Comparing Imaging and Non-Imaging Techniques for Reducing Background Clutter and Resolving Distant Point Sources (open access)

Comparing Imaging and Non-Imaging Techniques for Reducing Background Clutter and Resolving Distant Point Sources

To reach maximum sensitivity, any method used to search for orphan sources must be insensitive to local variations of the background. Using imaging and non-imaging techniques, we analyzed the same data acquired by a search instrument deployed as a large-area, coded-mask imager. Data from many passes past a 1 mCi source at 65 m from the instrument were used to construct a model of the instrument response. We then used the model to ''hide'' the source in data taken in a light urban environment. We compared the success of detecting the hidden sources using imaging coded-mask methods, pseudo-imaging based on a zero-area matched filter, and non-imaging using simple thresholding. The results clearly indicate the superiority of imaging with the coded-mask techniques returning the best results.
Date: November 10, 2005
Creator: Wurtz, Ron; Ziock, Klaus-Peter; Fabris, Lorenzo & Graham, Rion
System: The UNT Digital Library
Summary guide to the institutional problems confronting the geothermal energy industry (open access)

Summary guide to the institutional problems confronting the geothermal energy industry

None
Date: December 10, 1974
Creator: Finn, Donald F. X.
System: The UNT Digital Library
Time-Dependent Interfacial Properties and DNAPL Mobility (open access)

Time-Dependent Interfacial Properties and DNAPL Mobility

Interfacial properties play a major role in governing where and how dense nonaqueous phase liquids (DNAPLs) move in the subsurface. Interfacial tension and contact angle measurements were obtained for a simple, single component DNAPL (tetrachloroethene, PCE), complex laboratory DNAPLs (PCE plus Sudan IV dye), and a field DNAPL from the Savannah River Site (SRS) M-Area DNAPL (PCE, trichloroethene [TCE], and maching oils). Interfacial properties for complex DNAPLs were time-dependent, a phenomenon not observed for PCE alone. Drainage capillary pressure-saturation curves are strongly influenced by interfacial properties. Therefore time-dependence will alter the nature of DNAPL migration and penetration. Results indicate that the time-dependence of PCE with relatively high Sudan IV dye concentrations is comparable to that of the field DNAPL. Previous DNAPL mobility experiments in which the DNAPL was dyed should be reviewed to determine whether time-dependent properties influenced the resutls. Dyes appear to make DNAPL more complex, and therefore a more realistic analog for field DNAPLs than single component DNAPLs.
Date: March 10, 1999
Creator: Tuck, David M.
System: The UNT Digital Library
Application of Bi-2212 in Prototype Wind-and-React Accelerator Magnets (open access)

Application of Bi-2212 in Prototype Wind-and-React Accelerator Magnets

This report talks about Application of Bi-2212 in Prototype Wind-and-React Accelerator Magnets
Date: November 10, 2007
Creator: Godeke, A.; Cheng, D.; Dietderich, D.R.; Felice, H.; Hannaford,C.R.; Prestemon, S.O. et al.
System: The UNT Digital Library
Activity of the kinesin spindle protein inhibitor ispinesib (SB-715992) in models of breast cancer (open access)

Activity of the kinesin spindle protein inhibitor ispinesib (SB-715992) in models of breast cancer

Ispinesib (SB-715992) is a potent inhibitor of kinesin spindle protein (KSP), a kinesin motor protein essential for the formation of a bipolar mitotic spindle and cell cycle progression through mitosis. Clinical studies of ispinesib have demonstrated a 9% response rate in patients with locally advanced or metastatic breast cancer, and a favorable safety profile without significant neurotoxicities, gastrointestinal toxicities or hair loss. To better understand the potential of ispinesib in the treatment of breast cancer we explored the activity of ispinesib alone and in combination several therapies approved for the treatment of breast cancer. We measured the ispinesib sensitivity and pharmacodynamic response of breast cancer cell lines representative of various subtypes in vitro and as xenografts in vivo, and tested the ability of ispinesib to enhance the anti-tumor activity of approved therapies. In vitro, ispinesib displayed broad anti-proliferative activity against a panel of 53 breast cell-lines. In vivo, ispinesib produced regressions in each of five breast cancer models, and tumor free survivors in three of these models. The effects of ispinesib treatment on pharmacodynamic markers of mitosis and apoptosis were examined in vitro and in vivo, revealing a greater increase in both mitotic and apoptotic markers in the MDA-MB-468 model …
Date: June 10, 2009
Creator: Purcell, James W; Davis, Jefferson; Reddy, Mamatha; Martin, Shamra; Samayoa, Kimberly; Vo, Hung et al.
System: The UNT Digital Library
Challenges of 4th Generation Light Sources (open access)

Challenges of 4th Generation Light Sources

This report talks about Challenges of 4th Generation Light Sources
Date: December 10, 2012
Creator: Pellegrini, C.
System: The UNT Digital Library
Coalescence of Nanometer Silver Islands on Oxides Grown by Filtered Cathodic Arc Depostion (open access)

Coalescence of Nanometer Silver Islands on Oxides Grown by Filtered Cathodic Arc Depostion

This report talks about Coalescence of Nanometer Silver Islands on Oxides Grown by Filtered Cathodic Arc Depostion
Date: March 10, 2003
Creator: Byon, Eungsun; Oates, Thomas W.H. & Anders, Andre
System: The UNT Digital Library
Remotely detected high-field MRI of porous samples (open access)

Remotely detected high-field MRI of porous samples

None
Date: December 10, 2003
Creator: Seeley, Juliette A.; Han, Song-I & Pines, Alexander
System: The UNT Digital Library
Science and technology for industrial ecology (open access)

Science and technology for industrial ecology

This paper first discusses the challenge offered by natural and anthropogenic systems in all of their complexity and then indicates some areas of research in which specific scientific and technological needs are identifiable.
Date: July 10, 1996
Creator: Gilmartin, T. J. & Allenby, B.R.
System: The UNT Digital Library
Science and technology for industrial ecology (open access)

Science and technology for industrial ecology

Scientific and technological communities have a significant role to play and responsibility for the evolution of global sustainability (continuously improving quality of life into the indefinite future). Sustainability is not possible without a substantially improved science and technology basis for industrial ecology. Society needs data and understanding of complex ecological issues to govern itself in a sustainable manner. We should: support and develop multi-disciplinary programs which create the scientific basis for understanding natural and anthropogenic complex systems and for developing environmentally and economically efficient technology; demonstrate a systems-based approach to science and technology issues which is life-cycle comprehensive, integrates environmental considerations, and promotes conservation of natural resources; and encourage development of responsible, technically and scientifically valid, cost-effective environmental laws and practices.
Date: July 10, 1996
Creator: Gilmartin, T. J. & Allenby, B.R.
System: The UNT Digital Library
The RHIC and RHIC Pre-Injectors Controls Systems: Status and Plans (open access)

The RHIC and RHIC Pre-Injectors Controls Systems: Status and Plans

For the past twelve years experiments at the Relativistic Heavy Ion Collider (RHIC) have recorded data from collisions of heavy ions and polarized protons, leading to important discoveries in nuclear physics and the spin dynamics of quarks and gluons. BNL is the site of one of the first and still operating alternating gradient synchrotrons, the AGS, which first operated in 1960. The accelerator controls systems for these instruments span multiple generations of technologies. In this report we will describe the current status of the Collider-Accelerator Department controls systems, which are used to control seven different accelerator facilities and multiple science programs (high energy nuclear physics, high energy polarized proton physics, NASA programs, isotope production, and multiple accelerator research and development projects). We will describe the status of current projects, such as the just completed Electron Beam Ion Source (EBIS), our R&D programs in superconducting RF and an Energy Recovery LINAC (ERL), innovations in feedback systems and bunched beam stochastic cooling at RHIC, and plans for future controls system developments.
Date: October 10, 2011
Creator: Brown, K. A.; Altinbas, Z.; Aronson, J.; Binello, S.; Campbell, I.; Costanzo, M. et al.
System: The UNT Digital Library
The Proposed Yucca Mountain Repository From a Corrosive Perspective (open access)

The Proposed Yucca Mountain Repository From a Corrosive Perspective

The proposed Yucca Mountain Repository presents a familiar materials performance application that is regularly encountered in energy, transportation and other industries. The widely accepted approach to dealing with materials performance is to identify the performance requirements, to determine the operating conditions to which materials will be exposed and to select materials of construction that perform well in those conditions. A special feature of the proposed Repository is the extremely long time frame of interest, i.e. 10,000's of years and longer. Thus, the time evolution of the environment in contact with waste package surfaces and the time evolution of corrosion damage that may result are of primary interest in the determination of expected performance. Researchers at Case are part of a Department of Energy Corrosion and Materials Performance Cooperative. This team of leading scientists/engineers from major universities and national laboratories is working together to further enhance the understanding of the role of engineered barriers in waste isolation. The team is organized to address important topics: (1) Long-term behavior of protective, passive films; (2) Composition and properties of moisture in contact with metal surfaces; and (3) Rate of penetration and extent of corrosion damage over extremely long times. The work will also …
Date: February 10, 2006
Creator: Payer, Joe H.; Agarwal, Arun S.; Landau, Uziel; Liu, C. C.; Pharkya, Pallavi; Shan, Xi et al.
System: The UNT Digital Library
Effects of ArF Excimer Irradiation on Multi-Energy Ge and Se Ion Implanted Silica (open access)

Effects of ArF Excimer Irradiation on Multi-Energy Ge and Se Ion Implanted Silica

None
Date: January 10, 2001
Creator: Magruder, R. H., III
System: The UNT Digital Library
Rapid Method for Ra-226 and Ra-228 in Water Samples (open access)

Rapid Method for Ra-226 and Ra-228 in Water Samples

The measurement of radium isotopes in natural waters is important for oceanographic studies and for public health reasons. Ra-226 (1620 year half-life) is one of the most toxic of the long-lived alpha emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The analysis of radium-226 and radium-228 in natural waters can be tedious and time-consuming. Different sample preparation methods are often required to prepare Ra-226 and Ra-228 for separate analyses. A rapid method has been developed at the Savannah River Environmental Laboratory that effectively separates both Ra-226 and Ra-228 (via Ac-228) for assay. This method uses MnO{sub 2} Resin from Eichrom Technologies (Darien, IL, USA) to preconcentrate Ra-226 and Ra-228 rapidly from water samples, along with Ba-133 tracer. DGA Resin{reg_sign} (Eichrom) and Ln-Resin{reg_sign} (Eichrom) are employed in tandem to prepare Ra-226 for assay by alpha spectrometry and to determine Ra-228 via the measurement of Ac-228 by gas proportional counting. After preconcentration, the manganese dioxide is dissolved from the resin and passed through stacked Ln-Resin-DGA Resin cartridges that remove uranium and thorium interferences and retain Ac-228 on DGA Resin. The eluate that passed through this …
Date: February 10, 2006
Creator: Maxwell, Sherrod, L., III
System: The UNT Digital Library
Solar Radiation and Induction of DNA Damage, Mutations and Skin Cancers. (open access)

Solar Radiation and Induction of DNA Damage, Mutations and Skin Cancers.

An understanding of the effects of sunlight on human skin begins with the effects on DNA and extends to cells, animals and humans. The major DNA photoproducts arising from UVB (280-320 nm) exposures are cyclobutane pyrimidine dimers. If unrepaired, they may kill or mutate cells and result in basal and squamous cell carcinomas. Although UVA (320-400 nm) and visible wavelengths are poorly absorbed by DNA, the existing data indicate clearly that exposures to these wavelengths are responsible, in an animal model, for {approx}95 % of the incidence of cutaneous malignant melanoma (CMM). Six lines of evidence, to be discussed in detail, support the photosensitizing role of melanin in the induction of this cancer. They are: (1) Melanomas induced in backcross hybrids of small tropical fish of the genus Xiphophorus, exposed to wavelengths from 302-547 nm, indicate that {approx}95% of the cancers induced by exposure to sunlight would arise from UVA + visible wavelengths; (2) The action spectrum for inducing melanin-photosensitized oxidant production is very similar to the spectrum for inducing melanoma; (3) Albino whites and blacks, although very sensitive to sunburn and the sunlight induction of non-CMM, have very low incidences of CMM; (4) The incidence of CMM as a …
Date: May 10, 2007
Creator: Setlow, Richard. B.
System: The UNT Digital Library
Statistical Hot Spot Model for Explosive Detonation (open access)

Statistical Hot Spot Model for Explosive Detonation

The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a nonlocal equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.
Date: May 10, 2004
Creator: Nichols, A. L., III
System: The UNT Digital Library
Age-related changes in the plasticity and toughness of human cortical bone at multiple length-scales (open access)

Age-related changes in the plasticity and toughness of human cortical bone at multiple length-scales

The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone’s toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these …
Date: August 10, 2011
Creator: Zimmermann, Elizabeth A.; Schaible, Eric; Bale, Hrishikesh; Barth, Holly D.; Tang, Simon Y.; Reichert, Peter et al.
System: The UNT Digital Library
On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone (open access)

On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the …
Date: January 10, 2010
Creator: Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager, Joel W., III & Ritchie, Robert O.
System: The UNT Digital Library
How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks (open access)

How Tough is Human Cortical Bone? In-Situ Measurements on Realistically Short Cracks

Bone is more difficult to break than to split. Although this is well known, and many studies exist on the behavior of long cracks in bone, there is a need for data on the orientation-dependent crack-growth resistance behavior of human cortical bone which accurately assesses its toughness at appropriate size-scales. Here we use in-situ mechanical testing in the scanning electron microscope and x-ray computed tomography to examine how physiologically-pertinent short (<600 mu m) cracks propagate in both the transverse and longitudinal orientations in cortical bone, using both crack-deflection/twist mechanics and nonlinear-elastic fracture mechanics to determine crack-resistance curves. We find that after only 500 mu m of cracking, the driving force for crack propagation was more than five times higher in the transverse (breaking) direction than in the longitudinal (splitting) direction due to major crack deflections/twists principally at cement sheathes. Indeed, our results show that the true transverse toughness of cortical bone is far higher than previously reported. However, the toughness in the longitudinal orientation, where cracks tend to follow the cement lines, is quite low at these small crack sizes; it is only when cracks become several millimeters in length that bridging mechanisms can develop leading to the (larger-crack) toughnesses …
Date: May 10, 2008
Creator: Ritchie, Robert O.; Koester, K. J.; Ager, J. W., III & Ritchie, R. O.
System: The UNT Digital Library
Focused ion beam damage to MOS integrated circuits (open access)

Focused ion beam damage to MOS integrated circuits

Commercial focused ion beam (FIB) systems are commonly used to image integrated circuits (ICS) after device processing, especially in failure analysis applications. FIB systems are also often employed to repair faults in metal lines for otherwise functioning ICS, and are being evaluated for applications in film deposition and nanofabrication. A problem that is often seen in FIB imaging and repair is that ICS can be damaged during the exposure process. This can result in degraded response or out-right circuit failure. Because FIB processes typically require the surface of an IC to be exposed to an intense beam of 30--50 keV Ga{sup +} ions, both charging and secondary radiation damage are potential concerns. In previous studies, both types of effects have been suggested as possible causes of device degradation, depending on the type of device examined and/or the bias conditions. Understanding the causes of this damage is important for ICS that are imaged or repaired by a FIB between manufacture and operation, since the performance and reliability of a given IC is otherwise at risk in subsequent system application. In this summary, the authors discuss the relative roles of radiation damage and charging effects during FIB imaging. Data from exposures of …
Date: May 10, 2000
Creator: Fleetwood, D. M.; Campbell, Ann N.; Hembree, Charles E.; Tangyunyong, Paiboon; Jessing, Jeffrey R. & Soden, Jerry M.
System: The UNT Digital Library
Plutonium analysis in spiked bovine tissues: an interlaboratory study (open access)

Plutonium analysis in spiked bovine tissues: an interlaboratory study

One of the more useful tools to assure the reliability of results from analytical procedures is the interlaboratory comparison method. The present exercise was undertaken primarily to obtain a measure of the reliability of analyses performed by several laboratories on autopsy samples in support of the United States Transuranium Registry (USTR). The results of these and other leading laboratories which routinely conduct similar analyses will be presented and compared. Three types of bovine tissue were prepared for distribution at three levels of plutonium concentration near the detection level normally encountered in autopsy samples.
Date: August 10, 1977
Creator: Thomas, V. W., Jr.
System: The UNT Digital Library