1,522 research outputs found

    Developing Firmware for Space Weather Probes 2 Using HDL Coder

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    GPS and wireless communications are affected by interference from the ionosphere. Space weather affects plasma in the ionosphere, causing communication disruptions and reliability issues. To better understand how space weather affects the ionosphere, instruments are flown in space to collect data about the electrical characteristics of plasma in the ionosphere. Space systems require a lot of time and effort to develop and test. This thesis explores how a high level tool can be used to simplify the process and some obstacles that still exist with developing some space systems. To do this, the firmware architecture of a new version of the Space Weather Probes (SWP) was developed and documented in this thesis

    Defect Detection Limits for Additively Manufactured Parts Using Current Thermography Techniques

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    Additive manufacturing (AM) will support NASA in their moon and mars missions by reducing the amount of redundant equipment carried into space and by providing crew members with the flexibility to design and create parts as needed. The ability to monitor the quality of these additively manufactured parts is critical, especially when using recycled or in-situ materials as NASA plans to do. This project assesses the possibility of detecting small, shallow AM defects with existing active thermography techniques. An axisymmetric, numerical model was created in COMSOL to simulate the heat transfer within AM structures during active thermography. The effects of surface convection, heat conduction through the subsurface defect, and radiative in-depth absorption were included in the model. The simulation results estimate the minimum detectable defect diameter for a given defect depth using a common thermography technique. Additionally, the data demonstrates conditions for which 1D thermography models may be applied to 3D systems

    Automated Testing of Spatially-Dependent Environmental Hypotheses through Active Transfer Learning

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    The efficient collection of samples is an important factor in outdoor information gathering applications on account of high sampling costs such as time, energy, and potential destruction to the environment. Utilization of available a-priori data can be a powerful tool for increasing efficiency. However, the relationships of this data with the quantity of interest are often not known ahead of time, limiting the ability to leverage this knowledge for improved planning efficiency. To this end, this work combines transfer learning and active learning through a Multi-Task Gaussian Process and an information-based objective function. Through this combination it can explore the space of hypothetical inter-quantity relationships and evaluate these hypotheses in real-time, allowing this new knowledge to be immediately exploited for future plans. The performance of the proposed method is evaluated against synthetic data and is shown to evaluate multiple hypotheses correctly. Its effectiveness is also demonstrated on real datasets. The technique is able to identify and leverage hypotheses which show a medium or strong correlation to reduce prediction error by a factor of 1.4--3.4 within the first 7 samples, and poor hypotheses are quickly identified and rejected eventually having no adverse effect.Comment: Accepted for publication and presentation at ICRA 202

    An AGN Identification for 3EG J2006-2321

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    We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321. The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of archived radio data indicate that its radio counterpart is PMN J2005-2310, a flat-spectrum radio quasar with a 5-GHz flux density of 260 mJy. Study of the V=18.7V=18.7 optical counterpart indicates a redshift of 0.833 and variable linear polarization. No X-ray source has been detected near the position of PMN J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper limit provides for a spectral energy distribution with global characteristics similar to those of known gamma-ray blazars. Taken together, these data indicate that 3EG J2006-2321, listed as unidentified in the 3rd EGRET Catalog, is a member of the blazar class of AGN. The 5-GHz radio flux density of this blazar is the lowest of the 68 EGRET-detected AGN. The fact that EGRET has detected such a source has implications for unidentified EGRET sources, particularly those at high latitudes (∣b∣>30∘|b|>30^{\circ}), many of which may be blazars.Comment: 22 pages, 6 figures. To appear in ApJ v569 n1, 10 April 200

    [Wallace-Hardeman correspondence, May 19, 1945-October 3, 1945]

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    https://digitalcommons.acu.edu/crs_books/1424/thumbnail.jp

    Beta Human Papillomavirus 8E6 Attenuates Non-Homologous End Joining by Hindering DNA-PKcs Activity

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    Cutaneous viral infections occur in a background of near continual exposure to environmental genotoxins, like UV radiation in sunlight. Failure to repair damaged DNA is an established driver of tumorigenesis and substantial cellular resources are devoted to repairing DNA lesions. Beta-human papillomaviruses (β-HPVs) attenuate DNA repair signaling. However, their role in human disease is unclear. Some have proposed that β-HPV promotes tumorigenesis, while others suggest that β-HPV protects against skin cancer. Most of the molecular evidence that β-HPV impairs DNA repair has been gained via characterization of the E6 protein from β-HPV 8 (β-HPV 8E6). Moreover, β-HPV 8E6 hinders DNA repair by binding and destabilizing p300, a transcription factor for multiple DNA repair genes. By reducing p300 availability, β-HPV 8E6 attenuates a major double strand DNA break (DSB) repair pathway, homologous recombination. Here, β-HPV 8E6 impairs another DSB repair pathway, non-homologous end joining (NHEJ). Specifically, β-HPV 8E6 acts by attenuating DNA-dependent protein kinase (DNA-PK) activity, a critical NHEJ kinase. This includes DNA-PK activation and the downstream of steps in the pathway associated with DNA-PK activity. Notably, β-HPV 8E6 inhibits NHEJ through p300 dependent and independent means. Together, these data expand the known genome destabilizing capabilities of β-HPV 8E6

    Effect of Lunar Dust Simulant on Human Epithelial Cell Lines

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    The purpose of this project is to assess the potential toxicity of lunar dust to cause the release of pro-inflammatory cytokines by human lung cells. Some of this dust is on the scale of 1-2 micrometers and could enter the lungs when astronauts track dust into the habitat and inhale it. This could be a serious problem as NASA plans on going back to the moon for an extended period of time. Literature shows that quartz, which has a known cytoxicity, can cause acute cases of silicosis within 6 months, and in most cases cause silicosis after 3 years. The activation of lunar dust through impacts creates surface based radicals which, upon contact with water create hydroxl radicals and peroxyl radicals which are very reactive and potentially might even be as cytotoxic as quartz. These radicals could then react with lung cells to produce pro-inflammatory mediators such as interleukin-6 and interleukin-8, and TNF-alpha

    Spectral Absorption Coefficient of Additive Manufacturing Polymers

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    As NASA turns to additive manufacturing processes, there is a need to ensure that the parts they produce are reliable. This is especially true when creating parts in space, where resources are limited and failure could result in catastrophe. Active thermography has shown potential as a non-destructive quality assurance technique for additive manufacturing processes. Heat transfer models used in active thermography techniques require accurate material property measurements in order to extract useful information about the system, including defect location. The spectral absorption coefficient, which determines the depth at which radiative power is absorbed into a surface, is a material property necessary for performing active thermography on AM polymers. This paper presents measurements of spectral absorption coefficients of polymers commonly used in additive manufacturing. Spectral absorption coefficients for fully dense PLA, ABS, and Nylon 12 samples are reported. Future work is needed to measure the spectral absorption coefficients of different materials and colored filaments commonly used in additive manufacturing

    Cost of Attendance: The Development of Financial Literacy for First-Generation, Low-Income, Community College Students of Color

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    University of Minnesota PhD dissertation. February 2018. Major: Organizational Leadership, Policy, and Development. Advisor: Rebecca Ropers-Huilman. 1 computer file (PDF): x, 263 pages.First-generation, low-income, community college students of color represent one of the fastest growing segments of the undergraduate student population in the United States. With college costs continuing to rise, student debt levels at record highs, and socioeconomic disparities that include growing income and wealth gaps, it is particularly important to understand the development of financial literacy for these students. This qualitative research is a critical phenomenology and is rooted in critical race theory. Employing a semi-structured long-interview protocol, textural-structural themes and invariant constituents gleaned from the coded responses in 22 interviews were used to create 22 sub-thematic categories that organized the findings. A portion of these data are presented as ten counterstories, organized in four main themes that address the three questions presented in this research. The first theme that emerged from the data is that first-generation, low-income, community college students of color demonstrate tremendous resilience from early socioeconomic challenges in the development of their financial literacy. Second, first-generation, low-income, community college students of color expand understanding of students who attend community college by challenging flawed sociocultural assumptions of deficit. Third, a focus on financial assets versus financial deficits is key to development of financial literacy for these students. Finally, in the development of financial literacy for first-generation, low-income, community college students of color, structural racism originates and harms from inside as well as outside communities of color. This dissertation concludes with a discussion of theoretical implications for the development of critical race method as well as practical implications for financial aid and student services professionals, faculty, and other institutional administrators
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