also measured by immunoblotting in the retina of 1-month-diabetic mice. In the retinal sections of 4-month-diabetic mice, histological changes, cleaved caspase-3 and TUNEL staining were analysed.

RESULTS

Lutein did not affect the metabolic status of the diabetic mice, but it prevented ROS generation in the retina and the visual impairment induced by diabetes. ERK activation, the subsequent synaptophysin reduction, and the BDNF depletion in the diabetic retina were all prevented by lutein. Later, in 4-month-diabetic mice, a decrease in the thickness of the inner plexiform and nuclear layers, and ganglion cell number, together with increase in cleaved caspase-3- and TUNEL-positive cells, were avoided in the retina of lutein-fed mice.

CONCLUSIONS/INTERPRETATION

The results indicated that local oxidative stress that has a neurodegenerative influence in the diabetic retina is prevented by constant intake of a lutein-supplemented diet. The antioxidant, lutein may be a potential therapeutic approach to protect visual function in diabetes.

Chromosome evolution in the lizard genus Gekko (Gekkonidae, Squamata, Reptilia) in the East Asian islands

The lizard genus Gekko consists of over 30 species distributed in Asia and Oceania. From the insular region of East Asia including Japan and Taiwan, 9 species (G. hokouensis, G. japonicus, G. shibatai, G. tawaensis, G. vertebralis,G. yakuensis, and 3 undescribed species) are currently recognized. We made karyological analyses for all these species. Their karyotypes invariably consisted of 2N = 38 chromosomes, but exhibited considerable variation in fundamental number (ranging from 56-62). Substantial chromosomal variation was detected even among populations of a morphologically relatively uniform species, G. hokouensis. Populations of G. hokouensis from the central and northern Ryukyus exhibited prominent female heteromorphic (i.e., ZW type) sex chromosomes. Populations of the southern Ryukyus exclusive of Yonagunijima also had ZW sex chromosomes, whose heteromorphisms were, however, much less prominent. The other G. hokouensis populations including the topotypic continental representatives and the population from Yonagunijima of the southern Ryukyus exhibited no sex chromosome heteromorphism at all. These results strongly suggest that G. hokouensis in the current taxonomic definition actually includes more than 2 species. The process of chromosomal evolution in the East Asian Gekko is hypothesized.