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  • Analyzing & designing the security of shared resources on smartphone operating systems
    Scholarship
    Creator
    Demetriou, Soteris
    Description
    Smartphone penetration surpassed 80% in the US and nears 70% in Western Europe. In fact, smartphones became the de facto devices users leverage to manage personal information and access external data and other connected devices on a daily basis. To support such multi-faceted functionality, smartphones are designed with a multi-process architecture, which enables third-party developers to build smartphone applications which can utilize smartphone internal and external resources to offer creative utility to users. Unfortunately, such third-party programs can exploit security inefficiencies in smartphone operating systems to gain unauthorized access to available resources, compromising the confidentiality of rich, highly sensitive user data. The smartphone ecosystem, is designed such that users can readily install and replace applications on their smartphones. This facilitates users’ efforts in customizing the capabilities of their smartphones tailored to their needs. Statistics report an increasing number of available smartphone applications— in 2017 there were approximately 3.5 million third-party apps on the official application store of the most popular smartphone platform. In addition we expect users to have approximately 95 such applications installed on their smartphones at any given point. However, mobile apps are developed by untrusted sources. On Android—which enjoys 80% of the smartphone OS market share—application developers are identified based on self-sign certificates. Thus there is no good way of holding a developer accountable for a malicious behavior. This creates an issue of multi-tenancy on smartphones where principals from diverse untrusted sources share internal and external smartphone resources. Smartphone OSs rely on traditional operating system process isolation strategies to confine untrusted third-party applications. However this approach is insufficient because incidental seemingly harmless resources can be utilized by untrusted tenants as side-channels to bypass the process boundaries. Smartphones also introduced a permission model to allow their users to govern third-party application access to system resources (such as camera, microphone and location functionality). However, this permission model is both coarse-grained and does not distinguish whether a permission has been declared by a trusted or an untrusted principal. This allows malicious applications to perform privilege escalation attacks on the mobile platform. To make things worse, applications might include third- party libraries, for advertising or common recognition tasks. Such libraries share the process address space with their host apps and as such can inherit all the privileges the host app does. Identifying and mitigating these problems on smartphones is not a trivial process. Manual analysis on its own of all mobile apps is cumbersome and impractical, code analysis techniques suffer from scalability and coverage issues, ad-hoc approaches are impractical and susceptible to mistakes, while sometimes vulnerabilities are well hidden at the interplays between smartphone tenants and resources. In this work I follow an analytical approach to discover major security and privacy issues on smartphone platforms. I utilize the Android OS as a use case, because of its open-source nature but also its popularity. In particular I focus on the multi-tenancy characteristic of smartphones and identify the re- sources each tenant within a process, across processes and across devices can access. I design analytical tools to automate the discovery process, attacks to better understand the adversary models, and introduce design changes to the participating systems to enable robust fine-grained access control of resources. My approach revealed a new understanding of the threats introduced from third-party libraries within an application process; it revealed new capabilities of the mobile application adversary exploiting shared filesystem and permission resources; and shows how a mobile app adversary can exploit shared communication mediums to compromise the confidentiality of the data collected by external devices (e.g. fitness and medical accessories, NFC tags etc.). Moreover, I show how we can eradicate these problems following an architectural design approach to introduce backward-compatible, effective and efficient modifications in operating systems to achieve fine-grained application access to shared resources. My work has let to security changes in the official release of Android by Google.
  • Mechanistic insights into the direct synthesis of H2O2 on transition metal catalysts
    Scholarship
    Creator
    Wilson, Neil Marshall
    Description
    H2O2 is less environmentally impactful than many industrial oxidants such as Cl2. The auto-oxidation of anthraquinones is the current standard for industrial H2O2 production, however, this process requires significant energy input due to the extensive purification and concentration processes involved, making H2O2 cost-prohibitive for many oxidation processes. As a result, there is clear motivation for less expensive and energy-demanding chemistries for H2O2 production, such as the direct synthesis of H2O2 (H2 + O2 → H2O2), the most promising alternative to using anthraquinones. Unfortunately, the combustion of H2 is thermodynamically favored over direct synthesis to H2O2 on most transition metal catalysts, and so significant research has been directed towards improving catalyst selectivity towards H2O2 through various methods. Despite significant research, the mechanism of this reaction, and the reasons for the importance of seemingly unrelated factors (e.g., metal cluster size, solvent pH, alloying), have remained unclear. The aim of this work is to provide a fundamental understanding of these factors through rigorous experimental procedures and analysis. Here, we propose a mechanism for H2O2 formation on Pd clusters consistent with steady-state H2O2 and H2O formation rates measured as functions of reactant pressures and temperature, and the interpretations of proton concentration effects. H2O2 forms by sequential proton-electron transfer to O2 and OOH surface intermediates, whereas, H2O forms by O-O bond rupture within OOH surface species. Direct synthesis, therefore, does not proceed by the Langmuir-Hinshelwood mechanism often invoked. Rather, H2O2 forms by heterolytic reaction pathways resembling the two electron oxygen reduction reaction (ORR), however, the chemical potential of H2 replaces an external electrical potential as the thermodynamic driving force. Similar experimental procedures have shown that this proton-electron transfer mechanism is the same also on AuPd and PdZn catalysts. Among AuPd and PdZn catalysts, increases in the Au:Pd or Zn:Pd ratio leads to simultaneous but unequal increases in the activation enthalpies (∆H‡) for both H2O2 and H2O formation, which must result from significant electronic changes to Pd by Au or Zn. Detailed comparisons of these changes in ∆H‡ for H2O2 and H2O production to H2O2 selectivities provide compelling evidence that these electronic effects are primarily responsible for the high H2O2 selectivities commonly reported on bimetallic catalysts. Additionally, these results lack trends that suggest ensemble effects contribute significantly to the increase in H2O2 selectivity observed on bimetallic catalysts within the ranges of metal compositions tested here. AgPt octahedra with dilute concentrations of surface Pt atoms were synthesized to test for the presence of ensemble effects which presumably do not manifest until the active sites (i.e., Pt) are sufficiently diluted with a metal which weakly binds O2 (i.e., Ag). Combining Pt with Ag increases H2O2 selectivity and significantly modifies the electronic structure of Pt active sites, which is reflected by a red shift in the ν(C=O) singleton frequency in 13CO, which is accompanied by a significant decrease in ∆H‡ values for H2O2 formation and a smaller decrease for H2O formation. These combined results show that adding Ag to Pt increases H2O2 selectivity by a combination of electronic modification of Pt atoms (likely due to tensile strain effects) and a commensurate increase in the number of isolated Pt atoms that lack sufficiently large numbers of Pt atoms to cleave O-O bonds to form H2O. Collectively, the results of these studies clarify many previously reported phenomena and help to guide the rational design of selective catalysts for the direct synthesis of H2O2.
  • INHS Reports, Autumn 2009
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Revisionary Synthesis of Deltocephaline Leafhoppers | Big Railroad Blues | How We COPE with Outreach and Education | Calendar Sales Items for October through December | Species Spotlight: Cooper's Hawk | The Naturalist's Apprentice: Hawk Crossword Puzzle
  • INHS Reports, Winter 2010
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Interspecific Interactions between Invasive and Native Mosquitoes | Islands as Models for Biodiversity Studies | Can Riparian Forests Help Improve Stream communities in Illinois Agricultural Watersheds? | Ecosystem-scale Evaluation of Sound Bubble Barrier Technologies to Prevent Range Expansions of Asian Carps | Species Spotlight: Brown Recluse Spider | The Naturalist's Apprentice: Illinois Spiders
  • Facile Size-Controlled Synthesis of Fluorescent Carbon Nanoparticles with Size-Independent Optical Properties
    Scholarship
    Creator
    • Singh, Jasleena
    • Pan, Dipanjan
    • Schwartz-Duval, Aaron Star
    • Mistry, Neal
    • Golk, Kelsey
    • Srivastava, Indrajit
    Description
    Nanoparticle imaging probes and drug delivery systems have distinct advantages over free or diffusive delivery in that they can concentrate the imaging contrast agent and/or drug, elicit controlled release/degradation, and have a high surface area to volume ratio beneficial for attaching targeting ligands. The size of these nanoparticles affects delivery, retention, degradation rate, and sometimes the radiological properties of the particles. For many optically active nanoparticles (such as gold, silver, and quantum dots), the optical properties are directly dependent on the size and shape of the nanoparticles. While this provides a simplistic outlet for modifying the optical properties of those nanoparticles, it is limiting in that their applications are also dependent on morphology. In these works, we aim to determine if the optical properties of fluorescent carbon nanoparticles are dependent on size through variations in synthetic parameters. Fluorescent carbon nanoparticles with hydrodynamic diameters ranging from 10 – 500 nm were prepared through variations of sugar source, concentration of agave (as a sugar source) and incubation time. Through comparisons made between these nanoparticles, we found no change in the local absorbance maxima and refractive index, with < 5 nm shifting in fluorescence maxima location. We have observed that fluorescent carbon nanoparticles can be prepared within a large range of sizes (10 – 500 nm) without considerable shift in optical properties. Because of this observation, we can infer that the optical properties of fluorescent carbon nanoparticles are largely size independent.
  • The influence of early information on postsecondary affordability
    Scholarship
    Creator
    Hemenway, Bradley Keith
    Description
    Misconceptions on affordability remain a barrier to postsecondary access for millions of potential students. When students recognize financial aid availability during secondary school years, they gain the capability to better establish a curricular path that aligns with postsecondary aspirations. This dissertation assesses the use of residency-based financial aid programs and parents’ college assets as methods to generate early information on postsecondary affordability. Following a three-paper format, the first paper develops a typology organizing the growing number of residency-based “Promise” programs around the country. The typology captures variations in the geographic scope for eligibility, supplementary qualifications, funding sources, value, and redeeming criteria to generate a description and list of comparable programs. Identifying program comparability is a necessary step for research examining program outcomes. The first paper uses a cluster analysis methodology to identify programs comparable based on the advertised operational characteristics. I find three distinctly different groups of residency-based financial aid programs, which I term state-based aid programs, institutionally funded programs, and community-sustained programs. The typology is extended to identify the specific operational characteristics for which residency-based, community-sustained financial aid programs differ. The second paper uses a unique institutional-level dataset and quasi-experimental Difference-in-Difference design to examine changes in college readiness, postsecondary outcomes, and curriculum decisions resulting from the residency-based, community-sustained Dell and Evelyn Carroll Scholarship. The award guarantees all Meridian High School students last-dollar funding for unmet need at Richland Community College. I find that information about Carroll Scholarship eligibility increases the college-readiness levels among high-achieving high school graduates who elect to enroll at Richland. After enrollment, all Carroll-eligible students register for, and earn, a statistically significant increased number of credit hours. I also find evidence that the Carroll Scholarship impacts student’s curriculum selection. The final paper uses a quantitative, quasi-experimental design of the nationally representative Education Longitudinal Study of 2002. Propensity Score Matching models are used to estimate different parents’ college asset savings strategies impacts the likelihood of a child enrolling in postsecondary education after completing high school. I find an enrollment association from parent’s postsecondary savings across different socioeconomic and sociodemographic groups. The models evaluate student responsiveness differences based on socioeconomics, race, and ethnicity, and control for secondary school academic achievement and the amount saved.
  • Physics of the helicon antenna on the prototype materials exposure experiment
    Scholarship
    Creator
    Piotrowicz, Pawel A.
    Description
    Proto-MPEX has been operating in a high-density “helicon-mode” of operation. The helicon mode of operation is classified by an increase in target on-axis electron density (6e19 m^-3) and a decrease in electron temperature (2 – 3 eV) during a helicon pulse. This transition is observed when Deuterium gas is puffed into the device and is dependent on operating configurations. The Proto-MPEX helicon antenna is a quarter turn right handed helical twist antenna powered by RF at 13.56 MHz and > 110 kW of power. Establishing plasma densities and magnetic field strengths under the antenna that suppress non-resonant mode conversion to the slow-wave are thought to be responsible for operating in the "helicon-mode". Evidence for this phenomena to be responsible for the "helicon-mode" of operation is presented. The experimental results showing evidence of this phenomena are presented here. First, we present time-resolved measurements of an edge-to-core power transition during a "helicon-mode" plasma pulse in the form of infra-red camera imaging of a thin stainless steel target plate. The time-resolved images measure the two-dimensional distribution of power deposition in the helicon discharge. The discharge displays a mode transition characterized by a significant increase in the on-axis electron density and core power coupling, suppression of edge power coupling and the formation of a fast-wave radial normal mode. Although the self-consistent mechanism that drives this transition is not yet understood, the edge-to-core power transition displays characteristics that are consistent with the discharge entering a slow-wave anti-resonant regime. RF magnetic field measurements made across the plasma column, together with the power deposition results, provide direct evidence to support the suppression of the slow-wave in favour of core plasma production by the fast-wave in a light-ion helicon source. A full wave model of the helicon antenna has been made in the finite element analysis software, COMSOL Multiphysics, to investigate the wave fields produced and the power deposition inside the Proto-MPEX device. Core electron density and magnetic field under the helicon is scanned while tracking core power deposition. The peaks of core power deposition in this parameter space are then investigated and the propagating modes are analyzed. These areas of increased core power deposition are then identified as helicon normal modes that are predicted to decrease edge coupling of power and increase core power coupling by suppressing the non-resonant mode conversion of the fast-wave to the slow-wave in the periphery of the plasma.
  • Seismic Performance of Seat-Type Abutment Highway Bridges in Illinois
    Scholarship
    Creator
    • Fahnestock, Larry A.
    • Luo, Jie
    • Kozak, Derek L.
    • LaFave, James M.
    Description
    This study assesses the seismic performance of quasi-isolated highway bridges with seat-type abutments, validates the current IDOT design strategy, and provides recommendations for improving a bridge’s seismic behavior. To encompass common configurations of highway bridges with non-seismically designed bearing components employed as sacrificial connections between superstructures and substructures, a suite of prototype bridges with variations in span arrangement, girder type, skew angle, pier column height, and foundation soil condition were studied. Detailed three-dimensional nonlinear finite-element models were developed for the bridges, incorporating various critical structural components and geotechnical mechanisms. Multi-mode adaptive pushover analyses were conducted to investigate bridge response characteristics in terms of the force distribution among substructures, the sequence of limit state occurrences, the fusing of sacrificial connections, and the vulnerability of critical bridge components. Eigenvalue modal analyses were also performed in the elastic and inelastic deformation states to reveal modal response characteristics of the bridges. The study culminated in an extensive seismic performance assessment of quasi-isolated bridges, for which thousands of nonlinear dynamic time-history analyses were carried out. The bridges were subjected to a suite of site-specific earthquake ground motions, taking into account the site condition and the regional seismicity of Cairo, Illinois. Assessment results validated that the current quasi-isolation bridge design strategy is generally effective, and the majority of the studied prototype bridges are unlikely to fail in global collapse when subjected to horizontal earthquake ground motions with a 1,000-year return period in deep southern Illinois. Although most of the prototype bridges exhibited satisfactory seismic performance, the response of a small number of them demonstrated a risk of bearing unseating and severe pier column damage. With the aim of improving the seismic performance of these bridges, preliminary recommendations for calibrating the current design strategy were proposed, and their efficacy was demonstrated by comparative studies.
  • Tracking certificate misissuance in the wild
    Scholarship
    Creator
    Wang, Zhengping
    Description
    Certificate Authorities (CAs) are responsible for delegating trust in the TLS Public Key Infrastructure (PKI). Unfortunately, there is a long history of CAs abusing this responsibility, either due to negligence or in some cases, falling victim to attacks. As a result, the PKI community has established standards that define the correctness of certificates and how a well managed CA should operate. In this work, we evaluate a systematic approach to identifying whether certificates issued by CAs are compliant with community standards. To this end, we present ZLint, a system that determines whether a certificate is not conformant to standards, i.e., misissued. We find that while misissuance has decreased over time, there is still a long tail of non-conformant CAs in the ecosystem. Further, our results show that certificate misissuance serves as a reasonable indicator for mismanagement and untrustworthiness, suggesting that CAs that misissue more frequently pose a greater threat to security of the PKI. Community efforts thus far to curb these threats have been moderately successful, but the lack of a systematic approach to identifying these problems lets some classes of problems slip through the cracks. We argue that an automated and systematic approach to measuring misissuance in the ecosystem is a necessary first step in solving the problems that lie ahead.
  • Navigating the PDF/A standard: a case study of theses in the University of Oxford’s institutional repository
    Scholarship
    Creator
    Oates, Anna Irene
    Description
    The PDF/A (Portable Document Format–Archival) was established by the International Organization of Standardization as the ISO 19005 standard for long-term preservation of electronic documents. While the ISO requirements of a well-formed PDF/A ensure sustainability and easy recovery of content, the standard restricts some document features from being incorporated into a well-formed PDF/A. Non-conformances to the standard are found across electronic theses and dissertations, from non-Latin glyphs used in scientific and language papers to embedded content, such as images. A further complication for achieving ISO 19005 compliance is that, despite non-conformance to the ISO standard, validation tools do not always catch non-conformance errors in documents which claim to conform to PDF/A. While PDF/A is a logical solution for long-term preservation of electronic documents, the stringent standard prevents some content which is frequently used in academic research from conforming to the ISO 19005 standard. This thesis evaluates the PDF/A and its potential use as a preservation file format for electronic theses and dissertations.
  • Feeding peroxidized soybean oil to finishing pigs: Effects on performance, nutrient digestibility, carcass...
    Scholarship
    Creator
    Overholt, Martin F.
    Description
    Fifty-six barrows (46.7 ± 5.1 kg initial BW) were randomly assigned to 1 of 4 diets in each of two dietary phases, containing either 10% fresh SO (22.5°C) or thermally processed SO (45°C for 288 h, 90°Cfor 72 h, or 180°C for 6 h), each infused with of 15 L/min of air. Peroxide values were 2.0, 17.4, 123.6, and 19.4 mEq/kg; 2,4-decadienal values were 2.07, 1.90, 912.15, and 915.49 mg/kg; and 4-hydroxynonenal concentrations were 0.66, 1.49, 170.48, and 82.80 mg/kg, for the 22.5, 45, 90 and 180°C processed SO, respectively. Pigs were individually housed and fed ad libitum for 81 d to measure growth performance, including a metabolism period to collect urine and feces for determination of GE, lipid, N digestibility, and N retention. Following the last day of fecal and urine collection when pigs were in the metabolism crates, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability, while markers of oxidative stress were evaluated in plasma, urine, and liver. At 82 d pigs were slaughtered and hot carcass weight (HCW) and liver weights were recorded. Carcass characteristics and fresh loin quality were evaluated 1 d post-mortem. Loin chops from each carcass were overwrap-packaged and subjected to a 10 d simulated retail display. Daily measurements of L*, a*, b*, reflectance and visual discoloration were conducted, evaluation of cooking loss and Warner-Bratzler shear force were conducted on chops stored 0, 5, and 10 d, and thiobarbituric acid reactive substances (TBARS) were evaluated on chops stored 0 and 10 d. On d 83 carcasses were fabricated and bellies collected for recording of weight, dimensions, and flop distance. Belly adipose tissue cores were collected for analysis of iodine value (IV) by near-infrared spectroscopy (NIR-IV). Bacon was manufactured at a commercial processing facility and sliced bacon was subsequently transferred to food-service style packaging and subjected to 0, 30, 60, or 90 d storage at -20°C. Stored bacon was evaluated for thiobarbituric acid reactive substances (TBARS) and trained sensory evaluation of oxidized odor and flavor. Growth performance, nutrient digestibility, carcass traits, and bacon slicing yields were analyzed as a one-way ANOVA with the fixed effect of SO. Additionally, initial body weight was used as a covariate for analyses of growth performance and carcass traits. Shelf-life traits for both loin chops and sliced bacon were conducted as repeated measures in time using the mixed model approach, with fixed effects of SO and storage time. There were no differences observed in ADFI (P = 0.91), but ADG and GF were decreased in pigs fed 90°C SO diet (P ≤ 0.07) compared to pigs fed the other SO diets. Pigs fed the 90°C and 180°C SO had the lowest (P = 0.05) DE as a % of GE compared to pigs fed the 22.5°C SO, with pigs fed the 45°C SO being intermediate. Lipid digestibility was similarly affected (P = 0.01) as energy digestibility, but ME as a % of DE was not affected by dietary treatment (P = 0.16). There were no effects of lipid peroxidation on N digested, N retained, or the urinary lactulose:mannitol ratio (P ≥ 0.25). Pigs fed the SO processed at 90°C and 180°C had lower concentrations (P < 0.01) of plasma Trp compared to pigs fed the 22.5°C and 45°C SO treatments. Pigs fed 90°C SO had the greatest (P < 0.01) concentrations of F2-Isoprostane in plasma and urine TBARS compared to the other SO treatments. Carcasses of 90°C pigs weighed 6.0, 8.6, and 6.9 kg less than (P < 0.03) 22.5°C, 45°C, and 180°C carcasses, respectively. Livers of 90°C and 180°C pigs were 14.3 and 11.7%, respectively, heavier (P ≤ 0.02) than those from pigs fed 22.5°C SO, with livers of 45°C being intermediate. Livers of 90°C pigs represented 0.12 percentage units less (P = 0.02) of ending live weight than livers 180°C, and 180°C liver were 0.12 percentage units less (P < 0.01) of ending live weight than those from pigs fed 22.5°C SO, with 45°C being intermediate. There was no difference (P ≥ 0.19) BF depth, LMA, or estimated carcass lean percentage among SO treatments, nor was there an effect (P ≥ 0.13) of SO on any early post mortem loin quality traits or loin composition. There was no effect (P > 0.14) of SO on cooking loss, WBSF, L*, a*, b*, hue angle, reflectance, discoloration, or TBARS; however, there was a tendency (P = 0.09) for chops of 45°C pigs to have greater (P < 0.04) chroma than either 22.5°C or 180°C, with 90°C being intermediate. There was no effect (P ≥ 0.30) of SO on belly weight, length, width, or thickness; but bellies of pigs fed 90°C SO had greater (P ≤ 0.04) flop distance (more firm) than all other SO treatments. Belly fat NIR-IV of pigs fed 90°C SO were 10.22 units less (P < 0.0001) than pigs fed 180°C SO, which were 2.99 and 3.29 units less than belly adipose tissue of pigs fed 22.5°C and 45°C SO, respectively. There was no effect of SO on brine uptake or cooking yield of commercially manufactured bacon. There was a trend (P = 0.09) for bacon manufactured from bellies of pigs fed 45°C and 90°C SO to have greater slicing yields than those from pigs fed 22.5°C and 180°C SO. There were no SO × storage time interactions (P ≥ 0.27) for any shelf life trait. There was no difference in TBARS, oxidized odor, or oxidized flavor among the four SO treatments, though all three shelf life metrics increased (P < 0.0001) with storage time. Overall, the change in FA composition and/or the presence of lipid peroxidation products in thermally peroxidized SO resulted in increased markers of oxidative stress and digestibility of GE and ether extract, resulting in drastically reduced growth performance and significantly lighter carcasses. Despite the negative effect on digestibility and growth, feeding thermally peroxidized SO had no effect on the shelf life of loin chops or bacon. In conclusion, pig producers should be weary of feeding thermally peroxidized fat sources, but packers and processors have little cause for concern when it comes to the stability and quality of their pork products.
  • Food safety through fungal disease and mycotoxin mitigation on dairy farms: From field to feed and the rumen
    Scholarship
    Creator
    Weatherly, Maegan Elizabeth
    Description
    Dairy producers are faced with a multitude of challenges regarding dairy cattle production. One such challenge common for cows fed whole-plant corn silage (WPCS) is the often negative effect of fungi. Fungi affect WPCS both in the field and post-harvest; and can cause serious issues for cows that consume it. The use of fungicide (FUN) in the field and feeding adsorbents (AD) to cows are ways to combat the negative consequences caused by fungi and their resulting toxins (mycotoxins). Fungicides work on the corn plant in the field to halt fungus growth, while AD such as clay and yeast work in the rumen to mitigate the negative effects associated with the consumption of mycotoxins on WPCS and other feedstuffs. This research aimed to delve into the consequences of foliar FUN on WPCS and of feeding AD to cows challenged by aflatoxins (AF). To examine the effects of FUN on WPCS in the field and post-ensiling, treatments were assigned to 16 3.38-ha plots in a completely randomized split-plot block design. Treatments were: brown midrib corn (BMR) or floury corn (FLY) without FUN (CON), BMR with FUN (pyraclostrobin and metconazole; Headline AMP, BASF, Florham Park, NJ), and FLY with FUN. Samples of whole corn plants were collected and separated into leaves, stalks, flag leaf, and cobs. Fresh-cut, WPCS samples were collected at harvest and sealed inside mini-silos for the duration of their respective ensiling times. Brown midrib corn plants had a greater number of green leaves than FLY with 11.81 and 11.34 ± 0.09 leaves, respectively (P = 0.001). Corn plants in CON had a greater number of yellow leaves than corn plants in FUN with 0.28 and 0.08 ± 0.02, respectively (P < 0.0001). Corn treated with FUN tended to yield more total WPCS than CON with 63,634 and 60,488 ± 1,533 kg/ha, respectively (P = 0.08). Whole plant corn silage lignin (ADL) content decreased as days ensiled increased with 31.61, 28.48, 25.48, and 22.38 ± 0.77 g/kg of DM for d 0, 30, 90, and 150 d, respectively (P < 0.0001). Floury WPCS had a greater ADL content than BMR WPCS with 31.25 and 22.72 ± 0.61 g/kg of DM, respectively (P < 0.0001). Brown mid-rib WPCS had a greater NDF digestibility at 30 h than FLY WPCS with 572.6 and 492.3 ± 6.9 g/kg of DM, respectively (P < 0.0001). Floury WPCS had greater undigested NDF than BMR WPCS with 125.3 and 96.1 ± 2.1 g/kg of DM, respectively (P < 0.0001). Brown mid-rib corn kernels had a greater kernel vitreousness score than FLY corn kernels with scores of 3.11 and 2.65 ± 0.13, respectively (P = 0.05). A variety × treatment interaction was observed for kernel vitreousness score with scores of 3.23, 2.99, 2.49, and 2.80 ± 0.14 for BMR/CON, BMR/FUN, FLY/CON, and FLY/FUN, respectively (P < 0.0001). From this study we concluded that BMR WPCS treated with FUN and ensiled for 90 to 150 d may result in the most superior WPCS when fed to dairy cows. When FUN aren’t enough to protect WPCS from fungal infestation, AD are commonly fed to cows in order to alleviate the negative effects of toxins on cows. In the first cow trial, lactating Holstein cows [(n = 76); BW (mean ± SD) = 698 ± 72 kg; DIM = 153 ± 83 d] were assigned to 1 of 5 treatments in a randomized complete block design. The trial lasted 28 d and measurements were made from d 22 to 28. From d 22 to 24 cows received an AF challenge (100 μg of AFB1/kg of diet DM administered orally). Treatments were: no AD and no AF challenge (CON); no AD plus an AF challenge (POS); 30 g per cow per d of an AD with proprietary composition of yeast cell wall and bentonite clay (P30); 60 g per cow per d of the same AD previously mentioned (P60); and 60 g per cow per d of a prototype AD (PROT). Blood was sampled on days 22 and 26 (n = 2 per cow), and analyzed for superoxide dismutase (SOD) concentration. Milk samples from d 22 to 26 were analyzed for AFM1 concentrations by HPLC. Fecal samples collected from the rectum on d 22 and 24 were analyzed for AFB1 concentrations via HPLC. A quadratic treatment effect (P < 0.0001) was observed for plasma SOD concentrations at 2.77, 1.99, and 1.97 ± 0.05 U/mL for POS, P30, and P60 treatments, respectively. Aflatoxin M1 transfer (11.4 and 0.00 ± 1.60 g/kg), excretion (29.52 and 0.00 ± 4.58 µg/d), and concentrations in milk (0.76 and 0.00 ± 0.16 µg/kg) were greater for POS than CON, respectively (P < 0.0001) but no differences were observed among other treatments. A tendency for a quadratic treatment effect (P = 0.08) was observed for fecal AFB1 concentrations at 6.78, 8.55, and 5.07 µg/kg for the POS, P30, and P60 treatments, respectively. Oral supplementation of yeast and bentonite clay-based AD during AF challenge resulted in quadratic changes in plasma SOD and fecal AFB1 concentrations; however, no differences were observed for DMI or milk yield. From this study we concluded that yeast cell wall and bentonite-based AD may be beneficial in reducing inflammation during an AF challenge. In a second cow study, we sought to determine the ruminal degradability of feedstuffs in response to 3 concentrations of dietary clay in lactating dairy cows. Treatments were: no clay (CON), 10, or 20 g/kg of dietary DM as clay (EcoMix®, UMG, Ukraine). Samples (8 g) of dried alfalfa hay (AH), grass hay (GH), wet brewer’s grains (WBG), ground corn (GC), corn silage (WPCS), or soybean meal (SBM) were placed into polyester bags (3 replicates per feed) and incubated for 0, 2, 4, 8, 12, 48, 72, or 96 h in 3 rumen-cannulated cows. Recovered bags were analyzed for DM, NDF, ADF, starch, and CP for all feedstuffs, as well as total fatty acids (TFA), saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) for GH, WBG, and WPCS. Soluble (SF), digestible (D), and indigestible (I) fractions; and fractional rate of digestion (Kd) and effective degradability (ED), were estimated for each feedstuff, treatment, and cow combination. Dry matter SF for GH was 0.14, 0.17, and 0.12 g/100 g of DM for CON, 10, and 20 g/kg (P = 0.03). Dry matter Kd for GH was 0.026, 0.015, and 0.022 h-1 for CON, 10, and 20 g/kg (P = 0.02). Digestible DM for WBG was 0.59, 0.66 and 0.76 g/100 g of DM for CON, 10, and 20 g/kg (P = 0.04). Dry matter ED for WBG was 0.44, 0.41, and 0.31 g/100 g of DM for CON, 10, and 20 g/kg (P = 0.02). Soluble DM for SBM was 0.26, 0.34 and 0.15 g/100 g of DM for CON, 10, and 20 g/kg (P = 0.04). Dry matter ED for SBM was 0.48, 0.57, and 0.39 for CON, 10, and 20 g/kg (P = 0.002). From this study, we concluded that the addition of clay at 10 or 20 g/kg of total dietary DM increased SF of GH and SBM, ED of SBM, and D of WBG. As a whole, this research aimed to provide practical solutions to a common problem faced by dairy farmers regarding mycotoxins both in the field and in feedstuffs. In the field, FUN may improve the health and quality of corn plant and WPCS, while AD are useful for attenuating the negative effects of toxins within the cow. Lastly, the addition of a clay-based AD may improve the degradability of some feedstuffs making it effective in maximizing both health and productivity of dairy cows.
  • Essays in debt sustainability and financial stability
    Scholarship
    Creator
    Henao Arbelaez, Camila
    Description
    In chapter one, I construct a dynamic stochastic general equilibrium model of optimal default, in which the government optimally holds net debt and attachable assets. The model is novel as it allows for the possibility of debt to be enforced. This is a vast improvement upon previous models, which find that the optimal level of assets the sovereign chooses in the long run is zero. Here, asset savings have other roles different than consumption smoothing. They impact repayment incentives and borrowing costs. Whenever debt is enforceable through a fraction of assets that can be confiscated should the government default, equilibrium attachable asset holdings can be different than zero. I find that attachable asset holdings and attachability, increase debt sustainability, and further provide access to funds. The main mechanism by which this occurs is the endogenous interest rate. It is found to be decreasing in the attachability parameter, and increasing in the probability of redemption. I calibrate $\alpha$ to match observed attachable asset levels. Results indicate a ninefold increase in attachability from the late 1990s to 2010 (from $10\%$ to $93\%$); these results then allow me to match the observed rising trend in attachable asset holdings since the late 1990s. In synthesis, this paper argues that larger attachability—which can be interpreted as relentless litigation, severe threats of confiscation, and less favorable rulings toward sovereigns—explains the rise in the observed percentage of debt attached and attachable asset holdings. In chapter two, we ask if government financial assets help improve public debt sustainability. We assemble a comprehensive dataset on government assets using multiple sources and covering 110 advanced and emerging market economies since the 1980s. We then use this rich database to estimate the impact of assets on two key dimensions of debt sustainability: borrowing costs and the probability of debt distress. Government assets significantly reduce sovereign spreads and the probability of debt crises in emerging economies, but not in advanced economies; this effect varies with asset characteristics, notably liquidity. Assets also help discriminate among countries across the distribution of sovereign spreads, thus signaling information about emerging economies’ creditworthiness. Chapter three systematically documents the impact on output dynamics of an additional unit of debt-to-tax revenue, conditional on the occurrence of financial shocks. I examine whether banking crises are systematically different from other financial catastrophes (currency crises), and, most importantly, whether pre-crises fiscal buffers are particularly important whenever banking crises materialize. Lastly, the paper investigates post-crisis output dynamics considering pre-crisis debt-to-tax revenue, and examine whether the post-crisis dynamics are systematically different for emerging and developing economics than for advanced economies. Using panel data for 155 countries for the period of 1975-2011, I estimate a univariate autoregressive model in growth rates, and construct impulse response functions to display the relationship between debt-to-tax-revenue conditional on a financial crisis and output dynamics. Using three approaches to account for the endogeneity of crises and fiscal burden, I find that an additional unit of debt-to-tax revenue prior to a banking crisis is associated with larger output losses than when the same situation occurs prior to a currency crisis. Emerging and developing economies experience deeper losses than advanced countries; this is due not only to banking and currency crises, but because of marginal increases in the pre-crisis debt-to-tax-revenue ratios.
  • Closing yield gaps in South Asian wheat production (Bihar, India and Terai of Nepal)
    Scholarship
    Creator
    Park, Alexander Guy
    Description
    Rising wheat consumption and recurring climate extremes threaten food security in the Eastern Indo-Gangetic Plain. Closing wheat yield gaps in this region through agronomic practices currently available to farmers can contribute to a more secure future in this region. In Nepal and Bihar, India, a set of complementary management practices were associated with higher yields, namely: 1) early sowing with long maturing varieties, 2) higher rates of N, P and particularly K application, 3) transitions to zero-till for crop establishment, and 4) encouraging more frequent irrigation. Financial and policy support for infrastructure and agricultural inputs, extension, research and development of private service networks made a marked improvement in yield outcomes in Bihar. Nepal is at a crossroads of diminishing farm-labor and inadequate investment into farming operations that, among other factors, have stagnated domestic wheat yield. Cultural and economic constraints have hindered the widespread adoption of more expensive precision agriculture technologies like zero-till that have the capacity to improve labor and farm input efficiencies. To capture the benefits from added precision of application but with the ability to fit within the current semi-mechanized seed bed preparation and tillage system, we introduced a low-cost, chest mounted seed and fertilizer. We found that simple mechanization caused yield efficiencies to be positive and significant for nitrogen and phosphate. Seed rates using this method were positively associated with seedling density. This led to both yield and profit being more predictable for farmers. Conversely, hand-applied inputs caused a disassociation between inputs and end of season yield and therefore added a large measure of risk to their farming operations. Nepali farmers endure many types of risks in producing wheat. Some, such as those affiliated with socioeconomic and demographic pressures, they have little control over. Other sources of risk, such as stresses associated with particular agronomic practices, can be mitigated through better management. In this research, we found that waterlogging stress early in wheat phenology reduced yield. This was attributed to farmers applying flood irrigation to the crop to the point of ponding at early wheat growth stages when the plants were more vulnerable. Waterlogging stress was exacerbated by the common practice of applying seed and fertilizer by hand which created in-field heterogeneity of nutrient distribution, thereby reducing individual plant access to nutrients and making them less resilient to waterlogging stress. Two different solutions, one a technological intervention and the other a change in irrigation practices, reduced this stress. The first was the introduction of a chest-mounted spreader that added a greater measure of uniformity to input application and reduced the impact that waterlogging stress had on crop productivity by ensuring greater availability of nutrients across fields. The second was a delay in the timing of flood irrigation to coincide with greater crop maturity. Plants at the tillering development stage (zadoks stage 20) demonstrated a greater resilience to waterlogging stress and promoted greater yield. At the policy level, increasing the availability of diesel pumps on the landscape, and splitting irrigations, would offer farmers greater flexibility in their management to reduce crop stresses and overall risk.
  • Exploring photo elicitation to engage head start families of children with disabilities
    Scholarship
    Creator
    Hile, Kimberly Ann
    Description
    The Individuals with Disabilities Education Act mandates that children with disabilities be provided with individualized supports to maximize their overall development and learning. Caregivers of children ages birth to 5 years play an integral role in determining what supports are most beneficial for the child and their family. Research related to family empowerment and capacity-building suggest that families facing multiple risk factors (e.g., presence of a disability, poverty, single parents, and low levels of maternal education) may experience feelings of powerlessness when asked by professionals to make decisions on behalf of their families. The purpose of this study was to identify effective ways to engage families experiencing multiple risk factors including caring for young children with disabilities, to work collaboratively with Head Start professionals when planning and implementing family-centered interventions. Specifically, collaborations between families and Head Start Family Service Workers and the potential utility for a particular strategy, “photo elicitation,” to empower families to share their personal stories as a pathway to building meaningful relationships was examined. A qualitative approach via thematic analysis was utilized. Findings from this study begin to address the need for identifying innovative strategies for building family capacity with Head Start families, specifically those caring for young children with disabilities.
  • The effects of zinc source and supplemental copper on growth performance, carcass characteristics, and morbidity and...
    Scholarship
    Creator
    Schmitt, Rachel Loren
    Description
    Zinc hydroxychloride and tribasic copper chloride are relatively new mineral sources that are claimed to have improved bioavailability relative to commonly used zinc sources such as zinc oxide. Both sources were evaluated in two studies that were carried out to determine the effects of zinc source and supplemental copper on growth performance, carcass characteristics, and morbidity and mortality of growing-finishing pigs raised under commercial conditions. In both studies, the zinc sources were included at levels to marginally exceed the requirements of growing-finishing pigs suggested by NRC (2012); the copper source, which was only included in the first study, was included to provide pharmacological levels of copper. Study 1 was carried out using a randomized complete block design (blocking factor was date of start on test) to compare 4 treatments: Trt. 1: Control [zinc oxide (assuming 65% bioavailability) + supplemental copper (tribasic copper chloride at 150 ppm)]; Trt. 2: [zinc hydroxychloride (assuming 65% bioavailability) + supplemental copper (tribasic copper chloride at 150 ppm)]; Trt. 3: [zinc hydroxychloride (assuming 100% Bioavailability) + supplemental copper (tribasic copper chloride at 150 ppm)]; and Trt. 4: As Treatment 1 without supplemental copper. The pigs used for Study 2 had previously been allotted to additional experimental treatments that were independent of those used in the current study. Consequently, Study 2 used a split-plot design with the main plot being the additional experimental treatments and the subplot being the two zinc treatments: Trt. 1: Control (zinc oxide assuming 65% bioavailability) and Trt. 2: zinc hydroxychloride (assuming 100% bioavailability). A total of 2,040 (27 replicates) and 2,888 (66 replicates) commercial crossbred barrows and gilts (housed in single-sex groups of 22 at a floor space of 0.59 m2/pig) were used in Studies 1 and 2, respectively. Studies 1 and 2 were carried out from 47.0 ± 5.1 kg to 127.1 ± 3.9 kg body weight and from 41.9 ± 1.7 kg to 132.0 ± 4.4 kg body weight, respectively. There were 5 dietary phases in Study 1 and 3 dietary phases in Study 2. Diets were formulated to a constant standardized ileal digestible lysine:ME ratio within phase and to meet or exceed nutrient requirements suggested by NRC (2012). Ractopamine hydrochloride (7.5 ppm) was included in the final dietary phase in all dietary treatments for both studies. Pen weights and pen feed intakes were collected every 2 and 3 weeks for Studies 1 and 2, respectively, and used to calculate ADG, ADFI and G:F. At the end of the study, pigs were sent to a commercial facility for harvest and collection of carcass measurements. For both studies, the pen of pigs was the experimental unit; data were analyzed using the PROC MIXED procedure of SAS (v. 9.2; SAS Inst. Inc., Cary, NC) with the model accounting for the fixed effects of treatment and the random effects of replicate. Results from Study 1 showed that Trt. 3 had greater (P = 0.04) live weight ADG compared to Trt. 1, with Trt. 2 being intermediate and not different (P = 0.39) than the other 2 treatments (0.97, 0.98, 0.99 kg for Trt. 1, 2, and 3 respectively; SEM 0.03). Treatment 3 also had greater (P = 0.03) live weight G:F than Trt. 2, but not (P = 0.16) Trt. 1 (0.362, 0.361, 0.366 for Trt. 1, 2, and 3 respectively; SEM 0.0024). Adding supplemental copper to the diet had no effect (P > 0.05) on live weight ADG, ADFI, or G:F, however, carcass weight ADG was numerically increased (P = 0.07) and carcass weight G:F was significantly improved (P = 0.03) for Trt. 4 compared to Trt.1. In Study 2, pigs fed diets supplemented with zinc hydroxychloride (Trt. 2) had lower (P < 0.05) overall ADG, on both a live and carcass weight basis (1.021 and 1.002, and 0.821 and 0.780, for Trt. 1 and 2, respectively), and ADFI, (2.62 and 2.59 for Trt. 1 and 2, respectively), but similar (P > 0.05) live weight and carcass weight G:F compared to those fed diets containing zinc oxide (Trt. 1). There was no effect (P > 0.05) of zinc source on carcass measurements or morbidity and mortality in either study. The results for Study 1 suggested comparable or small improvements in growth performance from using zinc hydroxychloride (assumed bioavailability 100%; Trt. 3) compared to zinc oxide. However, the opposite was evident in Study 2. Study 1 also suggested small improvements in growth performance from feeding high levels of copper to growing-finishing pigs. Further research is needed to clearly establish the advantage, if any, of replacing zinc oxide with zinc hydroxychloride and of including high levels of copper as tribasic copper chloride in diets for growing-finishing pigs.
  • Interfacial spallation/delamination properties of self-assembled monolayers
    Scholarship
    Creator
    Zhang, Chen
    Description
    Self-assembled monolayers (SAMs) are short (nanometer-size) organic chains terminated by functional groups that can be selected to tailor the electrical, thermal and/or mechanical properties of interfaces. In this thesis, we investigate how the presence of SAMs affects the failure properties of gold film/silicon/fused silica substrate interfaces. In particular, we study how the presence of SAMs affects (i) the spallation strength and (ii) the fracture toughness of the interface. The modeling work summarized in this thesis is motivated by previous results of molecular dynamic (MD) simulations and laser-induced spallation/delamination tests to quantify the strength and toughness of SAM-enhanced interfaces. Though the results obtained from MD simulations and experimental observations yielded similar trends in comparing the contribution of various SAMs, their actual values were off by significant amounts. The research presented in this dissertation involves the development of continuum-level numerical models to analyze the dynamic spallation and delamination events to fill the gap between MD simulations and experimental results. In the first part of the thesis, a continuum-level study is performed to investigate the influence of surface roughness on the cohesive strength of the interface between a fused silica/SAM substrate and a transfer-printed gold film. We approximate the film as a deformable continuum interacting with a rough substrate of SAM. Using the cohesive law predicted by MD, spallation is simulated to evaluate the effective traction-separation characteristics for the rough SAM-gold interface. The separation attributes based on roughness parameters and material properties of gold film are observed. The dependence of the interfacial cohesive strength of SAM-enhanced interface on incorporating roughness and the thin film properties is studied. In the laser-induced delamination test, the interface fracture energy is computed by assuming all of the kinetic energy imparted into the weak adhesion layer of the film is converted into fracture energy. However, part of this effective interface fracture toughness is associated with plastic deformations in the film. To quantify the plasticity contribution to the effective fracture toughness of the SAM-enhanced interface, we perform an implicit finite element numerical analysis of the dynamic delamination event that incorporated both large deformation and plasticity effects. Cohesive elements whose failure law is derived from MD simulations are introduced along the interface to simulate the failure initiation and debonding process. The amount of dissipated plastic energy is quantified and the film profile is depicted depending on the properties of the thin film and the interfacial attributes. The model is validated with experimental measurements of the crack propagation length, profile of the debonded thin film, and interfacial fracture energy.
  • Creating a PCI express interconnect in the gem5 simulator
    Scholarship
    Creator
    Srinivasan, Krishna Parasuram
    Description
    In this thesis, the objective was to implement a PCI (Peripheral Component Interconnect) Express interconnect in the gem5 architecture simulator. The interconnect was designed with the goal of aiding accurate modeling of PCI Express-based devices in gem5 in the future. The PCI Express interconnect that was created consisted of a root complex, PCI Express switch, as well as individual PCI Express links. Each of these created components can work independently, and can be easily integrated into the existing gem5 platforms for the ARM Instruction Set Architecture. The created PCI Express interconnect was evaluated against a real PCI Express interconnect present on an Intel Xeon server platform. The bandwidth offered by both interconnects was compared by reading data from storage devices using the Linux utility “dd”. The results indicate that the gem5 PCI Express interconnect can provide between 81% - 91.6% of the bandwidth of the real PCI Express interconnect. However, architectural differences between the gem5 and Intel Xeon platforms used, as well as unimplemented features of the PCI Express protocol in the gem5 PCI Express interconnect, necessitate more strenuous validation of the created PCI Express interconnect before reaching a definitive conclusion on its performance.
  • Nelson Oppen combination as a rewrite theory
    Scholarship
    Creator
    Rodrigues, Nishant
    Description
    Solving Satisfiability Modulo Theories (SMT) problems in a key piece in automating tedious mathematical proofs. It involves deciding satisfiability of formulas of a decidable theory, which can often be reduced to solving systems of equalities and disequalities, in a variety of theories such as linear and non-linear real and integer arithmetic, arrays, uninterpreted and Boolean algebra. While solvers exist for many such theories or their subsets, it is common for interesting SMT problems to span multiple theories. SMT solvers typically use refinements of the Nelson-Oppen combination method, an algorithm for producing a solver for the quantifier free fragment of the combination of a number of such theories via cooperation between solvers of those theories, for this case. Here, we present the Nelson-Oppen algorithm adapted for an order-sorted setting as a rewriting logic theory. We implement this algorithm in the Maude System and instantiate it with the theories of real and integer matrices to demonstrate its use in automated theorem proving, and with hereditarily finite sets with reals to show its use with non-convex theories. This is done using both SMT solvers written in Maude itself via reflection (Variant-based satisfiability) and using external solvers (CVC4 and Yices). This work can be considered a first step towards building a rich ecosystem of cooperating SMT solvers in Maude, that modeling and automated theorem proving tools typically written using the Maude System can leverage.
  • Development of an ultraprecision shaping machine for manufacturing of Stavax lens molds
    Scholarship
    Creator
    Moore, Jack
    Description
    The production of high-precision aspheric microlenses has become increasingly difficult due to an increase in the complexity of the profile, the decrease in the lens’ size, and the demand for tighter tolerances. Machines built to fabricate these lenses generally include several expensive components due to the stringent stiffness, resolution, and bandwidth requirements necessary for proper machining. This thesis deals with reducing the cost of production by building an ultraprecision shaping machine that is comprised of three reasonably priced custom made axes that meet the requirements needed for ultraprecision machining. These three axes are (1) a flexure-based, single DOF axis driven by a voice coil actuator, (2) an inchworm axis driven by an assembly of five piezoelectric actuators, and (3) a long range fast tool servo driven by a large piezoelectric actuator. These three axes were developed individually to meet a set of requirements determined necessary for the machining of a microlens mold array in Stavax, a stainless steel variant. Each axis was designed such that it would not fail due to fatigue failure, was capable of achieving a high resolution (< 10 nm), and had a high stiffness in the degrees of constraint (> 200 N/µm). The X-axis needed a range greater than 250 µm, the Y-axis needed a range greater than 3 mm, and the Z-axis needed a range greater than 35 µm. The X-axis needed to be capable of following a low frequency sine wave, while the Z-axis needed to be capable of following high frequency wave forms (200 Hz). Simulations were performed to determine if the designs would meet all the requirements set. All the designed axes have met the requirements, but only the X- and Y-axes have been manufactured for testing. Preliminary testing has shown that the X-axis has at least a stiffness of 60 N/µm in both the degrees of constraint. Movement in the parasitic directions while the axis was being actuated was also tested and showed that the only movement in the parasitic directions is when the X-axis crosses the zero point. Most likely, this is due to the electronics being used, which are also making it difficult to determine the full range of the axis and close the loop. Testing on the Y-axis has revealed that it has a stiffness of at least 125 N/µm in the direction of motion and stiffnesses between 60 N/µm and 100 N/µm in the degrees of constraint. The axis is capable of running at a speed of 150 µm/s, which is only limited by the amplifiers being used. Closed loop testing has shown that the axis is capable of 10 nm steps.
  • Second-harmonic generation-based Mueller matrix polarization analysis of collagen-rich tissues
    Scholarship
    Creator
    Okoro, Chukwuemeka
    Description
    Quantitative assessment of the properties of fibrillar collagen in tissue can yield deeper insight into structure-function correlations of the cell and its surrounding matrix. Second-harmonic generation (SHG) microscopy is especially well-suited as an image acquisition technique, due to its specificity to the non-centrosymmetric structure of collagen, and inherent confocality which enables three-dimensional sectioning. SHG imaging can be undertaken in a quantifiable manner, or combined with other techniques that highlight desired properties. A powerful property for characterizing collagenous tissue microstructure is the Mueller matrix polarization response. Two polarimetric imaging approaches are demonstrated for robust Mueller matrix characterization of collagenous tissue. One approach, called the two-photon Mueller matrix second-harmonic generation (MMSHG) microscopy, involves the generalization of Mueller matrix to the case of two-photon excitation. This 4-by-9 two-photon Mueller matrix is extracted using second-harmonic generation microscopy and analyzed for quantitative collagen assessment. The matrix and associated degree-of-polarization parameter from different sample types and thicknesses are also investigated. It was observed that the polarization-dependent degree-of-polarization distribution shape changes and a model-based bimodal mean difference metric increases with sample thickness. The second polarization technique which we developed, called second-harmonic patterned polarization-analyzed reflection confocal (SPPARC) microscopy, uses the conventional linear polarimetry of confocal images, delineated with a second-harmonic mask. This latter approach, combining the metric richness of linear polarimetry with the specificity of SHG imaging, is used for assessing collagen, as well as non-collagenous regions, in porcine tendon and ligament. We observed differences in depolarization and circular degree-of-polarization parameters, that have potential for dfferentiating tissues in varying states. Next, we present the results of SPPARC microscopy and analysis of collagen on varying pathologies of breast tissues. Experiments were conducted on a breast tissue microarray having benign tissues (BT), malignant invasive lobular carcinoma (ILC), and benign stroma adjacent to the malignant tissues (called the benign adjacent tissue, or BAT). We observed that stroma in BAT and ILC exhibits the largest parameter differences, with collagen readings in ILC showing lower depolarization, lower diattenuation and higher linear degree-of-polarization values than stromal collagen in BAT. This result suggests that the optical properties of collagen change most in the vicinity of tumors. A similar trend is also exhibited in the non-collagenous extrafibrillar matrix plus cells (EFMC) region. We finally discuss additional work involving polarization modeling, setup optimization, and implementation of other decomposition techniques.
  • Stacks in Poisson geometry
    Scholarship
    Creator
    Villatoro, Joel David
    Description
    This thesis is divided into four chapters. The first chapter discusses the relationship between stacks on a site and groupoids internal to the site. It includes a rigorous proof of the folklore result that there is an equivalence between the bicategory of internal groupoids and the bicategory of geometric stacks. The second chapter discusses standard concepts in the theory of geometric stacks, including Morita equivalence, stack symmetries, and some Morita invariants. The third chapter introduces a new site of Dirac structures and provides a rigorous answer to the question: What is the stack associated to a symplectic groupoid? The last chapter discusses a remarkable class of Poisson manifolds, called b-symplectic manifolds, giving a classification of them up to Morita equivalence and computing their Picard group.
  • Relyzer+: An open source tool for application-level soft error resiliency analysis
    Scholarship
    Creator
    Ahmed, Khalique
    Description
    In the modern era of computing, processors are increasingly susceptible to soft errors. Current solutions in both hardware and software enable error detection and correction. Some of these errors, however, go unnoticed by detectors and manifest as silent data corruptions (SDCs) at the application level. Injecting errors into the system and evaluating the outcomes is one method to uncover SDC-causing errors and determine an application's overall resilience to soft errors. The number of possible locations that errors may appear in is large, therefore requiring many injection experiments. One resiliency analysis tool, Relyzer, addresses this issue by performing a comprehensive program analysis to create a small subset of the error injection experiments that can account for the entire application. The limitation of Relyzer is that current analysis can only be performed on one hardwarware instruction set architecture (ISA). Software is usually compiled to multiple ISAs in order to support users with varying hardware configurations. The primary contribution of this thesis is building Relyzer, an open source version of Relyzer implemented using the gem5 simulator. This enables the capability to analyze multiple ISAs and consequently support multiple hardware configurations in the long-term. Specifically, in this work, we develop support for x86. We also evaluate applications across ISAs by generating error resiliency profiles for both x86 and SPARC. After studying five workloads from different domains, we find that in general, application soft error resiliency varies based on the selection of the ISA. The percentage of static instructions that yield SDCs is, on average, 68\% for x86 and 60\% for SPARC, for the applications we studied. Furthermore, this work opens doors to future research in application-level soft error resiliency analysis.
  • Fatigue crack growth in hydrogen pipeline steels
    Scholarship
    Creator
    Che, Ziwei
    Description
    Pipeline hydrogen transport and distribution are contemplated for hydrogen applications. Hydrogen introduction in the natural gas pipeline systems is also considered in the power to gas (P2G) approach to utilizing excess renewable energy when the supply exceeds the demand. It is well known that hydrogen embrittles all carbon steels used to manufacture pipelines and hence, safety and reliability of hydrogen transport requires that pipelines be assessed and tested against hydrogen embrittlement. The most severe embrittlement mechanism is hydrogen accelerated fatigue crack growth since it is well known that hydrogen can enhance fatigue crack growth rates by a factor of 10. In this thesis, the fatigue life of a line pipe manufactured with API steel is calculated by investigating the growth of a semi-elliptical crack on the inner diameter surface due to hydrogen pressure fluctuation. This behavior is compared with the life of the line pipe in an inert environment (e.g. natural gas or N2) under the same pressure fluctuations. The hydrogen or the inert environment pressure history is analyzed with the rainflow counting method and the crack depth calculations are carried out for a variety of API steels at load ratios for a given initial crack depth. The load ratio R equals where and are respectively the minimum and maximum stress intensity factors in a pressure cycle the crack experiences due to the pressure fluctuations. In particular for API X42 steel for which experimental data are available for calculations with greater load ratio, the fatigue life is calculated at load ratios and . The calculation of the stress intensity factor was done by using the closed form solution of Zahoor for which the validity range with regard to the crack and line pipe dimensions was established through comparisons with numerical calculations. The results demonstrate that hydrogen markedly accelerates crack growth and the initial crack depth has significant effect on the pipeline life.
  • Power-law liquid in high-temperature superconductors
    Scholarship
    Creator
    Leong, Zhidong
    Description
    Inspired by recent photoemission measurements, we demonstrate that the normal state of cuprate superconductors can be described by a power-law liquid, a state of matter with a power-law self-energy $\Sigma^{\pr\pr}\sim(\omega^{2}+\pi^{2}T^{2})^{\alpha}$. The scaling exponent decreases from $\alpha\sim1$ in the overdoped Fermi-liquid state to $\alpha\lesssim\frac{1}{2}$ in the optimal and underdoped regime. We find that broad scale invariance of a power-law liquid leads to the cuprates' superconducting dome, vanishing Fermi velocity, and diverging effective mass. We propose that a power-law liquid can arise from the presence of a scale-invariant sector known as unparticles. To extend the power-law liquid framework to include the ubiquitous magnetic phases of high-$T_{c}$ superconductors, we study the local-itinerant dichotomy in iron pnictides. We show that an interplay between localized moments and itinerant electrons is needed to reproduce the spin excitations observed in inelastic neutron scattering experiments. These results further our understanding of the degrees of freedom in high-$T_{c}$ superconductors and will help formulate a consistent framework incorporating the physics of the antiferromagnetic, normal, and superconducting states.
  • A language independent debugger semantics based debugging in K
    Scholarship
    Creator
    Saxena, Manasvi
    Description
    This works presents the K debugger - a language independent program debugger. The debugger is a part of the suite of tools that form the K framework. Conventional language dependent debuggers rely on an ad-hoc model of the underlying programming semantics, and may thus be incapable, or inaccurate in their ability to rectify a program’s behavior. The K debugger uses a different approach - it’s parametric over the K semantics of the programming language, which exposes accurate and subtle faults. The K debugger generalizes behaviors of conventional debuggers, providing users with a uniform interface that works across programming languages. Moreover, the K debugger is formal, performant and highly configurable, allowing it to adapt to the any programming language. This makes the K debugger a suitable replacement to traditional language specific debuggers.
  • Lion: Listen online. Using GraphQL as a mediator for data integration and ingestion
    Scholarship
    Creator
    Tubbs, Dustyn James
    Description
    Data integration is the task of providing a unified view of multiple data sources. Thesesources can be, and are typically, heterogeneous in their data model, data query language (DQL), and data manipulation language (DML). In this thesis is described a system called”Listen Online”, or Lion for short. Lion utilizes the GraphQL specification to provide integration for querying of web services. Lion provides a general structure by which arbitrary mediators can be used within a query. Lastly, by building on top of open source libraries,Lion provides the open source community with components that enable it to function in the form of GraphQL servers, visual layout libraries, and query builders.
  • Water Demand in the Kankakee Water Supply Planning Subregion, 2010-2060
    Scholarship
    Creator
    • Zhang, Zhenxing
    • Kelly, Walton R.
    • Abrams, Daniel
    • Dziegielewski, Benedykt
    • Meyer, Scott C.
  • Geospatial analysis of residential mobility in media: Selling buildings and buying homes
    Scholarship
    Creator
    Shakespeare, Rebecca
    Description
    Americans love media about house-hunting; by analyzing media representations of house-hunting, we can understand more about the reasons that people move and how media narratives reinforce particular ideas about housing. This data visualization contributes to literature highlighting how house-hunting media content, like HGTV, reinforces the idea of housing as a commodity. Using New Yorkers’ residential histories, derived from the text of Joyce Cohen’s weekly real estate column “The Hunt” from the New York Times in 2017, this shows two households’ similar experiences of housing as a commodity. Vertical lines represent the time that households spent living in a specific area and horizontal connectors indicate times that they moved. In the inset, specific events which impacted residential mobility are displayed at the times and locations the events occurred. Two of the fifty weekly columns analyzed included “building sold” as a reason for moving. These households’ demonstrate two ways that housing is treated as a commodity: first, as renters’ buildings are sold for profit; second, as renters buy housing as investments. This geographic visualization of stories, called geo-narrative, provides a spatially and temporally situated view of the intertwined experiences of residents in the same city. Source: The Hunt, weekly house-hunting column in the New York Times.
  • Marital status across the world
    Scholarship
    Creator
    Worthington, Andrea
    Description
    The poster has a multidimensional diagram that represents material status across the world using radar graphs. Each graph has 5 points to represent age ranges from 15 to 65 +. The different sizes of pentagons represent population percentages. Furthermore, the different colored graphs represent male or female and if they are single or married. In addition, the single data also includes divorced and widowed people. This was done to simplify the data. As a result, the data shows the differences between countries and their marital status. The viewer sees how more people are married in Asia then in the United States. Additionally, female teenagers in India have a higher percentage of being married then teenagers in the United the States. In conclusion, the data shows how culture and location effects differences in marital status and creates curiosity into what factors effect why it is different.
  • 9 important facts about GIES courses in summer 2018
    Scholarship
    Creator
    Cao, Yingying
    Description
    This infographic was made per the preliminary survey of online courses in summer 2018. It gives an overview of students’ basic information and their concerns about the courses. Instructors will know better about their students through this info-graphic and can make some adjustments to make the courses fit students better. It also gives a reference for our eLearning office. So we know what technical support to provide to make the learning environment more friendly for students. Thank you for my instructor, Norma who gave me many suggestions for this infographic. Thank you for the eLearning team that trust me and give me the data to do this research.
  • Chicago area background contaminants in wetland sediments and surface waters: Supporting the Calumet Wetlands...
    Scholarship
    Creator
    • Chow, Teresa
    • Bordson, Gary
    • Bogner, William
    • Wiedenmann, Luann
    • Talbott, Jonathan
    • Wilcoxon, Monte
    • Piwani, Marvin
    Description
    The Illinois Department of Natural Resources funded a study at the lllinois Waste Management and Research Center and the Jllinois State Water Survey, to investigate background concentrations of toxic environmental contaminants in the south Chicago area. The study, funded through the Environmental Protection Trust Fund, was undertaken to provide background information on environmental contaminants in support of the Chicago Department of Environment's efforts to revitalize wetlands in the Calumet region of South Chicago. An important component of the revitalization effort is defining ecotoxicological risks in these environments. Criteria to minimize such risks have been developed by the Calumet Ecotox Protocol Technical Team (2005). Surface water and sediment background concentrations for the region's wetlands were identified as lacking. Eight ponds and lakes were sampled for surface waters and sediments. These samples were analyzed for a variety of toxic metal and organic constituents as well as a number of major constituents and other system properties. The water column was largely free of toxic constituents - median values for the measured parameters are provided for the surface waters. The sediment data was subjected to rigorous statistical assessment to generate defensible background concentrations for the region.
  • INHS Reports, December 1987
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Phyllophaga | Winter Populations of Bald Eagles in Illinois | Land Use/Cover and Stream Water Quality
  • INHS Reports, April 1988
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Mussel Die-offs of Biological or Chemical Origin? | Alkaline Hydrogen Peroxide-Treated Straws as Feeds for Crayfish | Plant Cell Response to Stress
  • INHS Reports, January 1986
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Mushrooms and Spring Fever | Pine Squirrels in Deciduous Forests | Conservation Tillage and Pesticides
  • INHS Reports, October 1986
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Seasonal Dynamics in Small Wetland Ponds | In Memoriam Philip Wayne Smith | Lead Poisoning in Waterfowl
  • Water Supply Planning: Middle Illinois Assessment of Water Resources for Water Supply-Final Report
    Scholarship
    Creator
    • Kelly, Walton R.
    • Zhang, Zhenxing
    • Mannix, Devin H.
    • Roadcap, George S.
    • Thomason, Jason F.
    • Knapp, H. Vernon
    • Dziegielewski, Benedykt
    • Lian, Yanqing
    • Abrams, Daniel B.
    • Hadley, Daniel R.
    • Meyer, Scott C.
  • INHS Reports, June 1987
    Scholarship
    Creator
    Illinois Natural History Survey
    Description
    Natural Resources Book Ready for Distribution | Mycology of Cypress Swamps | Biologic and Genetic Diversity of Illinois Plants
  • Illinois Fire Service Institute - 2006 82nd Annual Fire College Brochure
    Scholarship
    Creator
    Illinois Fire Service Institute
    Description
    This brochure, produced in 2006, describes the information and courses offered during the 82nd Annual Fire College at the Illinois Fire Service Institute.
  • Illinois Fire Service Institute - 2009 Winter Fire School Flier
    Scholarship
    Creator
    Illinois Fire Service Institute
    Description
    This marketing flier, produced in 2009, describes the information and courses offered during the Winter Fire School at the Illinois Fire Service Institute.