9,211 research outputs found
SPMHD simulations of Structure Formation
The intracluster medium of galaxy clusters is permeated by {\mu}G magnetic
fields. Observations with current and future facilities have the potential to
illuminate the role of these magnetic fields play in the astrophysical
processes of galaxy clusters. To obtain a greater understanding of how the
initial seed fields evolve to the magnetic fields in the intracluster medium
requires magnetohydrodynamic simulations. We critically assess the current
Smoothed Particle Magneto-Hydrodynamics (SPMHD) schemes, especially
highlighting the impact of a hyperbolic divergence cleaning scheme and
artificial resistivity switch on the magnetic field evolution in cosmological
simulations of the formation of a galaxy cluster using the N-body/SPMHD code
gcmhd++. The impact and performance of the cleaning scheme and two different
schemes for the artificial resistivity switch is demonstrated via idealized
test cases and cosmological simulations. We demonstrate that the hyperbolic
divergence cleaning scheme is effective at suppressing the growth of the
numerical divergence error of the magnetic field and should be applied to any
SPMHD simulation. Although the artificial resistivity is important in the
strong field regime, it can suppress the growth of the magnetic field in the
weak field regime, such as galaxy clusters. With sufficient resolution,
simulations with divergence cleaning can reproduce observed magnetic fields. We
conclude that the cleaning scheme alone is sufficient for galaxy cluster
simulations, but our results indicate that the SPMHD scheme must be carefully
chosen depending on the regime of the magnetic field.Comment: 15 pages, 11 figures, published (MNRAS 476 2890
An Epigenetic Hypothesis of Aging-Related Cognitive Dysfunction
This brief review will focus on a new hypothesis for the role of epigenetic mechanisms in aging-related disruptions of synaptic plasticity and memory. Epigenetics refers to a set of potentially self-perpetuating, covalent modifications of DNA and post-translational modifications of nuclear proteins that produce lasting alterations in chromatin structure. These mechanisms, in turn, result in alterations in specific patterns of gene expression. Aging-related memory decline is manifest prominently in declarative/episodic memory and working memory, memory modalities anatomically based largely in the hippocampus and prefrontal cortex, respectively. The neurobiological underpinnings of age-related memory deficits include aberrant changes in gene transcription that ultimately affect the ability of the aged brain to be “plastic”. The molecular mechanisms underlying these changes in gene transcription are not currently known, but recent work points toward a potential novel mechanism, dysregulation of epigenetic mechanisms. This has led us to hypothesize that dysregulation of epigenetic control mechanisms and aberrant epigenetic “marks” drive aging-related cognitive dysfunction. Here we focus on this theme, reviewing current knowledge concerning epigenetic molecular mechanisms, as well as recent results suggesting disruption of plasticity and memory formation during aging. Finally, several open questions will be discussed that we believe will fuel experimental discovery
Working Futures 2017-2027 : Long-run labour market and skills projections headline report
This report provides a concise overview of Working Futures 2017-2027 results for the UK. It presents historical trends and future prospects by sector for the UK and its constituent nations and the English regions. The prime focus of Working Futures is on the demand for skills as measured by employment by occupation and qualification, although the supply side is also considered. Its prime objective is to provide useful labour market information that can help to inform policy development and strategy around skills, careers and employment, for both policy makers and a much wider audience. The results are intended to provide a sound statistical foundation for reflection and debate among all those with an interest in the demand for and supply of skills. It is aimed at the general reader and focuses on the key messages from this very detailed study. It complements the more detailed outputs and results from the project available from the gov.uk website2 and cover sectors, occupations, geography and qualifications
An interactive three dimensional approach to anatomical description—the jaw musculature of the Australian laughing kookaburra (Dacelo novaeguineae)
The investigation of form-function relationships requires a detailed understanding of anatomical systems. Here we document the 3-dimensional morphology of the cranial musculoskeletal anatomy in the Australian Laughing Kookaburra Dacelo novaeguineae, with a focus upon the geometry and attachments of the jaw muscles in this species. The head of a deceased specimen was CT scanned, and an accurate 3D representation of the skull and jaw muscles was generated through manual segmentation of the CT scan images, and augmented by dissection of the specimen. We identified 14 major jaw muscles: 6 in the temporal group (M. adductor mandibulae and M. pseudotemporalis), 7 in the pterygoid group (M. pterygoideus dorsalis and M. pterygoideus ventralis), and the single jaw abductor M. depressor mandibulae. Previous descriptions of avian jaw musculature are hindered by limited visual representation and inconsistency in the nomenclature. To address these issues, we: (1) present the 3D model produced from the segmentation process as a digital, fully interactive model in the form of an embedded 3D image, which can be viewed from any angle, and within which major components can be set as opaque, transparent, or hidden, allowing the anatomy to be visualised as required to provide a detailed understanding of the jaw anatomy; (2) provide a summary of the nomenclature used throughout the avian jaw muscle literature. The approach presented here provides considerable advantages for the documentation and communication of detailed anatomical structures in a wide range of taxa
Partner selection in agile supply chains: A fuzzy intelligent approach
Partner selection is a fundamental issue in supply chain management as it contributes significantly to overall supply chain performance. However, such decision-making is problematic due to the need to consider both tangible and intangible factors, which cause vagueness, ambiguity and complexity. This paper proposes a new fuzzy intelligent approach for partner selection in agile supply chains by using fuzzy set theory in combination with radial basis function artificial neural network. Using these two approaches in combination enables the model to classify potential partners in the qualification phase of partner selection efficiently and effectively using very large amounts of both qualitative and quantitative data. The paper includes a worked empirical application of the model with data from 84 representative companies within the Chinese electrical components and equipment industry, to demonstrate its suitability for helping organisational decision-makers in partner selection
MEF2C regulates outflow tract alignment and transcriptional control of Tdgf1
Congenital heart defects are the most common birth defects in
humans, and those that affect the proper alignment of the outflow
tracts and septation of the ventricles are a highly significant cause of
morbidity and mortality in infants. A late differentiating population of
cardiac progenitors, referred to as the anterior second heart field
(AHF), gives rise to the outflow tract and the majority of the right
ventricle and provides an embryological context for understanding
cardiac outflow tract alignment and membranous ventricular septal
defects. However, the transcriptional pathways controlling AHF
development and their roles in congenital heart defects remain
incompletely elucidated. Here, we inactivated the gene encoding the
transcription factor MEF2C in the AHF in mice. Loss of Mef2c function
in the AHF results in a spectrum of outflow tract alignment defects
ranging from overriding aorta to double-outlet right ventricle and
dextro-transposition of the great arteries. We identify Tdgf1, which
encodes a Nodal co-receptor (also known as Cripto), as a direct
transcriptional target of MEF2C in the outflow tract via an AHFrestricted
Tdgf1 enhancer. Importantly, both the MEF2C and TDGF1
genes are associated with congenital heart defects in humans. Thus,
these studies establish a direct transcriptional pathway between the
core cardiac transcription factor MEF2C and the human congenital
heart disease gene TDGF1. Moreover, we found a range of outflow
tract alignment defects resulting from a single genetic lesion,
supporting the idea that AHF-derived outflow tract alignment
defects may constitute an embryological spectrum rather than
distinct anomalies
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