Measurement of the D-D fusion neutron energy spectrum and variation of the peak width with plasma ion temperature

and disposal, in whole or in part by or for the United States govern-ment is permitted. By acceptance of this article, the publisher and/or recipient ac-knowledges the U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright covering this paper. 1 Measurement of the d-d fusion neutron energy spectrum and variation of the peak width with plasma ion temperature W. A. Fisher*, S. H. Chen*, D. Gwinnt, R. R. Parkert We report a set of neutron spectrum measurements made at the Alcator C tokamak under ohmic heating conditions. It has been found that the width of the D-D fusion neutron peak increases with the plasma ion temperature consistent with the theoretical prediction. In particular the neutron spectra resulting from the sum of many plasma discharges with ion temperatures of 780 eV and 1050 eV have been ob-tained. The width for the 780 eV case is 64 +9,-11 keV and that of the 1050 eV case, 81 +10,-14 keV FWHM, corresponding to ion tempera-tures of 740 eV and 1190 eV respectively

Structural and electrical properties of c-axis oriented Y1-xCaxBa2(Cu1-yZny)3O7-delta thin films grown by pulsed laser deposition

Ca- and Zn-subsituted Y1-xCaxBa2(Cu1-yZny)O7-delta (x = 0, 0.05 and y = 0, 0.02, 0.04, 0.05) thin films were grown on SrTiO3 (100) substrates using the pulsed laser deposition (PLD) technique. Effects of various growth parameters on the quality of the film were studied via X-ray diffraction (XRD), atomic force microscopy (AFM), and in-plane resistivity, rhoab(T), measurements. The deposition temperature and oxygen partial pressure were gradually increased to 820C and 1.20 mbar respectively. Films grown under these conditions exhibited good c-axis orientation (primarily limited by the grain size) and low values of the extrapolated residual resistivity, rho(0), at zero temperature. The planar hole content, p, was determined from the room temperature thermopower, S[290K], measurements and the effects of oxygen annealing were also studied. Fully oxygenated samples were found to be overdoped with p ~ 0.195. The Superconducting transition temperature Tc(p), and rho(T,p) showed the expected systematic variations with changing Zn content.Comment: Submitted to Physica C (2003

Perturbations in choline metabolism cause neural tube defects in mouse embryos in vitro.

A role for choline during early stages of mammalian embryogenesis has not been established, although recent studies show that inhibitors of choline uptake and metabolism, 2-dimethylaminoethanol (DMAE), and 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3), produce neural tube defects in mouse embryos grown in vitro. To determine potential mechanisms responsible for these abnormalities, choline metabolism in the presence or absence of these inhibitors was evaluated in cultured, neurulating mouse embryos by using chromatographic techniques. Results showed that 90%-95% of 14C-choline was incorporated into phosphocholine and phosphatidylcholine (PtdCho), which was metabolized to sphingomyelin. Choline was oxidized to betaine, and betaine homocysteine methyltransferase was expressed. Acetylcholine was synthesized in yolk sacs, but 70 kDa choline acetyltransferase was undetectable by immunoblot. DMAE reduced embryonic choline uptake and inhibited phosphocholine, PtdCho, phosphatidylethanolamine (PtdEtn), and sphingomyelin synthesis. ET-18-OCH3 also inhibited PtdCho synthesis. In embryos and yolk sacs incubated with 3H-ethanolamine, 95% of recovered label was PtdEtn, but PtdEtn was not converted to PtdCho, which suggested that phosphatidylethanolamine methyltransferase (PeMT) activity was absent. In ET-18-OCH3 treated yolk sacs, PtdEtn was increased, but PtdCho was still not generated through PeMT. Results suggest that endogenous PtdCho synthesis is important during neurulation and that perturbed choline metabolism contributes to neural tube defects produced by DMAE and ET-18-OCH3

The effect of Zn substitution on the state of oxygen deficiency and hole concentration in Y1-xCaxBa2(Cu1-yZny)3O7-d

We have investigated the effect of Zn substitution on the hole content, p, and the oxygen deficiency, d, for a series of high-quality crystalline c-axis oriented thin films and polycrystalline Y1-xCaxBa2(Cu1-yZny)3O7-delta compounds over a wide range of composition (x, y, and delta). p was determined from the room-temperature thermopower, S[290K]. When annealed at a given temperature and oxygen partial pressure, a small but systematic variation in S[290K] was observed with Zn, for all the samples. From the analysis of the temperature derivative of resistivity, drho/dT, at 300K, which varies almost linearly with p, irrespective of the composition of the sample, and the thermo-gravimetric analysis (TGA), we have found that annealing under identical conditions makes the Zn-substituted compounds somewhat more oxygen deficient compared to the Zn-free ones

Mott Transition in An Anyon Gas

We introduce and analyze a lattice model of anyons in a periodic potential and an external magnetic field which exhibits a transition from a Mott insulator to a quantum Hall fluid. The transition is characterized by the anyon statistics, $\alpha$, which can vary between Fermions, $\alpha=0$, and Bosons, $\alpha=1$. For bosons the transition is in the universality class of the classical three-dimensional XY model. Near the Fermion limit, the transition is described by a massless $2+1$ Dirac theory coupled to a Chern-Simons gauge field. Analytic calculations perturbative in $\alpha$, and also a large N-expansion, show that due to gauge fluctuations, the critical properties of the transition are dependent on the anyon statistics. Comparison with previous calcualations at and near the Boson limit, strongly suggest that our lattice model exhibits a fixed line of critical points, with universal critical properties which vary continuosly and monotonically as one passes from Fermions to Bosons. Possible relevance to experiments on the transitions between plateaus in the fractional quantum Hall effect and the magnetic field-tuned superconductor-insulator transition are briefly discussed.Comment: text and figures in Latex, 41 pages, UBCTP-92-28, CTP\#215

Sulphonylurea Usage in Melioidosis Is Associated with Severe Disease and Suppressed Immune Response

10.1371/journal.pntd.0002795PLoS Neglected Tropical Diseases84

The types of Mott insulator

There are two classes of Mott insulators in nature, distinguished by their responses to weak doping. With increasing chemical potential, Type I Mott insulators undergo a first order phase transition from the undoped to the doped phase. In the presence of long-range Coulomb interactions, this leads to an inhomogeneous state exhibiting ``micro-phase separation.'' In contrast, in Type II Mott insulators charges go in continuously above a critical chemical potential. We show that if the insulating state has a broken symmetry, this increases the likelihood that it will be Type I. There exists a close analogy between these two types of Mott insulators and the familiar Type I and Type II superconductors

Low-energy excitations in the three-dimensional random-field Ising model

The random-field Ising model (RFIM), one of the basic models for quenched disorder, can be studied numerically with the help of efficient ground-state algorithms. In this study, we extend these algorithm by various methods in order to analyze low-energy excitations for the three-dimensional RFIM with Gaussian distributed disorder that appear in the form of clusters of connected spins. We analyze several properties of these clusters. Our results support the validity of the droplet-model description for the RFIM.Comment: 10 pages, 9 figure

The Role of Local Therapy in Multi-focal Epithelioid Haemangioendothelioma

Contains fulltext : 208930.pdf (publisher's version ) (Open Access)BACKGROUND/AIM: Epithelioid haemangioendothelioma (EHE) is a rare tumor with a wide spectrum of clinical behavior. There is no consensus on the role of local therapy in symptomatic, multi-focal disease. PATIENTS AND METHODS: A retrospective review of patients presenting to the Royal Marsden Hospital between January 2000 and December 2017 was conducted. RESULTS: Fifty-three patients with EHE were identified, of which 18 patients (34.0%) received local therapy, and 11 patients (20.8%) underwent active surveillance. A variety of local treatment modalities were used with few toxicities, and local recurrence was managed with other local treatments or systemic therapy. Distal disease progression was infrequent (n=4, 7.5%). Patients who developed pleural effusion (n=5, 9.4%) had poor outcome irrespective of treatment. CONCLUSION: Local therapy has a role in a selected patient group managed in a multidisciplinary setting, including patients with indolent disease, and patients with a solitary area of progression/symptomatic disease