110 research outputs found
Earnings Extrapolation And Predictable Stock Market Returns
The U.S. stock marketās return during the first month of a quarter correlates strongly with returns in future months, but the correlation is negative if the future month is the first month of a quarter, and positive if it is not. These effects offset, leaving the market return with its weak unconditional predictive ability known to the literature. The pattern accords with a model in which investors extrapolate announced earnings to predict future earnings, not recognizing that earnings in the first month of a quarter are inherently less predictable than in other months. Survey data support this model, as does out-of-sample return predictability across industries and international markets. These results challenge the Efficient Market Hypothesis and advance a novel mechanism of expectation formation
Nanoscale Texture and Microstructure in a NdFeAs(O,F)/IBAD-MgO Superconducting Thin Film with Superior Critical Current Properties
This paper reports the nanoscale texture and microstructure of a high-performance NdFeAs(O,F) superconducting thin film grown by molecular beam epitaxy on a textured MgO/Y2O3/Hastelloy substrate. The NdFeAs(O,F) film forms a highly textured columnar grain structure by epitaxial growth on the MgO template. Although the film contains stacking faults along the ab-plane as well as grain boundaries perpendicular to the ab-plane, good superconducting properties are measured: a critical temperature, T-c, of 46 K and a self-field critical current density, J(c), of 2 x 10(6) A/cm(2) at 4.2 K. Automated crystal orientation mapping by scanning precession electron diffraction in transmission electron microscope is employed to analyze the misorientation angles between adjacent grains in a large ensemble (247 grains), and 99% of the grain boundaries show in-plane misorientation angles (Delta gamma) less than the critical angle theta(c), which satisfies one of the necessary conditions for the high J(c). Comparing the columnar grain size distribution with the mean distance of the flux line lattice, the triple junctions of low-angle grain boundaries are found to be effective pinning centers, even at high temperatures (>= 35 K) and/or low magnetic fields
Potential immune evasion of the severe acute respiratory syndrome coronavirus 2 Omicron variants
Coronavirus disease 2019 (COVID-19), which is caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a global pandemic. The Omicron variant (B.1.1.529) was first discovered in November 2021 in specimens collected from Botswana, South Africa. Omicron has become the dominant variant worldwide, and several sublineages or subvariants have been identified recently. Compared to those of other mutants, the Omicron variant has the most highly expressed amino acid mutations, with almost 60 mutations throughout the genome, most of which are in the spike (S) protein, especially in the receptor-binding domain (RBD). These mutations increase the binding affinity of Omicron variants for the ACE2 receptor, and Omicron variants may also lead to immune escape. Despite causing milder symptoms, epidemiological evidence suggests that Omicron variants have exceptionally higher transmissibility, higher rates of reinfection and greater spread than the prototype strain as well as other preceding variants. Additionally, overwhelming amounts of data suggest that the levels of specific neutralization antibodies against Omicron variants decrease in most vaccinated populations, although CD4+ and CD8+ T-cell responses are maintained. Therefore, the mechanisms underlying Omicron variant evasion are still unclear. In this review, we surveyed the current epidemic status and potential immune escape mechanisms of Omicron variants. Especially, we focused on the potential roles of viral epitope mutations, antigenic drift, hybrid immunity, and āoriginal antigenic sinā in mediating immune evasion. These insights might supply more valuable concise information for us to understand the spreading of Omicron variants
The competition and equilibrium in power markets under decarbonization and decentralization
Equilibrium analysis has been widely studied as an effective tool to model gaming interactions and predict market results. However, as competition modes are fundamentally changed by the decarbonization and decentralization of power systems, analysis techniques must evolve. This article comprehensively reviews recent developments in modelling methods, practical settings and solution techniques in equilibrium analysis. Firstly, we review equilibrium in the evolving wholesale power markets which feature new entrants, novel trading products and multi-stage clearing. Secondly, the competition modes in the emerging distribution market and distributed resource aggregation are reviewed, and we compare peer-to-peer clearing, cooperative games and Stackelberg games. Furthermore, we summarize the methods to treat various information acquisition degrees, risk preferences and rationalities of market participants. To deal with increasingly complex market settings, this review also covers refined analytical techniques and agent-based models used to compute the equilibrium. Finally, based on this review, this paper summarizes key issues in the gaming and equilibrium analysis in power markets under decarbonization and decentralization
Household, community, sub-national and country-level predictors of primary cooking fuel switching in nine countries from the PURE study
Introduction. Switchingfrom polluting (e.g. wood, crop waste, coal)to clean (e.g. gas, electricity) cooking
fuels can reduce household air pollution exposures and climate-forcing emissions.While studies have
evaluated specific interventions and assessed fuel-switching in repeated cross-sectional surveys, the role
of different multilevel factors in household fuel switching, outside of interventions and across diverse
community settings, is not well understood. Methods.We examined longitudinal survey data from
24 172 households in 177 rural communities across nine countries within the Prospective Urban and
Rural Epidemiology study.We assessed household-level primary cooking fuel switching during a
median of 10 years offollow up (ā¼2005ā2015).We used hierarchical logistic regression models to
examine the relative importance of household, community, sub-national and national-level factors
contributing to primary fuel switching. Results. One-half of study households(12 369)reported
changing their primary cookingfuels between baseline andfollow up surveys. Of these, 61% (7582)
switchedfrom polluting (wood, dung, agricultural waste, charcoal, coal, kerosene)to clean (gas,
electricity)fuels, 26% (3109)switched between different polluting fuels, 10% (1164)switched from clean
to polluting fuels and 3% (522)switched between different clean fuels
Earnings Extrapolation and Predictable Stock Market Returns
The U.S. stock marketās return during the first month of a quarter correlates strongly with returns in future months, but the correlation is negative if the future month is the first month of a quarter, and positive if it is not. These effects offset, leaving the market return with its weak unconditional predictive ability known to the literature. The pattern accords with a model in which investors extrapolate announced earnings to predict future earnings, not recognizing that earnings in the first month of a quarter are inherently less predictable than in other months. Survey data support this model, as does out-of-sample return predictability across industries and international markets. These results challenge the Efficient Market Hypothesis and advance a novel mechanism of expectation formation
Thiol-acrylate side-chain liquid crystal elastomers
The Michael addition āclickā chemistry was used to graft acrylate-terminated mesogenic groups onto the polysiloxane backbone polymer chain with thiol functional groups, with a constant 15% fraction of diacrylate reacting monomers as crosslinkers. Three different types of mesogens were used, and also their 50:50 mixtures, and in all cases we have obtained the smectic-A phase of the resulting liquid crystalline elastomer. Using the Xray diffraction, calorimetry and dynamic mechanical testing, we investigated the relationship between the molecular structure of mesogenic side groups and the structure and properties of the elastomers. The shape-memory of smectic elastomers was verified. The unusual features were the semi-crystalline nature of elastomers with non-polar mesogens, and the clear role of of side-by-side rod dimerization of polar mesogens leading to the higher smectic layer spacing. We investigated the evolution of the smectic alignment on uniaxial stretching along the layer normal, and identified two distinct ways the elastomer response: the coarsened Helfrich-Hurault zig-zag layer texture, and the large-scale stripe domains of uniform layer rotation in the systems with lower order parameter and the associated layer constraints
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MaināChain Nematic SideāChain Smectic Composite Liquid Crystalline Elastomers
A composite liquid crystalline elastomer is designed, combining maināchain and sideāchain mesogenic polymers in the network, and resulting in microāphase separated regions of nematic and smectic ordering in the macroscopically homogeneous elastomer. A range of different fractions of the components is explored, from fully nematic maināchain system, across to fully smectic sideāchain elastomer. Thermal phase transitions of both phases coexisting in the material are detected by calorimetry, and the nematic/smectic structure investigated by Xāray scattering. The tensile stressāstrain data reveal the key effect of such a multiāphase composite, where the nematic fraction adds ductility while the smectic fraction increases the modulus and mechanical stiffness. Varying the composition, the authors are able to optimize the mechanical properties of this material type
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