MAP Estimation for Hyperspectral Image Resolution Enhancement Using an Auxiliary Sensor

This paper presents a novel maximum a posteriori (MAP) estimator for enhancing the spatial resolution of an image using co-registered high spatial-resolution imagery from an auxiliary sensor. Here we focus on the use of high-resolution panchomatic data to enhance hyperspectral imagery. However, the estimation framework developed allows for any number of spectral bands in the primary and auxiliary image. The proposed technique is suitable for applications where some correlation, either localized or global, exists between the auxiliary image and the image being enhanced. To exploit localized correlations, a spatially varying statistical model, based on vector quantization, is used. Another important aspect of the proposed algorithm is that it allows for the use of an accurate observation model relating the “true” scene with the low-resolutions observations. Experimental results with hyperspectral data derived from the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) are presented to demonstrate the efficacy of the proposed estimator

Secondary Electron Yield Measurements of Carbon Nanotube Forests: Dependence on Morphology and Substrate

Total, secondary, and backscatter electron yield data were taken with beam energies between 15 eV and 30 keV, in conjunction with energy emission data, to determine the extent of suppression of yield caused by carbon nanotube (CNT) forest coatings on substrates. CNT forests can potentially lower substrate yield due to both its inherently low-yield, low-atomic number (Z) carbon composition, and its bundled, high-aspect ratio structure. Rough surfaces, and in particular, surfaces with deep high-aspect-ratio voids, can suppress yields, as the electrons emitted from lower lying surfaces are recaptured by surface protrusions rather than escaping the near-surface region. Yields of multilayered materials can be modeled essentially serially as a combination of the constituents. However, it is shown that suppression of yields due to CNT forest morphology is more significant than simple predicted contributions of homogeneous layered components. This effect is found to be most pronounced at low energies, where the incident electrons interact preferentially with the CNTs. CNT forests between 20 and 50 μm tall were grown on a thick silicon substrate capped with a 3-nm diffusion barrier of evaporated aluminum using a wet injection chemical vapor deposition (CVD) method. Yields of an annealed substrate and constituent bulk materials were also investigated. At incident electron energies above ~1200 eV, the substrate secondary yield dominated those of the CNT forests, as incident electrons penetrated through the low-density, low-Z CNT forests, and backscattered from the higher-Z substrate. At lower energies \u3c1200 \u3eeV, the CNT forests substantially reduced the overall yields of the substrate, and for \u3c500 eV CNT forest yields were \u3c1, well below the already low yields of bulk graphite. This suppressed yield at low energies is attributed to the porosity and preferred vertical alignment of the CNT forest. The yield’s dependence on the height and density of the CNT forest is also discussed

Influence of Vibrationally-Induced Structural Changes on Carbon Nanotube Forests Suppression of Electron Yield

Carbon nanotube (CNT) forest coatings have been found to lower electron yield from material surfaces. The suppressed yields have been attributed to both the lower inherent yields of low-atomic number carbon and the enhanced electron recapture resulting from the morphology of the carbon layer. To explore the relative contributions of these two causes of yield suppression, tests have been made on CNT forest-coated conducting substrate samples subjected to vibrationally-induced changes of the coating structure. The extent of vibrationally-induced structural changes—due, for example, to shear-force conditions during space-vehicle transit—are of interest, as CNT have been a frequent topic of scientific curiosity and space applications due to their high tensile strength, high aspect ratio geometry, and unique electromagnetic characteristics. Their use has also been beneficial for sensor equipment, both terrestrial and space-faring, due to their extremely low photon and electron reflectivity

Suppresion of Electron Yield With Carbon Nanotube Forests: A Case Study

Electron emission of carbon nanotube (CNT) forests grown on silicon substrates was measured to investigate possible electron yield suppression due to the composition and morphology of CNT forests. CNT forests are vertically-oriented tubular formations of graphitic carbon grown on a substrate; these have been widely investigated for their extreme properties in optical, electrical, and mechanical aspects of physics and material sciences. CNT coatings are good candidates for yield reduction, in analogy with the near-ideal blackbody optical properties of CNT forests. Carbon with its low atomic number has an inherent low yield due to its low density of bulk electrons. Furthermore, the large aspect ratio of this vertically-aligned CNT allows for easy penetration of the high energy incident electrons, but enhanced recapture of lower-energy secondary electrons due to their wider angular distribution of emission. Total (TEY), secondary (SEY) and backscattered (BSEY) yield curves using 15 eV to 30 keV electron beams, along with energy emission spectra, were acquired for three CNT forest samples to determine the extent of yield suppression of the substrate due to the CNT forests [Wood, 2018]

Investigation into the mechanism of catalysis for the kinetic resolution of a,a-Disubstituted y-Hydroxy Esters

The synthesis of enantioenriched, biologically active compounds is a vital area of interest for synthetic chemists. The lactone motif is found in several biologically important molecules, and the development of kinetic resolutions capable of producing enantioenriched lactones is important for the total synthesis of these types of compounds. The chiral Brønsted-acid catalyst, R-TRIP, has proven to be effective in producing enantioenriched a,a-disubstituted lactones with up to 94% ee. A study of the effects of varying electronic substituents on the kinetic resolution of a,a-disubstituted-?-hydroxy esters to produce enantioenriched ?-lactones is the focus of this study. The introduction of varying electron-withdrawing and electron-donating substituents in the para position of an a-Ph group is hypothesized to cause a change in the selectivity and rate of reaction through resonance, induction, hydrogen bonding and pi-stacking. This project seeks to broaden the scope and understanding of the catalyst-substrate interaction to improve upon this synthetic methodology. [This abstract has been edited to remove characters that will not display in this system. Please see the PDF for the full abstract.]]]> 2018 Esterification Esters $x Synthesis Esters$x Synthesis English http://libres.uncg.edu/ir/uncg/f/Wilson_uncg_0154M_12503.pdf oai:libres.uncg.edu/23278 2018-07-10T14:19:31Z UNCG Grabbing him by the tweets: presidential parody as political activism NC DOCKS at The University of North Carolina at Greensboro Wood, Olivia <![CDATA[It has never been easier for presidents to communicate directly with voters. Social media allows world leaders to post messages to their followers anytime, anywhere, without going through the traditional channels of speechwriters or public relations staff. Donald Trump in particular has become famous--and heavily criticized--for his unorthodox use of Twitter. This criticism has taken many forms, including a crop of Trump-themed parody accounts, tweeting in character as some version of the president. Political satire is nothing new, but social media platforms offer a new genre in which to do it. In this paper, I examine the parodic methods of five different Donald Trump parody accounts on Twitter and compare them to the rhetorical style of @realDonaldTrump. Methods of analysis included code frequency comparisons across accounts, code intersection patterns, word and phrase frequency comparisons, interviews with account owners, and comparative ethnography. Donald Trump parody accounts on Twitter sit at the intersections of new forms of presidential communication, new uses of digital media, and new strategies for activism. Analyzing their role at this crossroads necessitates considerations of genre, rhetorical situation, and the affordances of the platform. My research thus contributes to discussions of genre and digital rhetorical theory by examining our current political situation and how rhetors are employing digital strategies in this controversial real world setting. I approach this project with four research questions: 1) In what ways are different accounts parodying the president, and what rhetorical effects do each of these methods have? 2) What elements of the actual president’s real account do the parodies focus on? How do they differ linguistically from each other and from @realDonaldTrump? 3) How do parody accounts fit into the broader set of anti-Trump activism? 4) What political issues do the different accounts highlight, and what can readers gain from them (other than entertainment)? How do parody accounts communicate a message differently than other types of activism? My results provide a rhetorical picture of @realDonaldTrump’s Twitter activity in late May/early June of 2017 alongside the activities of his parodists, showing how the parodists view the president and which political issues the parodists find most important to discuss

Can a combination of the conformal thin-sandwich and puncture methods yield binary black hole solutions in quasi-equilibrium?

We consider combining two important methods for constructing quasi-equilibrium initial data for binary black holes: the conformal thin-sandwich formalism and the puncture method. The former seeks to enforce stationarity in the conformal three-metric and the latter attempts to avoid internal boundaries, like minimal surfaces or apparent horizons. We show that these two methods make partially conflicting requirements on the boundary conditions that determine the time slices. In particular, it does not seem possible to construct slices that are quasi-stationary and avoid physical singularities and simultaneously are connected by an everywhere positive lapse function, a condition which must obtain if internal boundaries are to be avoided. Some relaxation of these conflicting requirements may yield a soluble system, but some of the advantages that were sought in combining these approaches will be lost.Comment: 8 pages, LaTeX2e, 2 postscript figure

Right ventricular outflow tract velocity time integral-to-pulmonary artery systolic pressure ratio: a non-invasive metric of pulmonary arterial compliance differs across the spectrum of pulmonary hypertension.

Pulmonary arterial compliance (PAC), invasively assessed by the ratio of stroke volume to pulmonary arterial (PA) pulse pressure, is a sensitive marker of right ventricular (RV)-PA coupling that differs across the spectrum of pulmonary hypertension (PH) and is predictive of outcomes. We assessed whether the echocardiographically derived ratio of RV outflow tract velocity time integral to PA systolic pressure (RVOT-VTI/PASP) (a) correlates with invasive PAC, (b) discriminates heart failure with preserved ejection-associated PH (HFpEF-PH) from pulmonary arterial hypertension (PAH), and (c) is associated with functional capacity. We performed a retrospective cohort study of patients with PAH (n = 70) and HFpEF-PH (n = 86), which was further dichotomized by diastolic pressure gradient (DPG) into isolated post-capillary PH (DPG \u3c 7 mmHg; Ipc-PH, n = 54), and combined post- and pre-capillary PH (DPG ≥ 7 mm Hg; Cpc-PH, n = 32). Of the 156 patients, 146 had measurable RVOT-VTI or PASP and were included in further analysis. RVOT-VTI/PASP correlated with invasive PAC overall (ρ = 0.61, P \u3c 0.001) and for the PAH (ρ = 0.38, P = 0.002) and HFpEF-PH (ρ = 0.63, P \u3c 0.001) groups individually. RVOT-VTI/PASP differed significantly across the PH spectrum (PAH: 0.13 [0.010-0.25] vs. Cpc-PH: 0.20 [0.12-0.25] vs. Ipc-PH: 0.35 [0.22-0.44]; P \u3c 0.001), distinguished HFpEF-PH from PAH (AUC = 0.72, 95% CI = 0.63-0.81) and Cpc-PH from Ipc-PH (AUC = 0.78, 95% CI = 0.68-0.88), and remained independently predictive of 6-min walk distance after multivariate analysis (standardized β-coefficient = 27.7, 95% CI = 9.2-46.3; P = 0.004). Echocardiographic RVOT-VTI/PASP is a novel non-invasive metric of PAC that differs across the spectrum of PH. It distinguishes the degree of pre-capillary disease within HFpEF-PH and is predictive of functional capacity

Sample preference for colorectal cancer screening tests: blood or stool?

Objective: Despite the high prevalence of CRC and the proven benefits of faecal sampling tests, participation rates in CRC screening are suboptimal. Literature has identified a number of barriers to participation, including faecal aversion. Emerging test technologies suggest blood-based molecular markers might provide an alternative, more acceptable option, for CRC screening tests. We aim to determine preference for blood compared to faeces as the sample for the screening test. Methods: A survey was mailed to 956 South Australians aged 50 to 74 years. Data were collected on sample preference, demographic variables, and ratings of screening test convenience and comfort. Results: The survey yielded a 43% response rate. The majority of participants preferred to provide a blood sample (78% v 22%, p < 0.001). Women were more likely to prefer blood than men (82% vs 74%, p = 0.05). Sample experience influenced preferences, with a significantly higher preference for faeces among participants with experience in faecal sampling (27% vs 17% with no experience, p < 0.05). Participants who preferred to provide a faecal sample rated it significantly more convenient (p < 0.001), more comfortable (p < 0.001), and more acceptable (p < 0.001) than those who preferred blood sampling. Conclusions: Survey participants overwhelmingly indicate a preference for the idea of a blood sample over a faecal sample for CRC screening. Preference was influenced by gender, experience with sampling method and the individual’s perception of sampling convenience, sampling comfort and sample acceptability. Our results suggest population participation rates are likely to improve with blood-based screening tests.Joanne M. Osborne, Carlene Wilson, Vivienne Moore, Tess Gregory, Ingrid Flight, Graeme P. Youn