TEM study of the martensitic phases in the ductile DyCu and YCu intermetallic compounds

DyCu and YCu are representatives of the family of CsCI-type B2 rare earth intermetallic compounds that exhibit high room temperature ductility. Structure, orientation relationship, and morphology of the martensites in the equiatomic compounds DyCu and YCu are examined using transmission electron microscopy (TEM). TEM studies show that the martensite structures in DyCu and YCu alloys are virtually identical. The martensite is of orthorhombic CrB-type B33 structure with lattice parameters a = 0.38 nm, b = 1.22 nm, and c = 0.40 nm. (02 (1) over bar) twins were observed in the B33 DyCu and YCu martensites. The orientation relationship of B33 and B2 phases is (11 (1) over bar)[112]B33 parallel to (110)[001]B2. The simulated electron diffraction patterns of the B33 phase are consistent with those of experimental observations. TEM investigations also reveal that a dominant orthorhombic FeB-type B27 martensite with lattice parameters a = 0.71 nm, b = 0.45 nm, and c = 0.54 nm exists in YCu alloy. (I (1) over barI) twins were observed in the B27 YCu martensite. The formation mechanism of B2 to B33 and B2 to B27 phase transformation is discussed

Los Alamos Pinhole Camera (LAPC): A new flexible x-ray pinhole camera

We have recently designed, built and fielded a versatile, multi-channel x-ray pinhole camera. The LAPC was designed to fit into any six inch manipulator (SIM) which is a standardized target chamber diagnostic tube. There are currently compatible SIMs available at the Trident, Omega, and NOVA laser systems. The camera uses 9 pinholes in a 3x3 array to produce images at the film plane. The film housing is designed to hold multiple sheets of stacked x-ray film which also uses a dark-slide to protect the film before exposure. Magnifications of 12, 8, 4 and 2X are selected by slip-on nosecones, which support pinholes, collimators, and blast shields. Individual channel filtering is provided by a 3x3 filterpack containing 9 separate filter sub-packs. Spatial resolution is limited by the pinhole diffraction limit and field of view is dependent on magnification and filterpack diameter

Meson loop effects in the NJL model at zero and non-zero temperature

We compare two different possibilities to include meson-loop corrections in the Nambu-Jona-Lasinio model: a strict 1/N_c-expansion in next-to-leading order and a non-perturbative scheme corresponding to a one-meson-loop approximation to the effective action. Both schemes are consistent with chiral symmetry, in particular with the Goldstone theorem and the Gell-Mann-Oakes-Renner relation. The numerical part at zero temperature focuses on the pion and the rho-meson sector. For the latter the meson-loop-corrections are crucial in order to include the dominant rho -> pipi-decay channel, while the standard Hartree + RPA approximation only contains unphysical qqbar-decay channels. We find that m_\pi, f_\pi, and quantities related to the rho-meson self-energy can be described reasonably with one parameter set in the 1/N_c-expansion scheme, whereas we did not succeed to obtain such a fit in the non-perturbative scheme. We also investigate the temperature dependence of the quark condensate. Here we find consistency with chiral perturbation theory to lowest order. Similarities and differences of both schemes are discussed.Comment: 51 pages, 18 figures, to be published in Physics of Atomic Nuclei, the volume dedicated to the 90th birthday of A.B. Migdal, error in Eq. 4.22 correcte

Dual microchannel plate module for a gated monochromatic x-ray imager

Development and testing of a dual microchannel plate (MCP) module to be used in the national Inertial Confinement Fusion (ICF) program has recently been completed. The MCP module is a key component of a new monochromatic x-ray imaging diagnostic which is designed around a 4 channel Kirkpatrick-Baez microscope and diffraction crystals which is located at University of Rochester`s Omega laser system. The MCP module has two separate MCP regions with centers spaced 53 mm apart. Each region contains a 25 mm MCP proximity focused to a P-11 phosphor coated fiberoptic faceplate. The two L/D = 40, MCPs have a 10.2 mm wide, 8 ohm stripline constructed of 500 nm Copper overcoated with 100 nm Gold. A 4 kV, 150 ps electrical pulse provides an optical gatewidth of 80 ps and spatial resolution has been measured at 20 1p/mm

On unifying the description of meson and baryon properties

A Poincare' covariant Faddeev equation is presented, which enables the simultaneous prediction of meson and baryon observables using the leading-order in a truncation of the Dyson-Schwinger equations that can systematically be improved. The solution describes a nucleon's dressed-quark core. The evolution of the nucleon mass with current-quark mass is discussed. A nucleon-photon current, which can produce nucleon form factors with realistic Q^2-evolution, is described. Axial-vector diquark correlations lead to a neutron Dirac form factor that is negative, with r_1^{nu}>r_1^{nd}. The proton electric-magnetic form factor ratio falls with increasing Q^2.Comment: 5 pages, 4 figures, 1 tabl

Little Higgs Models and Precision Electroweak Data

We study the low energy limit of Little Higgs models. The method consists in eliminating the heavy fields using their classical equations of motion in the infinite mass limit. After the elimination of the heavy degrees of freedom we can directly read off deviations from the precision electroweak data. We also examine the effects on the low energy precision experiments.Comment: Misprint in eps3 for the custodial model corrected and additional discussion of the triplet higg

Socioeconomic impact of restless legs syndrome and inadequate restless legs syndrome management across European settings

Restless legs syndrome (RLS) is one of the most common neurological disorders. It describes an irresistible urge to move the legs, mostly manifested in the evening and at night, which can lead to severe sleep disturbance. As part of the European Brain Council (EBC)-led Value-of-Treatment project, this study aimed at capturing the socioeconomic impact of RLS related to the inadequate diagnosis and treatment across different European healthcare settings. The economic burden of RLS was estimated using the published EBC framework of analysis in three separate European Union healthcare systems (France, Germany, and Italy). The RLS care pathway was mapped to identify the unmet needs of patients. Based on specific patient stories, the economic impact of correctly diagnosing RLS and changing between inadequate and target treatment was calculated using appropriate scenario analysis. RLS proved to be a significant personal and social burden, when epidemiological data, high prevalence of RLS, and its need for treatment are combined. By looking at the savings emerging from the provision of optimal care management (timely and correct diagnosis, evidence-based therapy, avoidance of therapy-related complications such as augmentation), the authors foresee substantial economic savings with the achievement of adequate diagnosis and treatment of RLS. Education about RLS is urgently needed for all subspecialties involved in RLS patient care as well as the general public. Equally important, the search for new causal treatment strategies should be intensified to reduce suffering and substantial societal cost

Photon emission from bare quark stars

We investigate the photon emission from the electrosphere of a quark star. It is shown that at temperatures T\sim 0.1-1 MeV the dominating mechanism is the bremsstrahlung due to bending of electron trajectories in the mean Coulomb field of the electrosphere. The radiated energy for this mechanism is much larger than that for the Bethe-Heitler bremsstrahlung. The energy flux from the mean field bremsstrahlung exceeds the one from the tunnel e^{+}e^{-} pair creation as well. We demonstrate that the LPM suppression of the photon emission is negligible.Comment: 35 pages, 5 figure

Critical temperature for kaon condensation in color-flavor locked quark matter

We study the behavior of Goldstone bosons in color-flavor-locked (CFL) quark matter at nonzero temperature. Chiral symmetry breaking in this phase of cold and dense matter gives rise to pseudo-Goldstone bosons, the lightest of these being the charged and neutral kaons K^+ and K^0. At zero temperature, Bose-Einstein condensation of the kaons occurs. Since all fermions are gapped, this kaon condensed CFL phase can, for energies below the fermionic energy gap, be described by an effective theory for the bosonic modes. We use this effective theory to investigate the melting of the condensate: we determine the temperature-dependent kaon masses self-consistently using the two-particle irreducible effective action, and we compute the transition temperature for Bose-Einstein condensation. Our results are important for studies of transport properties of the kaon condensed CFL phase, such as bulk viscosity.Comment: 24 pages, 8 figures, v2: new section about effect of electric neutrality on critical temperature added; references added; version to appear in J.Phys.