Electronic and optical hybrid materials via self-assembly and nanoimprint lithography

Polymer/nanoparticle hybrid materials organized at the local level by additive driven self-assembly and patterned at the device level using nanoimprint lithography offer versatile approaches to the solution-based fabrication of nanostructured devices. Block copolymers have long held promise for templating periodic functional materials, however the ability to fabricate well-ordered composites with high loadings of nanoparticles and with domain sizes large enough to be useful for the manipulation of visible light has remained challenging. We demonstrate the formation of well-ordered nanocomposites with tunable magnetic and optical characteristics containing up to 70 wt. % of metal, metal oxide and/or semiconducting nanoparticles through phase specific interactions of the particles with the block copolymer templates. In one example metallodielectric 1D photonic crystals with controlled domain spacings between 120 nm and 260 nm were prepared using amphiphilic (polynorbornene-g-polystyrene)-b-(polynorbornene-g-polyethylene oxide) brush BCPs as the templates and hydrogen bonding as a driving force for the selective incorporation of gold NPs into hydrophilic domains at gold core loadings of up to 50 wt.%. In a second example, we prepared composites with tunable magnetic permeability and high Verdet constants by phase selective incorporation of FePt and ZrO2 nanoparticles in poly(styrene-block-2-vinylpyridine) (PS-b-PVP) diblock copolymer templates in collaboration with the Norwood Group at the University of Arizona. The magnetic character of the composite was tuned by controlling the FePt particle size (2-12 nm) and loading within the PVP domains while the refractive index of the composite was tuned by controlling the loading of zirconia nanoparticles. The small size and excellent dispersion of the NPs in the block copolymer domains provide very good optical transmission. Applications include high performance magnetic field imaging sensors and optical isolators. Nanoimprint lithography (NIL) offers high precision patterning of structures as small as 50 nm using wafer-based or roll-to-roll process platforms, however current resist systems offer little functionality. We developed hybrid UV-NIL resists containing up to 90 wt. % nanoparticles with excellent optical transparency for direct patterning of device structures including a readily scalable print, lift, and stack approach for producing large-area, 3D photonic crystal (PC) structures and optical gratings. Grating structures composed of highly filled NP polymer composite resists with tunable refractive indices (RI) between 1.58 and 1.92 at 800 nm were prepared using hybrid resists composed of anatase titania (TiO2) NPs, between 5 and 30 nm in diameter, and a UV-curable acrylate host. The gratings were robust and upon release from a support substrate were oriented and stacked to yield 3D PCs. The grating structure dimensions, line width, depth, and pitch were easily varied by simply changing the imprint mold. A six-layer log-pile stack was prepared using a composite resist containing 50 wt. % TiO2 NPs with an RI of 1.72 and yielded up to 72% reflection at 840 nm. Extension of these approaches to other materials systems and applications will be discussed

Converging transnational financial reporting standards: Validating the joint FASB/IASB concept of information quality

Accelerating cross-border investing activity transformed global financial markets during the latter part of the 20th century. Due to lack of trans-cultural consistency comparability in financial reporting was compromised hindering multinational investment. In light thereof there is a movement afoot among international authorities to converge national financial reporting standards into a single international financial reporting system. In September 2010 Financial Accounting Standards Board and International Accounting Standards Board agreed on a concept of information quality to guide formulation of internationally acceptable financial reporting standards. The Boards\u27 goal is sustenance of local relevance while achieving transnational comparability. Toward that end, instead of trade-offs among qualities of information assumed by previous concepts, the new concept posits faithful representation working in concert with relevance in a sequential approach to information quality. Variously referred to as Framework 2010 the purpose of this dissertation was to determine its validity. The concept was tested using Partial Least Squares methodology over a survey of US accountants. Fundamental qualities of relevance and faithful representation were found to be significant predictors of decision usefulness as were enhancing qualities of verifiability and comparability. Faithful representation was found to be a significant, partial mediator of relationship between relevance (predictor) and decision usefulness (outcome). Final model predicted 43.1% of variance in decision usefulness

IT Outsourcing: Examined Under the Resource-Based View Lens

The proponents of the resource-based view (RBV) have long argued that a firm gains sustainable competitive advantage from those resources and capabilities it controls and which are valuable, rare, imperfectly imitable, and not substitutable. So, does information technology (IT) outsourcing strip companies of any competitive advantage that is attributed to IT? It has been said that information systems that cannot sustain competitive advantage are transient and are not expected to enhance firm valuation. In that case, does it imply that outsourcing of certain aspects of IT can lead to sustained competitive advantage? Therefore, this paper’s main research question is: Does IT outsourcing lead to sustained competitive advantage for a firm? In order to empirically examine this, it is proposed to study the impact of IT outsourcing announcements on firm valuation using the event study methodology

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

Spherulites are spherical clusters of radiating crystals that occur naturally in rhyolitic obsidian. The growth of spherulites requires diffusion and uptake of crystal forming components from the host rhyolite melt or glass, and rejection of non-crystal forming components from the crystallizing region. Water concentration profiles measured by synchrotron-source Fourier transform spectroscopy reveal that water is expelled into the surrounding matrix during spherulite growth, and that it diffuses outward ahead of the advancing crystalline front. We compare these profiles to models of water diffusion in rhyolite to estimate timescales for spherulite growth. Using a diffusion-controlled growth law, we find that spherulites can grow on the order of days to months at temperatures above the glass transition. The diffusion-controlled growth law also accounts for spherulite size distribution, spherulite growth below the glass transition, and why spherulitic glasses are not completely devitrified

A scoping review finds a growing trend in studies validating multimorbidity patterns and identifies five broad types of validation methods

Objectives: Multimorbidity, the presence of two or more long-term conditions, is a growing public health concern. Many studies use analytical methods to discover multimorbidity patterns from data. We aimed to review approaches used in published literature to validate these patterns.Study design and setting: We systematically searched PubMed and Web of Science for studies published between July 2017 and July 2023 that used analytical methods to discover multimorbidity patterns.Results: Out of 31,617 studies returned by the searches, 172 were included. Of these, 111 studies (64%) conducted validation, the number of studies with validation increased from 53.13% (17 out of 32 studies) to 71.25% (57 out of 80 studies) in 2017-2019 to 2022-2023, respectively. Five types of validation were identified: assessing the association of multimorbidity patterns with clinical outcomes (n = 79), stability across subsamples (n = 26), clinical plausibility (n = 22), stability across methods (n = 7) and exploring common determinants (n = 2). Some studies used multiple types of validation.Conclusion: The number of studies conducting a validation of multimorbidity patterns is clearly increasing. The most popular validation approach is assessing the association of multimorbidity patterns with clinical outcomes. Methodological guidance on the validation of multimorbidity patterns is needed

10-year multimorbidity patterns among people with and without rheumatic and musculoskeletal diseases: an observational cohort study using linked electronic health records from Wales, UK

Objectives To compare the patterns of multimorbidity between people with and without rheumatic and musculoskeletal diseases (RMDs) and to describe how these patterns change by age and sex over time, between 2010 and 2019.Participants 103 426 people with RMDs and 2.9 million comparators registered in 395 Wales general practices (GPs). Each patient with an RMD aged 0–100 years between January 2010 and December 2019 registered in Clinical Practice Research Welsh practices was matched with up to five comparators without an RMD, based on age, gender and GP code.Primary outcome measures The prevalence of 29 Elixhauser-defined comorbidities in people with RMDs and comparators categorised by age, gender and GP practices. Conditional logistic regression models were fitted to calculate differences (OR, 95% CI) in associations with comorbidities between cohorts.Results The most prevalent comorbidities were cardiovascular risk factors, hypertension and diabetes. Having an RMD diagnosis was associated with a significantly higher odds for many conditions including deficiency anaemia (OR 1.39, 95% CI (1.32 to 1.46)), hypothyroidism (OR 1.34, 95% CI (1.19 to 1.50)), pulmonary circulation disorders (OR 1.39, 95% CI 1.12 to 1.73) diabetes (OR 1.17, 95% CI (1.11 to 1.23)) and fluid and electrolyte disorders (OR 1.27, 95% CI (1.17 to 1.38)). RMDs have a higher proportion of multimorbidity (two or more conditions in addition to the RMD) compared with non-RMD group (81% and 73%, respectively in 2019) and the mean number of comorbidities was higher in women from the age of 25 and 50 in men than in non-RMDs group.Conclusion People with RMDs are approximately 1.5 times as likely to have multimorbidity as the general population and provide a high-risk group for targeted intervention studies. The individuals with RMDs experience a greater load of coexisting health conditions, which tend to manifest at earlier ages. This phenomenon is particularly pronounced among women. Additionally, there is an under-reporting of comorbidities in individuals with RMDs

Ranking sets of morbidities using hypergraph centrality

Multi-morbidity, the health state of having two or more concurrent chronic conditions, is becoming more common as populations age, but is poorly understood. Identifying and understanding commonly occurring sets of diseases is important to inform clinical decisions to improve patient services and outcomes. Network analysis has been previously used to investigate multi-morbidity, but a classic application only allows for information on binary sets of diseases to contribute to the graph. We propose the use of hypergraphs, which allows for the incorporation of data on people with any number of conditions, and also allows us to obtain a quantitative understanding of the centrality, a measure of how well connected items in the network are to each other, of both single diseases and sets of conditions. Using this framework we illustrate its application with the set of conditions described in the Charlson morbidity index using data extracted from routinely collected population-scale, patient level electronic health records (EHR) for a cohort of adults in Wales, UK. Stroke and diabetes were found to be the most central single conditions. Sets of diseases featuring diabetes; diabetes with Chronic Pulmonary Disease, Renal Disease, Congestive Heart Failure and Cancer were the most central pairs of diseases. We investigated the differences between results obtained from the hypergraph and a classic binary graph and found that the cen-trality of diseases such as paraplegia, which are connected strongly to a single other disease is exaggerated in binary graphs compared to hypergraphs. The measure of centrality is derived from the weighting metrics calculated for disease sets and further investigation is needed to better understand the effect of the metric used in identifying the clinical significance and ranked centrality of grouped diseases. These initial results indicate that hypergraphs can be used as a valuable tool for analysing previously poorly understood relationships and in-formation available in EHR data