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2010

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Full-Text Articles in Physical Sciences and Mathematics

Elasticity Of Krull Domains With Infinite Divisor Class Group, Benjamin Ryan Lynch Aug 2010

Elasticity Of Krull Domains With Infinite Divisor Class Group, Benjamin Ryan Lynch

Doctoral Dissertations

The elasticity of a Krull domain R is equivalent to the elasticity of the block monoid B(G,S), where G is the divisor class group of R and S is the set of elements of G containing a height-one prime ideal of R. Therefore the elasticity of R can by studied using the divisor class group. In this dissertation, we will study infinite divisor class groups to determine the elasticity of the associated Krull domain. The results will focus on the divisor class groups Z, Z(p infinity), Q, and general infinite groups. For the groups Z and Z(p infinity), it has …


Effects Of Interactions Among Two Prescribed Fires, Cover Type, And Canopy Cover On Oak And Red Maple Regeneration In Northern Lower Michigan, William W. Debord Aug 2010

Effects Of Interactions Among Two Prescribed Fires, Cover Type, And Canopy Cover On Oak And Red Maple Regeneration In Northern Lower Michigan, William W. Debord

Masters Theses

Regenerating oak (Quercus spp.) is a problem on most intermediate to high-quality sites throughout the eastern US. Oak is often present in the overstory and abundant in the understory, but is absent from the midstory due to increased competition from less-valuable mesic species such as Liriodendron tulipifera and Acer rubrum. Red maple has expanded its range dramatically since fire suppression began in the 1930s, and is an important competitor of oak. To study relationships between oak and silvicultural treatments, an experiment was initiated in 1990 that included three northern red oak (Quercus rubra)-dominated stands and three red pine (Pinus resinosa) …


A Morphological And Geochemical Investigation Of Grypania Spiralis: Implications For Early Earth Evolution, Miles Anthony Henderson Aug 2010

A Morphological And Geochemical Investigation Of Grypania Spiralis: Implications For Early Earth Evolution, Miles Anthony Henderson

Masters Theses

Macroscopic “carbonaceous” fossils such as Grypania, Katnia, Chuaria, and Tawuia play a critical role in our understanding of biological evolution in the Precambrian and their environmental implications. Unfortunately, understanding of these fossils remains limited by their relative simplicity of form, mode of preservation, and broad taphonomic variability. As a result, debate continues as to even the fundamental taxonomic affinity of the organisms. Megascopic coiled forms (i.e. Grypania and Katnia), for instance, have been interpreted as trace fossils, multicellular algae, prokaryotic filaments, macroscopic bacteria, cyanobacteria, or a transitional form from macroscopic to megascopic bacterial life. Similarly, Chuaria …


Elastic And Magnetic Properties Of Tb6fe(Sb,Bi)2 Using Resonant Ultrasound Spectroscopy., David Michael Mccarthy Aug 2010

Elastic And Magnetic Properties Of Tb6fe(Sb,Bi)2 Using Resonant Ultrasound Spectroscopy., David Michael Mccarthy

Masters Theses

Tb6FeSb2 and Tb6FeBi2 are novel rare earth compounds with little prior research. These compounds show high and variable curie temperatures for rare-earth compounds. This has lead to a literature review which includes the discussion of: elasticity, resonance, and magnetism. This review is used to discuss the theory and methodology which can relate these various properties to each other. Furthermore, synthesis, x-ray analysis, and RUS sample preparation of Tb6FeSb2 and Tb6FeBi2 were completed.

Resonant Ultrasound Spectroscopy (RUS) elastic studies were taken for Tb6FeSb2 and Tb6FeBi2 as a function temperature from 5-300K, in various magnetic fields ranging from 0-9T. Tb6FeSb2’s and Tb6FeBi2’s …


The Effects Of Changes In Water Content On Uranium(Vi) Leaching In Sediment Mixtures Containing Gravel, Andrew Weber Moore Aug 2010

The Effects Of Changes In Water Content On Uranium(Vi) Leaching In Sediment Mixtures Containing Gravel, Andrew Weber Moore

Masters Theses

This study is aimed at understanding the physical and chemical effects that changes in water content have on uranium leaching in sediment containing gravel. It was hypothesized that leaching will be more efficient under unsaturated conditions because flow will be restricted to the smallest pores and will have the most contact with the uranium contaminated sediment. Under saturated conditions, a large portion of the flow will bypass the < 2 mm material, and in turn not come into contact with uranium contaminated material. Batch adsorption and desorption experiments were performed on < 2 mm ERDF sediment to determine the linearity and reversibility of sorption processes and to aid in the interpretation of the leaching experiments. Results of the desorption experiments on aged, contaminated sediments show that the mass percent of sorbed U(VI) released to solution decreased as the sorbed concentration of U(VI) decreased. The opposite trend was observed on freshly contaminated sediments. This indicated that aging increased U(VI) affinity for the solid phase and was attributed to either the crystallization of calcite, which incorporated a portion of the sorbed U(VI) as it crystallized, or the presence of voids in basaltic lithic fragments accessed by diffusion. Column leaching experiments were performed at two water contents on artificially contaminated sediment collected from the Department of Energy’s (DOE) Hanford Site, Washington state. The sediment contained 81.3% gravel (> 2 mm) by mass. Non-reactive tracers were well fit with the convection-dispersion equation (CDE) at both high and low water contents indicating physical equilibrium. The column experimental data were fitted to an …


Propagation Of Periodic Waves Using Wave Confinement, Paula Cysneiros Sanematsu Aug 2010

Propagation Of Periodic Waves Using Wave Confinement, Paula Cysneiros Sanematsu

Masters Theses

This thesis studies the behavior of the Eulerian scheme, with "Wave Confinement" (WC), when propagating periodic waves. WC is a recently developed method that was derived from the scheme "vorticity confinement" used in fluid mechanics, and it efficiently solves the linear wave equation. This new method is applicable for numerous simulations such as radio wave propagation, target detection, cell phone and satellite communications.

The WC scheme adds a nonlinear term to the discrete wave equation that adds stability with negative and positive diffusion, conserves integral quantities such as total amplitude and wave speed, and it allows wave propagation over long …


Consumer Willingness To Pay For E85, Denise A. Skahan Aug 2010

Consumer Willingness To Pay For E85, Denise A. Skahan

Masters Theses

Concerns regarding energy security, resource sustainability, and environmental protection have heightened interests in renewable fuels and sparked the research and development of ethanol as a transportation fuel. This study examines consumers’ willingness to pay for ethanol from various potential feedstocks; corn, switchgrass and wood wastes. Data was collected via a survey of fuel consumers across the United States in 2009. Results show that consumers have a preference for E85 (a fuel blend with 85 percent ethanol and 15 percent gasoline) from corn, switchgrass and wood wastes compared to E0 (gasoline) and a preference for E85 from switchgrass and wood wastes, …


Nonlinear Acoustics Of Piston-Driven Gas-Column Oscillations, Andrew William Wilson Aug 2010

Nonlinear Acoustics Of Piston-Driven Gas-Column Oscillations, Andrew William Wilson

Masters Theses

The piston-driven oscillator is traditionally modeled by directly applying boundary conditions to the acoustic wave equations; with better models re-deriving the wave equations but retaining nonlinear and viscous effects. These better models are required as the acoustic solution exhibits singularity near the natural frequencies of the cavity, with an unbounded (and therefore unphysical) solution. Recently, a technique has been developed to model general pressure oscillations in propulsion systems and combustion devices. Here, it is shown that this technique applies equally well to the piston-driven gas-column oscillator; and that the piston experiment provides strong evidence for the validity of the general …


A Vegetation History From Emerald Pond, Great Abaco Island, The Bahamas, Based On Pollen Analysis, Ian Arthur Slayton Aug 2010

A Vegetation History From Emerald Pond, Great Abaco Island, The Bahamas, Based On Pollen Analysis, Ian Arthur Slayton

Masters Theses

Emerald Pond (26° 32' 12" N, 77° 06' 32" W) is a vertical-walled solution hole in the pine rocklands of Great Abaco Island, The Bahamas. In 2006, Sally Horn, Ken Orvis, and students recovered an 8.7 m-long sediment core from the center of the pond using a Colinvaux-Vohnout locking piston corer. AMS radiocarbon dates on macrofossils are in stratigraphic order and indicate that the sequence extends to ca. 8400 cal yr BP. Basal deposits consist of aeolian sands topped by a soil and then pond sediment, suggesting that the site began as a sheltered, dry hole during a Late Pleistocene …


Merging Schemas In A Collaborative Faceted Classification System, Jianxiang Li Aug 2010

Merging Schemas In A Collaborative Faceted Classification System, Jianxiang Li

Computer Science Theses & Dissertations

We have developed a system that improves access to a large, growing image collection by allowing users to collaboratively build a global faceted (multi-perspective) classification schema. We are extending our system to support both global and local schemas, where global schema provides a complete and uniform view of the collection whereas local schema provides a personal, possibly incomplete and idiosyncratic view of the collection. We argue that although users usually focus on their personal schemas, it is still desirable to have a global schema for the entire collection even if such local schemas are available. In order to keep the …


Internal Transitions In Nuclei And Applications To Astrophysics And Cosmochemistry, Joseph Johnson Aug 2010

Internal Transitions In Nuclei And Applications To Astrophysics And Cosmochemistry, Joseph Johnson

All Dissertations

In this dissertation I analyze internal transitions in nuclei and their potential effects on s-process branching and on accelerated β-decay in cosmochemical samples. To accomplish my analysis, I have constructed a number of computational tools, which I have publicly released or make available through this thesis. I apply my analysis to the question of s-process branching at 186Re and study the implications for the osmium isotopes in mainstream presolar SiC grains. My essential conclusion is that the problem of the large neutron flux inferred from the SiC osmium isotopic abundances cannot be solved by branching through an out-of-equilibrium isomer of …


A Computational Framework To Support The Automated Analysis Of Routine Electroencephalographic Data, William Pressly, Jr. Aug 2010

A Computational Framework To Support The Automated Analysis Of Routine Electroencephalographic Data, William Pressly, Jr.

All Dissertations

Epilepsy is a condition in which a patient has multiple unprovoked seizures which are not precipitated by another medical condition. It is a common neurological disorder that afflicts 1% of the population of the US, and is sometimes hard to diagnose if seizures are infrequent. Routine Electroencephalography (rEEG), where the electrical potentials of the brain are recorded on the scalp of a patient, is one of the main tools for diagnosing because rEEG can reveal indicators of epilepsy when patients are in a non-seizure state. Interpretation of rEEG is difficult and studies have shown that 20-30% of patients at specialized …


Simulation Of Contaminant Transport From Solid Domestic Waste Disposal Sites In The Warri Deltaic Plain Sands, Warri-Effurun, Nigeria, Charles Onoriode Usiaphre Aug 2010

Simulation Of Contaminant Transport From Solid Domestic Waste Disposal Sites In The Warri Deltaic Plain Sands, Warri-Effurun, Nigeria, Charles Onoriode Usiaphre

Theses, Dissertations and Culminating Projects

Protecting the groundwater resource in the Warri Deltaic Plain sand from the impact of anthropogenic contamination requires an understanding and knowledge of groundwater flow paths, transport processes and the source of contamination. This study was carried out to find out contaminant transport from solid domestic waste sites to the groundwater. The U.S. Geological Survey three-dimensional finite-difference code, MODFLOW, was used to simulate the groundwater flow. The flow pattern reveals predominantly downward flow, with major horizontal motion towards towns around Ekurede Urhobo and Ekurede Itsekiri in Warri. Simulation of advective contaminant transport using MODPATE1 for particle tracking indicates local movement of …


Algal Biomass Accrual In Relation To Nutrient Availability Along A Longitudinal Gradient In The Upper Green River, Kentucky, Mary Douglas Penick Aug 2010

Algal Biomass Accrual In Relation To Nutrient Availability Along A Longitudinal Gradient In The Upper Green River, Kentucky, Mary Douglas Penick

Masters Theses & Specialist Projects

Nutrient limitation in aquatic ecosystems results from a deficiency in nitrogen or phosphorus levels relative to cellular growth needs. Nutrient limitation of freshwater systems is a function of biotic and abiotic factors. Biotic factors include vascular and nonvascular plant community composition. Abiotic factors include underlying bedrock and land-use activities (e.g. agriculture, septic systems). Nutrient availability directly affects growth, productivity, and community structure of primary producers. The purpose of this study was two-fold: (1) to assess the relationship between ambient algal biomass. and in-stream nutrient levels along the longitudinal course of a river through a transition from weak to well-developed underlying …


Exploring Zirconia As A Column Packing Material, Tushar Ghugare Aug 2010

Exploring Zirconia As A Column Packing Material, Tushar Ghugare

Masters Theses & Specialist Projects

Zirconia is one of the most promising column packing materials for High Performance Liquid Chromatography (HPLC). The perfect HPLC support material should be energetically homogenous, have a high surface area on which different chemical species can reversibly attach and be physically and chemically stable over a wide range of pH, temperature and solvent conditions. Most existing supports do not have all of these properties. This project is also focused on a proteomics study. Zirconia, hafnium oxide and titanium oxide which are some of the more promising materials currently available, can be used for the separation and analysis of phosphorylated proteins. …


High Pressure Liquid Chromatography Studies Of The Reaction Of Platinum Complexes With Peptides, Khaja Muneeruddin Aug 2010

High Pressure Liquid Chromatography Studies Of The Reaction Of Platinum Complexes With Peptides, Khaja Muneeruddin

Masters Theses & Specialist Projects

Platinum complexes (cisplatin, carboplatin and oxaliplatin) are effective anticancer agents. However the major drawbacks of platinum chemotherapy are toxic side effects and resistance. The affinity of platinum complexes to sulfur donor ligands of side chains of methionine and cysteine amino acids was assumed to be responsible for toxicity and resistance. Recently, it was found that the reaction of platinum complex with proteins containing sulfur donor ligands could actually favor its anticancer activity. Copper transporter 1 (Ctr 1), a protein involved in the transport of copper into the cell, also helps in the influx of cisplatin by binding to N-terminal domain …


Synthesis, Kinetic And Photocatalytic Studies Of Porphyrin-Ruthenium-Oxo Complexes, Yan Huang Aug 2010

Synthesis, Kinetic And Photocatalytic Studies Of Porphyrin-Ruthenium-Oxo Complexes, Yan Huang

Masters Theses & Specialist Projects

Macrocyclic ligand-complexed transition metal-oxo intermediates are the active oxidizing species in a variety of important biological and catalytic oxidation reactions. Many transition metal catalysts have been designed to mimic the predominant oxidation catalysts in Nature, namely the cytochrome P450 enzymes. Ruthenium porphyrin complexes have been the center of the research and have successfully been utilized, as catalysts, in major oxidation reactions such as the hydroxylation of alkanes. This study focuses on kinetic and photocatalytic studies of oxidation reactions with wellcharacterized high-valent ruthenium-oxo porphyrin complexes.
The trans-dioxoruthenium(VI) porphyrins have been among the best characterized metal-oxo intermediates and their involvement as …


Performance Analysis Of Real-Time Component Architectures: An Enhanced Model Interchange Approach, Gabriel Moreno, Connie Smith Jul 2010

Performance Analysis Of Real-Time Component Architectures: An Enhanced Model Interchange Approach, Gabriel Moreno, Connie Smith

Gabriel A. Moreno

Model interchange approaches support the analysis of software architecture and design by enabling a variety of tools to exchange performance models using a common schema. This paper builds on the Software Performance Model Interchange Format (S-PMIF), extending it to support the analysis of real-time systems and adapting it to be suitable for implementation with modeling frameworks such as MOF or EMF. This enhances the model interchange process by making it possible to define model-to-model transformations from design models into software performance models. The paper addresses real-time system designs expressed in CCL and their transformation into the S-PMIF for additional performance …


Estimating Confidence Intervals For Eigenvalues In Exploratory Factor Analysis, Ross Larsen, Russell Warne Jul 2010

Estimating Confidence Intervals For Eigenvalues In Exploratory Factor Analysis, Ross Larsen, Russell Warne

Russell T Warne

Exploratory factor analysis (EFA) has become a common procedure in educational and psychological research. In the course of performing an EFA, researchers often base the decision of how many factors to retain on the eigenvalues for the factors. However, many researchers do not realize that eigenvalues, like all sample statistics, are subject to sampling error, which means that confidence intervals (CIs) can be estimated for each eigenvalue. In the present article, we demonstrate two methods of estimating CIs for eigenvalues: one based on the mathematical properties of the central limit theorem, and the other based on bootstrapping. References to appropriate …


Lignin Deconstruction For The Production Of Liquid Fuels, R. Andrews, M. Crocker, S. Debolt, M. Meier, Samuel Morton Jul 2010

Lignin Deconstruction For The Production Of Liquid Fuels, R. Andrews, M. Crocker, S. Debolt, M. Meier, Samuel Morton

Samuel A Morton

No abstract provided.


Effect Of Particle Properties And Light Polarization On The Plasmonic Resonances In Metallic Nanoparticles, U. Guler, R. Turan Jul 2010

Effect Of Particle Properties And Light Polarization On The Plasmonic Resonances In Metallic Nanoparticles, U. Guler, R. Turan

U. Guler

The resonance behavior of localized surface plasmons in silver and gold nanoparticles was studied in the visible and near-infrared regions of the electromagnetic spectrum. Arrays of nano-sized gold (Au) and silver (Ag) particles with different properties were produced with electron-beam lithography technique over glass substrates. The effect of the particle size, shape variations, period, thickness, metal type, substrate type and sulfidation were studied via transmission and reflectance measurements. The results are compared with the theoretical calculations based on the DDA simulations performed by software developed in this study. We propose a new intensity modulation technique based on localized surface plasmons …


The Effects Of Information Technology Processes On Computerized Clinical Decision Support Systems, Shari Valenta Jul 2010

The Effects Of Information Technology Processes On Computerized Clinical Decision Support Systems, Shari Valenta

Regis University Student Publications (comprehensive collection)

One of the most significant challenges facing healthcare executives today is investing in clinical decision support systems (CDSS) that can support diverse data and decision making needs of physicians and managers to accomplish their organization's mission. The Health Information Technology for Economic and Clinical Health Act provisions of the American Recovery and Reinvestment Act economic stimulus package have brought billions of dollars in incentive funds for CDSS and other healthcare information technology. CDSS can help healthcare organizations automate inefficient processes, lower costs and improve patient care with better decision making. Risks, however are that pre-implementation and customization of CDSS can …


A Case History Of The Science And Management Collaboration In Understanding Hypoxia Events In Long Bay, South Carolina, Usa., Denise Sanger, Debra Hernandez, Susan Libes, George Voulgaris, Braxton Davis, Erik Smith, Rebecca Shufford, Dwayne Porter, Eric Koepfler, Joseph Bennet Jul 2010

A Case History Of The Science And Management Collaboration In Understanding Hypoxia Events In Long Bay, South Carolina, Usa., Denise Sanger, Debra Hernandez, Susan Libes, George Voulgaris, Braxton Davis, Erik Smith, Rebecca Shufford, Dwayne Porter, Eric Koepfler, Joseph Bennet

George Voulgaris

Communication of knowledge between the scientific and management communities is a difficult process complicated by the distinctive nature of professional career goals of scientists and decision-makers. This article provides a case history highlighting a collaboration between the science and management communities that resulted from a response to a 2004 hypoxia, or low dissolved oxygen, event in Long Bay, off Myrtle Beach, South Carolina. A working group of scientists and decision-makers was established at the time of the event and has continued to interact to develop a firm understanding of the drivers responsible for hypoxia formation in Long Bay. Several factors …


Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller Jul 2010

Dark Matter Halos And Evolution Of Bars In Disk Galaxies: Varying Gas Fraction And Gas Spatial Resolution, Jorge Villa-Vargas, Isaac Shlosman, Clayton Heller

Department of Physics and Astronomy Faculty Publications

We conduct numerical experiments by evolving gaseous/stellar disks embedded in live dark matter halos aiming at quantifying the effect of gas spatial resolution and gas content on the bar evolution. Three model sequences have been constructed using different resolutions, and the gas fraction has been varied along each sequence within the range of f g = 0%-50%, but keeping the disk and halo properties unchanged. We find that the spatial resolution becomes important with an increase in the gas content. For the higher resolution model sequences, we observe a bimodal behavior in the bar evolution with respect to the gas …


Data Protection Models For Service Provisioning In The Cloud, Dan Lin, Anna Squicciarini Jul 2010

Data Protection Models For Service Provisioning In The Cloud, Dan Lin, Anna Squicciarini

Computer Science Faculty Research & Creative Works

Cloud computing enables highly scalable services to be easily consumed over the Internet on an as-needed basis. While cloud computing is expanding rapidly and used by many individuals and organizations internationally, data protection issues in the cloud have not been carefully addressed at current stage. in the cloud, users' data is usually processed remotely in unknown machines that users do not own or operate. Hence, users' fear of confidential data (particularly financial and health data) leakage and loss of privacy in the cloud becomes a significant barrier to the wide adoption of cloud services. to allay users' concerns of their …


A Suggested Building Block Geometry Without Continuous Radial Joints Of Possible Relevance For Particle Detectors, Jim Mcgovern Jul 2010

A Suggested Building Block Geometry Without Continuous Radial Joints Of Possible Relevance For Particle Detectors, Jim Mcgovern

Articles

A geometry for concentrc shells or tubes, built-up from a single rhombohedral block type, is described. Continuous radial joints are avoided.


Plans For The First Balloon Flight Of The Gamma-Ray Polarimeter Experiment (Grape), Taylor Connor, Chris Bancroft, Peter F. Bloser, Jason S. Legere, Mark L. Mcconnell, James M. Ryan Jul 2010

Plans For The First Balloon Flight Of The Gamma-Ray Polarimeter Experiment (Grape), Taylor Connor, Chris Bancroft, Peter F. Bloser, Jason S. Legere, Mark L. Mcconnell, James M. Ryan

Space Science Center

We have developed a design for a hard X-ray polarimeter operating in the energy range from 50 to 500 keV. This modular design, known as GRAPE (Gamma-Ray Polarimeter Experiment), has been successfully demonstrated in the lab using partially polarized gamma-ray sources and using fully polarized photon beams at Argonne National Laboratory. In June of 2007, a GRAPE engineering model, consisting of a single detector module, was flown on a high altitude balloon flight to further demonstrate the design and to collect background data. We are currently preparing a much larger balloon payload for a flight in the fall of 2011. …


A Fast Scintillator Compton Telescope For Medium-Energy Gamma-Ray Astronomy, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga Jul 2010

A Fast Scintillator Compton Telescope For Medium-Energy Gamma-Ray Astronomy, Peter F. Bloser, James M. Ryan, Jason S. Legere, Manuel Julien, Chris Bancroft, Mark L. Mcconnell, Mark Wallace, R M. Kippen, Shawn Tornga

Space Science Center

The field of medium-energy gamma-ray astronomy urgently needs a new mission to build on the success of the COMPTEL instrument on the Compton Gamma Ray Observatory. This mission must achieve sensitivity significantly greater than that of COMPTEL in order to advance the science of relativistic particle accelerators, nuclear astrophysics, and diffuse backgrounds, and bridge the gap between current and future hard X-ray missions and the high-energy Fermi mission. Such an increase in sensitivity can only come about via a dramatic decrease in the instrumental background. We are currently developing a concept for a low-background Compton telescope that employs modern scintillator …


Development Of The Advance Energetic Pair Telescope (Adept) For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Mark L. Mcconnell, Georgia A. Denolfo, Seunghee Son, James M. Ryan, Floyd Stecker Jul 2010

Development Of The Advance Energetic Pair Telescope (Adept) For Medium-Energy Gamma-Ray Astronomy, Stanley D. Hunter, Peter F. Bloser, Michael P. Dion, Mark L. Mcconnell, Georgia A. Denolfo, Seunghee Son, James M. Ryan, Floyd Stecker

Space Science Center

Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (~0.3< Eγ < ~200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, mediumenergy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30×30×30 cm3 prototype of the AdEPT instrument.


Real-Time Fracture Detection Of Individual Boron Nitride Nanotubes In Severe Cyclic Deformation Processes, Hessam Mir Shah Ghassemi, C. H. Lee, Yoke Khin Yap, Reza Shahbazian-Yassar Jul 2010

Real-Time Fracture Detection Of Individual Boron Nitride Nanotubes In Severe Cyclic Deformation Processes, Hessam Mir Shah Ghassemi, C. H. Lee, Yoke Khin Yap, Reza Shahbazian-Yassar

Department of Physics Publications

Real-time deformation of individual multiwalled boron nitride nanotubes (BNNTs) was investigated using an atomic force microscopy (AFM) stage installed inside the chamber of a transmission electron microscopy (TEM) system. These in situ AFM-TEM experiments were conducted in following two deformation regimes: a small-angle (∼65°) and a large-angle (∼120°) cyclic bending process. BNNTs survived from the low-angle test and their modulus was determined as ∼0.5 TPa. Fracture failure of individual BNNTs was discovered in the large-angle cyclic bending. The brittle failure mechanism was initiated from the outermost walls and propagated toward the tubular axis with discrete drops of applied forces