Kinetic Monte Carlo simulation of faceted islands in heteroepitaxy using multi-state lattice model

A solid-on-solid model is generalized to study the formation of Ge pyramid islands bounded by (105) facets on Si(100) substrates in two dimensions. Each atomic column is not only characterized by the local surface height but also by two deformation state variables dictating the local surface tilt and vertical extension. These deformations phenomenologically model surface reconstructions in (105) facets and enable the formation of islands which better resemble faceted pyramids. We demonstrate the model by application to a kinetic limited growth regime. We observe significantly reduced growth rates after faceting and a continuous nucleation of new islands until overcrowding occurs.Comment: 7 pages, 5 figure

Attitudes toward and inferred beliefs for religious ingroup/outgroup members: Muslim children of Pakistani heritage in the United Kingdom and Saudi Arabia

The post-9/11 era has seen a surge in writings on “Muslim” issues in the West, but little is known about Muslim children's perspectives. Attitudes toward, and beliefs about, the religious ingroup and outgroup were examined in the present study with 5–6-year-old Muslims of Pakistani heritage in the United Kingdom (UK) and Saudi Arabia (SA). Participants completed trait attribution and liking tasks and answered questions on God beliefs and religious practice about themselves, Muslims (ingroup) and non-Muslims (outgroup). Participants described ingroup members more positively, liked them more, and inferred that they held more religious beliefs than outgroup members. Liking was positively associated with outgroup liking for UK participants, who described outgroup members more positively with more religious beliefs, compared with SA participants whose ingroup attitudes were negatively associated with outgroup attitudes. Our findings are discussed in the light of theory and research, and implications for education contexts and well-being are considered

On Random Walks with a General Moving Barrier

Random walks with a general, nonlinear barrier have found recent applications ranging from reionization topology to refinements in the excursion set theory of halos. Here, we derive the first-crossing distribution of random walks with a moving barrier of an arbitrary shape. Such a distribution is shown to satisfy an integral equation that can be solved by a simple matrix inversion, without the need for Monte Carlo simulations, making this useful for exploring a large parameter space. We discuss examples in which common analytic approximations fail, a failure which can be remedied using the method described here.Comment: 6 pages, 7 figures, submitted to Ap

Animals, Superman, Fairy and God: Children’s Attributions of Nonhuman Agent Beliefs in Madrid and London

There have been major developments in the understanding of children’s nonhuman concepts, particularly God concepts, within the past two decades, with a body of cross-cultural studies accumulating. Relatively less research has studied those of non-Christian faiths or children’s concepts of popular occult characters. This paper describes two studies, one in Spain and one in England, examining 5- to 10-year-olds’ human and nonhuman agent beliefs. Both settings were secular, but the latter comprised a Muslim majority. Children were given a false-belief (unexpected contents) task in which they were asked to infer about three humans (mother, classmate, teacher), three animals (dog, bear, bird) and three supernatural beings (Superman, fairy, God). Similar false beliefs about humans, with subtle differences in inferences about animals and supernatural beings, were found between the two locations. In London different patterns for God between participants with a family religion, in particular Muslims, and non-affiliates, were identified as well as an association between religious beliefs and practice and inferences about God. Findings are discussed in the light of theory and research on the role of sociocultural inputs in children’s theory of mind development and understanding of agency

Understanding The Benefits of Growing Up Bilingual: The First Timepoint of A Longitudinal Study

Background: The UK is linguistically rich, but faces a decline in language learning, with no official policy on multilingualism (Taylor, 2013). A significant component in many linguistic minority communities is complementary schooling, which has wide-ranging educational and societal implications (Li, 2006). Aim: This study examines potential cognitive and social benefits of bilingual development in primary school children that attend complementary schools, compared to those who do not, from the first time-point/baseline data of a three-year longitudinal project in East London. Method: A sample of 153 bilingual pupils aged 4-9 years was recruited, including 73 across five complementary schools from Albanian, Russian, Tamil, and Gujarati communities, and 80 across four state primary schools, representing 35 heritage languages. Children were tested in two sessions: 1) cognitive measures (attentional control, executive functioning, object naming); 2) social development measures (ethnic and national identities, perceived competence). Additional information was collected on family affluence (a measure of socioeconomic status), and perceived exposure, use and proficiency for each language. Results: Correlational analyses revealed a positive association between English proficiency and family affluence, and ethnic and British identities were positively associated with respective language use and exposure. In comparative analyses, controlling for age and family affluence, children that attend complementary schooling reported significantly higher proficiencies in both English and heritage language, particularly in literacy of the latter, compared to non-attendees. Children with more balanced proficiencies reported stronger ethnic identity and performed better in the executive functioning task. Conclusions: Findings indicate the role of complementary schools in literacy and identity development and that of proficiency in producing cognitive benefits. Further considerations of these factors in subsequent time-points and modelling with these cohorts are discussed. Relevance to the general public, professionals, or policymakers: This study aims to bring to light the potential benefits of early bilingual development and how those may be enhanced by the under-recognised context of complementary schools. The presentation will highlight how such schools contribute to language learning and explore how they can better connect with the mainstream education sector

Solitons in a medium with linear dissipation and localized gain

We present a variety of dissipative solitons and breathing modes in a medium with localized gain and homogeneous linear dissipation. The system posses a number of unusual properties, like exponentially localized modes in both focusing and defocusing media, the existence of modes in focusing media at negative propagation constant values, the simultaneous existence of stable symmetric and anti-symmetric localized modes when the gain landscape possesses two local maxima, as well as the existence of stable breathing solutions.Comment: 4 pages, 5 figures, to appear in Optics Letter

Quasi-dark Mode in a Metamaterial for Analogous Electromagnetically-induced Transparency

We study a planar metamaterial supporting electromagnetically-induced transparency (EIT)-like effect by exploiting the coupling between bright and quasi-dark eigenmodes. The specific design of such a metamaterial consists of a cut-wire (CW) and a single-gap split-ring resonator (SRR). From the numerical and the analytical results we demonstrate that the response of SRR, which is weakly excited by external electric field, is mitigated to be a quasi-dark eigenmode in the presence of strongly radiative CW. This result suggests more relaxed conditions for the realization of devices utilizing the EIT-like effects in metamaterial, and thereby widens the possibilities for many different structural implementations.Comment: 11 pages, 4 figure

The Mechanical Properties of Native Porcine Aortic and Pulmonary Heart Valve Leaflets

Aortic heart valves and their replacements fail in vivo for reasons that are not fullyunderstood. Mechanical evaluation and simulations of the function of native aorticvalves and their replacements have been limited to tensile and biaxial tests that seek toquantify the behavior of leaflet tissues as a homogenous whole. However, it is widelyunderstood that valvular tissues are multi-layered structures composed of collagen,elastin, and glycosaminoglycans. The mechanical behavior of these layers within intactvalve leaflet tissues and their interactions are unknown. In addition, pulmonary valveshave been used as substitutes for diseased aortic valves without any real understanding ofthe mechanical differences between the aortic and pulmonary valves. The pulmonaryvalve operates in an environment significantly different than that of the aortic valve and,thus, mechanical behavioral differences between the two valve leaflets may exist. In thisstudy, we sought to determine the mechanical properties of the porcine aortic andpulmonary valves in flexure, and to determine the mechanical relationship between theleaflet layers: the fibrosa, spongiosa, and ventricularis. This was accomplished bydeveloping a novel flexure mechanical testing device that allowed for the determinationof the flexural stiffness of the leaflet tissue was determined using Bernoulli-Eulerbending. Moreover, transmural strains were quantified and used to determine thelocation of the neutral axis to determine if differences existed in the layer properties ofthe fibrosa and ventricularis. To contrast the flexural studies, biaxial experiments werealso performed on the aortic and pulmonary valves to determine the mechanicaldifferences in the tensile behavior between the two leaflets.Results indicated that the pulmonary valve is stiffer than the aortic valve inflexure but less compliant than the aortic valve in biaxial tensile tests. The interactionsbetween the layers of the leaflets suggest an isotropic mechanical response in flexure, butdo so through mechanisms that are not fully understood. For heart valve leafletreplacement therapy, this study illustrates the biomechanical differences between theaortic and pulmonary valve leaflets and emphasizes the need to fully characterize the twoas separate but related entities. Understanding the interactions of microscopic structuressuch as collagen and elastin fibers is critical to understanding the response of the tissue asa whole and how all these elements combine to provide a functioning component of theorgan system