51 research outputs found
Radio astronomical polarimetry and phase-coherent matrix convolution
A new phase-coherent technique for the calibration of polarimetric data is
presented. Similar to the one-dimensional form of convolution, data are
multiplied by the response function in the frequency domain. Therefore, the
system response may be corrected with arbitrarily high spectral resolution,
effectively treating the problem of bandwidth depolarization. As well, the
original temporal resolution of the data is retained. The method is therefore
particularly useful in the study of radio pulsars, where high time resolution
and polarization purity are essential requirements of high-precision timing. As
a demonstration of the technique, it is applied to full-polarization baseband
recordings of the nearby millisecond pulsar, PSR J0437-4715.Comment: 8 pages, 4 figures, accepted for publication in Ap
Radio Astronomical Polarimetry and Point-Source Calibration
A mathematical framework is presented for use in the experimental
determination of the polarimetric response of observatory instrumentation.
Elementary principles of linear algebra are applied to model the full matrix
description of the polarization measurement equation by least-squares
estimation of non-linear, scalar parameters. The formalism is applied to
calibrate the center element of the Parkes Multibeam receiver using
observations of the millisecond pulsar, PSR J0437-4715, and the radio galaxy,
3C 218 (Hydra A).Comment: 8 pages, 4 figures, to be published in ApJ
Linear complexions directly modify dislocation motion in face-centered cubic alloys
Linear complexions are defect phases that form in the presence of
dislocations and thus are promising for the direct control of plasticity. In
this study, atomistic simulations are used to model the effect of linear
complexions on dislocation-based mechanisms for plasticity, demonstrating
unique behaviors that differ from classical dislocation glide mechanisms.
Linear complexions impart higher resistance to the initiation and continuation
of dislocation motion when compared to solid solution strengthening in all of
the face-centered cubic alloys investigated here, with the exact strengthening
level determined by the linear complexion type. Stacking fault linear
complexions impart the most pronounced strengthening effect, as the dislocation
core is delocalized, and initiation of plastic flow requires a dislocation
nucleation event. The nanoparticle and platelet array linear complexions impart
strengthening by acting as pinning sites for the dislocations, where the
dislocations unpin one at a time through bowing mechanisms. For the
nanoparticle arrays, this event occurs even though the obstacles do not cross
the slip plane and instead only interact through modification of the
dislocation's stress field. The bowing modes observed in the current work
appear similar to traditional Orowan bowing around classical precipitates but
differ in a number of important ways depending on the complexion type. As a
whole, this study demonstrates that linear complexions are a unique tool for
microstructure engineering that can allow for the creation of alloys with new
plastic deformation mechanisms and extreme strength
Donor age affects proteome composition of tenocyte-derived engineered tendon
All proteins identified by PEAKS in young and old tendon-derived TEC with correpsonding cellular sublocations defined by IPA and Matrisome Project. (XLSX 57Ă‚Â kb
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