Classification of Multiple Types of Organic Carbon Composition in Atmospheric Particles by Scanning Transmission X-Ray Microscopy Analysis (open access)

Classification of Multiple Types of Organic Carbon Composition in Atmospheric Particles by Scanning Transmission X-Ray Microscopy Analysis

A scanning transmission X-ray microscope at the Lawrence Berkeley National Laboratory is used to measure organic functional group abundance and morphology of atmospheric aerosols. We present a summary of spectra, sizes, and shapes observed in 595 particles that were collected and analyzed between 2000 and 2006. These particles ranged between 0.1 and 12 mm and represent aerosols found in a large range of geographical areas, altitudes, and times. They include samples from seven different field campaigns: PELTI, ACE-ASIA, DYCOMS II, Princeton, MILAGRO (urban), MILAGRO (C-130), and INTEX-B. At least 14 different classes of organic particles show different types of spectroscopic signatures. Different particle types are found within the same region while the same particle types are also found in different geographical domains. Particles chemically resembling black carbon, humic-like aerosols, pine ultisol, and secondary or processed aerosol have been identified from functional group abundance and comparison of spectra with those published in the literature.
Date: May 16, 2007
Creator: Kilcoyne, Arthur L; Takahama, S.; Gilardoni, S.; Russell, L.M. & Kilcoyne, A.L.D.
Object Type: Article
System: The UNT Digital Library
Fabry-Perot / PDV Comparison (open access)

Fabry-Perot / PDV Comparison

Measures the fast pulses seen with exploding bridge flyers by PDV
Date: May 2, 2007
Creator: Hodgin, Ralph; May, Chadd; Hanks, Roy; Hansen, Don; Whitworth, Tony & Strand, Ted
Object Type: Article
System: The UNT Digital Library
New advances in three-dimensional controlled-sourceelectromagnetic inversion (open access)

New advances in three-dimensional controlled-sourceelectromagnetic inversion

New techniques for improving both the computational andimaging performance of the three dimensional (3D) electromagnetic inverseproblem are presented. A non-linear conjugate gradient algorithm is theframework of the inversion scheme. Full wave equation modelling forcontrolled sources is utilized for data simulation along with anefficient gradient computation approach for the model update. Improvingthe modelling efficiency of the 3D finite difference method involves theseparation of the potentially large modelling mesh, defining the set ofmodel parameters, from the computational finite difference meshes usedfor field simulation. Grid spacings and thus overall grid sizes can bereduced and optimized according to source frequencies and source-receiveroffsets of a given input data set. Further computational efficiency isobtained by combining different levels of parallelization. While theparallel scheme allows for an arbitrarily large number of parallel tasks,the relative amount of message passing is kept constant. Imageenhancement is achieved by model parameter transformation functions,which enforce bounded conductivity parameters and thus prevent parameterovershoots. Further, a remedy for treating distorted data within theinversion process is presented. Data distortions simulated here includepositioning errors and a highly conductive overburden, hiding the desiredtarget signal. The methods are demonstrated using both synthetic andfield data.
Date: May 19, 2007
Creator: Commer, Michael & Newman, Gregory A.
Object Type: Article
System: The UNT Digital Library
Diversity of Decline-Rate-Corrected Type 1a Supernova Rise times:One Mode or Two? (open access)

Diversity of Decline-Rate-Corrected Type 1a Supernova Rise times:One Mode or Two?

B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernova (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 {+-} 0.36 days, while five SNe rise in 16.64 {+-} 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96{sub -0.25}{sup +0.52} days--a first measurement of this dispersion. The corresponding global mean rise time is 17.44 {+-} 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is {approx}2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic …
Date: May 1, 2007
Creator: Strovink, Mark
Object Type: Article
System: The UNT Digital Library
Genome sequencing reveals complex secondary metabolome in themarine actinomycete Salinispora tropica (open access)

Genome sequencing reveals complex secondary metabolome in themarine actinomycete Salinispora tropica

Recent fermentation studies have identified actinomycetes ofthe marine-dwelling genus Salinispora as prolific natural productproducers. To further evaluate their biosynthetic potential, we analyzedall identifiable secondary natural product gene clusters from therecently sequenced 5,184,724 bp S. tropica CNB-440 circular genome. Ouranalysis shows that biosynthetic potential meets or exceeds that shown byprevious Streptomyces genome sequences as well as other naturalproduct-producing actinomycetes. The S. tropica genome features ninepolyketide synthase systems of every known formally classified family,non-ribosomal peptide synthetases and several hybrid clusters. While afew clusters appear to encode molecules previously identified inStreptomyces species,the majority of the 15 biosynthetic loci are novel.Specific chemical information about putative and observed natural productmolecules is presented and discussed. In addition, our bioinformaticanalysis was critical for the structure elucidation of the novelpolyenemacrolactam salinilactam A. This study demonstrates the potentialfor genomic analysis to complement and strengthen traditional naturalproduct isolation studies and firmly establishes the genus Salinispora asa rich source of novel drug-like molecules.
Date: May 1, 2007
Creator: Udwary, Daniel W.; Zeigler, Lisa; Asolkar, Ratnakar; Singan,Vasanth; Lapidus, Alla; Fenical, William et al.
Object Type: Article
System: The UNT Digital Library
2003 Nevada Test Site Annual Illness and Injury Surveillance Report (open access)

2003 Nevada Test Site Annual Illness and Injury Surveillance Report

Annual Illness and Injury Surveillance Program report for 2003 for the Nevada Test Site. The U.S. Department of Energy’s (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. The Illness and Injury Surveillance Program monitors illnesses and health conditions that result in an absence of workdays, occupational injuries and illnesses, and disabilities and deaths among current workers.
Date: May 23, 2007
Creator: United States. Department of Energy. Office of Illness and Injury Prevention Programs.
Object Type: Report
System: The UNT Digital Library
The Search for Muon Neutrinos from Northern HemisphereGamma-Ray Bursts with AMANDA (open access)

The Search for Muon Neutrinos from Northern HemisphereGamma-Ray Bursts with AMANDA

We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the Northern Hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of any other existing detector. Based on our observations of zero neutrinos during and immediately prior to the GRBs in the dataset, we set the most stringent upper limit on muon neutrino emission correlated with gamma-ray bursts. Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has a normalization at 1 PeV of E{sup 2}{Phi}{sub {nu}} {le} 6.0 x 10{sup -9} GeV cm{sup -2}s{sup -1}sr{sup -1}, with 90% of the events expected within the energy range of {approx}10 TeV to {approx}3 PeV. The impact of this limit on several theoretical models of GRBs is discussed, as well as the future potential for detection of GRBs by next generation neutrino telescopes. Finally, we briefly describe several modifications to this analysis in order to apply it to other types of transient point sources.
Date: May 8, 2007
Creator: Collaboration, IceCube; Klein, Spencer & Achterberg, A.
Object Type: Article
System: The UNT Digital Library
ESTIMATING THE STRENGTH OF SINGLE-ENDED DISLOCATION SOURCES IN MICROMETER-SIZED SINGLE CRYSTALS (open access)

ESTIMATING THE STRENGTH OF SINGLE-ENDED DISLOCATION SOURCES IN MICROMETER-SIZED SINGLE CRYSTALS

A recent study indicated that the behavior of single-ended dislocation sources contributes to the flow strength of micrometer-scale crystals. In this study 3D discrete dislocation dynamics simulations of micrometer-sized volumes are used to calculate the effects of anisotropy of dislocation line tension (increasing Poisson's ratio, {nu}) on the strength of single-ended dislocation sources and, to compare them with the strength of double-ended sources of equal length. This is done by directly modeling their plastic response within a 1 micron cubed FCC Ni single crystal using DDS. In general, double-ended sources are stronger than single-ended sources of an equal length and exhibit no significant effects from truncating the long-range elastic fields at this scale. The double-ended source strength increases with Poisson ratio ({nu}), exhibiting an increase of about 50% at u = 0.38 (value for Ni) as compared to the value at {nu} = 0. Independent of dislocation line direction, for {nu} greater than 0.20, the strengths of single-ended sources depend upon the sense of the stress applied. The value for {alpha}, in the expression for strength, {tau} = {alpha}(L){micro}b/L is shown to vary from 0.4 to 0.84 depending upon the character of the dislocation and the direction of operation of …
Date: May 3, 2007
Creator: Rao, S I; Dimiduk, D M; Tang, M; Parthasarathy, T A; Uchic, M D & Woodward, C
Object Type: Article
System: The UNT Digital Library
Mineral dissolution kinetics at the pore scale (open access)

Mineral dissolution kinetics at the pore scale

Mineral dissolution rates in the field have been reported to be orders of magnitude slower than those measured in the laboratory, an unresolved discrepancy that severely limits our ability to develop scientifically defensible predictive or even interpretive models for many geochemical processes in the earth and environmental sciences. One suggestion links this discrepancy to the role of physical and chemical heterogeneities typically found in subsurface soils and aquifers in producing scale-dependent rates where concentration gradients develop. In this paper, we examine the possibility that scale-dependent mineral dissolution rates can develop even at the single pore and fracture scale, the smallest and most fundamental building block of porous media. To do so, we develop two models to analyze mineral dissolution kinetics at the single pore scale: (1) a Poiseuille Flow model that applies laboratory-measured dissolution kinetics at the pore or fracture wall and couples this to a rigorous treatment of both advective and diffusive transport, and (2) a Well-Mixed Reactor model that assumes complete mixing within the pore, while maintaining the same reactive surface area, average flow rate, and geometry as the Poiseuille Flow model. For a fracture, a 1D Plug Flow Reactor model is considered in addition to quantify the …
Date: May 24, 2007
Creator: Li, L.; Steefel, C.I. & Yang, L.
Object Type: Article
System: The UNT Digital Library
Optimization of accelerator parameters using normal form methods on high-order transfer maps (open access)

Optimization of accelerator parameters using normal form methods on high-order transfer maps

Methods of analysis of the dynamics of ensembles of charged particles in collider rings are developed. The following problems are posed and solved using normal form transformations and other methods of perturbative nonlinear dynamics: (1) Optimization of the Tevatron dynamics: (a) Skew quadrupole correction of the dynamics of particles in the Tevatron in the presence of the systematic skew quadrupole errors in dipoles; (b) Calculation of the nonlinear tune shift with amplitude based on the results of measurements and the linear lattice information; (2) Optimization of the Muon Collider storage ring: (a) Computation and optimization of the dynamic aperture of the Muon Collider 50 x 50 GeV storage ring using higher order correctors; (b) 750 x 750 GeV Muon Collider storage ring lattice design matching the Tevatron footprint. The normal form coordinates have a very important advantage over the particle optical coordinates: if the transformation can be carried out successfully (general restrictions for that are not much stronger than the typical restrictions imposed on the behavior of the particles in the accelerator) then the motion in the new coordinates has a very clean representation allowing to extract more information about the dynamics of particles, and they are very convenient for …
Date: May 1, 2007
Creator: Snopok, Pavel
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Valuing the Environmental Benefits of Urban WaterConservation (open access)

Valuing the Environmental Benefits of Urban WaterConservation

This report documents a project undertaken for theCalifornia Urban Water Conservation Council (the Council) to create a newmethod of accounting for the diverse environmental benefits of raw watersavings. The environmental benefits (EB) model was designed to providewater utilities with a practical tool that they can use to assign amonetary value to the benefits that may accrue from implementing any ofthe Council-recommended Best Management Practices. The model treats onlyenvironmental services associated directly with water, and is intended tocover miscellaneous impacts that are not currently accounted for in anyother cost-benefit analysis.
Date: May 1, 2007
Creator: Coughlin, Katie M.; Bolduc, Chris A.; Chan, Peter T.; Dunham-Whitehead, C. & Van Buskirk, R.D.
Object Type: Report
System: The UNT Digital Library
RH-TRU Waste Content Codes (RH TRUCON) (open access)

RH-TRU Waste Content Codes (RH TRUCON)

The Remote-Handled Transuranic (RH-TRU) Content Codes (RH-TRUCON) document describes the inventory of RH-TRU waste within the transportation parameters specified by the Remote-Handled Transuranic Waste Authorized Methods for Payload Control (RH-TRAMPAC).1 The RH-TRAMPAC defines the allowable payload for the RH-TRU 72-B. This document is a catalog of RH-TRU 72-B authorized contents by site. A content code is defined by the following components: • A two-letter site abbreviation that designates the physical location of the generated/stored waste (e.g., ID for Idaho National Laboratory [INL]). The site-specific letter designations for each of the sites are provided in Table 1. • A three-digit code that designates the physical and chemical form of the waste (e.g., content code 317 denotes TRU Metal Waste). For RH-TRU waste to be transported in the RH-TRU 72-B, the first number of this three-digit code is “3.” The second and third numbers of the three-digit code describe the physical and chemical form of the waste. Table 2 provides a brief description of each generic code. Content codes are further defined as subcodes by an alpha trailer after the three-digit code to allow segregation of wastes that differ in one or more parameter(s). For example, the alpha trailers of the subcodes …
Date: May 1, 2007
Creator: Solutions, Washington TRU
Object Type: Report
System: The UNT Digital Library
Verification of Gyrokinetic (delta)f Simulations of Electron Temperature Gradient Turbulence (open access)

Verification of Gyrokinetic (delta)f Simulations of Electron Temperature Gradient Turbulence

The GEM gyrokinetic {delta}f simulation code [Chen, 2003] [Chen, 2007] is shown to reproduce electron temperature gradient turbulence at the benchmark operating point established in previous work [Nevins, 2006]. The electron thermal transport is within 10% of the expected value, while the turbulent fluctuation spectrum is shown to have the expected intensity and two-point correlation function.
Date: May 7, 2007
Creator: Nevins, W. M.; Parker, S. E.; Chen, Y.; Candy, J.; Dimits, A.; Dorland, W. et al.
Object Type: Article
System: The UNT Digital Library
Development of Waste Acceptance Criteria at 221-U Building: Initial Flow and Transport Scoping Calculations (open access)

Development of Waste Acceptance Criteria at 221-U Building: Initial Flow and Transport Scoping Calculations

This report documents numerical flow and transport simulations performed that establish initial waste acceptance criteria for the potential waste streams that may be safely sequestered in the 221-U Building and similar canyon structures. Specifically, simulations were executed to identify the maximum loading of contaminant mass (without respect to volume) that can be emplaced within the 221-U Building with no more than 1 pCi/m2 of contaminant migrating outside the structure within a 1,000 year time period. The initial scoping simulations were executed in one dimension to assess important processes, and then two dimensions to establish waste acceptance criteria. Two monolithic conditions were assessed: (1) a grouted canyon monolith; and (2) a canyon monolith filled with sand, both assuming no cracks or fissures were present to cause preferential transport. A three-staged approach was taken to account for different processes that may impact the amount of contaminant that can be safely sequestered in canyon structure. In the first stage, flow and transport simulations established waste acceptance criteria based on a linear (Kd) isotherm approach. In the second stage, impacts on thermal loading were examined and the differences in waste acceptance criteria quantified. In the third stage of modeling, precipitation/dissolution reactions were considered on …
Date: May 30, 2007
Creator: Freedman, Vicky L.; Zhang, Z. F.; Keller, Jason M. & Chen, Yousu
Object Type: Report
System: The UNT Digital Library
Quarkonium shadowing in pPb and Pb+Pb collisions (open access)

Quarkonium shadowing in pPb and Pb+Pb collisions

The d+Au data from RHIC, including the pA results from the fixed-target CERN SPS pA data, suggest increased importance of initial-state shadowing and decreasing nuclear absorption with increasing energy. This is not surprising since smaller x is probed at higher energy while absorption due to multiple scattering is predicted to decrease with energy. The CERN SPS data suggest a J/{psi} absorption cross section of about 4 mb without shadowing, and a larger absorption cross section if it is included since the SPS x range is in the antishadowing region. The d+Au RHIC data support smaller absorption, {sigma}{sup J/{psi}}{sub abs} {approx} 0-2 mb. Thus our predictions for J/{psi} and {Upsilon} production in pPb and Pb+Pb interactions at the LHC are shown for initial-state shadowing alone with no absorption or dense matter effects. We note that including absorption would only move the calculated ratios down in proportion to the absorption survival probability since, at LHC energies, any rapidity dependence of absorption is at very large |y|, outside the detector acceptance.
Date: May 21, 2007
Creator: Vogt, R
Object Type: Article
System: The UNT Digital Library
APPLICATION OF POLYURETHANE FOAM FOR IMPACT ABSORPTION AND THERMAL INSULATION FOR RADIOACTIVE MATERIALS PACKAGINGS. (open access)

APPLICATION OF POLYURETHANE FOAM FOR IMPACT ABSORPTION AND THERMAL INSULATION FOR RADIOACTIVE MATERIALS PACKAGINGS.

Polyurethane foam has been widely used as an impact absorbing and thermal insulating material for large radioactive materials packages, since the 1980's. With the adoption of the regulatory crush test requirement, for smaller packages, polyurethane foam has been adopted as a replacement for cane fiberboard, because of its ability to withstand the crush test. Polyurethane foam is an engineered material whose composition is much more closely controlled than that of cane fiberboard. In addition, the properties of the foam can be controlled by controlling the density of the foam. The conditions under which the foam is formed, whether confined or unconfined have an affect on foam properties. The study reported here reviewed the application of polyurethane foam in RAM packagings and compared property values reported in the literature with published property values and test results for foam specimens taken from a prototype 9977 packaging. The study confirmed that, polyurethane foam behaves in a predictable and consistent manner and fully satisfies the functional requirements for impact absorption and thermal insulation.
Date: May 15, 2007
Creator: Smith, A; Glenn Abramczyk, G; Paul Blanton, P; Steve Bellamy, S; William Daugherty, W & Sharon Williamson, S
Object Type: Article
System: The UNT Digital Library
Multilayer Phase-Only Diffraction Gratings: Fabrication andApplication to EUV Optics (open access)

Multilayer Phase-Only Diffraction Gratings: Fabrication andApplication to EUV Optics

The use of phase-only diffractive devices has long played an important role in advanced optical systems in varying fields. Such devices include gratings, diffractive and holographic optical elements, diffractive lenses, and phase-shift masks for advanced lithography. Extending such devices to the increasingly important regime of extreme ultraviolet (EUV) wavelengths, however, is not trivial. Here, we present an effective fabrication and etch process enabling high-resolution patterning of Mo/Si multilayers for use in EUV phase devices, providing another method for fabrication of high numerical aperture diffractive devices or high-resolution EUV phase shift masks.
Date: May 1, 2007
Creator: Salmassi, Farhad; Gullikson, Eric M.; Anderson, Erik H. & Naulleau, Patrick P.
Object Type: Article
System: The UNT Digital Library
Feasibility Study for Operable Unit 7-13/14 (open access)

Feasibility Study for Operable Unit 7-13/14

None
Date: May 1, 2007
Creator: Preussner, K. J. Holdren T. E. Bechtold B. D.
Object Type: Report
System: The UNT Digital Library
Chiral perturbation theory with tensor sources (open access)

Chiral perturbation theory with tensor sources

We construct the most general chirally-invariant Lagrangian for mesons in the presence of external sources coupled to the tensor current \bar psi sigma_mu nu psi. In order to have only even terms in the chiral expansion, we consider the new source of O(p2). With this choice, we build the even-parity effective Lagrangian up to the p6-order (NLO). While there are only 4 new terms at the p4-order, at p6-order we find 78 terms for n_f=2 and 113 terms for n_f=3. We provide a detailed discussion on the different mechanisms that ensure that our final set of operators is complete and non-redundant. We also examine the odd-parity sector, to conclude that the first operators appear at the p8-order (NNLO).
Date: May 21, 2007
Creator: Cata, Oscar; Cata, Oscar & Mateu, Vicent
Object Type: Article
System: The UNT Digital Library
Qualification of Automated Low-Field NMR Relaxometry for Quality Control of Polymers in a Production Setting (open access)

Qualification of Automated Low-Field NMR Relaxometry for Quality Control of Polymers in a Production Setting

Implementation of a low field time-domain NMR scanner as a diagnostic tool in the production of new polymer components is described in the context of qualification of a new QA/QC device. A study to determine the optimal experimental parameters was performed and a robotic autosampler was built to enable scanning of multiple pads. Relationships between T{sub 2} values and physical properties of DC745 slabs were investigated, and the appropriate sampling parameters for the production setting were determined. Two versions of a robotic autosampler were built, and for the component described here a fourth radial axis was required in addition to traditional X, Y, and Z movement to eliminate the large variability in T{sub 2} due to inconsistent sample coverage caused by complex rib geometry of the component. Data show that with appropriate choice of experimental conditions of the NMR detector and the detection geometry of the robotic autosampler, sufficient resolution of variations in crosslink density on the millimeter scale could be determined. All data to date demonstrates that low-field NMR devices are a feasible tool for use in production settings for non-destructive quality control of polymer components.
Date: May 11, 2007
Creator: Chinn, S; Cook-Tendulkar, A; Maxwell, R; Wheeler, H; Wilson, M & Xie, Z
Object Type: Article
System: The UNT Digital Library
Future Air Conditioning Energy Consumption in Developing Countriesand what can be done about it: The Potential of Efficiency in theResidential Sector (open access)

Future Air Conditioning Energy Consumption in Developing Countriesand what can be done about it: The Potential of Efficiency in theResidential Sector

The dynamics of air conditioning are of particular interestto energy analysts, both because of the high energy consumption of thisproduct, but also its disproportionate impact on peak load. This paperaddresses the special role of this end use as a driver of residentialelectricity consumption in rapidly developing economies. Recent historyhas shown that air conditioner ownership can grow grows more rapidly thaneconomic growth in warm-climate countries. In 1990, less than a percentof urban Chinese households owned an air conditioner; by 2003 this numberrose to 62 percent. The evidence suggests a similar explosion of airconditioner use in many other countries is not far behind. Room airconditioner purchases in India are currently growing at 20 percent peryear, with about half of these purchases attributed to the residentialsector. This paper draws on two distinct methodological elements toassess future residential air conditioner 'business as usual' electricityconsumption by country/region and to consider specific alternative 'highefficiency' scenarios. The first component is an econometric ownershipand use model based on household income, climate and demographicparameters. The second combines ownership forecasts and stock accountingwith geographically specific efficiency scenarios within a uniqueanalysis framework (BUENAS) developed by LBNL. The efficiency scenariomodule considers current efficiency baselines, available technologies,and achievable timelines for development of market …
Date: May 1, 2007
Creator: McNeil, Michael A. & Letschert, Virginie E.
Object Type: Article
System: The UNT Digital Library
Fusion Simulation Project. Workshop Sponsored by the U.S. Department of Energy, Rockville, MD, May 16-18, 2007 (open access)

Fusion Simulation Project. Workshop Sponsored by the U.S. Department of Energy, Rockville, MD, May 16-18, 2007

The mission of the Fusion Simulation Project is to develop a predictive capability for the integrated modeling of magnetically confined plasmas. This FSP report adds to the previous activities that defined an approach to integrated modeling in magnetic fusion. These previous activities included a Fusion Energy Sciences Advisory Committee panel that was charged to study integrated simulation in 2002. The report of that panel [Journal of Fusion Energy 20, 135 (2001)] recommended the prompt initiation of a Fusion Simulation Project. In 2003, the Office of Fusion Energy Sciences formed a steering committee that developed a project vision, roadmap, and governance concepts [Journal of Fusion Energy 23, 1 (2004)]. The current FSP planning effort involved forty-six physicists, applied mathematicians and computer scientists, from twenty-one institutions, formed into four panels and a coordinating committee. These panels were constituted to consider: Status of Physics Components, Required Computational and Applied Mathematics Tools, Integration and Management of Code Components, and Project Structure and Management. The ideas, reported here, are the products of these panels, working together over several months and culminating in a three-day workshop in May 2007.
Date: May 18, 2007
Creator: Kritz, A. & Keyes, D.
Object Type: Report
System: The UNT Digital Library
Error Estimates Derived from the Data for Least-Squares Spline Fitting (open access)

Error Estimates Derived from the Data for Least-Squares Spline Fitting

None
Date: May 1, 2007
Creator: Blair, Jerome
Object Type: Article
System: The UNT Digital Library
How to Find More Supernovae with Less Work: Object ClassificationTechniques for Difference Imaging (open access)

How to Find More Supernovae with Less Work: Object ClassificationTechniques for Difference Imaging

We present the results of applying new object classificationtechniques to difference images in the context of the Nearby SupernovaFactory supernova search. Most current supernova searches subtractreference images from new images, identify objects in these differenceimages, and apply simple threshold cuts on parameters such as statisticalsignificance, shape, and motionto reject objects such as cosmic rays,asteroids, and subtraction artifacts. Although most static objectssubtract cleanly, even a very low false positive detection rate can leadto hundreds of non-supernova candidates which must be vetted by humaninspection before triggering additional followup. In comparison to simplethreshold cuts, more sophisticated methods such as Boosted DecisionTrees, Random Forests, and Support Vector Machines provide dramaticallybetter object discrimination. At the Nearby Supernova Factory, we reducedthe number of non-supernova candidates by a factor of 10 while increasingour supernova identification efficiency. Methods such as these will becrucial for maintaining a reasonable false positive rate in the automatedtransient alert pipelines of upcoming projects such as PanSTARRS andLSST.
Date: May 2, 2007
Creator: Bailey, Stephen; Aragon, Cecilia; Romano, Raquel; Thomas, RollinC.; Weaver, Benjamin A. & Wong, Daniel
Object Type: Article
System: The UNT Digital Library