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Sweetwater Reporter (Sweetwater, Tex.), Vol. 112, No. 078, Ed. 1 Monday, February 15, 2010 (open access)

Sweetwater Reporter (Sweetwater, Tex.), Vol. 112, No. 078, Ed. 1 Monday, February 15, 2010

Daily newspaper from Sweetwater, Texas that includes local, state, and national news along with advertising.
Date: February 15, 2010
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History

Senior Recital: 2010-02-15 - Alessandra (Alex) Woods, flute

Access: Use of this item is restricted to the UNT Community
A senior recital presented at the UNT College of Music Recital Hall.
Date: February 15, 2010
Creator: Woods, Alessandra
Object Type: Sound
System: The UNT Digital Library
[Funeral Program for Leola Jones, February 15, 2010] (open access)

[Funeral Program for Leola Jones, February 15, 2010]

Funeral program for Ms. Leola Jones "Winnie", born July 22, 1923 and died February 3, 2010. The funeral was held Monday, February 15, 2010 at West End Baptist Church, officiated by Rev. L. A. Crenshaw. Funeral arrangements were made through Carter-Taylor-Williams Mortuary and she was buried in Meadowlawn Memorial Park in San Antonio, Texas.
Date: February 15, 2010
Creator: unknown
Object Type: Pamphlet
System: The Portal to Texas History
Texas Department of Criminal Justice 5% Biennial Budget Reduction Plan (open access)

Texas Department of Criminal Justice 5% Biennial Budget Reduction Plan

Tables outlining the Texas Department of Justice plan to reduce a total of 5% ($294.3 million) of the budget for fiscal years 2010-2011. Each cell describes an alternate funding source or change in activities with the amount of money that would be reduced in state funding.
Date: February 15, 2010
Creator: Texas. Department of Criminal Justice.
Object Type: Text
System: The Portal to Texas History
[Funeral Program for Doris Jean Poe Johnson, February 15, 2010] (open access)

[Funeral Program for Doris Jean Poe Johnson, February 15, 2010]

Funeral program for Doris Jean Poe Johnson, born March 6, 1918 and died February 11, 2010. The funeral was held February 15, 2010 at F.E. Lewis Memorial Chapel, officiated by Rev. Dr. Marcus Freeman, III. Funeral arrangements were made through Lewis Funeral Home.
Date: February 15, 2010
Creator: unknown
Object Type: Pamphlet
System: The Portal to Texas History
SLAC Cosmic Ray Telescope Facility (open access)

SLAC Cosmic Ray Telescope Facility

SLAC does not have a test beam for the HEP detector development at present. We have therefore created a cosmic ray telescope (CRT) facility, which is presently being used to test the FDIRC prototype. We have used it in the past to debug this prototype with the original SLAC electronics before going to the ESA test beam. Presently, it is used to test a new waveform digitizing electronics developed by the University of Hawaii, and we are also planning to incorporate the new Orsay TDC/ADC electronics. As a next step, we plan to put in a full size DIRC bar box with a new focusing optics, and test it together with a final SuberB electronics. The CRT is located in building 121 at SLAC. We anticipate more users to join in the future. This purpose of this note is to provide an introductory manual for newcomers.
Date: February 15, 2010
Creator: Va'vra, J.
Object Type: Report
System: The UNT Digital Library
Simulation of the Focusing DIRC Optics with Mathematica (open access)

Simulation of the Focusing DIRC Optics with Mathematica

The Focusing DIRC is considered for the Barrel PID at a possible Super-B factory. To reduce sensitivity to background, it would be desirable to reduce a size of the present BaBar photon detector. One way to do it is to replace it with a focusing optics and use smaller photon detector pixels. We have simulated the focusing optics with simulation software based on a 3D calculation performed with the Mathematica program. The software does not use Optica package, instead, it uses its own 3D algorithm. The advantage of the presented method is that it is transparent, fast and that it uses a full backing of the Mathematica graphics, and it does not require expertise to run Geat4 MC software.
Date: February 15, 2010
Creator: Va'vra, J.
Object Type: Article
System: The UNT Digital Library
Field-induced Gap and Quantized Charge Pumping in Nano-helix (open access)

Field-induced Gap and Quantized Charge Pumping in Nano-helix

We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to 'geometrically' constructing one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a new standard for the high precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nano-scale electro-mechanical motors. Finally, our methodology also enables new ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.
Date: February 15, 2010
Creator: Qi, Xiao-Liang; /Stanford U., Phys. Dept. /Tsinghua U., Beijing; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Report
System: The UNT Digital Library
Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps (open access)

Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps

We investigate massive star formation in turbulent, magnetized, parsec-scale clumps of molecular clouds including protostellar outflow feedback using three dimensional numerical simulations of effective resolution 2048{sup 3}. The calculations are carried out using a block structured adaptive mesh refinement code that solves the ideal MHD equations including self-gravity and implements accreting sink particles. We find that, in the absence of regulation by magnetic fields and outflow feedback, massive stars form readily in a turbulent, moderately condensed clump of {approx} 1,600 M{sub {circle_dot}} (containing {approx} 10{sup 2} initial Jeans masses), along with a cluster of hundreds of lower mass stars. The massive stars are fed at high rates by (1) transient dense filaments produced by large-scale turbulent compression at early times, and (2) by the clump-wide global collapse resulting from turbulence decay at late times. In both cases, the bulk of the massive star's mass is supplied from outside a 0.1 pc-sized 'core' that surrounds the star. In our simulation, the massive star is clump-fed rather than core-fed. The need for large-scale feeding makes the massive star formation prone to regulation by outflow feedback, which directly opposes the feeding processes. The outflows reduce the mass accretion rates onto the massive stars …
Date: February 15, 2010
Creator: Wang, Peng; /KIPAC, Menlo Park /Stanford U., Phys.Dept.; Li, Zhi-Yun; /Virginia U., Astron. Dept.; Abel, Tom; /KIPAC, Menlo Park /Stanford U., Phys.Dept. et al.
Object Type: Article
System: The UNT Digital Library
AdS/QCD and Light Front Holography: A New Approximation to QCD (open access)

AdS/QCD and Light Front Holography: A New Approximation to QCD

The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n+L+S/2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in …
Date: February 15, 2010
Creator: Brodsky, Stanley J. & de Teramond, Guy
Object Type: Article
System: The UNT Digital Library
Alpha Channeling in Rotating Plasma with Stationary Waves (open access)

Alpha Channeling in Rotating Plasma with Stationary Waves

An extension of the alpha channeling effect to supersonically rotating mirrors shows that the rotation itself can be driven using alpha particle energy. Alpha channeling uses radiofrequency waves to remove alpha particles collisionlessly at low energy. We show that stationary magnetic fields with high nθ can be used for this purpose, and simulations show that a large fraction of the alpha energy can be converted to rotation energy.
Date: February 15, 2010
Creator: Fetterman, A. & Fisch, N. J.
Object Type: Report
System: The UNT Digital Library
Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3 (open access)

Fermi Surface Evolution Across Multiple Charge Density Wave Transitions in ErTe3

The Fermi surface (FS) of ErTe{sub 3} is investigated using angle-resolved photoemission spectroscopy (ARPES). Low temperature measurements reveal two incommensurate charge density wave (CDW) gaps created by perpendicular FS nesting vectors. A large {Delta}{sub 1} = 175 meV gap arising from a CDW with c* - q{sub CDW1} {approx} 0.70(0)c* is in good agreement with the expected value. A second, smaller {Delta}{sub 2} = 50 meV gap is due to a second CDW with a* - q{sub CDW2} {approx} 0.68(5)a*. The temperature dependence of the FS, the two gaps and possible interaction between the CDWs are examined.
Date: February 15, 2010
Creator: Moore, R. G.; /SLAC, SSRL /Stanford U., Geballe Lab.; Brouet, V.; /Orsay, LPS; He, R.; /SLAC, SSRL /Stanford U., Geballe Lab. et al.
Object Type: Article
System: The UNT Digital Library
Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe3 (R = Ho, Dy, Tb) (open access)

Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe3 (R = Ho, Dy, Tb)

The coupling of phonons with collective modes and single-particle gap excitations associated with one (1d) and two-directional (2d) electronically-driven charge-density wave (CDW) ordering in metallic RTe{sub 3} is investigated as a function of rare-earth ion chemical pressure (R = Tb, Dy, Ho) using femtosecond pump-probe spectroscopy. From the T-dependence of the CDW gap {Delta}{sub CDW} and the amplitude mode (AM) we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean-field (MF)-like fashion, below T{sub c1}, {Delta}{sub CDW} is depressed and departs from the MF behavior. The effect is apparently triggered by resonant mode-mixing of the amplitude mode (AM) with a totally symmetric phonon at 1.75 THz. At low temperatures, when the state evolves into a 2d-CDW ordered state at T{sub c2} in the DyTe{sub 3} and HoTe{sub 3}, additional much weaker mode mixing is evident but no soft mode is observed.
Date: February 15, 2010
Creator: Yusupov, R. V.; Mertelj, T.; Chu, J.-H.; Fisher, I. R. & Mihailovic, D.
Object Type: Article
System: The UNT Digital Library
Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian (open access)

Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian

We study the semi-classical motion of holes by exact numerical solution of the Luttinger model. The trajectories obtained for the heavy and light holes agree well with the higher order corrections to the abelian and the non-abelian adiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378 (2003)], respectively. It is found that the hole trajectories contain rapid oscillations reminiscent of the 'Zitterbewegung' of relativistic electrons. We also comment on the non-conservation of helicity of the light holes.
Date: February 15, 2010
Creator: Jiang, Z. F.; Li, R. D.; Zhang, Shou-Cheng & Liu, W. M.
Object Type: Article
System: The UNT Digital Library
Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R= Y, La, Ce, Sm, Gd, Tb and Dy) (open access)

Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R= Y, La, Ce, Sm, Gd, Tb and Dy)

We present a detailed ARPES investigation of the RTe{sub 3} family, which sets this system as an ideal 'textbook' example for the formation of a nesting driven Charge Density Wave (CDW). This family indeed exhibits the full range of phenomena that can be associated to CDW instabilities, from the opening of large gaps on the best nested parts of Fermi Surface (FS) (up to 0.4eV), to the existence of residual metallic pockets. ARPES is the best suited technique to characterize these features, thanks to its unique ability to resolve the electronic structure in k-space. An additional advantage of RTe{sub 3} is that the band structure can be very accurately described by a simple 2D tight-binding (TB) model, which allows one to understand and easily reproduce many characteristics of the CDW. In this paper, we first establish the main features of the electronic structure, by comparing our ARPES measurements with Linear Muffin-Tin Orbital band calculations. We use this to define the validity and limits of the TB model. We then present a complete description of the CDW properties and, for the first time, of their strong evolution as a function of R. Using simple models, we are able to reproduce perfectly …
Date: February 15, 2010
Creator: Brouet, V.; Yang, W. L.; Zhou, X. J.; Hussain, Z.; Moore, R. G.; He, R. et al.
Object Type: Article
System: The UNT Digital Library
Time-Resolved Photoemission of Correlated Electrons Driven Out of Equilibrium (open access)

Time-Resolved Photoemission of Correlated Electrons Driven Out of Equilibrium

We describe the temporal evolution of the time-resolved photoemission response of the spinless Falicov-Kimball model driven out of equilibrium by strong, applied fields. The model is one of the few possessing a metal-insulator transition and admitting an exact solution in the time domain. The nonequilibrium dynamics, evaluated using an extension of dynamical mean-field theory, show how the driven system differs from two common viewpoints - a quasi-equilibrium system at an elevated, effective temperature (the 'hot' electron model) or a rapid interaction quench ('melting' of the Mott gap) - due to the rearrangement of electronic states and redistribution of spectral weight. The results demonstrate the inherent trade-off between energy and time resolution accompanying the finite width probe-pulses, characteristic of those employed in pump-probe, time-domain experiments, which can be used to focus attention on different aspects of the dynamics near the transition.
Date: February 15, 2010
Creator: Moritz, B.; /SLAC, SIMES; Devereaux, T.P.; /SLAC, SIMES /Stanford U., Geballe Lab.; Freericks, J.K. & U., /Georgetown
Object Type: Article
System: The UNT Digital Library
Unraveling L_{n,k}: Grassmannian Kinematics (open access)

Unraveling L_{n,k}: Grassmannian Kinematics

It was recently proposed that the leading singularities of the S-Matrix of N = 4 super Yang-Mills theory arise as the residues of a contour integral over a Grassmannian manifold, with space-time locality encoded through residue theorems generalizing Cauchy's theorem to more than one variable. We provide a method to identify the residue corresponding to any leading singularity, and we carry this out explicitly for all leading singularities at tree level and one-loop. We also give several examples at higher loops, including all generic two-loop leading singularities and an interesting four-loop object. As an example we consider a 12-pt N{sup 4}MHV leading singularity at two loops that has a kinematic structure involving double square roots. Our analysis results in a simple picture for how the topological structure of loop graphs is reflected in various substructures within the Grassmannian.
Date: February 15, 2010
Creator: Kaplan, Jared
Object Type: Article
System: The UNT Digital Library
Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride (open access)

Pressure induced Superconductivity in the Charge Density Wave Compound Tritelluride

A series of high-pressure electrical resistivity measurements on single crystals of TbTe{sub 3} reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge density wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near {approx} 12.4 GPa.
Date: February 15, 2010
Creator: Hamlin, J.J.; Zocco, D. A.; Sayles, T. A.; Maple, M. B.; Chu, J.-H.; Fisher, I.R. et al.
Object Type: Article
System: The UNT Digital Library
Electronic structure of the iron-based superconductor LaOFeP (open access)

Electronic structure of the iron-based superconductor LaOFeP

The recent discovery of superconductivity in the so-called iron-oxypnictide family of compounds has generated intense interest. The layered crystal structure with transition metal ions in planar square lattice form and the discovery of spin-density-wave order near 130K seem to hint at a strong similarity with the copper oxide superconductors. A burning current issue is the nature of the ground state of the parent compounds. Two distinct classes of theories have been put forward depending on the underlying band structures: local moment antiferromagnetic ground state for strong coupling approach and itinerant ground state for weak coupling approach. The local moment magnetism approach stresses on-site correlations and proximity to a Mott insulating state and thus the resemblance to cuprates; while the latter approach emphasizes the itinerant electron physics and the interplay between the competing ferromagnetic and antiferromagnetic fluctuations. Such a controversy is partly due to the lack of conclusive experimental information on the electronic structures. Here we report the first angle-resolved photoemission spectroscopy (ARPES) investigation of LaOFeP (T{sub c} = 5.9 K), the first reported iron-based superconductor. Our results favor the itinerant ground state, albeit with band renormalization. In addition, our data reveal important differences between these and copper based superconductors.
Date: February 15, 2010
Creator: Lu, D. H.; Yi, M.; /Stanford U., Phys. Dept. /SLAC, SSRL; Mo1, S.-K.; /Stanford U., Phys. Dept. /SLAC, SSRL /LBNL, ALS; Erickson, A. S. et al.
Object Type: Article
System: The UNT Digital Library
Multiple charge density wave transitions in Gd2Te5 (open access)

Multiple charge density wave transitions in Gd2Te5

Diffraction measurements performed via transmission electron microscopy and high resolution X-ray scattering reveal two distinct charge density wave transitions in Gd{sub 2}Te{sub 5} at T{sub c1} = 410(3) and T{sub c2} = 532(3) K, associated with the on-axis incommensurate lattice modulation and off-axis commensurate lattice modulation respectively. Analysis of the temperature dependence of the order parameters indicates a non-vanishing coupling between these two distinct CDW states.
Date: February 15, 2010
Creator: Shin, K. Y.; Ru, N.; Condron, C. L.; Wu, Y. Q.; Kramer, M. J.; Toney, M. F. et al.
Object Type: Article
System: The UNT Digital Library
Optical properties of the Ce and La ditelluride charge density wave compounds (open access)

Optical properties of the Ce and La ditelluride charge density wave compounds

The La and Ce di-tellurides LaTe{sub 2} and CeTe{sub 2} are deep in the charge-density-wave (CDW) ground state even at 300 K. We have collected their electrodynamic response over a broad spectral range from the far infrared up to the ultraviolet. We establish the energy scale of the single particle excitation across the CDW gap. Moreover, we find that the CDW collective state gaps a very large portion of the Fermi surface. Similarly to the related rare earth tri-tellurides, we envisage that interactions and Umklapp processes play a role in the onset of the CDW broken symmetry ground state.
Date: February 15, 2010
Creator: Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; Shin, K. Y. & Fisher, I. R.
Object Type: Article
System: The UNT Digital Library
NLO Jet Physics with BlackHat (open access)

NLO Jet Physics with BlackHat

We present several results obtained using the BLACKHAT next-to-leading order QCD program library, in conjunction with SHERPA. In particular, we present distributions for vector boson plus 1,2,3-jet production at the Tevatron and at the asymptotic running energy of the Large Hadron Collider, including new Z + 3-jet distributions. The Z + 2-jet predictions for the second-jet P{sub T} distribution are compared to CDF data. We present the jet-emission probability at NLO in W + 2-jet events at the LHC, where the tagging jets are taken to be the ones furthest apart in pseudorapidity. We analyze further the large left-handed W{sup {+-}} polarization, identified in our previous study, for W bosons produced at high P{sub T} at the LHC.
Date: February 15, 2010
Creator: Berger, C. F.; Bern, Z.; Dixon, L. J.; Cordero, F. Febres; Forde, D.; Gleisberg, T. et al.
Object Type: Article
System: The UNT Digital Library
Bulk Superconductivity and Disorder in Single Crystals of LaFePO (open access)

Bulk Superconductivity and Disorder in Single Crystals of LaFePO

We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.
Date: February 15, 2010
Creator: Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro et al.
Object Type: Article
System: The UNT Digital Library
Optical Properties of the Charge-Density-Wave Polychalcogenide Compounds R2Te5 (R=Nd, Sm and Gd) (open access)

Optical Properties of the Charge-Density-Wave Polychalcogenide Compounds R2Te5 (R=Nd, Sm and Gd)

We investigate the rare-earth polychalcogenide R{sub 2}Te{sub 5} (R = Nd, Sm and Gd) charge-density-wave (CDW) compounds by optical methods. From the absorption spectrum we extract the excitation energy of the CDW gap and estimate the fraction of the Fermi surface which is gapped by the formation of the CDW condensate. In analogy to previous findings on the related RTe{sub n} (n = 2 and 3) families, we establish the progressive closing of the CDW gap and the moderate enhancement of the metallic component upon chemically compressing the lattice.
Date: February 15, 2010
Creator: Pfuner, F.; Degiorgi, L.; /Zurich, ETH; Shin, K.Y.; Fisher, I.R. & /Stanford U., Geballe Lab.
Object Type: Article
System: The UNT Digital Library