3,495 research outputs found

    Poisson noise reduction with non-local PCA

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    Photon-limited imaging arises when the number of photons collected by a sensor array is small relative to the number of detector elements. Photon limitations are an important concern for many applications such as spectral imaging, night vision, nuclear medicine, and astronomy. Typically a Poisson distribution is used to model these observations, and the inherent heteroscedasticity of the data combined with standard noise removal methods yields significant artifacts. This paper introduces a novel denoising algorithm for photon-limited images which combines elements of dictionary learning and sparse patch-based representations of images. The method employs both an adaptation of Principal Component Analysis (PCA) for Poisson noise and recently developed sparsity-regularized convex optimization algorithms for photon-limited images. A comprehensive empirical evaluation of the proposed method helps characterize the performance of this approach relative to other state-of-the-art denoising methods. The results reveal that, despite its conceptual simplicity, Poisson PCA-based denoising appears to be highly competitive in very low light regimes.Comment: erratum: Image man is wrongly name pepper in the journal versio

    Assessing Bioavailability, Metal Fractionation, Magnetic Susceptibility, and Organic Matter Interactivity in Mine-Waste Contaminated Sediments in Turkey Creek, Joplin, Missouri

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    Joplin, Missouri, part of the Tri-State Mining District (TSMD), has a long history of mining that resulted in mine waste piles proximal to the mines throughout the area. A local lead smelter also resulted in smelter fallout in Joplin. Mine waste pile runoff and local smelter fallout resulted in contamination of sediments, soils, and waterways. In the 1990s, remediation of residential soils and play areas began after blood lead levels in children were much higher than the national average. Soon afterwards, the chat piles were removed and used for beneficial reuse purposes. In May of 2011, an EF5 tornado devastated the town of Joplin, and spread contaminated soils across the area yet again. This study investigates relationships between total metal concentration; it’s bioavailable fraction (exchangeable and carbonate-bound phases), potentially bioavailable fractions (reducible phases or metal stored in iron and manganese oxides) and their association to organic matter content, and magnetic susceptibility in sediments from Turkey Creek. Thirty-five samples from Turkey Creek were analyzed for total metal concentrations and bioavailability by assessing the percent of total metal released in the first two extractions according to the BCR sequential extraction scheme. Loss on ignition and magnetic susceptibility were determined to find any relation to either fraction. Fractionation trends were highly variable between sediment samples. 1-45% of Zn, 0-46% of Cd, and 0-11% of Pb occupied exchangeable and carbonate bound fractions, 3-97% of Zn, 2-91% of Cd, and 3-99% of Pb occupied iron and manganese oxide fractions and 2-97% of Zn, 8-94% of Cd, and 0-99% of Pb occupied organic and residual fractions of sediment. A risk assessment code (RAC) (%) was performed for Zn, Pb, and Cd where 17% of samples for Zn were considered very high risk and 23% were considered high risk, and 9% of samples for Cd were considered very high risk and 14% were considered high risk, whereas no Pb samples were considered high risk or very high risk. Total metal concentrations were high for Zn, Cd, and Pb in several samples, exceeding TSMD-specific Probable Effect Concentrations (PECs) in 57% of samples for Zn, 51% of samples for Cd, and 57% of samples for Pb. Further, 57% of samples exceeded the Sum Probable Effect Quotient which evaluates risk to aquatic fauna

    Dissemination of herpes simplex virus in the pregnant rabbit /

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    Assessment of the interrelationships between fish population dynamics and limnological characteristics of Iowa lakes

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    Lakes are important resources and understanding relationships between fish, humans, and environmental conditions is critical for guiding management activities. We examined fish populations, limnological conditions, lake basin morphology, and watershed characteristics in 129 Iowa lakes. Our purpose was to evaluate patterns in population characteristics of important fish species in relation to environmental conditions. Bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides abundance was highest in systems with high water transparency and nutrients. Catch rates of bluegill, black crappie, and largemouth bass were generally low when omnivores (e.g., black bullhead Ameiurus melas, common carp Cyprinus carpio) were present. Body condition of the study species was highest in highly productive lakes with clear water. Bluegill and largemouth bass condition and bluegill growth showed evidence of density dependence. This study suggests that high water transparency generally resulted in high relative abundance, good condition, and fast growth of sport fishes in Iowa\u27s highly productive lakes

    The Impact of Automation Etiquette on User Performance and Trust in Non-Personified Technology

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    Previous research has shown that good automation etiquette can yield positive effects on user performance, trust, satisfaction, and motivation. Automation etiquette is especially influential in personified technologies – users have increased etiquette expectations from technology that has human characteristics. Designers deliberately integrate etiquette into personified technologies to account for users’ anthropomorphization and meet user needs. The current study examined the impact of etiquette in non-personified technologies. The study aimed to demonstrate that automation etiquette also affects performance, trust, perceived workload, and motivation in technologies that possess little to no human characteristics. The study used a computer-based automation task to examine good and bad etiquette models and different domain-based perceived task-importance, or “criticality” levels (between-subjects) that contained various stages of automation and automation reliability levels (within-subjects). The study found that bad etiquette automation produced better performance in certain conditions. Confirming previous research, we found that users trust good etiquette automation more than bad etiquette automation in some trust categories. This study provides evidence that automation complexity correlates with automation etiquette’s impact – as automation complexity increases, so does automation etiquette’s impact on performance and in some cases trust. We found that bad automation etiquette can increase user’s subjective workload. Last, we confirmed that our domain-based task criticality manipulation was effective. Future research should examine additional domains, tasks, etiquette delivery mechanisms, and etiquette scales coupled with varied degrees of automation complexity to better understand etiquette’s role in human-automation interaction

    Spatial Biodegradation Of MC252 Crude Oil On A Coastal Headland Beach

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    Following the Deepwater Horizon oil spill in April, 2010, hard structures were constructed to deter oil migration into sensitive marsh areas behind Fourchon Beach, LA These hard structures created conditions for accumulation and burial of oil across an 8 foot deep beach vertical profile. Buried oil persists in these areas due to anaerobic conditions of beach groundwater. The objectives of this thesis are to compare the rate and extent of biodegradation of 3-ring PAHs in crude oil deposits from the surface and subsurface, and to investigate effects on beach groundwater after introduction of O2. Field samples were removed from 2011-2016 from the area including oil samples from depth with a Geoprobe, oil-sand aggregates distributed over the surface of the beach, free oil floating on the groundwater surface and oil recovered during excavations used as part of response in 2013 and 2015. Weathering of PAHs was estimated based on ratios of alkylated phenanthrenes and dibenzothiophenes to poorly biodegradable chrysenes. The average weathering ratio was 0.731±0.22 for phenanthrenes and 0.48±0.22 for dibenzothiophenes. Results indicate that oil weathers significantly differently based on location in the beach vertical profile. Oil above the groundwater table was significantly more than buried oil below groundwater level. Oil above the groundwater table weathers up to 2 orders of magnitude faster than buried oil below groundwater level. A field trial of in situ biostimulation demonstrated the ability to amend groundwater with oxygen. Weathering of oil buried below the groundwater surface was seen. Terminal electron acceptors and nutrients were evaluated based on repetitive (pre and post oxygen introduction) groundwater analysis of O2, nitrate, nitrite, ferrous and ferric iron, sulfate, sulfide, ammonium, orthophosphate, pH and alkalinity. Results suggest that oxygenated groundwater is confined locally to emitter wells due to slow groundwater movement. Nutrient concentrations pH and temperature are sufficient for microbial function; however the hypersaline nature of the groundwater may limit microbe population

    Foot-Controlled Supernumerary Robotic Arm: Control Methods and Human Abilities

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    Supernumerary robotic limbs (SRLs) are extra robotic appendages that help a user with various tasks. A challenge with SRLs is how to operate them effectively. One solution is to use the foot to teleoperate the arm, freeing the person to use their arms for other tasks. However, unlike hand interfaces, it is not known how to create effective foot control for robotic teleoperation. A foot interface is developed for an experiment to compare position and rate control with the foot. Position control is shown to be more effective than rate control for 2D positioning tasks. Even if an effective control strategy is implemented, it is currently unknown if a person has the ability to control a robot with their foot while simultaneously using both arms. A second experiment shows that humans can operate an SRL with the foot while performing a task with both hands

    Who Supports Labor? The Intersection of Race and Skill in Union Campaigns

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    In the past half century, there has been an unprecedented decline in labor union membership, organizing ability, political effectiveness and strike activity in the United States. As a result, the ability of labor unions to influence the debate on labor standards and social reforms has experienced a significant decline. Using a mixed method approach, this research explores differences in attitudes and orientations towards labor unions across racial groups in the United States as well as organizational strategies and capacities of a labor union in a right-to-work state. Although African Americans and Latinos have been discriminated against at the hands of organized labor, the quantitative component of this research indicates that minority groups hold more positive attitudes towards unions than whites. In light of this fact, organized labor has been slow to realize that its revitalization may be contingent upon the ability of unions to organize and recruit minority populations and very little emphasis has been placed on the effects of racial differences in attitudes and orientations toward union membership and union support. Although the quantitative component of this research indicates that minority groups hold more positive attitudes towards unions, the qualitative component of this research argues that the challenges of organizing in a cross-class, cross-race union extend beyond racial and ethnic difference to issues of skill. This research, therefore, attempts to illustrate how a labor union in a right-to-work state navigates the intersection of race and skill in union campaigns

    The State of the Union? Transnational Manufacturing and the US Labor Movement

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    The process of globalization has fundamentally altered the relationship between states, corporations, and trade unions. The increased mobility of capital combined with the desire among state actors to attract foreign direct invest has led to an unprecedent decline in trade union density in nearly every developed nation. This decline is concerning because numerous studies have indicated that trade union density is a key factor in mitigating the impacts of globalization and combatting economic inequality. As a result, states and state actors should increasingly look for ways to facilitate the expansion of trade union density. One promising avenue for doing so involves examining the behavior of foreign owned firms operating in the US. Using a combination of ethnographic and comparative historical methods, this dissertation explores the labor practices of Volkswagen Group of America with a specific eye towards how union representation is negotiated with the United Automobile Workers. Although Volkswagen is a company with a celebrated labor history and a unique model of employee representation, the efforts to organize a works council and certify a labor union at their Chattanooga facility were met with hostility on the part of the firm, outside pressure groups, and state politicians. This dissertation argues that the changing composition of the state apparatus has led to a situation in which the capitalist class is increasingly responsible for guiding policies that, in both the short and long term, disproportionately harm members of the working class

    Optimizing Cross-Battery Assessment Procedures For Reading-Based Specific Learning Disorder Diagnosis: A Monte Carlo Study

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    Specific Learning Disorder is a disorder in which deficits in academic skills are caused by specific cognitive deficits. Cross-Battery Assessment (Flanagan, Alfonso, & Ortiz, 2013), is a popular method of diagnosing specific learning disorders. A recent study using data simulation methods claimed that cross-battery assessment was insufficiently accurate for clinical use (Stuebing, Fletcher, Branum-Martin, & Francis, 2012). However, the study used the general population base rate for specific learning disorders, resulting in misleadingly low accuracy estimates. The current study attempted to accurately simulate the cross-battery assessment method with a referred population prevalence to provide a fair analysis of cross-battery assessment’s diagnostic accuracy. Under the assumptions modeled, cross-battery assessment’s positive predictive value for specific learning disorder detection was between 71% and 93%, with negative predictive value between 43% to 80%. In addition, each additional testing phase adds increased diagnostic accuracy with diminishing returns
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