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Climate implications of carbonaceous aerosols:  An aerosol microphysical study using the GISS/MATRIX climate model (open access)

Climate implications of carbonaceous aerosols: An aerosol microphysical study using the GISS/MATRIX climate model

Recently, attention has been drawn towards black carbon aerosols as a likely short-term climate warming mitigation candidate. However the global and regional impacts of the direct, cloud-indirect and semi-direct forcing effects are highly uncertain, due to the complex nature of aerosol evolution and its climate interactions. Black carbon is directly released as particle into the atmosphere, but then interacts with other gases and particles through condensation and coagulation processes leading to further aerosol growth, aging and internal mixing. A detailed aerosol microphysical scheme, MATRIX, embedded within the global GISS modelE includes the above processes that determine the lifecycle and climate impact of aerosols. This study presents a quantitative assessment of the impact of microphysical processes involving black carbon, such as emission size distributions and optical properties on aerosol cloud activation and radiative forcing. Our best estimate for net direct and indirect aerosol radiative forcing change is -0.56 W/m{sup 2} between 1750 and 2000. However, the direct and indirect aerosol effects are very sensitive to the black and organic carbon size distribution and consequential mixing state. The net radiative forcing change can vary between -0.32 to -0.75 W/m{sup 2} depending on these carbonaceous particle properties. Assuming that sulfates, nitrates and secondary …
Date: April 9, 2010
Creator: Bauer, Susanne E.; Menon, Surabi; Koch, Dorothy; Bond, Tami & Tsigaridis, Kostas
System: The UNT Digital Library
CMMAD Usability Case Study in Support of Countermine and Hazard Sensing (open access)

CMMAD Usability Case Study in Support of Countermine and Hazard Sensing

During field trials, operator usability data were collected in support of lane clearing missions and hazard sensing for two robot platforms with Robot Intelligence Kernel (RIK) software and sensor scanning payloads onboard. The tests featured autonomous and shared robot autonomy levels where tasking of the robot used a graphical interface featuring mine location and sensor readings. The goal of this work was to provide insights that could be used to further technology development. The efficacy of countermine systems in terms of mobility, search, path planning, detection, and localization were assessed. Findings from objective and subjective operator interaction measures are reviewed along with commentary from soldiers having taken part in the study who strongly endorse the system.
Date: April 1, 2010
Creator: Walker, Victor G. & Gertman, David I.
System: The UNT Digital Library
Coarse Spaces by Algebraic Multigrid: Multigrid Convergence and Upscaled Error Estimates (open access)

Coarse Spaces by Algebraic Multigrid: Multigrid Convergence and Upscaled Error Estimates

We give an overview of a number of algebraic multigrid methods targeting finite element discretization problems. The focus is on the properties of the constructed hierarchy of coarse spaces that guarantee (two-grid) convergence. In particular, a necessary condition known as 'weak approximation property', and a sufficient one, referred to as 'strong approximation property' are discussed. Their role in proving convergence of the TG method (as iterative method) and also on the approximation properties of the AMG coarse spaces if used as discretization tool is pointed out. Some preliminary numerical results illustrating the latter aspect are also reported.
Date: April 30, 2010
Creator: Vassilevski, P S
System: The UNT Digital Library
Cognitive biases resulting from the representativeness heuristic in operations management: an experimental investigation (open access)

Cognitive biases resulting from the representativeness heuristic in operations management: an experimental investigation

This article investigates the six cognitive biases resulting from the use of the representativeness heuristic, namely, insensitivity to prior probability of outcomes, insensitivity to sample size, misconception of chance, insensitivity to predictability, the illusion of validity, and misconception of regression. Specifically, the authors examine how cognitive reflection and training affect these six cognitive biases in the operations management context.
Date: April 10, 2019
Creator: AlKhars, Mohammed; Evangelopoulos, Nicholas; Pavur, Robert J. & Kulkarni, Shailesh S.
System: The UNT Digital Library
Coherent electron cooling proof of principle instrumentation design (open access)

Coherent electron cooling proof of principle instrumentation design

The goal of the Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment being designed at RHIC is to demonstrate longitudinal (energy spread) cooling before the expected CD-2 for eRHIC. The scope of the experiment is to longitudinally cool a single bunch of 40 GeV/u gold ions in RHIC. This paper will describe the instrumentation systems proposed to meet the diagnostics challenges. These include measurements of beam intensity, emittance, energy spread, bunch length, position, orbit stability, and transverse and temporal alignment of electron and ion beams.
Date: April 15, 2012
Creator: M., Gassner D.; Litvinenko, V.; Michnoff, R.; Miller, T.; Minty, M. & Pinayev, I.
System: The UNT Digital Library
Collaboratives for Wildlife-Wind Turbine Interaction Research: Fostering Multistakeholder Involvement (Poster) (open access)

Collaboratives for Wildlife-Wind Turbine Interaction Research: Fostering Multistakeholder Involvement (Poster)

This poster highlights the various wildlife-wind collaboratives (specific to wildlife-wind turbine interaction research) that currently exist. Examples of collaboratives are included along with contact information, objectives, benefits, and ways to advance the knowledge base.
Date: April 1, 2013
Creator: Sinclair, K.
System: The UNT Digital Library
Collapsing Bubble in Metal for High Energy Density Physics Study (open access)

Collapsing Bubble in Metal for High Energy Density Physics Study

This paper presents a new idea to produce matter in the high energy density physics (HEDP) regime in the laboratory using an intense ion beam. A gas bubble created inside a solid metal may collapse by driving it with an intense ion beam. The melted metal will compress the gas bubble and supply extra energy to it. Simulations show that the spherical implosion ratio can be about 5 and at the stagnation point, the maximum density, temperature and pressure inside the gas bubble can go up to nearly 2 times solid density, 10 eV and a few megabar (Mbar) respectively. The proposed experiment is the first to permit access into the Mbar regime with existing or near-term ion facilities, and opens up possibilities for new physics gained through careful comparisons of simulations with measurements of quantities like stagnation radius, peak temperature and peak pressure at the metal wall.
Date: April 13, 2011
Creator: Ng, S. F.; Barnard, J. J.; Leung, P. T. & Yu, S. S.
System: The UNT Digital Library
Collusion and Cynicism at the Urban Margins (open access)

Collusion and Cynicism at the Urban Margins

This article examines the connections between participants in the illicit drug trade and members of state security forces to understand how they impact everyday understandings of the law. The authors used ethnographic fieldwork in a poor, high-crime district in Argentina and information gathered for a court case involving a drug trafficking group active in the same area as the basis for their research.
Date: April 10, 2019
Creator: Sobering, Katherine & Auyero, Javier
System: The UNT Digital Library
Combination of CDF and D0 Measurements of the $W$ Boson Helicity in Top Quark Decays (open access)

Combination of CDF and D0 Measurements of the $W$ Boson Helicity in Top Quark Decays

This report talks about Combination of CDF and D0 Measurements of the $W$ Boson Helicity in Top Quark Decays
Date: April 20, 2012
Creator: Aaltonen, T
System: The UNT Digital Library
Combined Fit to BaBar and Belle Data on E E- to Phi Pi+ Pi- and Phi F0(980) (open access)

Combined Fit to BaBar and Belle Data on E E- to Phi Pi+ Pi- and Phi F0(980)

A combined fit is performed to the BaBar and Belle measurements of the e{sup +}e{sup -} {yields} {phi}{pi}{sup +}{pi}{sup -} and {phi}f{sub 0}(980) cross sections for center-of-mass energy between threshold and 3.0 GeV. The resonance parameters of the {phi}(1680) and Y(2175) are determined. The mass is (1681{sub -12}{sup +10}) MeV/c{sup 2} and the width is (221{sub -24}{sup +34}) MeV/c{sup 2} for the {phi}(1680), and the mass is (2117{sub -49}{sup +59}) MeV/c{sup 2} and the width is (164{sub -80}{sup +69}) MeV/c{sup 2} for the Y(2175). These information will shed light on the understanding of the nature of the excited {phi} and Y states observed in e{sup +}e{sup -} annihilation.
Date: April 3, 2012
Creator: Shen, C. P. & Yuan, C. Z.
System: The UNT Digital Library
Comment on"Sensitivity of the active fracture model parameter to fracture network orientation and injection scenarios" by Basagaoglu et al. (2009) (open access)

Comment on"Sensitivity of the active fracture model parameter to fracture network orientation and injection scenarios" by Basagaoglu et al. (2009)

Basagaoglu et al. (2009) present a study on detailed unsaturated flow behavior in two-dimensional fracture networks using numerical experiments (simulations) based on the lattice-Boltzmann method. Their results are valuable for improving our understanding of unsaturated flow processes and evaluating the active fracture model (AFM) that was developed for capturing large-scale preferential flow in fractured rocks (Liu et al., 1998; 2003). As indicated in Basagaoglu et al. (2009), a previous study was conducted to evaluate the AFM with numerical experiments (Seol et al., 2003). However, the methodology used in that study and the corresponding conclusions are highly questioned for the following two reasons. First, the evaluation relies on a condition that simulated water flow processes in a fracture network are adequately represented with a continuum approach, because they draw their conclusions by comparing simulation results with those obtained from a dual-continuum model based on the AFM. No effort was made by Seol et al. (2003) to justify the validity of the continuum approach for their specific fracture network that includes a small number of fractures only. (The analyses of Basagaoglu et al. (2009) do not need the similar condition.) Second, Seol et al. (2003) use numerical dispersion to represent the matrix …
Date: April 1, 2010
Creator: Liu, H.H.
System: The UNT Digital Library

Comments Regarding "Density, Speed of Sound, Refractive Index and Derivatives Properties of the Binary Mixture N-Hexane + N-Heptane (or N-Octane or N-Nonane), T = 288.15 - 313.15 K"

This article offers comment on "Density, speed of sound, refractive index and derivatives properties of the binary mixture N-Hexane + N-Heptane (or N-Octane or N-Nonane), T=288.15 - 313.15 K."
Date: April 9, 2013
Creator: Acree, William E. (William Eugene) & Stephens, Timothy W.
System: The UNT Digital Library
The compact Selaginella genome identifies changes in gene content associated with the evolution of vascular plants (open access)

The compact Selaginella genome identifies changes in gene content associated with the evolution of vascular plants

We report the genome sequence of the nonseed vascular plant, Selaginella moellendorffii, and by comparative genomics identify genes that likely played important roles in the early evolution of vascular plants and their subsequent evolution
Date: April 28, 2011
Creator: Grigoriev, Igor V.; Banks, Jo Ann; Nishiyama, Tomoaki; Hasebe, Mitsuyasu; Bowman, John L.; Gribskov, Michael et al.
System: The UNT Digital Library
Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88 (open access)

Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compels additional exploration. We therefore undertook whole genome sequencing of the acidogenic A. niger wild type strain (ATCC 1015), and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was utilized to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 megabase of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome …
Date: April 28, 2011
Creator: Grigoriev, Igor V.; Baker, Scott E.; Andersen, Mikael R.; Salazar, Margarita P.; Schaap, Peter J.; Vondervoot, Peter J.I. van de et al.
System: The UNT Digital Library
A Comparative Study of High-Performance Computing on the Cloud (open access)

A Comparative Study of High-Performance Computing on the Cloud

None
Date: April 9, 2013
Creator: Marathe, A.; Harris, R.; Lowenthal, D.; de Supinski, B.; Rountree, B.; Schulz, M. et al.
System: The UNT Digital Library
Comparison of independent D14CO2 records at Point Barrow, Alaska (open access)

Comparison of independent D14CO2 records at Point Barrow, Alaska

None
Date: April 8, 2013
Creator: Graven, H. D.; Xu, X.; Guilderson, T. P.; Keeling, R. F.; Trumbore, S. E. & Tyler, S.
System: The UNT Digital Library
Composition-dependent apparent activation-energy and sluggish grain-growth in high entropy alloys (open access)

Composition-dependent apparent activation-energy and sluggish grain-growth in high entropy alloys

Article discusses experimental results which reveal that the apparent activation-energy for grain-growth in an fcc-based AlxCoCrFeNi high entropy alloy (HEA) system increases from 179 to 486 kJ/mol when the Al content increases from x = 0.1 to 0.3.
Date: April 10, 2019
Creator: Gwalani, Bharat; Salloom, Riyadh; Alam, Talukder; Valentin, S.G.; Zhou, X.; Thompson, G. et al.
System: The UNT Digital Library
Compositional threshold for Nuclear Waste Glass Durability (open access)

Compositional threshold for Nuclear Waste Glass Durability

Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.
Date: April 24, 2013
Creator: Kruger, Albert A.; Farooqi, Rahmatullah & Hrma, Pavel R.
System: The UNT Digital Library
Conceptual Design of a High Precision Dual Directional Beam Position Monitoring System for Beam Crosstalk Cancellation and Improved Output Pulse Shapes (open access)

Conceptual Design of a High Precision Dual Directional Beam Position Monitoring System for Beam Crosstalk Cancellation and Improved Output Pulse Shapes

The Relativistic Heavy Ions Collider (RHIC) would benefit from improved beam position measurements near the interaction points that see both beams, especially as the tolerances become tighter when reducing the beam sizes to obtain increased luminosity. Two limitations of the present beam position monitors (BPMs) would be mitigated if the proposed approach is successful. The small but unavoidable cross-talk between signals from bunches traveling in opposite directions when using conventional BPMs will be reduced by adopting directional BPMs. Further improvements will be achieved by cancelling residual cross-talk using pairs of such BPMs. Appropriately delayed addition and integration of the signals will also provide pulses with relatively flat maxima that will be easier to digitize by relaxing the presently very stringent timing requirements.
Date: April 15, 2012
Creator: Thieberger, P.; Dawson, C.; Fischer, W.; Gassner, D.; Hulsart, R.; Mernick, K. et al.
System: The UNT Digital Library
Constitutive relationships for elastic deformation of clay rock: Data Analysis (open access)

Constitutive relationships for elastic deformation of clay rock: Data Analysis

Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate …
Date: April 15, 2011
Creator: Liu, H. H.; Rutqvist, J. & Birkholzer, J. T.
System: The UNT Digital Library
Constraints on the flux of Ultra-High Energy neutrinos from WSRT observations (open access)

Constraints on the flux of Ultra-High Energy neutrinos from WSRT observations

Context. Ultra-high energy (UHE) neutrinos and cosmic rays initiate particle cascades underneath theMoon?s surface. These cascades have a negative charge excess and radiate Cherenkov radio emission in a process known as the Askaryan effect. The optimal frequencywindow for observation of these pulses with radio telescopes on the Earth is around 150 MHz. Aims. By observing the Moon with the Westerbork Synthesis Radio Telescope array we are able to set a new limit on the UHEneutrino flux. Methods. The PuMa II backend is used to monitor the Moon in 4 frequency bands between 113 and 175 MHz with a samplingfrequency of 40 MHz. The narrowband radio interference is digitally filtered out and the dispersive effect of the Earth?s ionosphere is compensated for. A trigger system is implemented to search for short pulses. By inserting simulated pulses in the raw data, thedetection efficiency for pulses of various strength is calculated. Results. With 47.6 hours of observation time, we are able to set a limit onthe UHE neutrino flux. This new limit is an order of magnitude lower than existing limits. In the near future, the digital radio array LOFAR will be used to achieve an even lower limit.
Date: April 2, 2010
Creator: Scholten, O.; Bacelar, J.; Braun, R.; de Bruyn, A.G.; Falcke, H.; Singh, K. et al.
System: The UNT Digital Library
Contribution of active atrial contraction to cardiac output in anesthetized American alligators (Alligator mississippiensis) (open access)

Contribution of active atrial contraction to cardiac output in anesthetized American alligators (Alligator mississippiensis)

Article describes study which investigated the importance of atrial contraction in filling of the ventricle in American alligators (Alligator mississippiensis) by bypassing both atria (with the use of ligatures to prevent atrial filling) and measuring the resultant effects on cardiac output in anesthetized animals.
Date: April 30, 2018
Creator: Williams, Joyce E.; Crossley, Janna; Elsey, Ruth M.; Wang, Tobias & Crossley, Dane A., II
System: The UNT Digital Library
Cooperative Effects in the Annelation of Benzene by Multiple Etheno Groups (open access)

Cooperative Effects in the Annelation of Benzene by Multiple Etheno Groups

Article on cooperative effects in the annelation of benzene by multiple etheno groups.
Date: April 20, 2011
Creator: Bao, Xiaoguang; Hrovat, David A. & Borden, Weston T.
System: The UNT Digital Library
Core-Collapse Supernovae and Host Galaxy Stellar Populations (open access)

Core-Collapse Supernovae and Host Galaxy Stellar Populations

We have used images and spectra of the Sloan Digital Sky Survey to examine the host galaxies of 519 nearby supernovae. The colors at the sites of the explosions, as well as chemical abundances, and specific star formation rates of the host galaxies provide circumstantial evidence on the origin of each supernova type. We examine separately SN II, SN IIn, SN IIb, SN Ib, SN Ic, and SN Ic with broad lines (SN Ic-BL). For host galaxies that have multiple spectroscopic fibers, we select the fiber with host radial offset most similar to that of the SN. Type Ic SN explode at small host offsets, and their hosts have exceptionally strongly star-forming, metal-rich, and dusty stellar populations near their centers. The SN Ic-BL and SN IIb explode in exceptionally blue locations, and, in our sample, we find that the host spectra for SN Ic-BL show lower average oxygen abundances than those for SN Ic. SN IIb host fiber spectra are also more metal-poor than those for SN Ib, although a significant difference exists for only one of two strong-line diagnostics. SN Ic-BL host galaxy emission lines show strong central specific star formation rates. In contrast, we find no strong evidence …
Date: April 5, 2013
Creator: Kelly, Patrick L.; /KIPAC, Menlo Park /SLAC; Kirshner, Robert P. & Astrophys., /Harvard-Smithsonian Ctr.
System: The UNT Digital Library