9,061 research outputs found
University networks in the context of their academic excellence and openness: A comparative study of leading Czech and German universities
A simple methodology of multi-dimensional vector analysis for the comparison of the academic performance and the openness of university networks of the identical dimension was developed, which is illustrated by the example of the leading universities in the Czech Republic and GermanyyesBelgorod State Universit
Effects of Breed and Stage of Growing Season on the Metabolic Profile of Sheep Grazing Moorland
Previous studies have shown that the diet of sheep grazing heather moorland is affected by season (Grant et al., 1987) and the proportion of Calluna vulgaris cover (Osoro et al., 2000). In order to investigate the impact of these factors on the associated nutrient supply of animals grazing heathland, blood samples were taken to monitor the metabolic status of different breeds of sheep at different stages of the growing season when grazing sites with different proportions of heather cover
Computational Topology Techniques for Characterizing Time-Series Data
Topological data analysis (TDA), while abstract, allows a characterization of
time-series data obtained from nonlinear and complex dynamical systems. Though
it is surprising that such an abstract measure of structure - counting pieces
and holes - could be useful for real-world data, TDA lets us compare different
systems, and even do membership testing or change-point detection. However, TDA
is computationally expensive and involves a number of free parameters. This
complexity can be obviated by coarse-graining, using a construct called the
witness complex. The parametric dependence gives rise to the concept of
persistent homology: how shape changes with scale. Its results allow us to
distinguish time-series data from different systems - e.g., the same note
played on different musical instruments.Comment: 12 pages, 6 Figures, 1 Table, The Sixteenth International Symposium
on Intelligent Data Analysis (IDA 2017
An Evaluation of the \u3cem\u3eN\u3c/em\u3e-Alkane Technique for Determining Diet Composition in Animals Grazing Complex Swards
The n-alkane profiles of epicuticular waxes derived from different plant species are sufficiently distinct to allow assessment of the proportions of different herbages in two-component mixtures including perennial ryegrass/white clover, heather/hill grass and rush/perennial ryegrass (Dove & Mayes, 1996). Evidence suggests the reliability of such estimates declines as the number of different dietary components increases. However, recent studies have shown analysis of additional compounds, including long-chain fatty alcohols, may improve discrimination between different dietary components. The aim of this experiment was to quantify the accuracy of such methods for determining the diet composition of animals grazing complex swards
Adiabatic orientation of rotating dipole molecules in an external field
The induced polarization of a beam of polar clusters or molecules passing
through an electric or magnetic field region differs from the textbook
Langevin-Debye susceptibility. This distinction, which is important for the
interpretation of deflection and focusing experiments, arises because instead
of acquiring thermal equilibrium in the field region, the beam ensemble
typically enters the field adiabatically, i.e., with a previously fixed
distribution of rotational states. We discuss the orientation of rigid
symmetric-top systems with a body-fixed electric or magnetic dipole moment. The
analytical expression for their "adiabatic-entry" orientation is elucidated and
compared with exact numerical results for a range of parameters. The
differences between the polarization of thermodynamic and "adiabatic-entry"
ensembles, of prolate and oblate tops, and of symmetric-top and linear rotators
are illustrated and identified.Comment: 18 pages, 4 figure
Early Acquisition of Neural Crest Competence During hESCs Neuralization
Background:
Neural crest stem cells (NCSCs) are a transient multipotent embryonic cell population that represents a defining characteristic of vertebrates. The neural crest (NC) gives rise to many derivatives including the neurons and glia of the sensory and autonomic ganglia of the peripheral nervous system, enteric neurons and glia, melanocytes, and the cartilaginous, bony and connective tissue of the craniofacial skeleton, cephalic neuroendocrine organs, and some heart vessels.
Methodology/Principal Findings:
We present evidence that neural crest (NC) competence can be acquired very early when human embryonic stem cells (hESCs) are selectively neuralized towards dorsal neuroepithelium in the absence of feeder cells in fully defined conditions. When hESC-derived neurospheres are plated on fibronectin, some cells emigrate onto the substrate. These early migratory Neural Crest Stem Cells (emNCSCs) uniformly upregulate Sox10 and vimentin, downregulate N-cadherin, and remodel F-actin, consistent with a transition from neuroepithelium to a mesenchymal NC cell. Over 13% of emNCSCs upregulate CD73, a marker of mesenchymal lineage characteristic of cephalic NC and connexin 43, found on early migratory NC cells. We demonstrated that emNCSCs give rise in vitro to all NC lineages, are multipotent on clonal level, and appropriately respond to developmental factors. We suggest that human emNCSC resemble cephalic NC described in model organisms. Ex vivo emNCSCs can differentiate into neurons in Ret.k- mouse embryonic gut tissue cultures and transplanted emNCSCs incorporate into NC-derived structures but not CNS tissues in chick embryos.
Conclusions/Significance:
These findings will provide a framework for further studying early human NC development including the epithelial to mesenchymal transition during NC delamination
Can live weight be used as a proxy for enteric methane emissions from pasture-fed sheep?
To test the hypothesis that sheep live weight (LW) could be used to improve enteric methane (CH4) emission calculations, mature ewes of 4 different breeds representative of the UK sheep industry were studied: Welsh Mountain, Scottish Blackface, Welsh Mule and Texel (n = 8 per breed). The ewes were housed and offered ad libitum access to fresh cut pasture of three different types, varying in digestibility: (a) a relatively high digestibility monoculture of perennial ryegrass (Lolium perenne), (b) a medium digestibility permanent pasture comprising a range of grass species, and (c) a relatively low digestibility native grassland pasture comprising mainly Molinia caerulea. Individual LW, feed dry matter intake (DMI), and CH4 emissions in chambers were measured. The linear functional relationship between DMI and CH4 emissions was positive (r = 0.77) with little breed effect. The relationships between LW and DMI, and LW and CH4 emissions were also positive but weaker, regardless of pasture type. It is concluded that change to LW was a poor indicator of DMI and has limited value in the prediction of enteric CH4 emissions from mature ewes
Characterising the Fermentation Capabilities of Gut Microbial Populations from Different Breeds of Cattle and Sheep Grazing Heathland
Previous studies have demonstrated differences in the diet composition of sheep and cattle when grazing heather moorland, and such differences may in turn lead to differences in rumen fermentation characteristics and associated adaptation to diet. To investigate this further an in vitro gas production experiment was conducted using inocula from different breeds of cattle and sheep grazing heathland
Testing the neutrality of matter by acoustic means in a spherical resonator
New measurements to test the neutrality of matter by acoustic means are
reported. The apparatus is based on a spherical capacitor filled with gaseous
SF excited by an oscillating electric field. The apparatus has been
calibrated measuring the electric polarizability. Assuming charge conservation
in the decay of the neutron, the experiment gives a limit of
for the electron-proton charge
difference, the same limit holding for the charge of the neutron. Previous
measurements are critically reviewed and found incorrect: the present result is
the best limit obtained with this technique
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