A model for the scattering of high-frequency electromagnetic fields from dielectrics exhibiting thermally-activated electrical losses

An equivalent circuit model (ECM) approach is used to predict the scattering behavior of temperature-activated, electrically lossy dielectric layers. The total electrical response of the dielectric (relaxation + conductive) is given by the ECM and used in combination with transmission line theory to compute reflectance spectra for a Dallenbach layer configuration. The effects of thermally-activated relaxation processes on the scattering properties is discussed. Also, the effect of relaxation and conduction activation energy on the electrical properties of the dielectric is described

Glass formation, properties, and structure of soda-yttria-silicate glasses

The glass formation region of the soda yttria silicate system was determined. The glasses within this region were measured to have a density of 2.4 to 3.1 g/cu cm, a refractive index of 1.50 to 1.60, a coefficient of thermal expansion of 7 x 10(exp -6)/C, softening temperatures between 500 and 780 C, and Vickers hardness values of 3.7 to 5.8 GPa. Aqueous chemical durability measurements were made on select glass compositions while infrared transmission spectra were used to study the glass structure and its effect on glass properties. A compositional region was identified which exhibited high thermal expansion, high softening temperatures, and good chemical durability

Local growth of icosahedral quasicrystalline tilings

Icosahedral quasicrystals (IQCs) with extremely high degrees of translational order have been produced in the laboratory and found in naturally occurring minerals, yet questions remain about how IQCs form. In particular, the fundamental question of how locally determined additions to a growing cluster can lead to the intricate long-range correlations in IQCs remains open. In answer to this question, we have developed an algorithm that is capable of producing a perfectly ordered IQC, yet relies exclusively on local rules for sequential, face-to-face addition of tiles to a cluster. When the algorithm is seeded with a special type of cluster containing a defect, we find that growth is forced to infinity with high probability and that the resultant IQC has a vanishing density of defects. The geometric features underlying this algorithm can inform analyses of experimental systems and numerical models that generate highly ordered quasicrystals.Comment: 13 pages, 15 figures, 1 tabl

Dynamics of multi-kinks in the presence of wells and barriers

Sine-Gordon kinks are a much studied integrable system that possesses multi-soliton solutions. Recent studies on sine-Gordon kinks with space-dependent square-well-type potentials have revealed interesting dynamics of a single kink interacting with wells and barriers. In this paper, we study a class of smooth space-dependent potentials and discuss the dynamics of one kink in the presence of different wells. We also present values for the critical velocity for different types of barriers. Furthermore, we study two kinks interacting with various wells and describe interesting trajectories such as double-trapping, kink knock-out and double-escape.Comment: 17 pages, 7 figure

Evidence-Based Policy and Misinformation: Exploring the Public’s Processing of Information

As the online spread of misinformation increases, policymakers are finding it more difficult to ensure that the public is only exposed to the evidence they share and that their evidence is believed. Policymakers find they must now combat misinformation spread by a variety of entities. This dissertation explored thematic concepts regarding information in existing literature – information as a thing, information as a public good, information as propaganda, information use by elected officials, and information on social media. This dissertation exposed participants to conservative and liberal misinformation and corrective information to determine how they processed policy information. This study explored if the political nature of a resource, a person’s political ideology, and political party can influence participants’ trust of resources and the believability of policy information. It repeatedly measured participants’ policy support levels to identify if exposure to misinformation and corrective information has a significant impact on their support of a policy. The experiments measured these effects regarding climate change, immigration, and transgendered individuals serving in the military policy. This dissertation revealed misinformation and corrective information does not have a significant influence on person’s support of a policy. This study also confirmed that the political leaning of a source, political ideology, and political party values, in some cases, can sway if a person trusts a resource or if they believe policy information. This study determined that people are more likely to believe misinformation in conservative resources and conservatives are more likely to not trust corrective information, no matter the source

An ethnographic study of family, livelihoods and women's everyday lives in Dakar, Senegal

This thesis explores competing meanings of being a woman in Dakar, Senegal. Above all, it is concerned with the relationship between livelihoods – how ordinary Dakarois make ends meet – and women’s gendered identities. It explores the full spectrum of Dakar women’s economic activities, all the while keeping the definition of what, precisely, qualifies as ‘economic’ or as ‘work’ as open as possible. Distancing itself from approaches that privilege the sexual aspects of gender, this thesis asks what kinds of gendered economic identities emerge in the context of the various roles and relationships that constitute women’s everyday lives. What do women do that enables people in this society to get by and to secure their day-­‐to-­‐day needs? How are these activities experienced, and what kind of values are they imbued with? Based on three years’ fieldwork in low-­‐income neighbourhoods across the Dakar region, the thesis advances an ethnographic analysis of women’s roles as wives and girlfriends, sisters and sisters-­‐in-­‐law, daughters, mothers and grandmothers, and members of extended family and community networks. It explores women’s activities as dependents, consumers, providers and informal-­‐sector workers. Together, the chapters shed light on the complexities and contradictions involved in being a woman in this particular part of the world. Building on the ethnographic findings, this thesis argues that it is possible to identify two distinct, even competing conceptions of being a woman in Dakar. One of these can be framed in terms of ‘materialism’, the other around the emic concept of ‘mothering work’. Dakar women, this thesis suggests, draw on both in order to create, defend and challenge the meaning and the value of their everyday experiences

Modelling and system identification of a stiff stay wire fence machine

This paper investigates a severe gear backlash problem encountered in a stiff stay machine that is capable of producing a 26 line fence up to 2.6 metres in height at a speed of 80 stays/minute. Related problems in the literature, typically concentrate on the effect of gear backlash on the ability to control a shaft. However, in this case, very good control of the reference speed of the shaft was maintained in spite of the gear backlash. The problem was that the commanded torques were excessively large and threatened to damage the gear box. This problem motivated a complete analysis of the systems dynamics including the development of a model to better understand the response and allow the identification of external loads on the system. It was found that the method of sensing the shaft position (resolvers) was a major factor as well as the upgrading of the motor which was over responding to disturbances in the shaft. The model was validated using several torque limiting experiments and gave accurate prediction of the machine’s major dynamics. The simulation tool developed provides the basis to predict the effect of different loads, wire types and/or motors on the machine for future designs minimizing the amount of experimentation on the machine

Comprehensive analysis of common serum liver enzymes as prospective predictors of hepatocellular carcinoma in HBV patients.

BACKGROUND: Serum liver enzymes are frequently tested in clinics to aid disease diagnosis. Large observational studies indicated that these enzymes might predict cancer risk and mortality. However, no prospective study has reported on their relationships with the risk of HBV-related hepatocellular carcinoma (HCC). METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the predictive values of four routinely tested liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP], and gamma-glutamyltransferase [GGT]) in HCC risk in a prospectively enrolled clinical cohort of 588 Korean American HBV patients. For all four enzymes, the baseline level as well as the average and maximum levels during the first 1 or 2 years of follow-up were analyzed using multivariate Cox proportional hazards model. Patients were categorized into a normal or an elevated group based on the clinical cut-off of each enzyme. During a median follow-up of 7.5 years, 52 patients (incidence rate, 8.8%) developed HCC. The incidence rates were higher in the elevated groups for all four enzymes. The most significant finding was for GGT, with the highest incidence rate of 16.4% in the elevated group compared to 4.6% in the normal group (

A multi-modal data resource for investigating topographic heterogeneity in patient-derived xenograft tumors.

Patient-derived xenografts (PDXs) are an essential pre-clinical resource for investigating tumor biology. However, cellular heterogeneity within and across PDX tumors can strongly impact the interpretation of PDX studies. Here, we generated a multi-modal, large-scale dataset to investigate PDX heterogeneity in metastatic colorectal cancer (CRC) across tumor models, spatial scales and genomic, transcriptomic, proteomic and imaging assay modalities. To showcase this dataset, we present analysis to assess sources of PDX variation, including anatomical orientation within the implanted tumor, mouse contribution, and differences between replicate PDX tumors. A unique aspect of our dataset is deep characterization of intra-tumor heterogeneity via immunofluorescence imaging, which enables investigation of variation across multiple spatial scales, from subcellular to whole tumor levels. Our study provides a benchmark data resource to investigate PDX models of metastatic CRC and serves as a template for future, quantitative investigations of spatial heterogeneity within and across PDX tumor models