3,214 research outputs found
Stabilized lowest order finite element approximation for linear three-field poroelasticity
A stabilized conforming mixed finite element method for the three-field
(displacement, fluid flux and pressure) poroelasticity problem is developed and
analyzed. We use the lowest possible approximation order, namely piecewise
constant approximation for the pressure and piecewise linear continuous
elements for the displacements and fluid flux. By applying a local pressure
jump stabilization term to the mass conservation equation we ensure stability
and avoid pressure oscillations. Importantly, the discretization leads to a
symmetric linear system. For the fully discretized problem we prove existence
and uniqueness, an energy estimate and an optimal a-priori error estimate,
including an error estimate for the divergence of the fluid flux. Numerical
experiments in 2D and 3D illustrate the convergence of the method, show the
effectiveness of the method to overcome spurious pressure oscillations, and
evaluate the added mass effect of the stabilization term.Comment: 25 page
ASSOCIATIONS BETWEEN IDENTITY AND FUTURE PARENTHOOD AMONG LGBTQ+ ASIAN/PACIFIC ISLANDER AMERICANS
In recent years, the number of lesbian, gay, bisexual, transgender, and queer (and additional identities; LGBTQ+) identified people and the number of Asian Pacific Islander Americans (APIA) have been increasing in the United States (Movement Advancement Project 2019; Newport, 2018). As the individuals in these demographic groups develop over their lifespan, many will become parents and form families, but little work is currently available on the experiences of LGBTQ+ APIA individuals and future parenthood. Here, I report findings on the perceptions and importance of future parenthood, identity development, identity integration, and microaggressions and/or discrimination (as they relate to racial-ethnic and sexual identity) across three samples: LGBTQ+ APIA, LGBTQ+ White, and cisgender heterosexual people. Taking an intersectional, quantitative approach, I found that broadly, (racial-ethnic and sexual) identity development and integration, as well as experiences of microaggressions or discrimination, were not associated with perceptions and importance of future parenthood among LGBTQ+ APIA individuals. However, there were mixed findings such that racial-ethnic identity development and perceived racial-ethnic discrimination were associated with perceptions and importance of future parenthood, but only among LGBTQ+ White adults. Race-specific microaggressions against APIA were also associated with parenting intentions among cisgender heterosexual APIA people. How these findings can contribute to the foundation of literature on the experiences of LGBTQ+ APIA families and future parenthood is discussed
Evolutionary quantum game
We present the first study of a dynamical quantum game. Each agent has a
`memory' of her performance over the previous m timesteps, and her strategy can
evolve in time. The game exhibits distinct regimes of optimality. For small m
the classical game performs better, while for intermediate m the relative
performance depends on whether the source of qubits is `corrupt'. For large m,
the quantum players dramatically outperform the classical players by `freezing'
the game into high-performing attractors in which evolution ceases.Comment: 4 pages in two-column format. 4 figure
Procedures for the analysis and use of multiple view angle image data
It is recognised that the majority of vegetative cover types have anisotropic reflectance characteristics that are largely a function of their canopy geometry. Several studies have made attempts at formulating methods for the use of data remotely sensed from off-nadir directions. The best of these methods attempt to utilise the "extra" information implicitly contained in off-nadir image datasets. In this study, an attempt is made to extract information concerning agro-physical parameters of a number of vegetative cover types using imagery acquired by an airborne sensor, the Daedalus Airborne Thematic Mapper (ATM). It is also recognised in the literature that the nature of spatial variance in images is related to the size and distribution of the objects in the scene and the sampling characteristics of the sensor. In previous work this relationship has been explored by examining scenes using images of varying spatial resolutions, using a number of measurements of spatial variance. The underlying trend of these measurements is then used to interpret the nature of the objects in the scene. No previous work exists which attempts to utilise the change in variance of images acquired at different off-nadir view angles. In this study, the understanding of this relationship is developed by examining the change in variance of a number of vegetative cover types from multiple view angle image datasets. The geometry of the ATM sensor is derived to allow an understanding of the sampling characteristics of the instrument. Two important geometric factors are established: first, the area of the ground resolution element increases with view angle, which effectively reduces spatial resolution at off-nadir angles; and second, overlap between adjacent ground resolution elements increases with view angle, increasing the spatial auto-correlation between these samples. The effects of illumination, atmosphere and topography can all influence variance in an image. A parametric procedure for normalising multiple view angle (and therefore multitemporal) datasets for these factors is developed, based upon the production of reflectance images using a sky radiance model of the spectral and spatial distributions of irradiance, ground measurements of irradiance, and a digital terrain model of the study site. Finally, it is shown that image variance is likely to decrease at off-nadir view angles, the magnitude of this decrease being related to the sensor geometry and (more importantly) the geometry of the canopy. By a simple statistical analytical procedure it is possible to construct broad classes within which the nature of the canopy can be classified
The generic character table of a Sylow -subgroup of a finite Chevalley group of type
Let be a Sylow -subgroup of the finite Chevalley group of type
over the field of elements, where is a power of a prime . We
describe a construction of the generic character table of
A poroelastic model coupled to a fluid network with applications in lung modelling
Here we develop a lung ventilation model, based a continuum poroelastic
representation of lung parenchyma and a 0D airway tree flow model. For the
poroelastic approximation we design and implement a lowest order stabilised
finite element method. This component is strongly coupled to the 0D airway tree
model. The framework is applied to a realistic lung anatomical model derived
from computed tomography data and an artificially generated airway tree to
model the conducting airway region. Numerical simulations produce
physiologically realistic solutions, and demonstrate the effect of airway
constriction and reduced tissue elasticity on ventilation, tissue stress and
alveolar pressure distribution. The key advantage of the model is the ability
to provide insight into the mutual dependence between ventilation and
deformation. This is essential when studying lung diseases, such as chronic
obstructive pulmonary disease and pulmonary fibrosis. Thus the model can be
used to form a better understanding of integrated lung mechanics in both the
healthy and diseased states
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