21,648 research outputs found
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A TEM, STEM and backscattered electron channeling imaging study of martensite formation in Co-19.6Fe
A high purity, C-free Co-19.6Fe alloy is shown to undergo a variety of martensitic and bainitic reactions.
TEM, STEM and back-scattered electron channelling patterns and images have been used to study the effects of ageing at temperatures below the α solvus and of grain boundary misorientation on the occurrence of martensitic transformation in the adjacent grains and on the nature of their product
Electron cloud observations at the ISIS Proton Synchrotron
The build up of electron clouds inside a particle accelerator vacuum chamber
can produce strong transverse and longitudinal beam instabilities which in turn
can lead to high levels of beam loss often requiring the accelerator to be run
below its design specification. To study the behaviour of electron clouds at
the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud
detector has been developed. The detector is based on the Retarding Field
Analyser (RFA) design and consists of a retarding grid, which allows energy
analysis of the electron signal, and a MCP assembly placed in front of the
collector plate. The MCP assembly provides a current gain over the range 300 to
25K, thereby increasing the signal to noise ratio and dynamic range of the
measurements. This paper presents the first electron cloud observations at the
ISIS Proton Synchrotron. These results are compared against signals from a beam
position monitor and a fast beam loss monitor installed at the same location.Comment: 4 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop
on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba,
Ital
On the general position subset selection problem
Let be the maximum integer such that every set of points in
the plane with at most collinear contains a subset of points
with no three collinear. First we prove that if then
. Second we prove that if
then , which implies all previously known lower bounds on and
improves them when is not fixed. A more general problem is to consider
subsets with at most collinear points in a point set with at most
collinear. We also prove analogous results in this setting
Linear optics implementation of weak values in Hardy's paradox
We propose an experimental setup for the implementation of weak measurements
in the context of the gedankenexperiment known as Hardy's Paradox. As Aharonov
et al. showed, these weak values form a language with which the paradox can be
resolved. Our analysis shows that this language is indeed consistent and
experimentally testable. It also reveals exactly how a combination of weak
values can give rise to an apparently paradoxical result.Comment: 4 pages, accepted by PR
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Phosphoinositide-mediated clathrin adaptor progression at the trans-Golgi network.
Clathrin-coated vesicles mediate endocytosis and transport between the trans-Golgi network (TGN) and endosomes in eukaryotic cells. Clathrin adaptors play central roles in coat assembly, interacting with clathrin, cargo and membranes. Two main types of clathrin adaptor act in TGN-endosome traffic: GGA proteins and the AP-1 complex. Here we characterize the relationship between GGA proteins, AP-1 and other TGN clathrin adaptors using live-cell and super-resolution microscopy in yeast. We present evidence that GGA proteins and AP-1 are recruited sequentially in two waves of coat assembly at the TGN. Mutations that decrease phosphatidylinositol 4-phosphate (PtdIns(4)P) levels at the TGN slow or uncouple AP-1 coat assembly from GGA coat assembly. Conversely, enhanced PtdIns(4)P synthesis shortens the time between adaptor waves. Gga2p binds directly to the TGN PtdIns(4)-kinase Pik1p and contributes to Pik1p recruitment. These results identify a PtdIns(4)P-based mechanism for regulating progressive assembly of adaptor-specific clathrin coats at the TGN
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