157 research outputs found
Formalization of Transform Methods using HOL Light
Transform methods, like Laplace and Fourier, are frequently used for
analyzing the dynamical behaviour of engineering and physical systems, based on
their transfer function, and frequency response or the solutions of their
corresponding differential equations. In this paper, we present an ongoing
project, which focuses on the higher-order logic formalization of transform
methods using HOL Light theorem prover. In particular, we present the
motivation of the formalization, which is followed by the related work. Next,
we present the task completed so far while highlighting some of the challenges
faced during the formalization. Finally, we present a roadmap to achieve our
objectives, the current status and the future goals for this project.Comment: 15 Pages, CICM 201
Development of a Finite Volume Inter-cell Polynomial Expansion Method for the Neutron Diffusion Equation
Heterogeneous nuclear reactors require numerical methods to solve the neutron diffusion equation (NDE)
to obtain the neutron flux distribution inside them, by discretizing the heterogeneous geometry in a set of
homogeneous regions. This discretization requires additional equations at the inner faces of two adjacent
cells: neutron flux and current continuity, which imply an excess of equations. The finite volume method
(FVM) is suitable to be applied to NDE, because it can be easily applied to any mesh and it is typically
used in the transport equations due to the conservation of the transported quantity within the volume.
However, the gradient and face-averaged values in the FVM are typically calculated as a function of the
cell-averaged values of adjacent cells. So, if the materials of the adjacent cells are different, the neutron
current condition could not be accomplished. Therefore, a polynomial expansion of the neutron flux is
developed in each cell for assuring the accomplishment of the flux and current continuity and calculating
both analytically. In this polynomial expansion, the polynomial terms for each cell were assigned previously
and the constant coefficients are determined by solving the eigenvalue problem with SLEPc. A sensitivity
analysis for determining the best set of polynomial terms is performed.This work has been partially supported by the Spanish Ministerio de Eduacion Cultura y Deporte [grant number FPU13/01009]; the Spanish Ministerio de Ciencia e Innovacion [project number ENE2014-59442-P], [project number ENE2012-34585]; the Generalitat Valenciana [project number PROMETEOII/2014/008]; the Universitat Politecnica de Valencia [project number UPPTE/2012/118]; and the Spanish Ministerio de Economia y Competitividad [project number TIN2013-41049-P].Bernal García, Á.; Román Moltó, JE.; Miró Herrero, R.; Ginestar Peiro, D.; Verdú Martín, GJ. (2016). Development of a Finite Volume Inter-cell Polynomial Expansion Method for the Neutron Diffusion Equation. Journal of Nuclear Science and Technology. 53(8):1212-1223. https://doi.org/10.1080/00223131.2015.1102661S1212122353
Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae
We systematically surveyed period variations of superhumps in SU UMa-type
dwarf novae based on newly obtained data and past publications. In many
systems, the evolution of superhump period are found to be composed of three
distinct stages: early evolutionary stage with a longer superhump period,
middle stage with systematically varying periods, final stage with a shorter,
stable superhump period. During the middle stage, many systems with superhump
periods less than 0.08 d show positive period derivatives. Contrary to the
earlier claim, we found no clear evidence for variation of period derivatives
between superoutburst of the same object. We present an interpretation that the
lengthening of the superhump period is a result of outward propagation of the
eccentricity wave and is limited by the radius near the tidal truncation. We
interpret that late stage superhumps are rejuvenized excitation of 3:1
resonance when the superhumps in the outer disk is effectively quenched. Many
of WZ Sge-type dwarf novae showed long-enduring superhumps during the
post-superoutburst stage having periods longer than those during the main
superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to
be strongly correlated with the fractional superhump excess, or consequently,
mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with
multiple rebrightenings tend to have smaller period derivatives and are
excellent candidate for the systems around or after the period minimum of
evolution of cataclysmic variables (abridged).Comment: 239 pages, 225 figures, PASJ accepte
The dynamics of E1A in regulating networks and canonical pathways in quiescent cells
<p>Abstract</p> <p>Background</p> <p>Adenoviruses force quiescent cells to re-enter the cell cycle to replicate their DNA, and for the most part, this is accomplished after they express the E1A protein immediately after infection. In this context, E1A is believed to inactivate cellular proteins (e.g., p130) that are known to be involved in the silencing of E2F-dependent genes that are required for cell cycle entry. However, the potential perturbation of these types of genes by E1A relative to their functions in regulatory networks and canonical pathways remains poorly understood.</p> <p>Findings</p> <p>We have used DNA microarrays analyzed with Bayesian ANOVA for microarray (BAM) to assess changes in gene expression after E1A alone was introduced into quiescent cells from a regulated promoter. Approximately 2,401 genes were significantly modulated by E1A, and of these, 385 and 1033 met the criteria for generating networks and functional and canonical pathway analysis respectively, as determined by using Ingenuity Pathway Analysis software. After focusing on the highest-ranking cellular processes and regulatory networks that were responsive to E1A in quiescent cells, we observed that many of the up-regulated genes were associated with DNA replication, the cell cycle and cellular compromise. We also identified a cadre of up regulated genes with no previous connection to E1A; including genes that encode components of global DNA repair systems and DNA damage checkpoints. Among the down-regulated genes, we found that many were involved in cell signalling, cell movement, and cellular proliferation. Remarkably, a subset of these was also associated with p53-independent apoptosis, and the putative suppression of this pathway may be necessary in the viral life cycle until sufficient progeny have been produced.</p> <p>Conclusions</p> <p>These studies have identified for the first time a large number of genes that are relevant to E1A's activities in promoting quiescent cells to re-enter the cell cycle in order to create an optimum environment for adenoviral replication.</p
The barriers and facilitators influencing the sustainability of hospital-based interventions: a systematic review
Acknowledgements University of Stirling for providing financial support for open access costs Funding This review was funded by the Chief Scientist Office, grant number GCA/17/26. JC, PC and EAD are employed by the Nursing, Midwifery and Allied Health Professions Research Unit, which is funded by the Chief Scientist Office in Scotland.Peer reviewedPublisher PD
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