Notes on the early-type components of W Cep, o Cet, CH Cyg, AR Mon, and BL Tel

Low resolution IUE spectra in both spectral regions are used to clarify the nature of the warmer components of several binary systems. The W Cep, the primary of which is a luminous K-type supergiant, shows an ultraviolet absorption spectrum of type B0 or B1; this system is heavily reddened. The hot companion of Mira (o Cet) is surprisingly faint in the short wavelength region, but it excites a rich emission spectrum from the surrounding gas. The ultraviolet active M7 giant CH Cyg is shown to be a binary with a hot companion. This system was also observed at high resolution and shows variable Fe II emission and well-separated circumstellar and interstellar absorptions within the broad Mg II emission profiles. The eclipsing binaries AR Mon and BL Tel are shown not to have hot companions

Bridging Atomistic/Continuum Scales in Solids with Moving Dislocations

We propose a multiscale method for simulating solids with moving dislocations. Away from atomistic subdomains where the atomistic dynamics are fully resolved, a dislocation is represented by a localized jump profile, superposed on a defect-free field. We assign a thin relay zone around an atomistic subdomain to detect the dislocation profile and its propagation speed at a selected relay time. The detection technique utilizes a lattice time history integral treatment. After the relay, an atomistic computation is performed only for the defect-free field. The method allows one to effectively absorb the fine scale fluctuations and the dynamic dislocations at the interface between the atomistic and continuum domains. In the surrounding region, a coarse grid computation is adequate

Spontaneous spin ordering of Dirac spin liquid in a magnetic field

The Dirac spin liquid was proposed to be the ground state of the spin-1/2 Kagome antiferromagnets. In a magnetic field $B$, we show that the state with Fermi pocket is unstable to the Landau level (LL) state. The LL state breaks the spin rotation around the axis of the magnetic field. We find that the LL state has an in-plane 120$^{\circ}$ $q=0$ magnetization $M$ which scales with the external field $M\sim B^{\alpha}$, where $\alpha$ is an intrinsic calculable universal number of the Dirac spin liquid. We discuss the related experimental implications which can be used to detect the possible Dirac spin liquid phase in Herbertsmithite ZnCu$_3$(OH)$_6$Cl$_2$.Comment: rewritten for clarit

An epep collider based on proton-driven plasma wakefield acceleration

Recent simulations have shown that a high-energy proton bunch can excite strong plasma wakefields and accelerate a bunch of electrons to the energy frontier in a single stage of acceleration. This scheme could lead to a future $ep$ collider using the LHC for the proton beam and a compact electron accelerator of length 170 m, producing electrons of energy up to 100 GeV. The parameters of such a collider are discussed as well as conceptual layouts within the CERN accelerator complex. The physics of plasma wakefield acceleration will also be introduced, with the AWAKE experiment, a proof of principle demonstration of proton-driven plasma wakefield acceleration, briefly reviewed, as well as the physics possibilities of such an $ep$ collider.Comment: 6 pages, 2 figures, to appear in the proceedings of the DIS 2014 Workshop, 28 April - 2 May, Warsaw, Polan

Collider design issues based on proton-driven plasma wakefield acceleration

Recent simulations have shown that a high-energy proton bunch can excite strong plasma wakefields and accelerate a bunch of electrons to the energy frontier in a single stage of acceleration. It therefore paves the way towards a compact future collider design using the proton beams from existing high-energy proton machines, e.g. Tevatron or the LHC. This paper addresses some key issues in designing a compact electron-positron linear collider and an electron-proton collider based on existing CERN accelerator infrastructure

Two- and three-dimensional viscous computations of a hypersonic inlet flow

The three-dimensional parabolized Navier-Stokes code has been used to investigate the flow through a Mach 7.4 inlet. A two-dimensional parametric study of grid resolution, turbulence modeling and effect of gamma has been done and compared with experimental results. The results show that mesh resolution of the shock waves, real gas effects and turbulence length scaling are very important to get accurate results for hypersonic inlet flows. In addition a three-dimensional calculation of the Mach 7.4 inlet has been done on a straight sideplate configuration. The results show that the glancing shock/boundary layer interaction phenomena causes significant three-dimensional flow in the inlet

Synthesis of a Molecular Charm Bracelet via Click Cyclization and Olefin Metathesis Clipping

We describe the synthesis of a polycatenated cyclic polymer, a structure that resembles a molecular charm bracelet. Ruthenium-catalyzed ring-opening metathesis polymerization of an aminocontaining cyclic olefin monomer in the presence of a chain transfer agent generated an α,ω-diazide functionalized polyamine. Cyclization of the resulting linear polyamine using pseudo-high-dilution coppercatalyzed click cyclization produced a cyclic polymer in 19% yield. The click reaction was then further employed to remove linear contaminants from the cyclic polymer using azide- and alkyne-functionalized scavenging resins, and the purified cyclic polymer product was characterized by gel permeation chromatography, ^1H NMR spectroscopy, and IR spectroscopy. Polymer hydrogenation and conversion to the corresponding polyammonium species enabled coordination and interlocking of diolefin polyether fragments around the cyclic polymer backbone using ruthenium-catalyzed ring-closing olefin metathesis to afford a molecular charm bracelet structure. This charm bracelet complex was characterized by ^1H NMR spectroscopy, and the catenated nature of the small rings was confirmed using two-dimensional diffusion-ordered NMR spectroscopy

Tuning of coupling modes in laterally parallel double open quantum dots

We consider electronic transport through laterally parallel double open quantum dots embedded in a quantum wire in a perpendicular magnetic field. The coupling modes of the dots are tunable by adjusting the strength of a central barrier and the applied magnetic field. Probability density and electron current density are calculated to demonstrate transport effects including magnetic blocking, magnetic turbulence, and a hole-like quasibound state feature. Fano to dip line-shape crossover in the conductance is found by varying the magnetic field.Comment: RevTeX, 13 pages with 18 included postscript figures, high resolution version is available at http://hartree.raunvis.hi.is/~vidar/Rann/CSTVG_DOQD_05.pd