One particle interchain hopping in coupled Hubbard chains

Interchain hopping in systems of coupled chains of correlated electrons is investigated by exact diagonalizations and Quantum-Monte-Carlo methods. For two weakly coupled Hubbard chains at commensurate densities (e.g. n=1/3) the splitting at the Fermi level between bonding and antibonding bands is strongly reduced (but not suppressed) by repulsive interactions extending to a few lattice spacings. The magnitude of this reduction is directly connected to the exponent $\alpha$ of the 1D Luttinger liquid. However, we show that the incoherent part of the single particle spectral function is much less affected by the interchain coupling. This suggests that incoherent interchain hopping could occur for intermediate $\alpha$ values.Comment: 4 pages, LaTeX 3.0, 7 PostScript figures in uuencoded for

A Galaxy-scale Fountain of Cold Molecular Gas Pumped by a Black Hole

We present Atacama Large Millimeter/submillimeter Array and Multi-Unit Spectroscopic Explorer observations of the brightest cluster galaxy in Abell 2597, a nearby (z = 0.0821) cool core cluster of galaxies. The data map the kinematics of a three billion solar mass filamentary nebula that spans the innermost 30 kpc of the galaxy's core. Its warm ionized and cold molecular components are both cospatial and comoving, consistent with the hypothesis that the optical nebula traces the warm envelopes of many cold molecular clouds that drift in the velocity field of the hot X-ray atmosphere. The clouds are not in dynamical equilibrium, and instead show evidence for inflow toward the central supermassive black hole, outflow along the jets it launches, and uplift by the buoyant hot bubbles those jets inflate. The entire scenario is therefore consistent with a galaxy-spanning "fountain," wherein cold gas clouds drain into the black hole accretion reservoir, powering jets and bubbles that uplift a cooling plume of low-entropy multiphase gas, which may stimulate additional cooling and accretion as part of a self-regulating feedback loop. All velocities are below the escape speed from the galaxy, and so these clouds should rain back toward the galaxy center from which they came, keeping the fountain long lived. The data are consistent with major predictions of chaotic cold accretion, precipitation, and stimulated feedback models, and may trace processes fundamental to galaxy evolution at effectively all mass scales

Cosmology with clusters of galaxies

In this Chapter I review the role that galaxy clusters play as tools to constrain cosmological parameters. I will concentrate mostly on the application of the mass function of galaxy clusters, while other methods, such as that based on the baryon fraction, are covered by other Chapters of the book. Since most of the cosmological applications of galaxy clusters rely on precise measurements of their masses, a substantial part of my Lectures concentrates on the different methods that have been applied so far to weight galaxy clusters. I provide in Section 2 a short introduction to the basics of cosmic structure formation. In Section 3 I describe the Press--Schechter (PS) formalism to derive the cosmological mass function, then discussing extensions of the PS approach and the most recent calibrations from N--body simulations. In Section 4 I review the methods to build samples of galaxy clusters at different wavelengths. Section 5 is devoted to the discussion of different methods to derive cluster masses. In Section 6 I describe the cosmological constraints, which have been obtained so far by tracing the cluster mass function with a variety of methods. Finally, I describe in Section 7 the future perspectives for cosmology with galaxy clusters and the challenges for clusters to keep playing an important role in the era of precision cosmology.Comment: 49 pages, 19 figures, Lectures for 2005 Guillermo Haro Summer School on Clusters, to appear in "Lecture notes in Physics" (Springer

An analysis of radioactive waste minimization efforts at Los Alamos National Laboratory

LANL will be the primary DOE facility for plutonium research and development and plutonium processing. A summary of the currently generated waste types, volumes, generating facilities or programs, and disposal costs are given in this report along with future waste generation projections. Several key existing technologies have been identified that could be introduced to reduce the generated waste at LANL. Four of these are discussed in detail in this report: (1) electrolytic surface decontamination, (2) electrochemical treatment of mixed wastes, (3) Long Range Alpha Detection (LRAD), and (4) Segmented Gate and Containerized Vat Leach System (SGS/CVL). These technologies may be implemented as modifications in upstream processes as well as more efficient volume reduction and segregation. The four technologies are mature enough to be implemented in the next two to three years and can be done so with the support for capital and operational costs. Also discussed in this report is a small sample of some of the recent waste minimization success stories that have been implemented. Several technologies are presented that are either currently being investigated or on hold due to lack of funding at LANL but show potential for making significant gains in waste minimization. This report is intended to provide a review of the waste minimization issues and analysis of the impact of implementing a few of these technologies

X-ray fluorescence spectroscopy for the elemental analysis of plutonium-bearing materials for the materials disposition program

The US Fissile Materials Disposition (MD) program will disposition about 50 MT of plutonium in the next century. Both of the alternative technologies for disposition, MOX Fuel and Immobilization require knowledge of the incoming composition to 1--5 wt%. Wavelength Dispersive X-Ray Fluorescence (WDXRF) systems, a common elemental analysis technology with a variety of industrial applications and commercial vendors, can readily achieve this level of characterization. Since much of the excess plutonium will be packaged in a long-term storage container as part of the DOE Environmental Management (DOE-EM) program to stabilize plutonium-bearing materials, the characterization system must be implemented during the packaging process. The authors describe a preliminary design for the integration of the WDXRF system into the packaging system to be used at the Rocky Flats site. The Plutonium Stabilization and Packaging System (PuSPS), coupled with the WDXRF characterization system will provide MD with stabilized plutonium-bearing excess material that can be more readily fed to an immobilization facility. The overall added expense to the MD program of obtaining analytical information after materials have been packaged in long-term storage containers could far exceed the expense of implementing XRF analysis during the packaging process

The FUTURIX-Transmutation Experiment in PHENIX: Status of Fuel Fabrication

The objective of FUTURIX-FTA experiment is to increase the understanding of fuels containing significant quantities of minor actinides. Eight pins: metallic, nitride, CERMET and CERCER fuels prepared by the DOE (INL, LANL), ITU (MALAB) and CEA (ATALANTE) will be irradiated in PHENIX reactor. This experiment will provide essential data concerning behaviour under irradiation and will allow qualification and validation of models developed to predict fuel performance. DOE is performing the fabrication and characterization of two metallic fuel alloys, U-29Pu-4Am-2Np-30Zr and Pu-12Am-40Zr, and two nitride fuel compositions, (U0.50,Pu0.25,Am0.15,Np0.10)N and (Pu0.50,Am0.50)N+36wt per cent ZrN. These fuel compositions have already been tested in the Advanced Test Reactor to a peak burnup of 8per cent and are currently undergoing post irradiation examination. Fuel crystallographic structures, microstructure and their thermal properties have been measured. At ITU, two CERMET composite fuel types are proposed, a zirconia based compound (Am,Pu,Zr)O2-x and a mixed oxide (Am,Pu)O2-x, which are mixed with Mo powder that acts as the fuel matrix. The fabrication process is based on particles containing the actinide phase produced by a combination of the sol gel external gelation, GSP, and the infiltration methods followed by compacting and sintering. At CEA, two CERCER composite oxide fuel types are manufactured by an oxalic co-conversion and by powder metallurgy. The resulting microstructure, performed by SEM, shows a good homogeneity and fissile repartition in the magnesia matrix. A cubic centred structure with O/M=1.66 and a face-centred cubic lattice with a O/M=1.93 are found for (Pu0,5Am0,5)Ox-MgO(70 per cent vol) fuel. For the (Pu0,2Am0,8)Ox-MgO(65 per cent vol) component a single monoclinic phase structure with O/ M=1.64 is measured.JRC.E.4-Nuclear fuel

Far-ultraviolet morphology of star-forming filaments in cool core brightest cluster galaxies

We present a multiwavelength morphological analysis of star-forming clouds and filaments in the central (≲50 kpc) regions of 16 low-redshift (z < 0.3) cool core brightest cluster galaxies. New Hubble Space Telescope imaging of far-ultraviolet continuum emission from young (≲10 Myr), massive (≳5 M⊙) stars reveals filamentary and clumpy morphologies, which we quantify by means of structural indices. The FUV data are compared with X-ray, Lyα, narrow-band Hα, broad-band optical/IR, and radio maps, providing a high spatial resolution atlas of star formation locales relative to the ambient hot (∼107–8 K) and warm ionized (∼104 K) gas phases, as well as the old stellar population and radio-bright active galactic nucleus (AGN) outflows. Nearly half of the sample possesses kpc-scale filaments that, in projection, extend towards and around radio lobes and/or X-ray cavities. These filaments may have been uplifted by the propagating jet or buoyant X-ray bubble, or may have formed in situ by cloud collapse at the interface of a radio lobe or rapid cooling in a cavity's compressed shell. The morphological diversity of nearly the entire FUV sample is reproduced by recent hydrodynamical simulations in which the AGN powers a self-regulating rain of thermally unstable star-forming clouds that precipitate from the hot atmosphere. In this model, precipitation triggers where the cooling-to-free-fall time ratio is tcool/tff ∼ 10. This condition is roughly met at the maximal projected FUV radius for more than half of our sample, and clustering about this ratio is stronger for sources with higher star formation rates

Primary adhalinopathy: a common cause of autosomal recessive muscular dystrophy of variable severity.

Marked deficiency of muscle adhalin, a 50 kDa sarcolemmal dystrophin-associated glycoprotein, has been reported in severe childhood autosomal recessive muscular dystrophy (SCARMD). This is a Duchenne-like disease affecting both males and females first described in Tunisian families. Adhalin deficiency has been found in SCARMD patients from North Africa Europe, Brazil, Japan and North America (SLR &amp; KPC, unpublished data). The disease was initially linked to an unidentified gene on chromosome 13 in families from North Africa, and to the adhalin gene itself on chromosome 17q in one French family in which missense mutations were identified. Thus there are two kinds of myopathies with adhalin deficiency: one with a primary defect of adhalin (primary adhalinopathies), and one in which absence of adhalin is secondary to a separate gene defect on chromosome 13. We have examined the importance of primary adhalinopathies among myopathies with adhalin deficiency, and describe several additional mutations (null and missense) in the adhalin gene in 10 new families from Europe and North Africa. Disease severity varies in age of onset and rate of progression, and patients with null mutations are the most severely affected

Herschel photometry of brightest cluster galaxies in cooling flow clusters

The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present Herschel PACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (>3 x 10^7 Mo) at temperatures significantly lower (20-28K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear to match those of the cold gas traced by CO with a gas-to-dust ratio of 80-120.Comment: Accepted for A&A Herschel Special Issue, 7 pages, 3 figure