1,367 research outputs found
System and method of analyzing vibrations and identifying failure signatures in the vibrations
An apparatus, computer program product and method of analyzing structures. Intrinsic Mode Functions (IMFs) are extracted from the data and the most energetic IMF is selected. A spline is fit to the envelope for the selected IMF. The spline derivative is determined. A stability spectrum is developed by separating the positive and negative results into two different spectra representing stable (positive) and unstable (negative) damping factors. The stability spectrum and the non-linearity indicator are applied to the data to isolate unstable vibrations
Inhibitory neuron migration and IPL formation in the developing zebrafish retina.
The mature vertebrate retina is a highly ordered neuronal network of cell bodies and synaptic neuropils arranged in distinct layers. Little, however, is known about the emergence of this spatial arrangement. Here, we investigate how the three main types of retinal inhibitory neuron (RIN)--horizontal cells (HCs), inner nuclear layer amacrine cells (iACs) and displaced amacrine cells (dACs)--reach their specific laminar positions during development. Using in vivo time-lapse imaging of zebrafish retinas, we show that RINs undergo distinct phases of migration. The first phase, common to all RINs, is bipolar migration directed towards the apicobasal centre of the retina. All RINs then transition to a less directionally persistent multipolar phase of migration. Finally, HCs, iACs and dACs each undergo cell type-specific migration. In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity. By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.This work was supported by Wellcome Trust Senior Investigator Award 100329/Z/12/Z to WH and a UK Commonwealth Scholarship to RC.This is the final version of the article. It first appeared from the Company of Biologists via http://dx.doi.org/10.1242/dev.12247
A new bond fluctuation method for a polymer undergoing gel electrophoresis
We present a new computational methodology for the investigation of gel
electrophoresis of polyelectrolytes. We have developed the method initially to
incorporate sliding motion of tight parts of a polymer pulled by an electric
field into the bond fluctuation method (BFM). Such motion due to tensile force
over distances much larger than the persistent length is realized by non-local
movement of a slack monomer at an either end of the tight part. The latter
movement is introduced stochastically. This new BFM overcomes the well-known
difficulty in the conventional BFM that polymers are trapped by gel fibers in
relatively large fields. At the same time it also reproduces properly
equilibrium properties of a polymer in a vanishing filed limit. The new BFM
thus turns out an efficient computational method to study gel electrophoresis
in a wide range of the electric field strength.Comment: 15 pages, 11 figure
Normal frames and the validity of the equivalence principle. I. Cases in a neighborhood and at a point
A treatment in a neighborhood and at a point of the equivalence principle on
the basis of derivations of the tensor algebra over a manifold is given.
Necessary and sufficient conditions are given for the existence of local bases,
called normal frames, in which the components of derivations vanish in a
neighborhood or at a point. These frames (bases), if any, are explicitly
described and the problem of their holonomicity is considered. In particular,
the obtained results concern symmetric as well as nonsymmetric linear
connections.Comment: LaTeX2e, 9 pages, to be published in Journal of Physics A:
Mathematical and Genera
The argument of the broken pane: Suffragette consumerism and newspapers
Within the cut-throat world of newspaper advertising the newspapers of Britain's Women's Social and Political Union (WSPU) Votes for Women and the Suffragette managed to achieve a balance that has often proved to be an impossible challenge for social movement pressânamely the maintenance of a highly political stance whilst simultaneously exploiting the market system with advertising and merchandising. When the militant papers advocated window smashing of West End stores in 1912â1913, the companies who were the target still took advertisements. Why? What was the relationship between news values, militant violence and advertising income? âDo-it-yourselfâ journalism operated within a context of ethical consumerism and promotionally orientated militancy. This resulted in newspaper connections between politics, commerce and a distinct market profile, evident in the customisation of advertising, retailer dialogue with militants and longer-term loyaltyâsymptomatic of a wider trend towards newspaper commercialism during this period
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