258 research outputs found
Temperature-Dependent X-Ray Absorption Spectroscopy of Colossal Magnetoresistive Perovskites
The temperature dependence of the O K-edge pre-edge structure in the x-ray
absorption spectra of the perovskites La(1-x)A(x)MnO(3), (A = Ca, Sr; x = 0.3,
0.4) reveals a correlation between the disappearance of the splitting in the
pre-edge region and the presence of Jahn-Teller distortions. The different
magnitudes of the distortions for different compounds is proposed to explain
some dissimilarity in the line shape of the spectra taken above the Curie
temperature.Comment: To appear in Phys. Rev. B, 5 pages, 3 figure
Three dimensional tracking of exploratory behavior of barnacle cyprids using stereoscopy
Surface exploration is a key step in the colonization of surfaces by sessile marine biofoulers. As many biofouling organisms can delay settlement until a suitable surface is encountered, colonization can comprise surface exploration and intermittent swimming. As such, the process is best followed in three dimensions. Here we present a low-cost transportable stereoscopic system consisting of two consumer camcorders. We apply this novel apparatus to behavioral analysis of barnacle larvae (? 800 lm length) during surface exploration and extract and analyze the three-dimensional patterns of movement. The resolution of the system and the accuracy of position determination are characterized. As a first practical result, three-dimensional swimming trajectories of the cypris larva of the barnacle Semibalanus balanoides are recorded in the vicinity of a glass surface and close to PEG2000-OH and C11NMe3 +Cl- terminated self-assembled monolayers. Although less frequently used in biofouling experiments due to its short reproductive season, the selected model species [Marechal and Hellio (2011), Int Biodeterior Biodegrad, 65(1):92-101] has been used following a number of recent investigations on the settlement behavior on chemically different surfaces [Aldred et al. (2011), ACS Appl Mater Interfaces, 3(6):2085-2091]. Experiments were scheduled to match the availability of cyprids off the north east coast of England so that natural material could be used. In order to demonstrate the biological applicability of the system, analysis of parameters such as swimming direction, swimming velocity and swimming angle are performed.DFG/Ro 2524/2-2DFG/Ro 2497/7-2ONR/N00014-08-1-1116ONR/N00014-12-1-0498EC/FP7/2007-2013/23799
Correction of non-linearity effects in detectors for electron spectroscopy
Using photoemission intensities and a detection system employed by many
groups in the electron spectroscopy community as an example, we have
quantitatively characterized and corrected detector non-linearity effects over
the full dynamic range of the system. Non-linearity effects are found to be
important whenever measuring relative peak intensities accurately is important,
even in the low-countrate regime. This includes, for example, performing
quantitative analyses for surface contaminants or sample bulk stoichiometries,
where the peak intensities involved can differ by one or two orders of
magnitude, and thus could occupy a significant portion of the detector dynamic
range. Two successful procedures for correcting non-linearity effects are
presented. The first one yields directly the detector efficiency by measuring a
flat-background reference intensity as a function of incident x-ray flux, while
the second one determines the detector response from a least-squares analysis
of broad-scan survey spectra at different incident x-ray fluxes. Although we
have used one spectrometer and detection system as an example, these
methodologies should be useful for many other cases.Comment: 13 pages, 12 figure
Making Higher Order {MOT} Scalable: {A}n Efficient Approximate Solver for Lifted Disjoint Paths
Investigation of motile marine organisms with digital in-line holographic microscopy in situ and under lab conditions
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