Matching Items (434)

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The Effect of Executive Control Depletion on Within-Task Transfer

Description

In everyday life, mental fatigue can be detrimental across many domains including driving, learning, and working. Given the importance of understanding and accounting for the deleterious effects of mental fatigue

In everyday life, mental fatigue can be detrimental across many domains including driving, learning, and working. Given the importance of understanding and accounting for the deleterious effects of mental fatigue on behavior, a growing body of literature has studied the role of executive control processes in mental fatigue. In a laboratory setup, participants complete a task that places demands on executive control processes and are later given a transfer task. Generally speaking, decrements to subsequent task performance are taken as evidence that the initial executive control task created mental fatigue through the continued engagement of executive control. Several hypotheses have been developed to account for negative transfer resulting from executive control depletion including cognitive resource depletion and task-switching. In the current study, we provide a brief literature review, specify current theoretical approaches to depletion, and provide a strong empirical test of theories for negative transfer from executive control depletion (i.e., does continued performance of an executive control task negatively transfer to that exact same task).

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Date Created
  • 2014-12

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An Analysis of Bias in Competitive Academic Debate

Description

Through collection of survey data on the characteristics of college debaters, disparities in participation and success for women and racial and ethnic minorities are measured. This study then uses econometric

Through collection of survey data on the characteristics of college debaters, disparities in participation and success for women and racial and ethnic minorities are measured. This study then uses econometric tools to assess whether there is an in-group judging bias in college debate that systematically disadvantages female and minority participants. Debate is used as a testing ground for competing economic theories of taste-based and statistical discrimination, applied to a higher education context. The study finds persistent disparities in participation and success for female participants. Judges are more likely to vote for debaters who share their gender. There is also a significant disparity in the participation of racial and ethnic minority debaters and judges, as well as female judges.

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Date Created
  • 2014-12

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University Student Knowledge and Perception of Influenza

Description

Influenza has shown its potential to affect and even kill millions of people within an extremely short time frame, yet studies and surveys show that the general public is not

Influenza has shown its potential to affect and even kill millions of people within an extremely short time frame, yet studies and surveys show that the general public is not well educated about the facts about influenza, including prevention and treatment. For this reason, public perception of influenza is extremely skewed, with people generally not taking the disease as seriously as they should given its severity. To investigate the inconsistencies between action and awareness of best available knowledge regarding influenza, this study conducted literature review and a survey of university students about their knowledge, perceptions, and action taken in relationship to influenza. Due to their dense living quarters, constant daily interactions, and mindset that they are "immune" to fairly common diseases like influenza, university students are a representative sample of urban populations. According to the World Health Organization (WHO), 54% of the world's population lived in cities as of 2014 (Urban population growth). Between 2015 and 2020, the global urban population is expected to grow 1.84% per year, 1.63% between 2020 and 2025, and 1.44% between 2025 and 2030 (Urban population growth). Similar projections estimate that by 2017, an overwhelming majority of the world's population, even in less developed countries, will be living in cities (Urban population growth). Results of this study suggest possible reasons for the large gap between best available knowledge and the perceptions and actions of individuals on the other hand. This may lead to better-oriented influenza education initiatives, more effective prevention and treatment plans, and generally raise excitement and awareness surrounding public health and scientific communication.

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  • 2014-12

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Life, Death, and In-between: When Biomedical Technology Meets Science Fiction Films

Description

Science fiction has a unique ability to express, analyze, and critique concepts in a subtle way that emphasizes a point but is still entertaining to the audience. Because of science

Science fiction has a unique ability to express, analyze, and critique concepts in a subtle way that emphasizes a point but is still entertaining to the audience. Because of science fiction's ability to do this it has long been a powerful way to ask questions that would normally not be addressed. As such, this paper provides an overview of the effects of biomedical technology in science fiction films. The discussions in this paper will analyze the different portrayals of the technology in the viewed cinematic pieces and the effects they have on the characters in the film. The discussion will begin with the films that have technology based in Genetic Engineering. This will then be followed by a discussion of the biomedical technology based in the fields of Endocrinology; Reanimation; Preservation; Prosthetics; Physical Metamorphosis; Super-Drugs and Super-Viruses; and Diagnostic, Surgical, and Monitoring Equipment. At the end of this paper movie summaries are provided to assist in clarifying plot details.

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Created

Date Created
  • 2014-05

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Development of a Novel Smart Contrast Agent for Magnetic Resonance Imaging

Description

Smart contrast agents allow for noninvasive study of specific events or tissue conditions inside of a patient's body using Magnetic Resonance Imaging (MRI). This research aims to develop and characterize

Smart contrast agents allow for noninvasive study of specific events or tissue conditions inside of a patient's body using Magnetic Resonance Imaging (MRI). This research aims to develop and characterize novel smart contrast agents for MRI that respond to temperature changes in tissue microenvironments. Transmission Electron Microscopy, Nuclear Magnetic Resonance, and cell culture growth assays were used to characterize the physical, magnetic, and cytotoxic properties of candidate nanoprobes. The nanoprobes displayed thermosensitve MR properties with decreasing relaxivity with temperature. Future work will be focused on generating and characterizing photo-active analogues of the nanoprobes that could be used for both treatment of tissues and assessment of therapy.

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Date Created
  • 2014-05

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Phase Recovery and Unimodular Waveform Design

Description

In many systems, it is difficult or impossible to measure the phase of a signal. Direct recovery from magnitude is an ill-posed problem. Nevertheless, with a sufficiently large set of

In many systems, it is difficult or impossible to measure the phase of a signal. Direct recovery from magnitude is an ill-posed problem. Nevertheless, with a sufficiently large set of magnitude measurements, it is often possible to reconstruct the original signal using algorithms that implicitly impose regularization conditions on this ill-posed problem. Two such algorithms were examined: alternating projections, utilizing iterative Fourier transforms with manipulations performed in each domain on every iteration, and phase lifting, converting the problem to that of trace minimization, allowing for the use of convex optimization algorithms to perform the signal recovery. These recovery algorithms were compared on a basis of robustness as a function of signal-to-noise ratio. A second problem examined was that of unimodular polyphase radar waveform design. Under a finite signal energy constraint, the maximal energy return of a scene operator is obtained by transmitting the eigenvector of the scene Gramian associated with the largest eigenvalue. It is shown that if instead the problem is considered under a power constraint, a unimodular signal can be constructed starting from such an eigenvector that will have a greater return.

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Date Created
  • 2014-05

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Preferences for Group Risk and Inequality

Description

Economists, political philosophers, and others have often characterized social preferences regarding inequality by imagining a hypothetical choice of distributions behind "a veil of ignorance". Recent behavioral economics work has shown

Economists, political philosophers, and others have often characterized social preferences regarding inequality by imagining a hypothetical choice of distributions behind "a veil of ignorance". Recent behavioral economics work has shown that subjects care about equality of outcomes, and are willing to sacrifice, in experimental contexts, some amount of personal gain in order to achieve greater equality. We review some of this literature and then conduct an experiment of our own, comparing subjects' choices in two risky situations, one being a choice for a purely individualized lottery for themselves, and the other a choice among possible distributions to members of a randomly selected group. We find that choosing in the group situation makes subjects significantly more risk averse than when choosing an individual lottery. This supports the hypothesis that an additional preference for equality exists alongside ordinary risk aversion, and that in a hypothetical "veil of ignorance" scenario, such preferences may make subjects significantly more averse to unequal distributions of rewards than can be explained by risk aversion alone.

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Created

Date Created
  • 2014-05

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Ways of Thinking for Developing an Understanding of Covariational Reasoning in Undergraduate Calculus Students

Description

Previous research discusses students' difficulties in grasping an operational understanding of covariational reasoning. In this study, I interviewed four undergraduate students in calculus and pre-calculus classes to determine their ways

Previous research discusses students' difficulties in grasping an operational understanding of covariational reasoning. In this study, I interviewed four undergraduate students in calculus and pre-calculus classes to determine their ways of thinking when working on an animated covariation problem. With previous studies in mind and with the use of technology, I devised an interview method, which I structured using multiple phases of pre-planned support. With these interviews, I gathered information about two main aspects about students' thinking: how students think when attempting to reason covariationally and which of the identified ways of thinking are most propitious for the development of an understanding of covariational reasoning. I will discuss how, based on interview data, one of the five identified ways of thinking about covariational reasoning is highly propitious, while the other four are somewhat less propitious.

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Date Created
  • 2014-05

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Incorporating the Sparsity of Edges into the Fourier Reconstruction of Piecewise Smooth Functions

Description

In applications such as Magnetic Resonance Imaging (MRI), data are acquired as Fourier samples. Since the underlying images are only piecewise smooth, standard recon- struction techniques will yield the Gibbs

In applications such as Magnetic Resonance Imaging (MRI), data are acquired as Fourier samples. Since the underlying images are only piecewise smooth, standard recon- struction techniques will yield the Gibbs phenomenon, which can lead to misdiagnosis. Although filtering will reduce the oscillations at jump locations, it can often have the adverse effect of blurring at these critical junctures, which can also lead to misdiagno- sis. Incorporating prior information into reconstruction methods can help reconstruct a sharper solution. For example, compressed sensing (CS) algorithms exploit the expected sparsity of some features of the image. In this thesis, we develop a method to exploit the sparsity in the edges of the underlying image. We design a convex optimization problem that exploits this sparsity to provide an approximation of the underlying image. Our method successfully reduces the Gibbs phenomenon with only minimal "blurring" at the discontinuities. In addition, we see a high rate of convergence in smooth regions.

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Date Created
  • 2014-05

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Nutrient dynamics of photodegradation for Ambrosia deltoidea litter in an arid, urban ecosystem

Description

The nutrient dynamics of degradation have been studied almost exclusively in mesic (not arid or semi-arid) ecosystems. In arid ecosystems, we do know that photodegradation can cause significant mass loss

The nutrient dynamics of degradation have been studied almost exclusively in mesic (not arid or semi-arid) ecosystems. In arid ecosystems, we do know that photodegradation can cause significant mass loss and that lignin plays a dual role in the processes of degradation: it slows biodegradation due to its rigid chemical structure but can speed up photodegradation via the carbon mineralization process. This experiment attempts to assess the nutrient dynamics of nitrogen (N) and phosphorus (P) that occur while overall mass is being lost via photodegradation. We took Ambrosia deltoidea litter from 5 sites within the Phoenix city core and 5 sites downwind of the city of Phoenix. Half of this litter was N and P enriched from a previous experiment and half was control. We split the litter into UV opaque and UV transparent litter bags that had holes punched in them to allow microbial interaction. These bags were picked up at sampling periods of 10, 20, 30, and 40 weeks. All samples were then tested for mass loss, lignin content, carbon (C) content, N content, and P content. We found that downwind samples lost more mass than the core. There was little effect over time on N content and little disparity in P trends between the samples. P behaved as expected with an initial rise due to microbial interaction and then a decline as the microbes released P. Lignin concentration rose in a similar fashion at both core and downwind sites confirming that lignin remains in litter through the process of photodegradation. One interesting result was an logarithmic-like decrease in C:N ratio and C:P ratio for the downwind samples but a fairly constant ratio in the core samples. It is clear that these decreasing ratios result not from increased N or P, but instead from rapidly decreasing C. Overall, we conclude that neither N nor P is affected significantly by photodegradation at either site. N deposition appears to slow mass loss, but speed up N release, at least in the early stages of decomposition.

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  • 2013-12