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The BaBar Level 1 Drift-Chamber Trigger Upgrade With 3D Tracking (open access)

The BaBar Level 1 Drift-Chamber Trigger Upgrade With 3D Tracking

At BABAR, the Level 1 Drift Chamber trigger is being upgraded to reduce increasing background rates while the PEP-II luminosity keeps improving. This upgrade uses the drift time information and stereo wires in the drift chamber to perform a 3D track reconstruction that effectively rejects background events spread out along the beam line.
Date: November 29, 2005
Creator: Chai, X. D.
System: The UNT Digital Library
Alternative approach to general coupled linear optics (open access)

Alternative approach to general coupled linear optics

The Twiss parameters provide a convenient description of beam optics in uncoupled linear beamlines. For coupled beamlines, a variety of approaches are possible for describing the linear optics; here, we propose an approach and notation that naturally generalizes the familiar Twiss parameters to the coupled case in three degrees of freedom. Our approach is based on an eigensystem analysis of the matrix of second-order beam moments, or alternatively (in the case of a storage ring) on an eigensystem analysis of the linear single-turn map. The lattice functions that emerge from this approach have an interpretation that is conceptually very simple: in particular, the lattice functions directly relate the beam distribution in phase space to the invariant emittances. To emphasize the physical significance of the coupled lattice functions, we develop the theory from first principles, using only the assumption of linear symplectic transport. We also give some examples of the application of this approach, demonstrating its advantages of conceptual and notational simplicity.
Date: November 29, 2005
Creator: Wolski, Andrzej
System: The UNT Digital Library
Application of Sequence-based Methods in Human MicrobialEcology (open access)

Application of Sequence-based Methods in Human MicrobialEcology

Ecologists studying microbial life in the environment have recognized the enormous complexity of microbial diversity for many years, and the development of a variety of culture-independent methods, many of them coupled with high-throughput DNA sequencing, has allowed this diversity to be explored in ever greater detail. Despite the widespread application of these new techniques to the characterization of uncultivated microbes and microbial communities in the environment, their application to human health and disease has lagged behind. Because DNA based-techniques for defining uncultured microbes allow not only cataloging of microbial diversity, but also insight into microbial functions, investigators are beginning to apply these tools to the microbial communities that abound on and within us, in what has aptly been called the second Human Genome Project. In this review we discuss the sequence-based methods for microbial analysis that are currently available and their application to identify novel human pathogens, improve diagnosis of known infectious diseases, and to advance understanding of our relationship with microbial communities that normally reside in and on the human body.
Date: August 29, 2005
Creator: Weng, Li; Rubin, Edward M. & Bristow, James
System: The UNT Digital Library
Current Status of Deep Geological Repository Development (open access)

Current Status of Deep Geological Repository Development

This talk provided an overview of the current status of deep-geological-repository development worldwide. Its principal observation is that a broad consensus exists internationally that deep-geological disposal is the only long-term solution for disposition of highly radioactive nuclear waste. Also, it is now clear that the institutional and political aspects are as important as the technical aspects in achieving overall progress. Different nations have taken different approaches to overall management of their highly radioactive wastes. Some have begun active programs to develop a deep repository for permanent disposal: the most active such programs are in the United States, Sweden, and Finland. Other countries (including France and Russia) are still deciding on whether to proceed quickly to develop such a repository, while still others (including the UK, China, Japan) have affirmatively decided to delay repository development for a long time, typically for a generation of two. In recent years, a major conclusion has been reached around the world that there is very high confidence that deep repositories can be built, operated, and closed safely and can meet whatever safety requirements are imposed by the regulatory agencies. This confidence, which has emerged in the last few years, is based on extensive work around …
Date: August 29, 2005
Creator: Budnitz, R. J.
System: The UNT Digital Library
Hadron Physics in BaBar (open access)

Hadron Physics in BaBar

Some recent results in hadron physics from the BaBar experiment are discussed. In particular, the observation of two new charmed states, the D*{sub sJ}{sup +}(2317) and the D*{sub sJ}{sup +}(2457), is described, and results are presented on the first measurement of the rare decay mode of the B meson, B{sup 0} {pi}{sup 0}{pi}{sup 0}.
Date: August 29, 2005
Creator: Lafferty, G.D.
System: The UNT Digital Library
The phylogeny of Mediterranean tortoises and their close relativesbased on complete mitochondrial genome sequences from museumspecimens (open access)

The phylogeny of Mediterranean tortoises and their close relativesbased on complete mitochondrial genome sequences from museumspecimens

As part of an ongoing project to generate a mitochondrial database for terrestrial tortoises based on museum specimens, the complete mitochondrial genome sequences of 10 species and a {approx}14 kb sequence from an eleventh species are reported. The sampling of the present study emphasizes Mediterranean tortoises (genus Testudo and their close relatives). Our new sequences are aligned, along with those of two testudinoid turtles from GenBank, Chrysemys picta and Mauremys reevesii, yielding an alignment of 14,858 positions, of which 3,238 are parsimony informative. We develop a phylogenetic taxonomy for Testudo and related species based on well-supported, diagnosable clades. Several well-supported nodes are recovered, including the monophyly of a restricted Testudo, T. kleinmanni + T. marginata (the Chersus clade), and the placement of the enigmatic African pancake tortoise (Malacochersustornieri) within the predominantly Palearctic greater Testudo group (Testudona tax. nov.). Despite the large amount of sequence reported, there is low statistical support for some nodes within Testudona and Sowe do not propose names for those groups. A preliminary and conservative estimation of divergence times implies a late Miocene diversification for the testudonan clade (6-12 million years ago), matching their first appearance in the fossil record. The multi-continental distribution of testudonan turtles can …
Date: April 29, 2005
Creator: Parham, James F.; Macey, J. Robert; Papenfuss, Theodore J.; Feldman, Chris R.; Turkozan, Oguz; Polymeni, Rosa et al.
System: The UNT Digital Library
Measurements of Eavesdropping in a Wavelength/Time Optical CDMA (O-CDMA) System, with Data Confidentiality Implications (open access)

Measurements of Eavesdropping in a Wavelength/Time Optical CDMA (O-CDMA) System, with Data Confidentiality Implications

We report measurements on what an eavesdropper ''sees'' when tapping into a wavelength/time O-CDMA system in which 16 of 32 codes are ''lit''. Severe multi-access interference (MAI) provides some data confidentiality.
Date: July 29, 2005
Creator: Mendez, A. J.; Hernandez, V. J.; Bennett, C. V.; Gagliardi, R. M. & Lennon, W. J.
System: The UNT Digital Library
K-(alpha) Radiography at 20-100 keV Using Short-Pulse Lasers (open access)

K-(alpha) Radiography at 20-100 keV Using Short-Pulse Lasers

X-ray radiography is an important tool for diagnosing and imaging planar and convergent hydrodynamics phenomena for laser experiments. Until now, hydrodynamics experiments at Omega and NIF utilize E{sub x-ray} < 9 keV backlighter x-rays emitted by thermal plasmas. However, future experiments will need to diagnose larger and denser targets and will require x-ray probes of energies from 20-100 keV and possibly up to 1 MeV. Hard K-{alpha} x-ray photons can be created through high-energy electron interactions in the target material after irradiation by petawatt-class high-intensity-short-pulse lasers with > 10{sup 17} W/cm{sup 2}. We have performed several experiments on the JanUSP, and the Vulcan 100TW, and Vulcan Petawatt lasers to understand K-{alpha} sources and to test radiography concepts. 1-D radiography using an edge-on foil and 2-D radiography using buried wires and cone-fiber targets were tested. We find that 1-D thin edge-on foils can have imaging resolution better than 10 {micro}m. Micro volume targets produce bright sources with measured conversion efficiency from laser energy to x-ray photons of {approx} 1 x 10{sup -5}. This level of conversion may not be enough for 2-D point projection radiography. A comparison of our experimental measurements of small volume sources with the LSP/PIC simulation show similar …
Date: August 29, 2005
Creator: Park, H. S.; Chambers, D.; Clarke, R.; Eagleton, R.; Giraldez, E.; Goldsack, T. et al.
System: The UNT Digital Library
Resolving the tips of the tree of life: How much mitochondrialdata doe we need? (open access)

Resolving the tips of the tree of life: How much mitochondrialdata doe we need?

Mitochondrial (mt) DNA sequences are used extensively to reconstruct evolutionary relationships among recently diverged animals,and have constituted the most widely used markers for species- and generic-level relationships for the last decade or more. However, most studies to date have employed relatively small portions of the mt-genome. In contrast, complete mt-genomes primarily have been used to investigate deep divergences, including several studies of the amount of mt sequence necessary to recover ancient relationships. We sequenced and analyzed 24 complete mt-genomes from a group of salamander species exhibiting divergences typical of those in many species-level studies. We present the first comprehensive investigation of the amount of mt sequence data necessary to consistently recover the mt-genome tree at this level, using parsimony and Bayesian methods. Both methods of phylogenetic analysis revealed extremely similar results. A surprising number of well supported, yet conflicting, relationships were found in trees based on fragments less than {approx}2000 nucleotides (nt), typical of the vast majority of the thousands of mt-based studies published to date. Large amounts of data (11,500+ nt) were necessary to consistently recover the whole mt-genome tree. Some relationships consistently were recovered with fragments of all sizes, but many nodes required the majority of the mt-genome …
Date: April 29, 2005
Creator: Bonett, Ronald M.; Macey, J. Robert; Boore, Jeffrey L. & Chippindale, Paul T.
System: The UNT Digital Library
Energy Technologies for the 21st Century-The Roles of Renewable Energy (open access)

Energy Technologies for the 21st Century-The Roles of Renewable Energy

Renewable energy sources, originating for the most part from the sun's radiant energy, are ubiquitous, long-lived, essentially free of carbon emissions, and have the potential to contribute significantly to mounting energy needs of the globe. In terms of percentage increase in installed capacity, renewable energy collectively is the fastest growing energy source. Even assuming that the developing world raises its standard of living considerably, the technical potential of renewable energies is more than enough to meet annual global needs several times over a century from now. Realizing even some of this potential involves overcoming obstacles in generation costs, proximity to markets, and in many cases intermittency, as well as others. From the perspective of work on a wide range of energy technologies by both the World Energy Council and the Intergovernmental Panel on Climate Change, the potential, timing, and investment costs for renewable energy technologies in the 21st century have become clearer. The marketplace, based on cost and performance, will determine which technologies are commercialized along with government policies that at a minimum do not hinder their introduction, and--at a maximum--may encourage more rapid and successful introduction. A wide range of possible scenarios (34) based on factors that include energy …
Date: July 29, 2005
Creator: Schock, R N
System: The UNT Digital Library
Yield Functions and Plastic Potentials for BCC Metals and Possibly Other Materials (open access)

Yield Functions and Plastic Potentials for BCC Metals and Possibly Other Materials

Yield functions and plastic potentials are expressed in terms of the invariants of the stress tensor for polycrystalline metals and other isotropic materials. The plastic volume change data of Richmond is used to evaluate the embedded materials properties for some bcc metals and one polymer. A general form for the plastic potential is found that is intended to represent and cover a wide range of materials types.
Date: September 29, 2005
Creator: Christensen, R M
System: The UNT Digital Library
Soft Radiative Strength in Warm Nuclei (open access)

Soft Radiative Strength in Warm Nuclei

We present data on the soft (E{sub {gamma}} < 3-4 MeV) radiative strength function (RSF) for electromagnetic transitions between warm states (i.e. states several MeV above the yrast line) from two different types of experiments. The Oslo method provides data on the total level density and the sum (over all multipolarities) of all RSFs by sequential extraction from primary-{gamma} spectra. Measurements of two-step-decay spectra following neutron capture yields two-step-cascade (TSC) intensities which are roughly proportional to the product of two RSFs. Investigations on {sup 172}Yb and {sup 57}Fe have produced unexpected results. In the first case, a strong (B(M1 {up_arrow}) = 6.5 {mu}{sub N}{sup 2}) resonance at E = 3.3 MeV was identified. In the second case, a large (more than a factor of 10) enhancement compared to theoretical estimates of the very soft (E{sub {gamma}} {le} 3 MeV), summed RSF for transitions between warm states was observed. A somewhat weaker (factor {approx} 3) enhancement of the RSF in Mo isotopes observed within the Oslo method still awaits confirmation from TSC experiments.
Date: September 29, 2005
Creator: Schiller, A.; Voinov, A.; Agvaanluvsan, U.; Algin, E.; Becker, J.; Belgya, T. et al.
System: The UNT Digital Library
Prediction of coherent optical radiation from shock waves in polarizable crystals (open access)

Prediction of coherent optical radiation from shock waves in polarizable crystals

We predict that coherent electromagnetic radiation in the 1-100 THz frequency range can be generated in crystalline materials when subject to a shock wave or soliton-like propagating excitation. To our knowledge, this phenomenon represents a fundamentally new form of coherent optical radiation source that is distinct from lasers and free-electron lasers. General analytical theory and molecular dynamics simulations demonstrate coherence lengths on the order of mm (around 20 THz) and potentially greater. The emission frequencies are determined by the shock speed and the lattice constants of the crystal and can potentially be used to determine atomic-scale properties of the shocked material.
Date: August 29, 2005
Creator: Reed, E J; Soljacic, M; Gee, R & Joannopoulos, J D
System: The UNT Digital Library
Quantitative Composition Analysis of Lipid Membranes by High-Resolution Secondary Ion Mass Spectrometry (open access)

Quantitative Composition Analysis of Lipid Membranes by High-Resolution Secondary Ion Mass Spectrometry

The lateral organization and interactions of lipid and protein components within biological membranes are essential for their functions. Investigations of the lateral organization within membranes hinge upon the ability to differentiate one component of interest from another. Typically, fluorophores are conjugated to specific components, and the organization is probed with fluorescence microscopy. However, bulky fluorophores may change the physical properties of the components they label, only the labeled components can be visualized, and the diffraction limit of light restricts the lateral resolution. Here we present a method to image microdomains within supported lipid membranes using isotopic labels and high-resolution secondary ion mass spectrometry (SIMS) performed with the NanoSIMS 50 (Cameca). Lateral resolution of 100 nm is achieved with high sensitivity. Quantitative information on the lipid composition within each domain was determined using calibration curves constructed from homogeneous lipid bilayer samples that systematically varied in the isotopically labeled lipid content.
Date: April 29, 2005
Creator: Kraft, M. L.; Weber, P. K.; Lin, W. C.; Blanchette, C. D.; Longo, M. L.; Hutcheon, I. D. et al.
System: The UNT Digital Library
Branching Fraction for B+ -> pi0 l+ nu, Measured in Upsilon (4S) -> BBbar Events Tagged by B- -> D0 l- nubar (X) Decays (open access)

Branching Fraction for B+ -> pi0 l+ nu, Measured in Upsilon (4S) -> BBbar Events Tagged by B- -> D0 l- nubar (X) Decays

We report a preliminary branching fraction of (1.80 {+-} 0.37{sub stat.} {+-} 0.23{sub syst.}) x 10{sup -4} for the charmless exclusive semileptonic B{sup +} {yields} {pi}{sup 0}{ell}{sup +}{nu} decay, where {ell} can be either a muon or an electron. This result is based on data corresponding to an integrated luminosity of 81 fb{sup -1} collected at the {Upsilon}(4S) resonance with the BABAR detector. The analysis uses B{bar B} events that are tagged by a B meson reconstructed in the semileptonic B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}(X) decays, where X can be either a {gamma} or a {pi}{sup 0} from a D* decay.
Date: June 29, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Analysis of Radially Resolved Spectra and Potential for Lasing in Mo Wire Array Z Pinches (open access)

Analysis of Radially Resolved Spectra and Potential for Lasing in Mo Wire Array Z Pinches

Measurements of radially resolved L-shell Mo spectra from wire array pinches on Sandia's Z generator are presented and analyzed using a collisional-radiative model. The spectra indicate large radial gradients in density over the {approx}8-mm-diameter plasma column, but only the emission from the {approx}2 mm central region of the pinch appears to be influenced by opacity. Population inversions and significant gain factors for 100-200 {angstrom} transitions in Ne-like Mo are predicted to exist at the diagnosed plasma conditions.
Date: April 29, 2005
Creator: Hansen, S B; Safronova, A S; Apruzese, J P; LePell, P D; Coverdale, C; Deeney, C et al.
System: The UNT Digital Library
Liquid Hydrogen Target Experience at SLAC (open access)

Liquid Hydrogen Target Experience at SLAC

Liquid hydrogen targets have played a vital role in the physics program at SLAC for the past 40 years. These targets have ranged from small ''beer can'' targets to the 1.5 m long E158 target that was capable of absorbing up to 800 W without any significant density changes. Successful use of these targets has required the development of thin wall designs, liquid hydrogen pumps, remote positioning and alignment systems, safety systems, control and data acquisition systems, cryogenic cooling circuits and heat exchangers. Detailed operating procedures have been created to ensure safety and operational reliability. This paper surveys the evolution of liquid hydrogen targets at SLAC and discusses advances in several of the enabling technologies that made these targets possible.
Date: August 29, 2005
Creator: Weisend, J. G.; Boyce, R.; Candia, A.; Kaminskas, W.; Mark, J.; Racine, M. et al.
System: The UNT Digital Library
Distributed Generation with Heat Recovery and Storage (open access)

Distributed Generation with Heat Recovery and Storage

Electricity generated by distributed energy resources (DER) located close to end-use loads has the potential to meet consumer requirements more efficiently than the existing centralized grid. Installation of DER allows consumers to circumvent the costs associated with transmission congestion and other non-energy costs of electricity delivery and potentially to take advantage of market opportunities to purchase energy when attractive. On-site thermal power generation is typically less efficient than central station generation, but by avoiding non-fuel costs of grid power and utilizing combined heat and power (CHP) applications, i.e., recovering heat from small-scale on-site generation to displace fuel purchases, then DER can become attractive to a strictly cost-minimizing consumer. In previous efforts, the decisions facing typical commercial consumers have been addressed using a mixed-integer linear programme, the DER Customer Adoption Model(DER-CAM). Given the site s energy loads, utility tariff structure, and information (both technical and financial) on candidate DER technologies, DER-CAM minimizes the overall energy cost for a test year by selecting the units to install and determining their hourly operating schedules. In this paper, the capabilities of DER-CAM are enhanced by the inclusion of the option to store recovered low-grade heat. By being able to keep an inventory of heat …
Date: July 29, 2005
Creator: Siddiqui, Afzal; Marnay, Chris; Firestone, Ryan M. & Zhou, Nan
System: The UNT Digital Library
Evidence of a barrier oxidation dependence on the interfacialmagnetism in co/alumina based magnetic tunnel junctions (open access)

Evidence of a barrier oxidation dependence on the interfacialmagnetism in co/alumina based magnetic tunnel junctions

Soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co L{sub 2,3} edge have been applied to explore the near-interfacial magnetism of Co electrodes in Co/alumina based magnetic tunnel junctions. By taking into account the formation of CoO at the FM/barrier interface, the change in the total magnetic moment on metallic Co atoms as a function of barrier oxidation has been determined. The results demonstrate a strong correlation between the Co moments and measured TMR values, and an enhancement in the Co moments for moderate oxidation times.
Date: September 29, 2005
Creator: Telling, N. D.; van der Laan, G.; Ladak, S.; Hicken, R. J. & Arenholz, E.
System: The UNT Digital Library
Hadronic B and D Studies at BaBar (open access)

Hadronic B and D Studies at BaBar

We present new results on hadronic B and D decays from the BABAR experiment. The first part of this document presents searches for new channels which may be used for CP measurements. The second part is dedicated to hadronic decays with tests of QCD factorization predictions and other models for B structure and decay mechanisms. A new result on the reference branching ratio D{sub s}{sup +} {yields} {phi}{pi}{sup +} is also reported.
Date: June 29, 2005
Creator: Couderc, F.
System: The UNT Digital Library
Cathodic Arcs: Fractal Voltage and Cohesive Energy Rule (open access)

Cathodic Arcs: Fractal Voltage and Cohesive Energy Rule

This report talks about Cathodic Arcs: Fractal Voltage and Cohesive Energy Rule
Date: January 29, 2005
Creator: Anders, Andre; Oks, Efim M. & Gera, Yu. Yushkov
System: The UNT Digital Library
Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers (open access)

Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers

This report was prepared to talk about Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers
Date: July 29, 2005
Creator: Cody, K Lai-Fook; Hambric, SA & Pollack, ML
System: The UNT Digital Library