Digital Frequency Domain Multiplexer for mm-Wavelength Telescopes (open access)

Digital Frequency Domain Multiplexer for mm-Wavelength Telescopes

An FPGA based digital signal processing (DSP) system for biasing and reading out multiplexed bolometric detectors for mm-wavelength telescopes is presented. This readout system is being deployed for balloon-borne and ground based cosmology experiments with the primary goal of measuring the signature of inflation with the Cosmic Microwave Background Radiation. The system consists of analog superconducting electronics running at 250 mK and 4 K, coupled to digital room temperature backend electronics described here. The digital electronics perform the real time functionality with DSP algorithms implemented in firmware. A soft embedded processor provides all of the slow housekeeping control and communications. Each board in the system synthesizes multi-frequency combs of 8 to 32 carriers in the MHz band to bias the detectors. After the carriers have been modulated with the sky-signal by the detectors, the same boards digitize the comb directly. The carriers are mixed down to base-band and low pass filtered. The signal bandwidth of 0.050Hz-100 Hz places extreme requirements on stability and requires powerful filtering techniques to recover the sky-signal from the MHz carriers.
Date: July 23, 2007
Creator: Spieler, Helmuth G; Dobbs, Matt; Bissonnette, Eric & Spieler, Helmuth G.
System: The UNT Digital Library
Exact de Rham Sequences of Spaces Defined on Macro-elements in Two and Three Spatial Dimensions (open access)

Exact de Rham Sequences of Spaces Defined on Macro-elements in Two and Three Spatial Dimensions

This paper proposes new finite element spaces that can be constructed for agglomerates of standard elements that have certain regular structure. The main requirement is that the agglomerates share faces that have closed boundaries composed of 1-d edges. The spaces resulting from the agglomerated elements are subspaces of the original de Rham sequence of H{sup 1}-conforming, H(curl) conforming, H(div) conforming and piecewise constant spaces associated with an unstructured 'fine' mesh. The procedure can be recursively applied so that a sequence of nested de Rham complexes can be constructed. As an illustration we generate coarser spaces from the sequence corresponding to the lowest order Nedelec spaces, lowest order Raviart-Thomas spaces, and for piecewise linear H{sup 1}-conforming spaces, all in three-dimensions. The resulting V-cycle multigrid methods used in preconditioned conjugate gradient iterations appear to perform similar to those of the geometrically refined case.
Date: July 23, 2007
Creator: Pasciak, J. & Vassilevski, P.
System: The UNT Digital Library
Enhancing Scalability of Sparse Direct Methods (open access)

Enhancing Scalability of Sparse Direct Methods

TOPS is providing high-performance, scalable sparse direct solvers, which have had significant impacts on the SciDAC applications, including fusion simulation (CEMM), accelerator modeling (COMPASS), as well as many other mission-critical applications in DOE and elsewhere. Our recent developments have been focusing on new techniques to overcome scalability bottleneck of direct methods, in both time and memory. These include parallelizing symbolic analysis phase and developing linear-complexity sparse factorization methods. The new techniques will make sparse direct methods more widely usable in large 3D simulations on highly-parallel petascale computers.
Date: July 23, 2007
Creator: Li, Xiaoye S.; Demmel, James; Grigori, Laura; Gu, Ming; Xia,Jianlin; Jardin, Steve et al.
System: The UNT Digital Library
Comparing Computer Run Time of Building Simulation Programs (open access)

Comparing Computer Run Time of Building Simulation Programs

This paper presents an approach to comparing computer run time of building simulation programs. The computing run time of a simulation program depends on several key factors, including the calculation algorithm and modeling capabilities of the program, the run period, the simulation time step, the complexity of the energy models, the run control settings, and the software and hardware configurations of the computer that is used to make the simulation runs. To demonstrate the approach, simulation runs are performed for several representative DOE-2.1E and EnergyPlus energy models. The computer run time of these energy models are then compared and analyzed.
Date: July 23, 2008
Creator: Hong, Tianzhen; Buhl, Fred; Haves, Philip; Selkowitz, Stephen & Wetter, Michael
System: The UNT Digital Library
ATLAS TrackingEvent Data Model -- 12.0.0 (open access)

ATLAS TrackingEvent Data Model -- 12.0.0

In this report the event data model (EDM) relevant for tracking in the ATLAS experiment is presented. The core component of the tracking EDM is a common track object which is suited to describe tracks in the innermost tracking sub-detectors and in the muon detectors in offline as well as online reconstruction. The design of the EDM was driven by a demand for modularity and extensibility while taking into account the different requirements of the clients. The structure of the track object and the representation of the tracking-relevant information are described in detail.
Date: July 23, 2006
Creator: ATLAS; Akesson, F.; Atkinson, T.; Costa, M.J.; Elsing, M.; Fleischmann, S. et al.
System: The UNT Digital Library
Ovarian carcinomas with genetic and epigenetic BRCA1 loss havedistinct molecular abnormalities (open access)

Ovarian carcinomas with genetic and epigenetic BRCA1 loss havedistinct molecular abnormalities

Subclassification of ovarian carcinomas can be used to guide treatment and determine prognosis. Germline and somatic mutations, loss of heterozygosity (LOH), and epigenetic events such as promoter hypermethylation can lead to decreased expression of BRCA1/2 in ovarian cancers. The mechanism of BRCA1/2 loss is a potential method of subclassifying high grade serous carcinomas. A consecutive series of 49 ovarian cancers was assessed for mutations status of BRCA1 and BRCA2, LOH at the BRCA1 and BRCA2 loci, methylation of the BRCA1 promoter, BRCA1, BRCA2, PTEN, and PIK3CA transcript levels, PIK3CA gene copy number, and BRCA1, p21, p53, and WT-1 immunohistochemistry. Eighteen (37%) of the ovarian carcinomas had germline or somatic BRCA1 mutations, or epigenetic loss of BRCA1. All of these tumors were high-grade serous or undifferentiated type. None of the endometrioid (n = 5), clear cell (n = 4), or low grade serous (n = 2) carcinomas showed loss of BRCA1, whereas 47% of the 38 high-grade serous or undifferentiated carcinomas had loss of BRCA1. It was possible to distinguish high grade serous carcinomas with BRCA1 mutations from those with epigenetic BRCA1 loss: tumors with BRCA1 mutations typically had decreased PTEN mRNA levels while those with epigenetic loss of BRCA1 had …
Date: July 23, 2007
Creator: Press, Joshua Z.; De Luca, Alessandro; Boyd, Niki; Young, Sean; Troussard, Armelle; Ridge, Yolanda et al.
System: The UNT Digital Library
Fast Neutron Radioactivity and Damage Studies on Materials (open access)

Fast Neutron Radioactivity and Damage Studies on Materials

None
Date: July 23, 2007
Creator: Anderson, S.; Spencer, J.; Wolf, Z.; Gallagher, G.; Pellett, D.; Boussoufi, M. et al.
System: The UNT Digital Library
Functional One-Dimensional Lipid Bilayers on Carbon Nanotube Templates (open access)

Functional One-Dimensional Lipid Bilayers on Carbon Nanotube Templates

We present one-dimensional (1-D) lipid bilayer structures that integrate carbon nanotubes with a key biological environment-phospholipid membrane. Our structures consist of lipid bilayers wrapped around carbon nanotubes modified with a hydrophilic polymer cushion layer. Despite high bilayer curvature, the lipid membrane maintains its fluidity and can sustain repeated damage-recovery cycles. We also present the first evidence of spontaneous insertion of pore-forming proteins into 1-D lipid bilayers. These structures could lead to the development of new classes of biosensors and bioelectronic devices.
Date: July 23, 2004
Creator: Artyukhin, Alexander; Shestakov, Alexei; Harper, Jennifer; Bakajin, Olgica; Stroeve, Pieter & Noy, Aleksandr
System: The UNT Digital Library
Multiple Oscillation Stabilizing Control (open access)

Multiple Oscillation Stabilizing Control

This paper presents a strategy that may be used to guide stabilizing control design for multiple oscillations, which are difficult to control using conventional control design procedures. A multiple oscillation phenomena is observed in an example power system. A local bifurcation and an interarea bifurcation develop in an example power system due to multiple bifurcation parameter variations. The dynamic behaviors of the bifurcating system are complex due to the overlapping of the two different bifurcation subsystems and are shown to be difficult to control. The double bifurcations are studied in this paper and in order to stabilize them, three kind of {mu}-synthesis robust controls are designed, (a) {mu}-synthesis power system stabilizer (MPSS); (b) {mu}-synthesis SVC control (MSVC); and (c) a mixed MPSS/MSVC control. Based on the bifurcation subsystem analysis, the measurement signals and locations of the controls are selected. The control performances of three kind of controls are evaluated and compared. The conclusions are given according to the analysis and time simulation results.
Date: July 23, 2004
Creator: Yue, M.; Schlueter, R.; Azarm, M. & Bari, R.
System: The UNT Digital Library
Application of PILATUS II Detector Modules for High Resolution X-Ray Imaging Crystal Spectrometers on the Alcator C-Mod Tokamak (open access)

Application of PILATUS II Detector Modules for High Resolution X-Ray Imaging Crystal Spectrometers on the Alcator C-Mod Tokamak

A new type of X-ray imaging crystal spectrometer for Doppler measurements of the radial profiles of the ion temperature and plasma rotation velocity in tokamak plasmas is presently being developed in a collaboration between various laboratories. The spectrometer will consist of a spherically bent crystal and a two-dimensional position sensitive detector; and it will record temporally and spatially resolved X-ray line spectra from highly-charged ions. The detector must satisfy challenging requirements with respect to count rate and spatial resolution. The paper presents the results from a recent test of a PILATUS II detector module on Alcator C-Mod, which demonstrate that the PILATUS II detector modules will satisfy these requirements.
Date: July 23, 2007
Creator: M.L. Bitter, Ch. Borennimann, E.F. Eikenberry, K.W. Hill, A. Ince-Chushman, S.G. Lee, J.E. Rice, and S. Scott.
System: The UNT Digital Library
A Heterobimetallic Complex With an Unsupported Uranium(III)-Aluminum(I) Bond: (CpSiMe3)3U-AlCp* (Cp* = C5Me5) (open access)

A Heterobimetallic Complex With an Unsupported Uranium(III)-Aluminum(I) Bond: (CpSiMe3)3U-AlCp* (Cp* = C5Me5)

The discovery of molecular metal-metal bonds has been of fundamental importance to the understanding of chemical bonding. For the actinides, examples of unsupported metal-metal bonds are relatively uncommon, consisting of Cp{sub 3}U-SnPh{sub 3}, and several actinide-transition metal complexes. Traditionally, bonding in the f-elements has been described as electrostatic; however, elucidating the degree of covalency is a subject of recent research. In carbon monoxide complexes of the trivalent uranium metallocenes, decreased {nu}{sub CO} values relative to free CO suggest that the U(III) atom acts as a {pi}-donor. Ephritikhine and coworkers have demonstrated that {pi}-accepting ligands can differentiate trivalent lanthanide and actinide ions, an effect that renders this chemistry of interest in the context of nuclear waste separation technology.
Date: July 23, 2008
Creator: Minasian, Stefan; Krinsky Ph.D., Jamin; Williams, Valerie & Arnold Ph.D., John
System: The UNT Digital Library
LATTICE QCD AT FINITE DENSITY. (open access)

LATTICE QCD AT FINITE DENSITY.

I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transition line as function of the chemical potential (T{sub c}({mu}{sub q})) are reviewed. Along the transition line, hadronic fluctuations have been calculated; which can be used to characterize properties of the Quark Gluon plasma and eventually can also help to identify the location of the critical end-point in the QCD phase diagram on the lattice and in heavy ion experiments. Furthermore, I comment on the structure of the phase diagram at large {mu}{sub q}.
Date: July 23, 2006
Creator: SCHMIDT, C.
System: The UNT Digital Library
Wide-field surveys from the SNAP mission (open access)

Wide-field surveys from the SNAP mission

The Supernova/Acceleration Probe (SNAP) is a proposed space-borne observatory that will survey the sky with a wide-field optical/NIR imager. The images produced by SNAP will have an unprecedented combination of depth, solid-angle, angular resolution, and temporal sampling. Two 7.5 square-degree fields will be observed every four days over 16 months to a magnitude depth of AB = 27.7 in each of nine filters. Co-adding images over all epochs will give an AB = 30.3 per filter. A 300 square-degree field will be surveyed with no repeat visits to AB = 28 per filter. The nine filters span 3500-17000 {angstrom}. Although the survey strategy is tailored for supernova and weak gravitational lensing observations, the resulting data supports a broad range of auxiliary science programs.
Date: July 23, 2002
Creator: agkim@lbl.gov
System: The UNT Digital Library
ISO/GUM UNCERTAINTIES AND CIAAW (UNCERTAINTY TREATMENT FOR RECOMMENDED ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES) (open access)

ISO/GUM UNCERTAINTIES AND CIAAW (UNCERTAINTY TREATMENT FOR RECOMMENDED ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES)

The International Organization for Standardization (ISO) has published a Guide to the expression of Uncertainty in Measurement (GUM). The IUPAC Commission on Isotopic Abundance and Atomic Weight (CIAAW) began attaching uncertainty limits to their recommended values about forty years ago. CIAAW's method for determining and assigning uncertainties has evolved over time. We trace this evolution to their present method and their effort to incorporate the basic ISO/GUM procedures into evaluations of these uncertainties. We discuss some dilemma the CIAAW faces in their present method and whether it is consistent with the application of the ISO/GUM rules. We discuss the attempt to incorporate variations in measured isotope ratios, due to natural fractionation, into the ISO/GUM system. We make some observations about the inconsistent treatment in the incorporation of natural variations into recommended data and uncertainties. A recommendation for expressing atomic weight values using a tabulated range of values for various chemical elements is discussed.
Date: July 23, 2007
Creator: Holden, N. E.
System: The UNT Digital Library
CALCULATION OF DELTA I = 3/2 KAON WEAK MATRIX ELEMENTS INCLUDING TWO-PION INTERACTION EFFECTS IN FINITE VOLUME. (open access)

CALCULATION OF DELTA I = 3/2 KAON WEAK MATRIX ELEMENTS INCLUDING TWO-PION INTERACTION EFFECTS IN FINITE VOLUME.

We calculate {Delta}I = 3/2 kaon decay matrix elements using domain wall fermions and the DBW2 gauge action at one coarse lattice spacing corresponding to a{sup -1} = 1.3 GeV. We employ the Lellouch and Luescher formula and its extension for non-zero total momentum to extract the infinite volume, center-of-mass frame decay amplitudes. The decay amplitudes obtained from the methods correspond to those from the indirect method with full order chiral perturbation theory. We confirm that the result is consistent with the previous result calculated with H-parity (anti-periodic) boundary condition by investigating the relative momentum dependence. We evaluate the decay amplitude ReA{sub 2} at the physical point by a chiral extrapolation with a polynomial function of m{sub {pi}}{sup 2} and the relative momentum as well as the {Delta}I = 3/2 electroweak penguin contributions to {var_epsilon}{prime}/{var_epsilon}. We found that the result of ReA{sub 2} reasonably agrees with the experiment.
Date: July 23, 2006
Creator: YAMAZAKI, T.
System: The UNT Digital Library
QCD THERMODYNAMICS WITH NF=2+1 NEAR THE CONTINUUM LIMIT AT REALISTIC QUARK MASSES. (open access)

QCD THERMODYNAMICS WITH NF=2+1 NEAR THE CONTINUUM LIMIT AT REALISTIC QUARK MASSES.

We report on our study of QCD thermodynamics with 2 + 1 flavors of dynamical quarks. In this proceeding we present several thermodynamic quantities and our recent calculation of the critical temperature. In order to investigate the thermodynamic properties of QCD near the continuum limit we adopt improved staggered (p4) quarks coupled with tree-level Symanzik improved glue on N{sub t} = 4 and 6 lattices. The simulations are performed with a physical value of the strange quark mass and light quark masses which are in the range of m{sub q}/m{sub s} = 0.05 - 0.4. The lightest quark mass corresponds to a pion mass of about 150 MeV.
Date: July 23, 2006
Creator: UMEDA, T.
System: The UNT Digital Library
Justification for Onsite Transfer of Type B Packages after Extended Storage (open access)

Justification for Onsite Transfer of Type B Packages after Extended Storage

None
Date: July 23, 2006
Creator: HOUGHTALING, THEODORE
System: The UNT Digital Library
Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques (open access)

Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques

The challenge of chemistry in the 21st century is to achieve 100% selectivity of the desired product molecule in multipath reactions ('green chemistry') and develop renewable energy based processes. Surface chemistry and catalysis play key roles in this enterprise. Development of in situ surface techniques such as high-pressure scanning tunneling microscopy, sum frequency generation (SFG) vibrational spectroscopy, time-resolved Fourier transform infrared methods, and ambient pressure X-ray photoelectron spectroscopy enabled the rapid advancement of three fields: nanocatalysts, biointerfaces, and renewable energy conversion chemistry. In materials nanoscience, synthetic methods have been developed to produce monodisperse metal and oxide nanoparticles (NPs) in the 0.8-10 nm range with controlled shape, oxidation states, and composition; these NPs can be used as selective catalysts since chemical selectivity appears to be dependent on all of these experimental parameters. New spectroscopic and microscopic techniques have been developed that operate under reaction conditions and reveal the dynamic change of molecular structure of catalysts and adsorbed molecules as the reactions proceed with changes in reaction intermediates, catalyst composition, and oxidation states. SFG vibrational spectroscopy detects amino acids, peptides, and proteins adsorbed at hydrophobic and hydrophilic interfaces and monitors the change of surface structure and interactions with coadsorbed water. Exothermic reactions …
Date: July 23, 2009
Creator: Somorjai, G. A.; Frei, H. & Park, J. Y.
System: The UNT Digital Library
The CDFII Silicon Detector (open access)

The CDFII Silicon Detector

The CDFII silicon detector consists of 8 layers of double-sided silicon micro-strip sensors totaling 722,432 readout channels, making it one of the largest silicon detectors in present use by an HEP experiment. After two years of data taking, we report on our experience operating the complex device. The performance of the CDFII silicon detector is presented and its impact on physics analyses is discussed. We have already observed measurable effects from radiation damage. These results and their impact on the expected lifetime of the detector are briefly reviewed.
Date: July 23, 2004
Creator: Thom, Julia
System: The UNT Digital Library
Diluted II-VI oxide semiconductors with multiple band gaps (open access)

Diluted II-VI oxide semiconductors with multiple band gaps

None
Date: July 23, 2003
Creator: Yu, K. M.; Walukiewicz, W.; Wu, J.; Shan, W.; Beeman, J. W.; Scarpulla, M. A. et al.
System: The UNT Digital Library
Diluted magnetic semiconductors formed by an ion implantation and pulsed-laser melting (open access)

Diluted magnetic semiconductors formed by an ion implantation and pulsed-laser melting

Using ion implantation followed by pulsed-laser melting (PLM), we have synthesized ferromagnetic films of Ga{sub 1-x}Mn{sub x}As. Ion-channeling experiments reveal that these films are single crystalline and have high Mn substitutionality while variable temperature resistivity measurements reveal the strong Mn-hole interactions characteristic of carrier-mediated ferromagnetism in homogeneous DMS's. We have observed Curie temperatures (T{sub C}'s) of approximately 80 K for films with substitutional Mn concentrations of x=0.04. The use of n-type counter doping as a means of increasing Mn substitutionality and T{sub c} is explored by co-implantation of Mn and Te into GaAs. In Ga{sub 1-x}Mn{sub x}P samples synthesized using our technique, the implanted layer regrows as an epitaxial single crystal capped by a highly defective surface layer. These samples display ferromagnetism with T{sub c} {approx} 23 K.
Date: July 23, 2003
Creator: Scarpulla, M. A.; Daud, U.; Yu, K. M.; Monteiro, O.; Liliental-Weber; Zakharov, D. et al.
System: The UNT Digital Library
The Lost tribes of charmonium (open access)

The Lost tribes of charmonium

To illustrate the campaign to extend our knowledge of the charmonium spectrum, the author focuses on a puzzling new state, X(3872) {yields} {pi}{sup +} {pi}{sup -} J/{psi}. Studying the influence of open-charm channels on charmonium properties leads us to propose a new charmonium spectroscopy: additional discrete charmonium levels that can be discovered as narrow resonances of charmed and anticharmed mesons. The author calls attention to open issues for theory and experiment.
Date: July 23, 2004
Creator: Quigg, Chris
System: The UNT Digital Library
Antenna-coupled arrays of voltage-biased superconducting bolometers (open access)

Antenna-coupled arrays of voltage-biased superconducting bolometers

We report on the development of antenna-coupled Voltage-biased Superconducting Bolometers (VSBs) which use Transition-edge Sensors (TES). Antenna coupling can greatly simplify the fabrication of large multi-frequency bolometer arrays compared to horn-coupled techniques. This simplification can make it practical to implement 1000+ element arrays that fill the focal plane of mm/sub-mm wave telescopes. We have designed a prototype device with a double-slot dipole antenna, integrated band-defining filters, and a membrane-suspended bolometer. A test chip has been constructed and will be tested shortly.
Date: July 23, 2001
Creator: Myers, Michael J.; Lee, Adrian T.; Richards, P. L.; Schwan, D.; Skidmore, J. T.; Smith, A. D. et al.
System: The UNT Digital Library
Mutual passivation of group IV donors and isovalent nitrogen in diluted GaN{sub x}As{sub 1-x} alloys (open access)

Mutual passivation of group IV donors and isovalent nitrogen in diluted GaN{sub x}As{sub 1-x} alloys

We demonstrate the mutual passivation of electrically active group IV donors and isovalent N atoms in the GaN{sub x}As{sub 1-x} alloy system. This phenomenon occurs through the formation of a donor-nitrogen bond in the nearest neighbor IV{sub Ga}-N{sub As} pairs. In Si doped GaInN{sub 0.017}As{sub 0.983} the electron concentration starts to decrease rapidly at an annealing temperature of 700 C from {approx} 3 x 10{sup 19}cm{sup -3} in the as-grown state to less than 10{sup 16}cm{sup -3} after an annealing at 900 C for 10 s. At the same time annealing of this sample at 950 C increases the gap by about 35 meV, corresponding to a reduction of the concentration of the active N atoms by an amount very close to the total Si concentration. We also show that the formation of Si{sub Ga}-N{sub As} pairs is controlled by the diffusion of Si via Ga vacancies to the nearest N{sub As} site. The general nature of this mutual passivation effect is confirmed by our study of Ge doped GaN{sub x}As{sub 1-x} layers formed by N and Ge co-implantation in GaAs followed by pulsed laser melting.
Date: July 23, 2003
Creator: Yu, K.M.; Wu, J.; Walukiewicz, W.; Shan, W.; Beeman, J.; Mars, D.E. et al.
System: The UNT Digital Library